@article {pmid31445309, year = {2019}, author = {Wu, X and Pan, J and Li, M and Li, Y and Bartlam, M and Wang, Y}, title = {Selective enrichment of bacterial pathogens by microplastic biofilm.}, journal = {Water research}, volume = {165}, number = {}, pages = {114979}, doi = {10.1016/j.watres.2019.114979}, pmid = {31445309}, issn = {1879-2448}, abstract = {Microplastics have been found to be ubiquitous in freshwater ecosystems, providing a novel substrate for biofilm formation. Here, we incubated biofilm on microplastics and two natural substrates (rock and leaf) under a controlled environment to investigate the differences of microbial community structure, antibiotic resistance gene (ARG) profiles, and ARG microbial hosts between biofilms on three types of substrates. Results from high-throughput sequencing of 16S rRNA gene revealed that microplastic biofilm had a distinctive community structure. Network analyses suggested that microplastic biofilm possessed the highest node connected community, but with lower average path length, network diameter and modularity compared with biofilm on two natural particles. Metagenomic analyses further revealed microplastic biofilm with broad-spectrum and distinctive resistome. Specifically, according to taxonomic annotation of ARG microbial hosts, two opportunisitic human pathogens (Pseudomonas monteilii, Pseudomonas mendocina) and one plant pathogen (Pseudomonas syringae) were detected only in the microplastic biofilm, but not in biofilms formed on natural substrates. Our findings suggest that microplastic is a novel microbial niche and may serve as a vector for ARGs and pathogens to new environment in river water, generating freshwater environmental risk and exerting adverse impacts on human health.}, } @article {pmid31444121, year = {2019}, author = {Cui, MH and Sangeetha, T and Gao, L and Wang, AJ}, title = {Efficient azo dye wastewater treatment in a hybrid anaerobic reactor with a built-in integrated bioelectrochemical system and an aerobic biofilm reactor: Evaluation of the combined forms and reflux ratio.}, journal = {Bioresource technology}, volume = {}, number = {}, pages = {122001}, doi = {10.1016/j.biortech.2019.122001}, pmid = {31444121}, issn = {1873-2976}, abstract = {A combined process that consisted of a hybrid anaerobic reactor (HAR) with an integral bioelectrochemical system and aerobic biofilm reactor (ABFR) was established for simulated azo dye wastewater treatment (domestic wastewater containing dye acid orange 7). The split combination form that separated HAR and ABFR into two individual reactors recorded a decolorization efficiency of 81.23 ± 0.12%, which was about 8% higher than that HAR and ABFR were stacked together into a single up-flow reactor. Implementation of reflux improved the decolorization and chemical oxygen demand (COD) removal in both the processes. Decolorization efficiency achieved 97.52 ± 0.66% in split process at a reflux ratio of 1 and the COD was 89 ± 2 mg/L in the final effluent. Further increasing the reflux ratio to 3 did not have any significance in treatment performance of the reactors. This study comprehensively revealed the influence of combination forms and reflux ratio on the performance of combined process.}, } @article {pmid31444120, year = {2019}, author = {Sun, S and Liu, J and Zhang, M and He, S}, title = {Simultaneous improving nitrogen removal and decreasing greenhouse gas emission with biofilm carriers addition in ecological floating bed.}, journal = {Bioresource technology}, volume = {}, number = {}, pages = {121944}, doi = {10.1016/j.biortech.2019.121944}, pmid = {31444120}, issn = {1873-2976}, abstract = {Ecological floating bed (EFB) is a green technology for treatment of micro-polluted wastewater. However, its nitrogen removal efficiency is still unsatisfactory. In this study, two EFBs with additional carbon source were established to explore biofilm carriers addition on nitrogen removal and greenhouse gas (GHG) emissions at different C/N ratios and temperatures. Results showed that biofilm carriers addition increased nitrification and nitrogen removal efficiencies in EFB, and more denitrifying and nitrifying bacteria were attached to the biofilm carriers. Higher N2O and CH4 emissions were found in control EFB without biofilm carriers addition which was consistent with higher nitrite accumulation. In addition, high-throughput sequencing analysis revealed that adding biofilm carriers could improve the richness and diversity of biological communities. For EFB with additional carbon source treating secondary effluent, adding biofilm carrier can obtain higher TN removal efficiency and lower greenhouse gas emission.}, } @article {pmid31443115, year = {2019}, author = {Wroe, JA and Johnson, CT and García, AJ}, title = {Bacteriophage Delivering Hydrogels Reduce Biofilm Formation In Vitro and Infection In Vivo.}, journal = {Journal of biomedical materials research. Part A}, volume = {}, number = {}, pages = {}, doi = {10.1002/jbm.a.36790}, pmid = {31443115}, issn = {1552-4965}, abstract = {Implanted orthopaedic devices become infected more frequently than any other implanted surgical device. These infections can be extremely costly and result in significant patient morbidity. Current treatment options typically involve the long term, systemic administration of a combination of antibiotics, often followed by implant removal. Here we engineered an injectable hydrogel capable of encapsulating Pseudomonas aeruginosa bacteriophage and delivering active phage to the site of bone infections. Bacteriophage retain their bacteriolytic activity after encapsulation and release from the hydrogel, and their rate of release from the hydrogel can be controlled by gel formulation. Bacteriophage-encapsulating hydrogels effectively kill their host bacteria in both planktonic and biofilm phenotypes in vitro without influencing the metabolic activity of human mesenchymal stromal cells. Bacteriophage-encapsulating hydrogels were used to treat murine radial segmental defects infected with P. aeruginosa. The hydrogels achieved a 4.seven fold reduction in live P. aeruginosa counts at the infection site compared to bacteriophage-free hydrogels at 7 days post-implantation. These results support the development of bacteriophage-delivering hydrogels to treat local bone infections. This article is protected by copyright. All rights reserved.}, } @article {pmid31442835, year = {2019}, author = {Wu, X and Cen, Q and Addy, M and Zheng, H and Luo, S and Liu, Y and Cheng, Y and Zhou, W and Chen, P and Ruan, R}, title = {A novel algal biofilm photobioreactor for efficient hog manure wastewater utilization and treatment.}, journal = {Bioresource technology}, volume = {292}, number = {}, pages = {121925}, doi = {10.1016/j.biortech.2019.121925}, pmid = {31442835}, issn = {1873-2976}, abstract = {This study developed a high-efficiency algal biofilm photobioreactor for microalgae by designing a special array of curtain membrane components. This paper also discusses the growth and nutrient composition of Chlorella vulgaris, and hog manure wastewater utilization and purification. It was found that after about 5 days of culture, the biomass of C. vulgaris on the membrane could reach as high as 7.37 g/m2 and the algae were easily harvested by mechanical scraping. The lipid content of C. vulgaris on the membrane structure was 10.17% while the lipid content of the algae in suspension was 14.29%. The light intensity showed a significant effect on the fatty acid composition. The C. vulgaris grew very well, and achieved deep purification of the hog manure wastewater; the COD, TP, TN, and NH4+-N removal rates reached 95.67%, 64.40%, 69.55%, and 91.24%, respectively.}, } @article {pmid31440218, year = {2019}, author = {Todhanakasem, T and Salangsing, OL and Koomphongse, P and Kaewket, S and Kanokratana, P and Champreda, V}, title = {Zymomonas mobilis Biofilm Reactor for Ethanol Production Using Rice Straw Hydrolysate Under Continuous and Repeated Batch Processes.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1777}, doi = {10.3389/fmicb.2019.01777}, pmid = {31440218}, issn = {1664-302X}, abstract = {Plastic composited corn silk was developed as a biotic/abiotic carrier for Zymomonas mobilis biofilm formation for the purpose of ethanol production. Furthermore, we explored the use of rice straw hydrolysate as substrate in both multistage continuous culture and repeated batch processes and compared the ethanol production efficiency by two strains of Z. mobilis. Biofilm formed by bacterial strains Z. mobilis ZM4 and TISTR551 were detected, and its proficiencies were compared under various conditions by scanning electron microscopy (SEM) and crystal violet assays. The greatest biofilm formed by both strains was found on day five after the inoculation. Z. mobilis strain ZM4 grown in repeated batch biofilm reactors produced higher yields of ethanol than TISTR551 grown under the same conditions, while TISTR551 produced higher yields of ethanol in the multistage continuous process. The yields were highly maintained, with no significant differences (p < 0.05) among the three consecutive repeated batches. These experiments highlight exciting uses for agricultural byproducts in the production of ethanol using Z. mobilis biofilm reactors.}, } @article {pmid31440064, year = {2019}, author = {Shariati, A and Asadian, E and Fallah, F and Azimi, T and Hashemi, A and Yasbolaghi Sharahi, J and Taati Moghadam, M}, title = {Evaluation of Nano-curcumin effects on expression levels of virulence genes and biofilm production of multidrug-resistant Pseudomonas aeruginosa isolated from burn wound infection in Tehran, Iran.}, journal = {Infection and drug resistance}, volume = {12}, number = {}, pages = {2223-2235}, doi = {10.2147/IDR.S213200}, pmid = {31440064}, issn = {1178-6973}, abstract = {Background: P. aeruginosa is considered as one of the most important pathogens, and high antibiotic resistance to P. aeruginosa has become an alarming concern. This study attempts to further improve curcumin solubility and stability by producing the involved nanoparticle and investigate the effect of this nanoparticle on those virulence genes of P. aeruginosa in pathogenicity and biofilm formation.

Methods: In this study, the curcumin nanoparticles were synthesized and characterized, and the antibacterial and antibiofilm effects of Nano-curcumin and curcumin were investigated by microdilution broth and microtiter plate, respectively. In addition, cytotoxic effect of Nano-curcumin on human epithelial cell lines (A549) was determined. The effects of Nano-curcumin on P. aeruginosa virulence genes, mexD, mexB, and mexT (efflux pumps), lecA (adhesion), nfxB (negative regulator of MexCD-OprJ), and rsmZ (biofilm formation) were determined using real-time quantitative PCR.

Results: Synthesized Nano-curcumins were soluble in water, which inhibited the growth of multidrug-resistant (MDR) P. aeruginosa at 128 µg/mL, whereas it was inhibited at 256 µg/mL for soluble curcumin in DMSO. Sub-inhibitory concentrations of Nano-curcumin reduced biofilm formation and, at 64 μg/mL, disrupted 58% of the established bacterial biofilms. In addition, curcumin nanoparticle downregulated the transcription of virulence genes except nfxB and exerted no cytotoxic effect on human epithelial cell lines (A549).

Conclusions: Results suggest that Nano-curcumin could be potentially used to reduce P. aeruginosa virulence and biofilm. However, in vivo studies with respect to an animal model are necessary to validate these results.}, } @article {pmid31439876, year = {2019}, author = {Champion, AE and Catanzaro, KCF and Bandara, AB and Inzana, TJ}, title = {Formation of the Francisella tularensis Biofilm is Affected by Cell Surface Glycosylation, Growth Medium, and a Glucan Exopolysaccharide.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {12252}, doi = {10.1038/s41598-019-48697-x}, pmid = {31439876}, issn = {2045-2322}, support = {DE-FG02-93ER20097//U.S. Department of Energy (DOE)/ ; }, abstract = {Biofilms are matrix-associated communities that enable bacteria to colonise environments unsuitable for free-living bacteria. The facultative intracellular pathogen Francisella tularensis can persist in water, amoebae, and arthropods, as well as within mammalian macrophages. F. tularensis Types A and B form poor biofilms, but F. tularensis mutants lacking lipopolysaccharide O-antigen, O-antigen capsule, and capsule-like complex formed up to 15-fold more biofilm than fully glycosylated cells. The Type B live vaccine strain was also 50% less capable of initiating surface attachment than mutants deficient in O-antigen and capsule-like complex. However, the growth medium of all strains tested also influenced the formation of biofilm, which contained a novel exopolysaccharide consisting of an amylose-like glucan. In addition, the surface polysaccharide composition of the bacterium affected the protein:DNA:polysaccharide composition of the biofilm matrix. In contrast, F. novicida attached to surfaces more efficiently and made a more robust biofilm than Type A or B strains, but loss of O-antigen or capsule-like complex did not significantly affect F. novicida biofilm formation. These results indicated that suppression of surface polysaccharides may promote biofilm formation by F. tularensis Types A and B. Whether biofilm formation enhances survival of F. tularensis in aquatic or other environmental niches has yet to be determined.}, } @article {pmid31439670, year = {2019}, author = {Kaus, K and Biester, A and Chupp, E and Lu, J and Visudharomn, C and Olson, R}, title = {The 1.9 Å crystal structure of the extracellular matrix protein Bap1 from Vibrio cholerae provides insights into bacterial biofilm adhesion.}, journal = {The Journal of biological chemistry}, volume = {}, number = {}, pages = {}, doi = {10.1074/jbc.RA119.008335}, pmid = {31439670}, issn = {1083-351X}, abstract = {Growth of the cholera bacterium Vibrio cholerae in a biofilm community contributes to both its pathogenicity and survival in aquatic environmental niches. The major components of V. cholerae biofilms include Vibriopolysaccharide (VPS) and the extracellular matrix proteins RbmA, RbmC, and Bap1. To further elucidate the previously observed overlapping roles of Bap1 and RbmC in biofilm architecture and surface attachment, here we investigated the structural and functional properties of Bap1. Soluble expression of Bap1 was possible only after the removal of an internal 57-amino-acid-long hydrophobic insertion sequence. The crystal structure of Bap1 at 1.9 Å resolution revealed a two-domain assembly made up of an eight-bladed β-propeller interrupted by a β-prism domain. The structure also revealed metal-binding sites within canonical calcium blade motifs, which appear to have structural rather than functional roles. Contrary to results previously observed with RbmC, the Bap1 β-prism domain did not exhibit affinity for complex N-glycans, suggesting an altered role of this domain in biofilm-surface adhesion. Native polyacrylamide gel shift analysis did suggest that Bap1 exhibits lectin activity with a preference for anionic and/or linear polysaccharides. Our results suggest a model for V. cholerae biofilms in which Bap1 and RbmC play dominant but differing adhesive roles in biofilms, allowing bacterial attachment to diverse environmental or host surfaces.}, } @article {pmid31438836, year = {2019}, author = {Pires, MEE and Parreira, AG and Silva, TNL and Colares, HC and da Silva, JA and de Magalhães, JT and Galdino, AS and Gonçalves, DB and Granjeiro, JM and Granjeiro, PA}, title = {Recent patents on impact of lipopeptide on the biofilm formation onto titanium and stainless steel surfaces.}, journal = {Recent patents on biotechnology}, volume = {}, number = {}, pages = {}, doi = {10.2174/1872208313666190822150323}, pmid = {31438836}, issn = {2212-4012}, abstract = {BACKGROUND: Numerous causes of infection in arthroplasties are related to biofilm formation on implant surfaces. In order to circumvent this problem, new alternatives to prevent bacterial adhesion biosurfactants-based are emerging due to low toxicity, biodegradability and antimicrobial activity of several biosurfactants. We revised all patents relating to biosurfactants of applicability in orthopedic implants.

METHODS: This work aims to evaluate the capability of a lipopeptide produced by Bacillus subtilis ATCC 19659 isolates acting as inhibitors of the adhesion of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213 onto titanium and stainless steel surfaces and its antimicrobial activity.

RESULTS: The adhesion of the strains to the stainless-steel surface was higher than that of titanium. Preconditioning of titanium and stainless-steel surfaces with 10 mg mL-1 lipopeptide reduced the adhesion of E. coli by up to 93% and the adhesion of S. aureus by up to 99.9%, suggesting the strong potential of lipopeptides in the control of orthopedic infections. The minimal inhibitory concentration and minimum bactericidal concentration were 10 and 240 μg mL-1 for E. coli and S. aureus, respectively.

CONCLUSION: The lipopeptide produced by Bacillus subtilis ATCC 19659 presented high biotechnological application in human health against orthopedic implants infections.}, } @article {pmid31438656, year = {2019}, author = {Skowron, K and Wałecka-Zacharska, E and Grudlewska, K and Gajewski, P and Wiktorczyk, N and Wietlicka-Piszcz, M and Dudek, A and Skowron, KJ and Gospodarek-Komkowska, E}, title = {Disinfectant Susceptibility of Biofilm Formed by Listeria monocytogenes under Selected Environmental Conditions.}, journal = {Microorganisms}, volume = {7}, number = {9}, pages = {}, doi = {10.3390/microorganisms7090280}, pmid = {31438656}, issn = {2076-2607}, abstract = {Listeria monocytogenes is a one of the most important food-borne pathogens. Its ability to form biofilm contributes to increased resistance to disinfectants and inefficient disinfection, posing a serious threat for the food industry, and in the end the consumer. The aim of this study was the comparison of the biofilm formation ability of L. monocytogenes strains on stainless steel, under different environmental conditions (temperature, pH, NaCl concentration, nutrients availability), and the assessment of biofilm susceptibility to disinfectants. The bactericidal activity of four disinfectants in two concentrations (100% and 50% of working solution) against biofilm was conducted on four clinical strains, four strains isolated from food and one reference strain ATCC 19111. It was found that biofilm susceptibility to disinfectants was influenced by environmental conditions. Biofilm susceptibility correlated with the decrease of temperature, pH, nutrients availability and salinity of the environment. The least sensitive to disinfectants was biofilm produced at pH = 4 (the bacterial number ranged from 0.25 log CFU × cm-2 to 1.72 log CFU × cm-2) whereas the most sensitive was biofilm produced at pH = 9 (5.16 log CFU × cm-2 to 7.84 log CFU × cm-2). Quatosept was the most effective disinfectant, regardless of the conditions. In conclusion, biofilm susceptibility to disinfectants is strain-dependent and is affected by environmental conditions.}, } @article {pmid31438629, year = {2019}, author = {Lorenzo, D}, title = {Chloramphenicol Resurrected: A Journey from Antibiotic Resistance in Eye Infections to Biofilm and Ocular Microbiota.}, journal = {Microorganisms}, volume = {7}, number = {9}, pages = {}, doi = {10.3390/microorganisms7090278}, pmid = {31438629}, issn = {2076-2607}, abstract = {The advent of multidrug resistance among pathogenic bacteria is devastating the worth of antibiotics and changing the way of their administration, as well as the approach to use new or old drugs. The crisis of antimicrobial resistance is also due to the unavailability of newer drugs, attributable to exigent regulatory requirements and reduced financial inducements. The emerging resistance to antibiotics worldwide has led to renewed interest in old drugs that have fallen into disuse because of toxic side effects. Thus, comprehensive efforts are needed to minimize the pace of resistance by studying emergent microorganisms and optimize the use of old antimicrobial agents able to maintain their profile of susceptibility. Chloramphenicol is experiencing its renaissance because it is widely used in the treatment and prevention of superficial eye infections due to its broad spectrum of activity and other useful antimicrobial peculiarities, such as the antibiofilm properties. Concerns have been raised in the past for the risk of aplastic anemia when chloramphenicol is given intravenously. Chloramphenicol seems suitable to be used as topical eye formulation for the limited rate of resistance compared to fluoroquinolones, for its scarce induction of bacterial resistance and antibiofilm activity, and for the hypothetical low impact on ocular microbiota disturbance. Further in-vitro and in vivo studies on pharmacodynamics properties of ocular formulation of chloramphenicol, as well as its real impact against biofilm and the ocular microbiota, need to be better addressed in the near future.}, } @article {pmid31437576, year = {2019}, author = {Khan, F and Jeong, MC and Park, SK and Kim, SK and Kim, YM}, title = {Contribution of chitooligosaccharides to biofilm formation, antibiotics resistance and disinfectants tolerance of Listeria monocytogenes.}, journal = {Microbial pathogenesis}, volume = {}, number = {}, pages = {103673}, doi = {10.1016/j.micpath.2019.103673}, pmid = {31437576}, issn = {1096-1208}, abstract = {Listeria monocytogenes is a food-borne pathogen present in various environmental reservoirs. It exhibits resistance and tolerance to antibiotics and sanitizing agents used in several food processing industries. It has been reported that L. monocytogenes chitinase can catalyze hydrolysis of chitin polymeric carbohydrate present in the environment and act as a virulence factor that supports its survival in mammalian host cells. By taking advantage of chitinase, L. monocytogenes has both saprophytic and pathogenic lifestyles in the soil and living host, respectively. The objective of the present study was to determine the involvement of chitin degradation products such as chitooligosaccharides (COS) in biofilm formation of L. monocytogenes. Results showed that different concentrations of COS with various molecular weight enhanced biofilm formation of L. monocytogenes. Such enhancement in biofilm formation contributed to the development of antibiotics resistance and disinfectant tolerance of cells present in the biofilm. The present article also describes diverse roles of chitin, chitinase, and degradation of chitin and chitin-like substrates in saprophytic and pathogenic lifestyles of L. monocytogenes. This study offers a new direction for further exploration of the mechanisms of pathogenesis caused by L. monocytogenes.}, } @article {pmid31437202, year = {2019}, author = {Romero-Lastra, P and Sánchez, MC and Llama-Palacios, A and Figuero, E and Herrera, D and Sanz, M}, title = {Gene expression of Porphyromonas gingivalis ATCC 33277 when growing in an in vitro multispecies biofilm.}, journal = {PloS one}, volume = {14}, number = {8}, pages = {e0221234}, doi = {10.1371/journal.pone.0221234}, pmid = {31437202}, issn = {1932-6203}, abstract = {BACKGROUND AND OBJECTIVE: Porphyromonas gingivalis, an oral microorganism residing in the subgingival biofilm, may exert diverse pathogenicity depending on the presence of specific virulence factors, but its gene expression has not been completely established. This investigation aims to compare the transcriptomic profile of this pathogen when growing within an in vitro multispecies biofilm or in a planktonic state.

MATERIALS AND METHODS: P. gingivalis ATCC 33277 was grown in anaerobiosis within multi-well culture plates at 37°C under two conditions: (a) planktonic samples (no hydroxyapatite discs) or (b) within a multispecies-biofilm containing Streptococcus oralis, Actinomyces naeslundii, Veillonella parvula, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans deposited on hydroxyapatite discs. Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) combined with Fluorescence In Situ Hybridization (FISH) were used to verify the formation of the biofilm and the presence of P. gingivalis. Total RNA was extracted from both the multispecies biofilm and planktonic samples, then purified and, with the use of a microarray, its differential gene expression was analyzed. A linear model was used for determining the differentially expressed genes using a filtering criterion of two-fold change (up or down) and a significance p-value of <0.05. Differential expression was confirmed by Reverse Transcription-quantitative Polymerase Chain Reaction (RT-qPCR).

RESULTS: SEM verified the development of the multispecies biofilm and FISH confirmed the incorporation of P. gingivalis. The microarray demonstrated that, when growing within the multispecies biofilm, 19.1% of P. gingivalis genes were significantly and differentially expressed (165 genes were up-regulated and 200 down-regulated), compared with planktonic growth. These genes were mainly involved in functions related to the oxidative stress, cell envelope, transposons and metabolism. The results of the microarray were confirmed by RT-qPCR.

CONCLUSION: Significant transcriptional changes occurred in P. gingivalis when growing in a multispecies biofilm compared to planktonic state.}, } @article {pmid31437081, year = {2019}, author = {Sun, R and Xu, Y and Wu, Y and Tang, J and Esquivel-Elizondo, S and Kerr, PG and Staddon, PL and Liu, J}, title = {Functional sustainability of nutrient accumulation by periphytic biofilm under temperature fluctuations.}, journal = {Environmental technology}, volume = {}, number = {}, pages = {1-28}, doi = {10.1080/09593330.2019.1659422}, pmid = {31437081}, issn = {1479-487X}, abstract = {Temperature can fluctuate widely between different seasons, and this may greatly impact many biological process. However, little is known about its influence on the functioning of benthic microbial communities. Here we investigated the nutrient accumulation capability of periphytic biofilm under temperature fluctuations (17-35 °C). Periphytic biofilm maintained the same nutrient accumulation capacity after experiencing the "warming-hot-cooling" temperature fluctuation under both lab and outdoor conditions as those without temperature disturbance. In response to temperature increase, both community composition and species richness changed greatly and the increase in biodiversity was identified as being the underlying mechanism boosting the sustainable function in nutrient accumulation, indicating zero net effects of community changes. These findings provide insights into the underlying mechanisms of how benthic microbial communities adapt to temperature fluctuations to maintain nutrient accumulation capacity and elucidate that periphytic biofilm plays important roles in influencing nutrient cycling in aquatic ecosystems under temperature changes such as seasonal fluctuations.}, } @article {pmid31435968, year = {2019}, author = {Cho, P and Boost, MV}, title = {Evaluation of prevention and disruption of biofilm in contact lens cases.}, journal = {Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists)}, volume = {}, number = {}, pages = {}, doi = {10.1111/opo.12635}, pmid = {31435968}, issn = {1475-1313}, abstract = {PURPOSE: The presence of biofilm in the lens case has been shown to be a risk factor for contamination of lenses and consequently microbial keratitis. This study aimed to evaluate effectiveness of solutions for rigid contact lenses in prevention and disruption of biofilm in lens cases and methods for biofilm detection.

METHOD: This study adopted a stepwise approach to evaluate effectiveness of four rigid lens disinfecting solutions against biofilm. These included two polyhexamethylene bigiuanide (PHMB) solutions and a chlorhexidine/PHMB-based solution, as well as a novel povidone-iodine formulation. The presence of biofilm following exposure to the solutions was assessed using both crystal violet (CV) staining and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) viability assay, taking into account the effect of lens case design. Three lens case designs, conventional flat, large bucket type, and cylindrical cases, were investigated for the ability to trap stain and allow biofilm formation.

RESULTS: Considerable differences were noted between solutions in their ability to prevent and disrupt biofilm (p < 0.001). Lens case design greatly influenced optical density (OD) measurements even in negative controls, as cylindrical cases trapped more stain, increasing OD readings. Correcting for this factor reduced variations, but could not differentiate between residues and biofilm. MTT assay revealed that both povidone-iodine and chlorhexidine-containing solutions could effectively kill > 95% of organisms, whilst PHMB-based solutions were less effective with up to 55% of staphylococci and 41% of Pseudomonas surviving at 24 h.

CONCLUSION: Biofilm can rapidly form in lens cases and may not be killed by disinfecting solutions. Of the solutions tested, none were able to prevent biofilm formation or disrupt established biofilm, but those containing chlorhexidine or povidone iodine were able to penetrate the biofilm and kill organisms. Assessment of biofilm by CV assay may be confounded by lens case design. Whilst CV assay can demonstrate presence of biofilm, this technique should be accompanied by viability assay to determine bactericidal activity.}, } @article {pmid31432881, year = {2019}, author = {Ran, HH and Cheng, X and Bao, YW and Hua, XW and Gao, G and Zhang, X and Jiang, YW and Zhu, YX and Wu, FG}, title = {Multifunctional quaternized carbon dots with enhanced biofilm penetration and eradication efficiencies.}, journal = {Journal of materials chemistry. B}, volume = {7}, number = {33}, pages = {5104-5114}, doi = {10.1039/c9tb00681h}, pmid = {31432881}, issn = {2050-7518}, abstract = {Biofilm formation can lead to the treatment failure of persistent bacterial infections. Although a variety of antibacterial agents have been developed, the restricted drug penetration and the embedded bacteria's potentiated recalcitrance to these agents synergistically lead to the unsatisfactory anti-biofilm effect. Herein, we report the applications of metal-free quaternized carbon dots (CDs) in imaging and eliminating bacterial biofilms. The CDs prepared by the solvothermal treatment of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (abbreviated as Si-QAC) and glycerol possess ultrasmall size (ca. 3.3 ± 0.4 nm) and strong positively charged (zeta potential: ca. +33.1 ± 2.5 mV) surfaces with long alkyl chain-linked quaternary ammonium groups. The small size of the CDs endows them with the penetration ability into the interior of Gram-negative and Gram-positive bacterial biofilms, which enables excellent fluorescence imaging of the biofilms. Due to the different surfaces of the two types of bacteria, the positively charged CDs selectively interact with the more negatively charged Gram-positive bacteria via electrostatic and hydrophobic interactions, which inactivates the Gram-positive bacteria and ultimately eradicates the Gram-positive bacterial biofilms. In addition, we synthesize a new type of quaternized CDs without long alkyl chains (termed TTPAC CDs), and validate that the long alkyl chains potentiate the hydrophobic adhesion between CDs and Gram-positive bacteria. Meanwhile, the crystal violet staining results reveal that the cationic CDs inhibit the formation of Gram-positive bacterial biofilms. Collectively, our work highlights the feasibility of using cationic and ultrasmall metal-free CDs to eliminate and inhibit Gram-positive bacterial biofilms, which represents a highly effective strategy to cope with refractory biofilm-associated infections.}, } @article {pmid31432051, year = {2019}, author = {Kuper, NK and Hollanders, ACC and Dekkers, EAM and Maske, TT and Huysmans, MDNJM and Cenci, MS}, title = {Aging Reduces the Anticaries Effect of Antibacterial Adhesive - An In Vitro Biofilm Study.}, journal = {The journal of adhesive dentistry}, volume = {21}, number = {4}, pages = {365-372}, doi = {10.3290/j.jad.a42999}, pmid = {31432051}, issn = {1757-9988}, abstract = {PURPOSE: This in vitro study investigated whether aging different restorative materials influences secondary caries development using a short-term in vitro biofilm model, hypothesizing that the antibacterial adhesive employed may lose its effect over time.

MATERIALS AND METHODS: Sixty enamel-dentin blocks were divided into 6 groups with n = 10 per group. The groups were restored with three different restorative materials, of which each sample contained an artificial gap: composite with conventional adhesive (CCA; negative control), composite with an antibacterial adhesive (CAA), and amalgam (A; positive control). Half of the groups were prepared fresh and half of the groups were submitted to an aging protocol consisting of water storage, thermocycling, storage in human saliva, and storage in 0.9% saline solution. All specimens were subjected to an intermittent 1% sucrose biofilm model for 20 days to create artificial caries lesions. Lesion progression in the enamel and dentin next to the different materials was measured as lesion depth (LD) and mineral loss (ML), using transverse wavelength independent microradiography (T-WIM). Regression analysis was used to evaluate the effect of aging on LD and ML per restorative material, corrected for gap size.

RESULTS: In the amalgam group, aging led to shallower lesions and less mineral loss. Fresh amalgam samples showed an average lesion depth of 156.65 ± 39.18 µm at wall dentin locations. Aged amalgam samples had an average lesion depth of 73.42 ± 73.50 µm. Fresh CAA samples showed lower average surface mineral loss values (9104 ± 2631 µm•vol%) than did fresh CCA samples (13166 ± 4769 µm•vol%). After aging, this effect was absent, and the average mineral loss in the CAA group was 13382 ± 5586 µm•vol%, while in the CCA group it was 15518 ± 9283 µm•vol%.

CONCLUSION: Aging can influence secondary caries development either positively or negatively depending on the kind of restorative material. Antibacterial adhesives may lose their effectiveness over time.}, } @article {pmid31430670, year = {2019}, author = {Li, H and Wang, B and Deng, S and Dai, J and Shao, S}, title = {Oxygen-containing functional groups on bioelectrode surface enhance expression of c-type cytochromes in biofilm and boost extracellular electron transfer.}, journal = {Bioresource technology}, volume = {292}, number = {}, pages = {121995}, doi = {10.1016/j.biortech.2019.121995}, pmid = {31430670}, issn = {1873-2976}, abstract = {Introducing oxygen-containing functional groups is a common and convenient method to increase the hydrophilicity of bioelectrodes. In this study, the effect of oxygen-containing functional groups on biofilm was systematically studied to understand how the electron transfer between electrochemically active bacteria (EAB) and bioelectrode was boosted. After electrolysis pretreatment in sulfuric and nitric acid mixture, the oxygen content of the carbon fiber brushes increased from 4.6% to 30.9%. Comparing with the control, the maximum power density increased by 27.7%, while the anode resistance decreased by 21.8%, because charge transfer resistance significantly reduced. The analysis results showed that the content of c-type cytochromes (c-Cyts) in the EAB biofilm was four times higher than that in the control, while the biomass just slightly increased and the bacteria community was similar with that of the control. These findings suggested that the fundamental reason for the enhanced extracellular electron transfer between EAB and electrode was the increased c-Cyts.}, } @article {pmid31430343, year = {2019}, author = {Giacomucci, S and Cros, CD and Perron, X and Mathieu-Denoncourt, A and Duperthuy, M}, title = {Flagella-dependent inhibition of biofilm formation by sub-inhibitory concentration of polymyxin B in Vibrio cholerae.}, journal = {PloS one}, volume = {14}, number = {8}, pages = {e0221431}, doi = {10.1371/journal.pone.0221431}, pmid = {31430343}, issn = {1932-6203}, abstract = {Biofilm formation is a common strategy used by bacteria in order to survive and persist in the environment. In Vibrio cholerae (V. cholerae), a Gram-negative pathogen responsible for the cholera disease, biofilm-like aggregates are important for the pathogenesis and disease transmission. Biofilm formation is initiated by the attachment of the bacteria to a surface, followed by maturation stages involving the formation of a biofilm matrix. In V. cholerae, flagella are essential for the initial step of biofilm formation, allowing the bacteria to swim and to detect a surface. In this study, we explored the effect of polymyxin B (PmB), a cationic bacterial antimicrobial peptide, on biofilm formation in pathogenic V. cholerae strains belonging to the O1 and O139 serotypes. We found that sub-inhibitory concentration of PmB induces a reduction of the biofilm formation by V. cholerae O1 and O139. Experiment on preformed biofilm demonstrated that the biofilm formation inhibition occurs at the initial step of biofilm formation, where the flagella are essential. We further characterize the effect of PmB on V. cholerae flagellation. Our results demonstrate that the flagellin expression is not reduced in presence of sub-inhibitory concentration of PmB. However, a decrease of the abundance of flagellin associated with the bacterial cells together with an increase in the secretome was observed. Electron microscopy observations also suggest that the abundance of aflagellated bacteria increases upon PmB supplementation. Finally, in agreement with the effect on the flagellation, a reduction of the bacterial motility is observed. Altogether, our results suggest that the PmB affect V. cholerae flagella resulting in a decrease of the motility and a compromised ability to form biofilm.}, } @article {pmid31430121, year = {2019}, author = {Wang, S and Breslawec, AP and Alvarez, E and Tyrlik, M and Li, C and Poulin, MB}, title = {Differential Recognition of Deacetylated PNAG Oligosaccharides by a Biofilm Degrading Glycosidase.}, journal = {ACS chemical biology}, volume = {}, number = {}, pages = {}, doi = {10.1021/acschembio.9b00467}, pmid = {31430121}, issn = {1554-8937}, abstract = {Exopolysaccharides consisting of partially de-N-acetylated poly-β-D-(1→6)-N-acetyl-glucosamine (dPNAG) are key structural components of the biofilm extracellular polymeric substance of both gram-positive and gram-negative human pathogens. De-N-acetylation is required for the proper assembly and function of dPNAG in biofilm development suggesting that different patterns of deacetylation may be preferentially recognized by proteins that interact with dPNAG, such as Dispersin B (DspB). The enzymatic degradation of dPNAG by the Aggregatibacter actinomycetemcomitans native β-hexosaminidase enzyme DspB plays a role in biofilm dispersal. To test the role of substrate de-N-acetylation on substrate recognition by DspB, we applied an efficient pre-activation based one-pot glycosylation approach to prepare a panel of dPNAG trisaccharide analogs with defined acetylation patterns. These analogs served as effective DspB substrates and the rate of hydrolysis was dependent on the specific substrate de-N-acetylation pattern, with glucosamine (GlcN) located +2 from the site of cleavage being preferentially hydrolyzed. The product distributions support a primarily exoglycosidase cleavage activity following a substrate assisted cleavage mechanism, with the exception of substrates containing a non-reducing GlcN that were cleaved endo leading to the exclusive formation of a non-reducing disaccharide product. These observations provide critical insight into the substrate specificity of dPNAG specific glycosidase that can help guide their design as biocatalysts.}, } @article {pmid31429746, year = {2019}, author = {Funk, B and Kirmayer, D and Sahar-Heft, S and Gati, I and Friedman, M and Steinberg, D}, title = {Efficacy and potential use of novel sustained release fillers as intracanal medicaments against Enterococcus faecalis biofilm in vitro.}, journal = {BMC oral health}, volume = {19}, number = {1}, pages = {190}, doi = {10.1186/s12903-019-0879-1}, pmid = {31429746}, issn = {1472-6831}, abstract = {BACKGROUND: Enterococcus faecalis is a bacterium frequently isolated after failed root canal therapy. This study analyzed the antibacterial and antibiofilm effects in vitro of sustained-release fillers (SRF) containing cetylpyridinium chloride (CPC) against vancomycin resistant E. faecalis.

METHODS: First, the solidification capability was tested by introducing liquid SRF into phosphate buffered saline, followed by 30 s of vortexing. The antimicrobial effects of SRF-CPC against static monospecies biofilms were analyzed with a metabolic assay. Inhibition of biofilm formation was tested by exposing daily refreshed E. faecalis suspensions to SRF-CPC for 9 weeks. To evaluate the effects of SRF-CPC against preformed biofilms, biofilms were grown for 1, 3 and 7 days, and then treated with SRF-CPC for 24 h. Biofilm kill time was tested by applying SRF-CPC to a 3-day-old biofilm and measuring its viability at different time points. All experiments were compared to Placebo SRFs and to untreated control biofilms. Data were analyzed with two-way ANOVA followed by Tukey's test. Results were considered significant at P < 0.05.

RESULTS: The liquid SRF solidified within seconds and no structural changes were observed after 30 s of vortexing at maximum speed. SRF-CPC inhibited E. faecalis biofilm formation for 7 weeks and significantly reduced its viability in weeks 8 and 9. Mature biofilms grown for 1, 3 and 7 days were destructed by SRF-CPC in less than 24 h. Fifty percent of a 3-day-old biofilm was destructed in 2 h and complete destruction occurred in less than 12 h. (P < 0.05 in all cases, compared to SRII-Placebo).

CONCLUSIONS: SRF-CPC's physical properties and long-lasting anti-biofilm effects make it a promising coadjuvant medication for endodontic therapy.}, } @article {pmid31429088, year = {2019}, author = {Brodersen, KE and Koren, K and Revsbech, NP and Kühl, M}, title = {Strong leaf surface basification and CO2 limitation of seagrass induced by epiphytic biofilm microenvironments.}, journal = {Plant, cell & environment}, volume = {}, number = {}, pages = {}, doi = {10.1111/pce.13645}, pmid = {31429088}, issn = {1365-3040}, abstract = {Coastal eutrophication is a growing problem worldwide, leading to increased epiphyte overgrowth of seagrass leaves. Yet, little is known about how epiphytes affect key biogeochemical conditions and processes in the seagrass phyllosphere. We used electrochemical microsensors to measure microgradients of O2 , pH, and CO2 at the bare and epiphyte-covered leaf surface of seagrass (Zostera marina L.) to determine effects of epiphytes on the leaf chemical microenvironment. Epiphytes result in extreme daily fluctuations in pH, O2 and inorganic carbon concentrations at the seagrass leaf surface severely hampering the plant's performance. In light, leaf epiphyte biofilms and their diffusive boundary layer (DBL) lead to strong basification, markedly reducing the CO2 and HCO3- availability at the leaf surface, leading to reduced photosynthetic efficiency as a result of carbon limitation and enhanced photorespiration. With epiphytes, leaf surface pH increased to >10, thereby exceeding final pH levels (~9.62) and CO2 compensation points for active photosynthesis. In darkness, epiphyte biofilms resulted in increased CO2 and hypoxia at the leaf surface. Epiphytes can lead to severe carbon limitation in seagrasses owing to strong phyllosphere basification leading to CO2 depletion and costly, yet limiting, HCO3- utilization, increasing the risk of plant starvation.}, } @article {pmid31428077, year = {2019}, author = {Cirri, E and De Decker, S and Bilcke, G and Werner, M and Osuna-Cruz, CM and De Veylder, L and Vandepoele, K and Werz, O and Vyverman, W and Pohnert, G}, title = {Associated Bacteria Affect Sexual Reproduction by Altering Gene Expression and Metabolic Processes in a Biofilm Inhabiting Diatom.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1790}, doi = {10.3389/fmicb.2019.01790}, pmid = {31428077}, issn = {1664-302X}, abstract = {Diatoms are unicellular algae with a fundamental role in global biogeochemical cycles as major primary producers at the base of aquatic food webs. In recent years, chemical communication between diatoms and associated bacteria has emerged as a key factor in diatom ecology, spurred by conceptual and technological advancements to study the mechanisms underlying these interactions. Here, we use a combination of physiological, transcriptomic, and metabolomic approaches to study the influence of naturally co-existing bacteria, Maribacter sp. and Roseovarius sp., on the sexual reproduction of the biofilm inhabiting marine pennate diatom Seminavis robusta. While Maribacter sp. severely reduces the reproductive success of S. robusta cultures, Roseovarius sp. slightly enhances it. Contrary to our expectation, we demonstrate that the effect of the bacterial exudates is not caused by altered cell-cycle regulation prior to the switch to meiosis. Instead, Maribacter sp. exudates cause a reduced production of diproline, the sexual attraction pheromone of S. robusta. Transcriptomic analyses show that this is likely an indirect consequence of altered intracellular metabolic fluxes in the diatom, especially those related to amino acid biosynthesis, oxidative stress response, and biosynthesis of defense molecules. This study provides the first insights into the influence of bacteria on diatom sexual reproduction and adds a new dimension to the complexity of a still understudied phenomenon in natural diatom populations.}, } @article {pmid31428070, year = {2019}, author = {Chen, T and Liu, N and Ren, P and Xi, X and Yang, L and Sun, W and Yu, B and Ying, H and Ouyang, P and Liu, D and Chen, Y}, title = {Efficient Biofilm-Based Fermentation Strategies for L-Threonine Production by Escherichia coli.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1773}, doi = {10.3389/fmicb.2019.01773}, pmid = {31428070}, issn = {1664-302X}, abstract = {Biofilms provide cells favorable growth conditions, which have been exploited in industrial biotechnological processes. However, industrial application of the biofilm has not yet been reported in Escherichia coli, one of the most important platform strains, though the biofilm has been extensively studied for pathogenic reasons. Here, we engineered E. coli by overexpressing the fimH gene, which successfully enhanced its biofilm formation under industrial aerobic cultivation conditions. Subsequently, a biofilm-based immobilized fermentation strategy was developed. L-threonine production was increased from 10.5 to 14.1 g/L during batch fermentations and further to 17.5 g/L during continuous (repeated-batch) fermentations with enhanced productivities. Molecular basis for the enhanced biofilm formation and L-threonine biosynthesis was also studied by transcriptome analysis. This study goes beyond the conventional research focusing on pathogenic aspects of E. coli biofilm and represents a successful application case of engineered E. coli biofilm to industrial processes.}, } @article {pmid31427961, year = {2019}, author = {Oves, M and Rauf, MA and Hussain, A and Qari, HA and Khan, AAP and Muhammad, P and Rehman, MT and Alajmi, MF and Ismail, IIM}, title = {Antibacterial Silver Nanomaterial Synthesis From Mesoflavibacter zeaxanthinifaciens and Targeting Biofilm Formation.}, journal = {Frontiers in pharmacology}, volume = {10}, number = {}, pages = {801}, doi = {10.3389/fphar.2019.00801}, pmid = {31427961}, issn = {1663-9812}, abstract = {Considering the significance of biological and eco-friendly nanomaterials, in the present study, we have synthesized silver nanoparticles from the exopolysaccharide of recently recovered bacterial strain CEES51 from the Red Sea coastal area of Jeddah, Saudi Arabia. 16S ribosomal RNA gene sequencing was used to characterize the isolated bacteria, and it was identified as Mesoflavibacter zeaxanthinifaciens and assigned an accession number MH707257.1 GenBank. The bacterial strain is an excellent exopolysaccharide producer and survived at hypersaline (30%) and high-temperature (50°C) conditions. The bacterial exopolysaccharides were employed for the fabrication of silver nanoparticles at room temperature. UV-visible spectrophotometer optimized the synthesized nanoparticles, and their size was determined by Nanophox particle size analyzer and dynamic light scattering. Additionally, the X-ray powder diffraction and Fourier-transform infrared spectroscopy studies also approved its crystalline nature and the involvement of organic functional groups in their formation. The synthesized nanomaterials were tested for their antibacterial and antibiofilm properties against pathogenic microorganisms Bacillus subtilis and methicillin-resistant Staphylococcus aureus. The antimicrobial property showed time, and dose-dependent response with a maximum of zone inhibition was observed at around 22 and 18 mm at a dose of 50 µg/well against B. subtilis and S. aureus and a minimum inhibitory concentration of 8 and 10 µg/ml, respectively. Furthermore, the synthesized silver nanoparticles possessed a substantial antibiofilm property and were also found to be biocompatible as depicted by red blood cell lysis assay and their interaction with peripheral blood mononuclear cells and human embryonic kidney 293 cells. Therefore, Mesoflavibacter zeaxanthinifaciens is found to be an excellent source for exopolysaccharide synthesis that assists in the silver nanoparticle production.}, } @article {pmid31427659, year = {2019}, author = {Kindler, O and Pulkkinen, O and Cherstvy, AG and Metzler, R}, title = {Burst statistics in an early biofilm quorum sensing model: the role of spatial colony-growth heterogeneity.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {12077}, doi = {10.1038/s41598-019-48525-2}, pmid = {31427659}, issn = {2045-2322}, support = {Humboldt Polish Honorary Research Fellowship//Fundacja na rzecz Nauki Polskiej (Foundation for Polish Science)/ ; ME 1535/7-1//Deutsche Forschungsgemeinschaft (German Research Foundation)/ ; }, abstract = {Quorum-sensing bacteria in a growing colony of cells send out signalling molecules (so-called "autoinducers") and themselves sense the autoinducer concentration in their vicinity. Once-due to increased local cell density inside a "cluster" of the growing colony-the concentration of autoinducers exceeds a threshold value, cells in this clusters get "induced" into a communal, multi-cell biofilm-forming mode in a cluster-wide burst event. We analyse quantitatively the influence of spatial disorder, the local heterogeneity of the spatial distribution of cells in the colony, and additional physical parameters such as the autoinducer signal range on the induction dynamics of the cell colony. Spatial inhomogeneity with higher local cell concentrations in clusters leads to earlier but more localised induction events, while homogeneous distributions lead to comparatively delayed but more concerted induction of the cell colony, and, thus, a behaviour close to the mean-field dynamics. We quantify the induction dynamics with quantifiers such as the time series of induction events and burst sizes, the grouping into induction families, and the mean autoinducer concentration levels. Consequences for different scenarios of biofilm growth are discussed, providing possible cues for biofilm control in both health care and biotechnology.}, } @article {pmid31427301, year = {2019}, author = {Bilal, H and Bergen, PJ and Kim, TH and Chung, SE and Peleg, AY and Oliver, A and Nation, RL and Landersdorfer, CB}, title = {Synergistic meropenem-tobramycin combination dosage regimens against clinical hypermutable Pseudomonas aeruginosa at simulated epithelial lining fluid concentrations in a dynamic biofilm model.}, journal = {Antimicrobial agents and chemotherapy}, volume = {}, number = {}, pages = {}, doi = {10.1128/AAC.01293-19}, pmid = {31427301}, issn = {1098-6596}, abstract = {Exacerbations of chronic Pseudomonas aeruginosa infections are a major treatment challenge in cystic fibrosis due to biofilm formation and hypermutation. We aimed to evaluate different dosage regimens of meropenem and tobramycin in monotherapies and combination against hypermutable carbapenem-resistant P. aeruginosa A hypermutable P. aeruginosa isolate (MICmeropenem and MICtobramycin 8 mg/L) was investigated in the dynamic CDC biofilm reactor over 120 h. Regimens were meropenem as standard (2 g 8-hourly, 30% epithelial lining fluid (ELF) penetration) and continuous infusion (CI, 6 g/day, 30% and 60% ELF penetration), and tobramycin 10 mg/kg 24-hourly (50% ELF penetration). The time-courses of total and less-susceptible bacteria and MICs were determined and antibiotic concentrations quantified by LC-MS/MS. All monotherapies failed with substantial regrowth of planktonic (>6 log10 CFU/mL) and biofilm (≥6 log10 CFU/cm2) bacteria. Except for meropenem CI (60% ELF penetration) all monotherapies amplified less-susceptible planktonic and biofilm bacteria by 120 h. The meropenem standard regimen with tobramycin caused initial killing followed by considerable regrowth with resistance (MICmeropenem 64 mg/L, MICtobramycin 32 mg/L) for planktonic and biofilm bacteria. The combination containing the meropenem CI, at both levels of ELF penetration, synergistically suppressed regrowth of total planktonic bacteria and resistance of planktonic and biofilm bacteria. The combination with meropenem CI at 60% ELF penetration in addition synergistically suppressed regrowth of total biofilm bacteria. Standard regimens of meropenem and tobramycin were ineffective against planktonic and biofilm bacteria. The combination with meropenem CI exhibited enhanced bacterial killing and resistance suppression of carbapenem-resistant hypermutable P. aeruginosa.}, } @article {pmid31426832, year = {2019}, author = {Bujold, AR and Lani, NR and Sanz, MG}, title = {Strain-to-strain variation of Rhodococcus equi growth and biofilm formation in vitro.}, journal = {BMC research notes}, volume = {12}, number = {1}, pages = {519}, doi = {10.1186/s13104-019-4560-1}, pmid = {31426832}, issn = {1756-0500}, abstract = {OBJECTIVE: Rhodococcus equi is an opportunistic pathogen that causes disease worldwide in young foals and immunocompromised humans. The interactions of R. equi with the host immune system have been described; however, most studies have been conducted using a few well-characterized strains. Because biological differences between R. equi strains are not well characterized, it is unknown if experimental results will replicate when different strains are used. Therefore, our objective was to compare the growth and biofilm formation of low-passage-rate clinical isolates of R. equi to higher-passage-rate, commonly studied isolates to determine whether strain-to-strain variation exists.

RESULTS: Twelve strains were used: 103+, ATCC 33701, UKVDL206 103S harboring a GFP-expressing plasmid, a plasmid-cured 33701 (higher-passage-rate) and seven low-passage clinical isolates. Generation time in liquid revealed fast, moderate-fast, moderate-slow, and slow-growing isolates. The higher-passage-rate isolates were among the moderate-slow growing strains. A strain's rate of growth did not correspond to its ability to form biofilm nor to its colony size on solid media. Based on our results, care should be taken not to extrapolate in vitro work that may be conducted using different R. equi strains. Further work is needed to evaluate the effect that the observed differences may have on experimental results.}, } @article {pmid31424553, year = {2019}, author = {Soares, A and Alexandre, K and Lamoureux, F and Lemée, L and Caron, F and Pestel-Caron, M and Etienne, M}, title = {Efficacy of a ciprofloxacin/amikacin combination against planktonic and biofilm cultures of susceptible and low-level resistant Pseudomonas aeruginosa.}, journal = {The Journal of antimicrobial chemotherapy}, volume = {}, number = {}, pages = {}, doi = {10.1093/jac/dkz355}, pmid = {31424553}, issn = {1460-2091}, abstract = {BACKGROUND: Eradicating bacterial biofilm without mechanical dispersion remains a challenge. Combination therapy has been suggested as a suitable strategy to eradicate biofilm.

OBJECTIVES: To evaluate the efficacy of a ciprofloxacin/amikacin combination in a model of in vitro Pseudomonas aeruginosa biofilm.

METHODS: The antibacterial activity of ciprofloxacin and amikacin (alone, in combination and successively) was evaluated by planktonic and biofilm time-kill assays against five P. aeruginosa strains: PAO1, a WT clinical strain and three clinical strains overexpressing the efflux pumps MexAB-OprM (AB), MexXY-OprM (XY) and MexCD-OprJ (CD), respectively. Amikacin MIC was 16 mg/L for XY and ciprofloxacin MIC was 0.5 mg/L for CD. The other strains were fully susceptible to ciprofloxacin and amikacin. The numbers of total and resistant cells were determined.

RESULTS: In planktonic cultures, regrowth of high-level resistant mutants was observed when CD was exposed to ciprofloxacin alone and XY to amikacin alone. Eradication was obtained with ciprofloxacin or amikacin in the other strains, or with the combination in XY and CD strains. In biofilm, bactericidal reduction after 8 h followed by a mean 4 log10 cfu/mL plateau in all strains and for all regimens was noticed. No regrowth of resistant mutants was observed whatever the antibiotic regimen. The bacterial reduction obtained with a second antibiotic used simultaneously or consecutively was not significant.

CONCLUSIONS: The ciprofloxacin/amikacin combination prevented the emergence of resistant mutants in low-level resistant strains in planktonic cultures. Biofilm persister cells were not eradicated, either with monotherapy or with the combination.}, } @article {pmid31423363, year = {2019}, author = {Payette, G and Geoffroy, V and Martineau, C and Villemur, R}, title = {Dynamics of a methanol-fed marine denitrifying biofilm: 1-Impact of environmental changes on the denitrification and the co-occurrence of Methylophaga nitratireducenticrescens and Hyphomicrobium nitrativorans.}, journal = {PeerJ}, volume = {7}, number = {}, pages = {e7497}, doi = {10.7717/peerj.7497}, pmid = {31423363}, issn = {2167-8359}, abstract = {Background: The biofilm of a methanol-fed denitrification system that treated a marine effluent is composed of multi-species microorganisms, among which Hyphomicrobium nitrativorans strain NL23 and Methylophaga nitratireducenticrescens strain JAM1 are the principal bacteria involved in the denitrifying activities. Here, we report the capacity of the denitrifying biofilm to sustain environmental changes, and the impact of these changes on the co-occurrence of H. nitrativorans and M. nitratireducenticrescens.

Methods: In a first set of assays, the original biofilm (OB) was cultivated in an artificial seawater (ASW) medium under anoxic conditions to colonize new carriers. The new formed biofilm was then subjected to short exposures (1-5 days) of a range of NaCl, methanol, nitrate (NO3-) and nitrite (NO2-) concentrations, and to different pHs and temperatures. In a second set of assays, the OB was cultivated in ASW medium for five weeks with (i) a range of NaCl concentrations, (ii) four combinations of NO3-/methanol concentrations and temperatures, (iii) NO2-, and (iv) under oxic conditions. Finally, the OB was cultivated for five weeks in the commercial Instant Ocean (IO) seawater. The growth of the biofilm and the dynamics of NO3- and NO2- were determined. The levels of M. nitratireducenticrescens and H. nitrativorans were measured by qPCR.

Results: In the first set of assays, the biofilm cultures had the capacity to sustain denitrifying activities in most of the tested conditions. Inhibition occurred when they were exposed to high pH (10) or to high methanol concentration (1.5%). In the second set of assays, the highest specific denitrification rates occurred with the biofilm cultures cultivated at 64.3 mM NO3- and 0.45% methanol, and at 30 °C. Poor biofilm development occurred with the biofilm cultures cultivated at 5% and 8% NaCl. In all biofilm cultures cultivated in ASW at 2.75% NaCl, H. nitrativorans strain NL23 decreased by three orders of magnitude in concentrations compared to that found in OB. This decrease coincided with the increase of the same magnitude of a subpopulation of M. nitratireducenticrescens (strain GP59 as representative). In the biofilm cultures cultivated at low NaCl concentrations (0% to 1.0%), persistence of H. nitrativorans strain NL23 was observed, with the gradual increase in concentrations of M. nitratireducenticrescens strain GP59. High levels of H. nitrativorans strain NL23 were found in the IO biofilm cultures. The concentrations of M. nitratireducenticrescens strain JAM1 were lower in most of the biofilms cultures than in OB.

Conclusions: These results demonstrate the plasticity of the marine methylotrophic denitrifying biofilm in adapting to different environmental changes. The NaCl concentration is a crucial factor in the dynamics of H. nitrativorans strain NL23, for which growth was impaired above 1% NaCl in the ASW-based biofilm cultures in favor of M. nitratireducenticrescens strain GP59.}, } @article {pmid31423359, year = {2019}, author = {Villemur, R and Payette, G and Geoffroy, V and Mauffrey, F and Martineau, C}, title = {Dynamics of a methanol-fed marine denitrifying biofilm: 2-impact of environmental changes on the microbial community.}, journal = {PeerJ}, volume = {7}, number = {}, pages = {e7467}, doi = {10.7717/peerj.7467}, pmid = {31423359}, issn = {2167-8359}, abstract = {Background: The biofilm of a methanol-fed, marine denitrification system is composed of a multi-species microbial community, among which Hyphomicrobium nitrativorans and Methylophaga nitratireducenticrescens are the principal bacteria involved in the denitrifying activities. To assess its resilience to environmental changes, the biofilm was cultivated in artificial seawater (ASW) under anoxic conditions and exposed to a range of specific environmental conditions. We previously reported the impact of these changes on the denitrifying activities and the co-occurrence of H. nitrativorans strain NL23 and M. nitratireducenticrescens in the biofilm cultures. Here, we report the impact of these changes on the dynamics of the overall microbial community of the denitrifying biofilm.

Methods: The original biofilm (OB) taken from the denitrification system was cultivated in ASW under anoxic conditions with a range of NaCl concentrations, and with four combinations of nitrate/methanol concentrations and temperatures. The OB was also cultivated in the commercial Instant Ocean seawater (IO). The bacterial diversity of the biofilm cultures and the OB was determined by 16S ribosomal RNA gene sequences. Culture approach was used to isolate other denitrifying bacteria from the biofilm cultures. The metatranscriptomes of selected biofilm cultures were derived, along with the transcriptomes of planktonic pure cultures of H. nitrativorans strain NL23 and M. nitratireducenticrescens strain GP59.

Results: High proportions of M. nitratireducenticrescens occurred in the biofilm cultures. H. nitrativorans strain NL23 was found in high proportion in the OB, but was absent in the biofilm cultures cultivated in the ASW medium at 2.75% NaCl. It was found however in low proportions in the biofilm cultures cultivated in the ASW medium at 0-1% NaCl and in the IO biofilm cultures. Denitrifying bacterial isolates affiliated to Marinobacter spp. and Paracoccus spp. were isolated. Up regulation of the denitrification genes of strains GP59 and NL23 occurred in the biofilm cultures compared to the planktonic pure cultures. Denitrifying bacteria affiliated to the Stappia spp. were metabolically active in the biofilm cultures.

Conclusions: These results illustrate the dynamics of the microbial community in the denitrifying biofilm cultures in adapting to different environmental conditions. The NaCl concentration is an important factor affecting the microbial community in the biofilm cultures. Up regulation of the denitrification genes of M. nitratireducenticrescens strain GP59 and H. nitrativorans strain NL23 in the biofilm cultures suggests different mechanisms of regulation of the denitrification pathway in the biofilm. Other denitrifying heterotrophic bacteria are present in low proportions, suggesting that the biofilm has the potential to adapt to heterotrophic, non-methylotrophic environments.}, } @article {pmid31421719, year = {2019}, author = {Velmourougane, K and Prasanna, R and Supriya, P and Ramakrishnan, B and Thapa, S and Saxena, AK}, title = {Transcriptome profiling provides insights into regulatory factors involved in Trichoderma viride-Azotobacter chroococcum biofilm formation.}, journal = {Microbiological research}, volume = {227}, number = {}, pages = {126292}, doi = {10.1016/j.micres.2019.06.002}, pmid = {31421719}, issn = {1618-0623}, abstract = {Azotobacter chroococcum (Az) and Trichoderma viride (Tv) represent agriculturally important and beneficial plant growth promoting options which contribute towards nutrient management and biocontrol, respectively. When Az and Tv are co-cultured, they form a biofilm, which has proved promising as an inoculant in several crops; however, the basic aspects related to regulation of biofilm formation were not investigated. Therefore, whole transcriptome sequencing (Illumina NextSeq500) and gene expression analyses were undertaken, related to biofilm formation vis a vis Tv and Az growing individually. Significant changes in the transcriptome profiles of biofilm were recorded and validated through qPCR analyses. In-depth evaluation also identified several genes (phoA, phoB, glgP, alg8, sipW, purB, pssA, fadD) specifically involved in biofilm formation in Az, Tv and Tv-Az. Genes coding for RNA-dependent RNA polymerase, ABC transporters, translation elongation factor EF-1, molecular chaperones and double homeobox 4 were either up-regulated or down-regulated during biofilm formation. To our knowledge, this is the first report on the modulation of gene expression in an agriculturally beneficial association, as a biofilm. Our results provide insights into the regulatory factors involved during biofilm formation, which can help to improve the beneficial effects and develop more effective and promising plant- microbe associations.}, } @article {pmid31421577, year = {2019}, author = {Song, W and Qi, R and Zhao, L and Xue, N and Wang, L and Yang, Y}, title = {Bacterial community rather than metals shaping metal resistance genes in water, sediment and biofilm in lakes from arid northwestern China.}, journal = {Environmental pollution (Barking, Essex : 1987)}, volume = {254}, number = {Pt A}, pages = {113041}, doi = {10.1016/j.envpol.2019.113041}, pmid = {31421577}, issn = {1873-6424}, abstract = {Lakes in arid northwestern China are valuable freshwater resources that drive socioeconomic development. Environmental pollution can significantly influence the composition of microbial communities and the distribution of functional genes in lakes. This study investigated heavy metal pollution to identify possible correlations with metal resistance genes (MRGs) and bacterial community composition in water, sediment and biofilm samples from Bosten Lake and Ebi Lake in northwestern China. High levels of zinc were detected in all samples. However, the metals detected in the sediment samples of both lakes were determined to be at low risk levels according to an ecological index. The mercury resistance gene subtype merP had the greatest average abundance (4.61 × 10-3 copies per 16S rRNA) among all the samples, followed by merA and merC. The high abundance of merA in the pelagic zone rather than in benthic sediment suggests that the pelagic microbial community was important in mercury reduction. Proteobacteria were the main phylum found in the microbial communities in all samples. However, microbial communities in most of the water, sediment and biofilm samples had different compositions, indicating that the habitat niche plays an important role in shaping the bacterial communities in lakes. The microbial community, rather than the heavy metals, was the main driver of MRG distribution. The abundances of some bacterial genera involved in the decomposition of organic matter and the terrestrial nitrogen cycle were negatively correlated with heavy metals. This result suggests that metal pollution can adversely affect the biogeochemical processes that occur in lakes.}, } @article {pmid31421576, year = {2019}, author = {Lukwambe, B and Zhao, L and Nicholaus, R and Yang, W and Zhu, J and Zheng, Z}, title = {Bacterioplankton community in response to biological filters (clam, biofilm, and macrophytes) in an integrated aquaculture wastewater bioremediation system.}, journal = {Environmental pollution (Barking, Essex : 1987)}, volume = {254}, number = {Pt A}, pages = {113035}, doi = {10.1016/j.envpol.2019.113035}, pmid = {31421576}, issn = {1873-6424}, abstract = {Integrated systems with appropriate bio-filters can be used to treat aquaculture effluents. However, the information on bio-filters that alters the ecological functions of the bacterioplankton community (BC) in biodegradation of the aquaculture effluents remains controversial. In this study, we implemented a comprehensive restoration technology combined with bio-filters [biofilm, clam (Tegillarca granosa), and macrophytes (Spartina anglica)] to investigate their influence on the stability of the BC and nutrient removal. We found that the diversity of BC was linked with biogeochemical factors in processing and upcycling nitrogen-rich effluents into high-value biomass. The BC exhibited significant distinct patterns in the bio-filter areas. Potential biomarkers for constrained harmfully algae-bacteria (Nitriliruptoraceae, Bacillales, and Rhodobacteraceae) and nutrient removal were significantly higher in the bio-filters areas. The bio-filters significantly promoted the restoration effects of N and P balance by reducing 82.34% of total nitrogen (TN) and 81.64% of total phosphorus (TP) loads at the water interface. The main mechanisms for TN and TP removal and nutrient transformation were achieved by assimilation and absorption by the emergent macrophytes (Spartina anglica). The bio-filters significantly influenced the biodegradability and resolvability of particulate organic matter through ammonification, nitrification, and denitrification of microbes, which meliorated the nutrient removal. Beside bio-filter effects, the BC was significantly controlled by abiotic factors [nitrate (NO3--N), dissolved oxygen (DO), total nitrogen (TN), and water temperature (WT)], and biotic factors (chlorophyll ɑ and green algae). Our study revealed that the co-existence system with bio-filters may greatly improve our understanding on the ecological functions of the BC in aquaculture systems. Overall, combined bio-filters provide an opportunity for the development of efficient and optimized aquaculture wastewater treatment technology.}, } @article {pmid31421403, year = {2019}, author = {Martín, ML and Dassie, SA and Valenti, LE and Giacomelli, CE}, title = {A simple surface biofunctionalization strategy to inhibit the biofilm formation by Staphylococcus aureus on solid substrates.}, journal = {Colloids and surfaces. B, Biointerfaces}, volume = {183}, number = {}, pages = {110432}, doi = {10.1016/j.colsurfb.2019.110432}, pmid = {31421403}, issn = {1873-4367}, abstract = {Staphylococcus aureus is an important opportunistic pathogen that causes a broad range of infections due to the bacteria capacity to form biofilms on medical devices. This work is aimed at inhibiting the biofilm formation by S. aureus on solid substrates using a simple surface biofunctionalization strategy. We previously found that surface biofunctionalization with structural perturbed albumin inhibited the initial stage of S. aureus adhesion. The current work extends this strategy with other plasma protein, fibrinogen, which in addition can be bond specifically to the cell wall-anchored proteins of S. aureus. The study of fibrinogen adsorption indicates that the fraction of surface-perturbed molecules is enlarged at long adsorption times and low protein concentration. In these conditions, a significant diminution of ca.60% of alive adhered bacteria were observed after 40 min and the biofilm formation was completely prevented. Thus, it seems that the inhibition of bacterial adhesion on substrates with surface-perturbed proteins represents a general trend even when specific interactions are present. On this basis, we developed a simple strategy to inhibit the formation of S. aureus biofilm, using thermally treated albumin or fibrinogen molecules prior to the substrate biofunctionalization. This strategy shows an excellent performance since the alive adhered bacteria diminishes ca. 90% at short incubation time, followed by the fully inhibition of biofilm formation. This novel and simple resource represents a change of the usual notion in avoiding post-surgery infections, mostly related to the use of medical devices.}, } @article {pmid31420537, year = {2019}, author = {Qin, Y and He, Y and She, Q and Larese-Casanova, P and Li, P and Chai, Y}, title = {Heterogeneity in respiratory electron transfer and adaptive iron utilization in a bacterial biofilm.}, journal = {Nature communications}, volume = {10}, number = {1}, pages = {3702}, doi = {10.1038/s41467-019-11681-0}, pmid = {31420537}, issn = {2041-1723}, support = {MCB1651732//National Science Foundation (NSF)/ ; }, abstract = {In Bacillus subtilis, robust biofilm formation requires large quantities of ferric iron. Here we show that this process requires preferential production of a siderophore precursor, 2,3-dihydroxybenzoate, instead of the siderophore bacillibactin. A large proportion of iron is associated extracellularly with the biofilm matrix. The biofilms are conductive, with extracellular iron potentially acting as electron acceptor. A relatively small proportion of ferric iron is internalized and boosts production of iron-containing enzymes involved in respiratory electron transfer and establishing strong membrane potential, which is key to biofilm matrix production. Our study highlights metabolic diversity and versatile energy generation strategies within B. subtilis biofilms.}, } @article {pmid31420126, year = {2019}, author = {Fulaz, S and Vitale, S and Quinn, L and Casey, E}, title = {Nanoparticle-Biofilm Interactions: The Role of the EPS Matrix.}, journal = {Trends in microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.tim.2019.07.004}, pmid = {31420126}, issn = {1878-4380}, abstract = {The negative consequences of biofilms are widely reported. A defining feature of biofilms is the extracellular matrix, a complex mixture of biomacromolecules, termed EPS, which contributes to reduced antimicrobial susceptibility. EPS targeting is a promising, but underexploited, approach to biofilm control allowing disruption of the matrix and thereby increasing the susceptibility to antimicrobials. Nanoparticles (NPs) can play a very important role as 'carriers' of EPS matrix disruptors, and several approaches have recently been proposed. In this review, we discuss the application of nanoparticles as antibiofilm technologies with a special emphasis on the role of the EPS matrix in the physicochemical regulation of the nanoparticle-biofilm interaction. We highlight the use of nanoparticles as a platform for a new generation of antibiofilm approaches.}, } @article {pmid31419460, year = {2019}, author = {Miryala, SK and Anbarasu, A and Ramaiah, S}, title = {Systems biology studies in Pseudomonas aeruginosa PA01 to understand their role in biofilm formation and multidrug efflux pumps.}, journal = {Microbial pathogenesis}, volume = {}, number = {}, pages = {103668}, doi = {10.1016/j.micpath.2019.103668}, pmid = {31419460}, issn = {1096-1208}, abstract = {The antimicrobial resistance (AMR) exhibited against broad spectrum and new generation antibiotics used for Pseudomonas infections is a major threat and renders the treatment ineffective. In our present study, we have used a computational approach to understand various drug resistance mechanisms which contribute to Multi-Drug Resistance (MDR) in P. aeruginosa. The interaction network of 60 AMR genes along with the 337 functional interactions was analyzed. Functional enrichment analysis of AMR genes has shown that the genes in the network are mainly associated with efflux pump mechanisms, alginate biosynthesis, biofilm formation, and ampC beta-lactamase biosynthesis. Interestingly, the genes phoP, phoQ, and cat genes are observed to have roles in more than one drug-resistant mechanism. The genes phoP and phoQ apart from their role in two-component regulatory systems also play major roles in multidrug efflux pumps and alteration in drug target. The gene cat involves in alteration of drug target and enzymatic inactivation. The interaction network analysis has shown that the AMR genes oprJ, oprM, oprN, ampC, gyrA, mexA, oprD, mexB and nfxB have higher number of direct interactors and they are considered as the hub nodes in the network and these genes can be used as potential drug targets for developing new drugs. The results from our study will be helpful in better understanding of the antibiotic resistance mechanisms in P. aeruginosa. The gene targets reported, can be used for new drug discovery against Pseudomonas infections.}, } @article {pmid31413280, year = {2019}, author = {Inui, T and Palmer, RJ and Shah, N and Li, W and Cisar, JO and Wu, CD}, title = {Effect of mechanically stimulated saliva on initial human dental biofilm formation.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {11805}, doi = {10.1038/s41598-019-48211-3}, pmid = {31413280}, issn = {2045-2322}, support = {Intramural Research Program//U.S. Department of Health & Human Services | NIH | National Institute of Dental and Craniofacial Research (NIDCR)/ ; NA//Mars Incorporated | Wm. Wrigley Jr. Company (Wrigley Company)/ ; }, abstract = {This study evaluated the impact of mechanically stimulated saliva on initial bacterial colonization. Interaction between oral bacteria and both unstimulated and stimulated saliva was examined in vitro by laying labeled bacteria over SDS-PAGE-separated salivary proteins. The effects of chewing on in vivo biofilm, microbial composition, and spatial arrangement were examined in two human volunteers using an intraoral stent containing retrievable enamel chips. In vitro experiments showed that bacterial binding to proteins from stimulated saliva was lower than that to proteins from unstimulated saliva. Lack of binding activity was noted with Streptococcus mutans and Lactobacillus casei. Human Oral Microbe Identification Microarray (HOMIM) analyses revealed a consistent chewing-related increase in the binding of Streptococcus anginosus and Streptococcus gordonii. Immunofluorescence microscopy demonstrated the presence of multi-species colonies and cells bearing different serotypes of the coaggregation-mediating streptococcal cell-surface receptor polysaccharides (RPS). Differences in bacterial colonization were noted between the two volunteers, while the type 4 RPS-reactive serotype was absent in one volunteer. Cells reacting with antibody against Rothia or Haemophilus were prominent in the early biofilm. While analysis of the data obtained demonstrated inter-individual variations in both in vitro and in vivo bacterial binding patterns, stimulating saliva with multiple orosensory stimuli may modulate oral bacterial colonization of tooth surfaces.}, } @article {pmid31412645, year = {2019}, author = {Magin, V and Garrec, N and Andrés, Y}, title = {Selection of Bacteriophages to Control In Vitro 24 h Old Biofilm of Pseudomonas Aeruginosa Isolated from Drinking and Thermal Water.}, journal = {Viruses}, volume = {11}, number = {8}, pages = {}, doi = {10.3390/v11080749}, pmid = {31412645}, issn = {1999-4915}, abstract = {Pseudomonas aeruginosa is an opportunistic pathogen that causes public healthcare issues. In moist environments, this Gram-negative bacterium persists through biofilm-associated contamination on surfaces. Bacteriophages are seen as a promising alternative strategy to chemical biocides. This study evaluates the potential of nine lytic bacteriophages as biocontrol treatments against nine environmental P. aerginosa isolates. The spot test method is preliminarily used to define the host range of each virus and to identify their minimum infectious titer, depending on the strain. Based on these results, newly isolated bacteriophages 14.1, LUZ7, and B1 are selected and assessed on a planktonic cell culture of the most susceptible isolates (strains MLM, D1, ST395E, and PAO1). All liquid infection assays are achieved in a mineral minimum medium that is much more representative of real moist environments than standard culture medium. Phages 14.1 and LUZ7 eliminate up to 90% of the PAO1 and D1 bacterial strains. Hence, their effectiveness is evaluated on the 24 h old biofilms of these strains, established on a stainless steel coupon that is characteristic of materials found in thermal and industrial environments. The results of quantitative PCR viability show a maximum reduction of 1.7 equivalent Log CFU/cm2 in the coupon between treated and untreated surfaces and shed light on the importance of considering the entire virus/host/environment system for optimizing the treatment.}, } @article {pmid31411265, year = {2019}, author = {Yu, MK and Kim, MA and Rosa, V and Hwang, YC and Del Fabbro, M and Sohn, WJ and Min, KS}, title = {Role of extracellular DNA in Enterococcus faecalis biofilm formation and its susceptibility to sodium hypochlorite.}, journal = {Journal of applied oral science : revista FOB}, volume = {27}, number = {}, pages = {e20180699}, doi = {10.1590/1678-7757-2018-0699}, pmid = {31411265}, issn = {1678-7765}, abstract = {OBJECTIVE: This study investigated the role of extracellular deoxyribonucleic acid (eDNA) on Enterococcus faecalis (E. faecalis) biofilm and the susceptibility of E. faecalis to sodium hypochlorite (NaOCl).

METHODOLOGY: E. faecalis biofilm was formed in bovine tooth specimens and the biofilm was cultured with or without deoxyribonuclease (DNase), an inhibitor of eDNA. Then, the role of eDNA in E. faecalis growth and biofilm formation was investigated using colony forming unit (CFUs) counting, eDNA level assay, crystal violet staining, confocal laser scanning microscopy, and scanning electron microscopy. The susceptibility of E. faecalis biofilm to low (0.5%) or high (5%) NaOCl concentrations was also analyzed by CFU counting.

RESULTS: CFUs and biofilm formation decreased significantly with DNase treatment (p<0.05). The microstructure of DNase-treated biofilms exhibited less structured features when compared to the control. The volume of exopolysaccharides in the DNase-treated biofilm was significantly lower than that of control (p<0.05). Moreover, the CFUs, eDNA level, biofilm formation, and exopolysaccharides volume were lower when the biofilm was treated with DNase de novo when compared to when DNase was applied to matured biofilm (p<0.05). E. faecalis in the biofilm was more susceptible to NaOCl when it was cultured with DNase (p<0.05). Furthermore, 0.5% NaOCl combined with DNase treatment was as efficient as 5% NaOCl alone regarding susceptibility (p>0.05).

CONCLUSIONS: Inhibition of eDNA leads to decrease of E. faecalis biofilm formation and increase of susceptibility of E. faecalis to NaOCl even at low concentrations. Therefore, our results suggest that inhibition of eDNA would be beneficial in facilitating the efficacy of NaOCl and reducing its concentration.}, } @article {pmid31410982, year = {2019}, author = {Petrovich, ML and Ben Maamar, S and Hartmann, EM and Murphy, BT and Poretsky, RS and Wells, GF}, title = {Viral composition and context in metagenomes from biofilm and suspended growth municipal wastewater treatment plants.}, journal = {Microbial biotechnology}, volume = {}, number = {}, pages = {}, doi = {10.1111/1751-7915.13464}, pmid = {31410982}, issn = {1751-7915}, support = {C-060//Chicago Biomedical Consortium/ ; //Northwestern University/ ; //Searle Funds at The Chicago Community Trust/ ; }, abstract = {Wastewater treatment plants (WWTPs) contain high density and diversity of viruses which can significantly impact microbial communities in aquatic systems. While previous studies have investigated viruses in WWTP samples that have been specifically concentrated for viruses and filtered to exclude bacteria, little is known about viral communities associated with bacterial communities throughout wastewater treatment systems. Additionally, differences in viral composition between attached and suspended growth wastewater treatment bioprocesses are not well characterized. Here, shotgun metagenomics was used to analyse wastewater and biomass from transects through two full-scale WWTPs for viral composition and associations with bacterial hosts. One WWTP used a suspended growth activated sludge bioreactor and the other used a biofilm reactor (trickling filter). Myoviridae, Podoviridae and Siphoviridae were the dominant viral families throughout both WWTPs, which are all from the order Caudovirales. Beta diversity analysis of viral sequences showed that samples clustered significantly both by plant and by specific sampling location. For each WWTP, the overall bacterial community structure was significantly different than community structure of bacterial taxa associated with viral sequences. These findings highlight viral community composition in transects through different WWTPs and provide context for dsDNA viral sequences in bacterial communities from these systems.}, } @article {pmid31410606, year = {2019}, author = {Wang, Z and Shi, LD and Lai, CY and Zhao, HP}, title = {Methane oxidation coupled to vanadate reduction in a membrane biofilm batch reactor under hypoxic condition.}, journal = {Biodegradation}, volume = {}, number = {}, pages = {}, doi = {10.1007/s10532-019-09887-6}, pmid = {31410606}, issn = {1572-9729}, support = {LR17B070001//Natural Science Funds for Distinguished Young Scholar of Zhejiang Province/ ; 21577123//National Natural Science Foundation of China/ ; 51878596//National Natural Science Foundation of China/ ; 2018YFC1802203//National Key Technology R&D Program/ ; }, abstract = {This study shows vanadate (V(V)) reduction in a methane (CH4) based membrane biofilm batch reactor when the concentration of dissolved oxygen (O2) was extremely low. V(IV) was the dominant products formed from V(V) bio-reduction, and majority of produced V(IV) transformed into precipitates with green color. Quantitative polymerase chain reaction and Illumina sequencing analysis showed that archaea methanosarcina were significantly enriched. Metagenomic predictive analysis further showed the enrichment of genes associated with reverse methanogenesis pathway, the key CH4-activating mechanism for anaerobic methane oxidation (AnMO), as well as the enrichment of genes related to acetate synthesis, in archaea. The enrichment of aerobic methanotrophs Methylococcus and Methylomonas implied their role in CH4 activation using trace level of O2, or their participation in V(V) reduction.}, } @article {pmid31410037, year = {2019}, author = {Bidossi, A and Bottagisio, M and De Grandi, R and Drago, L and De Vecchi, E}, title = {Chlorquinaldol, a topical agent for skin and wound infections: anti-biofilm activity and biofilm-related antimicrobial cross-resistance.}, journal = {Infection and drug resistance}, volume = {12}, number = {}, pages = {2177-2189}, doi = {10.2147/IDR.S211007}, pmid = {31410037}, issn = {1178-6973}, abstract = {Purpose: Persistence of skin and wound infections is nowadays accepted being linked to bacterial biofilms, which are highly recalcitrant to treatments and contribute to maintain a constant inflammation state and prevent a correct healing. Topical antimicrobials are the most common first-line self-medications; however, treatment failure is not uncommon and emerging resistance to antibiotics is alarming. Chlorquinaldol is an antimicrobial with a wide spectrum of activity and desirable characteristics for topical application. Aim of this study was to evaluate the efficacy of chlorquinaldol to prevent or eradicate S. aureus and P. aeruginosa biofilms, in comparison to classic topical antibiotics like gentamicin and fusidic acid.

Methods: Minimum inhibitory concentrations (MIC) were assessed for each strain and subinhibitory concentrations (½ and ¼ MIC) were used in the biofilm assay. Antimicrobial assays were performed during biofilm formation or were applied on mature biofilms and were evaluated by means of crystal violet assay and confocal laser scan microscopy.

Results: Chlorquinaldol and gentamicin were the most effective antimicrobials in both eradicating and preventing pathogens biofilm; however, resistance to methicillin and impermeability to carbapenems impaired chlorquinaldol effect. In addition, similarly to other hydroxyquinolines, aspecific metal chelation is here proposed as chlorquinaldol mode of action.

Conclusion: Relying on an acceptable antibiofilm and a wide spectrum of activity, an aspecific mode of action and consequent absence of resistance development, chlorquinaldol proved to be a good antimicrobial for topical use.}, } @article {pmid31409687, year = {2019}, author = {Jung, YC and Lee, MA and Lee, KH}, title = {Role of Flagellin-Homologous Proteins in Biofilm Formation by Pathogenic Vibrio Species.}, journal = {mBio}, volume = {10}, number = {4}, pages = {}, doi = {10.1128/mBio.01793-19}, pmid = {31409687}, issn = {2150-7511}, abstract = {The pathogenic bacterium Vibrio vulnificus exhibits the ability to form biofilm, for which initiation is dependent upon swimming motility by virtue of a polar flagellum. The filament of its flagellum is composed of multiple flagellin subunits, FlaA, -B, -C, and -D. In V. vulnificus genomes, however, open reading frames (ORFs) annotated by FlaE and -F are also present. Although neither FlaE nor FlaF is involved in filament formation and cellular motility, they are well expressed and secreted to the extracellular milieu through the secretion apparatus for flagellar assembly. In the extrapolymeric matrix of V. vulnificus biofilm, significant levels of FlaEF were detected. Mutants defective in both flaE and flaF formed significantly decreased biofilms compared to the wild-type biofilm. Thus, the potential role of FlaEF during the biofilm-forming process was investigated by exogenous addition of recombinant FlaEF (rFlaEF) to the biofilm assays. The added rFlaE and rFlaF were predominantly incorporated into the biofilm matrix formed by the wild type. However, biofilms formed by a mutant defective in exopolysaccharide (EPS) biosynthesis were not affected by added FlaEF. These results raised a possibility that FlaEF specifically interact with EPS within the biofilm matrix. In vitro pulldown assays using His-tagged rFlaEF or rFlaC revealed the specific binding of EPS to rFlaEF but not to rFlaC. Taken together, our results demonstrate that V. vulnificus FlaEF, flagellin-homologous proteins (FHPs), are crucial for biofilm formation by directly interacting with the essential determinant for biofilm maturation, EPS. Further analyses performed with other pathogenic Vibrio species demonstrated both the presence of FHPs and their important role in biofilm formation.IMPORTANCE Flagellar filaments of the pathogenic Vibrio species, including V. vulnificus, V. parahaemolyticus, and V. cholerae, are composed of multiple flagellin subunits. In their genomes, however, there are higher numbers of the ORFs encoding flagellin-like proteins than the numbers of flagellin subunits required for filament assembly. Since these flagellin-homologous proteins (FHPs) are well expressed and excreted to environments via a flagellin transport channel, their extracellular role in the pathogenic Vibrio has been enigmatic. Their biological significance, which is not related with flagellar functions, has been revealed to be in maturation of biofilm structures. Among various components of the extracellular polymeric matrix produced in the V. vulnificus biofilms, the exopolysaccharides (EPS) are dominant constituents and crucial in maturation of biofilms. The enhancing role of the V. vulnificus FHPs in biofilm formation requires the presence of EPS, as indicated by highly specific interactions among two FHPs and three EPS.}, } @article {pmid31408199, year = {2019}, author = {Ali, IAA and Cheung, BPK and Yau, JYY and Matinlinna, JP and Lévesque, CM and Belibasakis, GN and Neelakantan, P}, title = {The influence of substrate surface conditioning and biofilm age on the composition of Enterococcus faecalis biofilms.}, journal = {International endodontic journal}, volume = {}, number = {}, pages = {}, doi = {10.1111/iej.13202}, pmid = {31408199}, issn = {1365-2591}, abstract = {AIM: To investigate the null hypothesis that neither the surface conditioning (collagen, serum, saliva) of HA discs, nor the biofilm age (3 days vs 21 days) have a significant effect on the cellular and matrix composition of biofilms, using Enterococcus faecalis as the model organism.

METHODOLOGY: Sterile Hydroxyapatite (HA) discs were conditioned with collagen, saliva or serum, and inoculated with E. faecalis to form 3-day and 21-day-old biofilms. Unconditioned discs served as controls. The biofilms were analysed using culture-dependent and independent (confocal microscopy and biochemical analysis) methods, to determine the colony forming units (CFU) and the biofilm matrix composition (polysaccharides and proteins), respectively. Statistical analyses were performed using appropriate parametric and non-parametric tests (P=0.05).

RESULTS: Collagen conditioning significantly increased the number of CFUs in the 21-day biofilms, compared to the 3-day biofilms (P<0.05). Although the biochemical analysis revealed that surface conditioning had no significant effect on the total carbohydrate content in the 21-day biofilms, confocal microscopic analysis revealed that collagen and saliva conditioning selectively increased the polysaccharide content of 21-day biofilms, compared to the 3-day biofilms (P<0.05).

CONCLUSIONS: The results of this study raise an important methodological concern that the substrate conditioning substances and biofilm age differentially influence the cellular and extracellular matrix components of E. faecalis biofilms.}, } @article {pmid31407877, year = {2019}, author = {Nie, L and Li, Y and Chen, S and Li, K and Huang, Y and Zhu, Y and Sun, Z and Zhang, J and He, Y and Cui, M and Wei, S and Qiu, F and Zhong, C and Liu, W}, title = {Biofilm Nanofibers-Coated Separator for Dendrite-Free Lithium Metal Anode and Ultrahigh-Rate Lithium Batteries.}, journal = {ACS applied materials & interfaces}, volume = {}, number = {}, pages = {}, doi = {10.1021/acsami.9b08656}, pmid = {31407877}, issn = {1944-8252}, abstract = {Rechargeable batteries that combine high energy density with high power density are highly demanded. However, the wide utilization of lithium metal anode is limited by the uncontrollable dendrite growth and the conventional lithium-ion batteries (LIBs) commonly suffer from low rate capability. Here, we for the first time develop a biofilm-coated separator for high-energy and high-power batteries. It reveals that the coating of Escherichia coli protein nanofibers can improve electrolyte wettability and enhance adhesion between separators and electrodes. Thus, lithium dendrite growth is impeded due to the uniform distribution of Li-ion flux. The modified separator also enables the stable cycling of high-voltage Li|Li1.2Mn0.6Ni0.2O2 cells at an extremely high rate of 20 C, delivering a high specific capacity of 83.1 mAh g-1, which exceeds the conventional counterpart. In addition, the modified separator in the Li4Ti5O12|Li1.2Mn0.6Ni0.2O2 full cell also exhibits a larger capacity of 68.2 mAh g-1 at 10 C than the uncoated separator of 48.1 mAh g-1. Such remarkably performances of the modified separators arise from the conformal, adhesive and endurable coating of biofilm nanofibers. Our work opens up a new opportunity for protein-based biomaterials in practical application of high-energy and high-power batteries.}, } @article {pmid31407437, year = {2019}, author = {Daubert, DM and Weinstein, BF}, title = {Biofilm as a risk factor in implant treatment.}, journal = {Periodontology 2000}, volume = {81}, number = {1}, pages = {29-40}, doi = {10.1111/prd.12280}, pmid = {31407437}, issn = {1600-0757}, abstract = {This article summarizes the microbiological findings at dental implants, drawing distinctions between the peri-implant microbiome and the periodontal microbiome, and summarizes what is known regarding biofilm as a risk factor for specific stages of implant treatment. Targeted microbial analysis is reviewed as well as the latest results from open-ended sequencing of the peri-implant flora. At this time there remains a lack of consensus for a specific microbial profile that is associated with peri-implantitis, suggesting that there may be other factors which influence the microbiome such as titanium surface dissolution. Therapeutic interventions to address the biofilm are presented at the preoperative, perioperative, and postoperative stages. Evidence supports that perioperative chlorhexidine reduces biofilm-related implant complications and failure. Regular maintenance for dental implants is also shown to reduce peri-implant mucositis and implant failure. Maintenance procedures should aim to disrupt the biofilm without damaging the titanium dioxide surface layer in an effort to prevent further oxidation. Evidence supports the use of glycine powder air polishing as a valuable adjunct to conventional therapies for use at implant maintenance visits. For the treatment of peri-implantitis, nonsurgical therapy has not been shown to be effective, and while surgical intervention is not always predictable, it has been shown to be superior to nonsurgical treatment for decontamination of the implant surface that is not covered by bone.}, } @article {pmid31406097, year = {2019}, author = {Saad, A and Nikaido, T and Abdou, A and Matin, K and Burrow, MF and Tagami, J}, title = {Inhibitory effect of zinc-containing desensitizer on bacterial biofilm formation and root dentin demineralization.}, journal = {Dental materials journal}, volume = {}, number = {}, pages = {}, doi = {10.4012/dmj.2018-352}, pmid = {31406097}, issn = {1881-1361}, abstract = {This study compared the effect of a novel zinc containing, Caredyne Shield (CS), and a fluoroaluminocalciumsilicate-based, Nanoseal (NS) desensitizers on dentin tubule occlusion, inhibition of Streptococcus mutans (S. mutans) biofilm growth, and resistance to bacterial demineralization. Desensitizers were applied to simulated hypersensitive bovine dentin, with distilled water used as a control. S. mutans biofilms were grown on the surface of each specimen in an oral biofilm simulator. CS showed the least bacterial count and water insoluble glucan amount followed by NS. Transverse micro radiography revealed that both CS and NS showed significant reduction in mineral loss and lesion depth of the associated lesion. Scanning electron micrographs showed that the two desensitizers formed obvious depositions on the dentin surfaces, occlusion of tubules and mineral tag formation.}, } @article {pmid31405860, year = {2019}, author = {Willems, HME and Stultz, JS and Coltrane, ME and Fortwendel, JP and Peters, BM}, title = {Disparate Candida albicans biofilm formation in clinical lipid emulsions due to capric acid mediated inhibition.}, journal = {Antimicrobial agents and chemotherapy}, volume = {}, number = {}, pages = {}, doi = {10.1128/AAC.01394-19}, pmid = {31405860}, issn = {1098-6596}, abstract = {Receipt of parenteral nutrition (PN) remains an independent risk factor for developing catheter-related blood stream infections (CR-BSI) caused by fungi, including the polymorphic fungus Candida albicans that is notoriously adept at forming drug-resistant biofilm structures. Among a variety of macronutrients, PN solutions contain lipid emulsions to supply daily essential fats and are often delivered via central venous catheters (CVC). Therefore, using an in vitro biofilm model system, we sought to determine whether various clinical lipid emulsions differentially impacted biofilm growth in C. albicans We observed that lipid emulsions Intralipid® and Omegaven® both stimulated C. albicans biofilm formation during growth in minimal medium or a macronutrient PN solution. Conversely, Smoflipid® inhibited C. albicans biofilm formation by approximately 50%. Follow up studies revealed that while Smoflipid did not impair C. albicans growth, it did significantly inhibit hypha formation and hyphal elongation. Moreover, growth inhibition could be recapitulated in Intralipid® when supplemented with capric acid-a fatty acid present in Smoflipid® but absent in Intralipid®. Capric acid was also found to dose-dependently inhibit C. albicans biofilm formation in PN solutions. This is the first study to directly compare different clinical lipid emulsions for their capacity to affect C. albicans biofilm growth. Results derived from this study necessitate further research regarding different lipid emulsions and rates of fungal-associated CR-BSIs.}, } @article {pmid31405233, year = {2019}, author = {Kwiecińska-Piróg, J and Skowron, K and Bogiel, T and Białucha, A and Przekwas, J and Gospodarek-Komkowska, E}, title = {Vitamin C in the Presence of Sub-Inhibitory Concentration of Aminoglycosides and Fluoroquinolones Alters Proteus mirabilis Biofilm Inhibitory Rate.}, journal = {Antibiotics (Basel, Switzerland)}, volume = {8}, number = {3}, pages = {}, doi = {10.3390/antibiotics8030116}, pmid = {31405233}, issn = {2079-6382}, abstract = {Vitamin C has antimicrobial activity and is often used as an oral supplement accompanying antibiotic treatment in urinary tract infections (UTI). Proteus mirabilis is the third common species responsible for UTIs that are mostly treated with fluoroquinolones or aminoglycosides. Treatment of the UTI caused by P. mirabilis is problematic due to the ability to form biofilm on the urinary catheters. The aim of the study was to evaluate the influence of ascorbic acid in combination with antibiotics on P. mirabilis abilities to form biofilm. The susceptibility of P. mirabilis reference strain ATCC® 29906™ and four clinical strains isolated from the urine samples of patients with urinary catheter were evaluated according to EUCAST recommendations. The influence of ascorbic acid (0.4 mg × mL-1) in combination with antibiotics on biofilm formation was evaluated spectrophotometrically. Aminoglycosides at sub-inhibitory concentrations more successfully limited biofilm formation by P. mirabilis strains without ascorbic acid addition. Inhibition rate differences at the lowest concentrations of gentamicin and amikacin were statistically significant (p ≤ 0.05). Ascorbic acid addition to the culture medium limited the inhibitory effect of fluoroquinolones, facilitating biofilm formation by P. mirabilis strains. The addition of ascorbic acid during aminoglycosides therapy may disturb treatment of urinary tract infections related to the presence of P. mirabilis biofilm.}, } @article {pmid31405172, year = {2019}, author = {Guzzon, A and Di Pippo, F and Congestri, R}, title = {Wastewater Biofilm Photosynthesis in Photobioreactors.}, journal = {Microorganisms}, volume = {7}, number = {8}, pages = {}, doi = {10.3390/microorganisms7080252}, pmid = {31405172}, issn = {2076-2607}, support = {QLK3-CT2002-01938//EC/ ; }, abstract = {Photosynthetic performance of algal-bacterial biofilms from an Italian wastewater treatment plant was studied in a flow-lane photobioreactor at different irradiances, temperatures, and flow regime to evaluate the effects of these environmental parameters on biofilms' functioning, in view of application of these communities in wastewater biological treatment. Pulse amplitude modulated fluorescence was used to estimate the effective quantum yield of PSII (ΔF/Fm') of the light-acclimated biofilms and to perform rapid light curves (RLCs) for the determination of the photosynthetic parameters (rel.ETRmax, α, Ik). Chl a, ash free dry weight (AFDW), and dry weight (DW) were measured to assess phototrophic and whole biofilm biomass development over time. From the analysis of photosynthetic parameter variation with light intensity, temperature and flow rate, it was possible to identify the set of experimental values favoring biofilm photosynthetic activity. Biomass increased over time, especially at the highest irradiances, where substrata were fastly colonized and mature biofilms developed at all temperatures and flow conditions tested.}, } @article {pmid31404843, year = {2019}, author = {Kłodzińska, SN and Wan, F and Jumaa, H and Sternberg, C and Rades, T and Nielsen, HM}, title = {Utilizing nanoparticles for improving anti-biofilm effects of azithromycin: A head-to-head comparison of modified hyaluronic acid nanogels and coated poly (lactic-co-glycolic acid) nanoparticles.}, journal = {Journal of colloid and interface science}, volume = {555}, number = {}, pages = {595-606}, doi = {10.1016/j.jcis.2019.08.006}, pmid = {31404843}, issn = {1095-7103}, abstract = {HYPOTHESIS: The widespread resistance of bacteria to traditional antibiotic treatments has expedited the search for novel therapies against these pathogens. The hypothesis of this work is that two distinctively different polymeric delivery systems, specifically D-α-tocopherol polyethylene glycol 1000 succinate (TPGS)-poly(lactic-co-glycolic acid) (PLGA) nanoparticles and octenyl succinic anhydride-modified low molecular weight hyaluronic acid (OSA-HA) nanogels may be used to substantially improve the properties of azithromycin, allowing its use for effective treatment of Pseudomonas aeruginosa biofilm infections.

EXPERIMENTS: Azithromycin was encapsulated in both delivery systems and the physicochemical properties of the loaded delivery systems, including size, surface charge and drug loading were evaluated. Additionally, particle interaction with a mucin layer, penetration into a bacterial biofilm, prevention of biofilm formation and eradication of pre-formed biofilms, the influence on production of virulence factors and bacterial motility as well as cytotoxicity towards hepatocytes and lung epithelial cells were compared head-to-head.

FINDINGS: The TPGS-PLGA nanoparticles noticeably improved the antimicrobial activity and the biofilm prevention activity of azithromycin whereas the OSA-HA nanogels showed reduced mucin interactions together with improved reduction of pre-formed biofilms and maintained the low eukaryotic cell cytotoxicity of azithromycin.}, } @article {pmid31404739, year = {2019}, author = {Sun, G and Wan, J and Sun, Y and Li, H and Chang, C and Wang, Y}, title = {Enhanced removal of nitrate and refractory organic pollutants from bio-treated coking wastewater using corncobs as carbon sources and biofilm carriers.}, journal = {Chemosphere}, volume = {237}, number = {}, pages = {124520}, doi = {10.1016/j.chemosphere.2019.124520}, pmid = {31404739}, issn = {1879-1298}, abstract = {The quality of the bio-treated coking wastewater (BTCW) is difficult to meet increasingly stringent coking wastewater discharge standards and future wastewater recycling needs. In this study, the pre-treatment process of BTCW was installed including the two up-flow fixed-bed bioreactors (UFBRs) which were separately filled with alkali-pretreated or no alkali-pretreated corncobs used as solid carbon sources as well as biofilm carriers. Results showed that this pre-treatment process could significantly improve the biodegradability of BTCW and increase the C/N ratio. Thus, over 90% of residual nitrate in BTCW were removed stably. Furthermore, GC-MS analysis confirmed that the typical refractory organic matters decreased significantly after UFBRs pre-treatment. High-throughput sequencing analysis using 16S rRNA demonstrated that dominant denitrifiers, fermentative bacteria and refractory-organic-pollutants-degrading bacteria co-existed inside the UFBRs system. Compared with no alkali-pretreated corncobs, alkali-pretreated corncobs provided more porous structure and much stable release of carbon to guarantee the growth and the quantity of the functional bacteria such as denitrifiers. This study indicated that the UFBRs filled with alkali-pretreated corncobs could be utilized as an effective alternative for the enhanced treatment of the BTCW.}, } @article {pmid31404326, year = {2019}, author = {Wang, S and Wang, Y and Wang, Y and Duan, Z and Ling, Z and Wu, W and Tong, S and Wang, H and Deng, S}, title = {Theaflavin-3,3'-Digallate Suppresses Biofilm Formation, Acid Production, and Acid Tolerance in Streptococcus mutans by Targeting Virulence Factors.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1705}, doi = {10.3389/fmicb.2019.01705}, pmid = {31404326}, issn = {1664-302X}, abstract = {As one of the most important cariogenic pathogens, Streptococcus mutans has strong abilities to form biofilms, produce acid and tolerate acid. In present study, we found that theaflavin-3,3'-digallate (TF3) had an inhibitory effect on S. mutans UA159 in vitro. Visualized by field emission-scanning electron microscopy, the suppressed formation of S. mutans biofilms grown with TF3 at sub-inhibitory concentrations could be attributed to the reduced biofilm matrix, which was proven to contain glucans and extracellular DNA (eDNA). Glucan-reduced effect of TF3 was achieved by down-regulating expression levels of gtfB, gtfC, and gtfD encoding glucosyltransferases. Besides, TF3 reduced eDNA formation of S. mutans by negatively regulating lrgA, lrgB, and srtA, which govern cell autolysis and membrane vesicle components. Furthermore, TF3 also played vital roles in antagonizing preformed biofilms of S. mutans. Bactericidal effects of TF3 became significant when its concentrations increased more than twofold of minimum inhibitory concentration (MIC). Moreover, the capacities of S. mutans biofilms to produce acid and tolerate acid were significantly weakened by TF3 at MIC. Based on real-time PCR (RT-PCR) analysis, the mechanistic effects of TF3 were speculated to comprise the inhibition of enolase, lactate dehydrogenase, F-type ATPase and the agmatine deiminase system. Moreover, TF3 has been found to downregulate LytST, VicRK, and ComDE two component systems in S. mutans, which play critical roles in the regulatory network of virulence factors. Our present study found that TF3 could suppress the formation and cariogenic capacities of S. mutans biofilms, which will provide new strategies for anti-caries in the future.}, } @article {pmid31403663, year = {2019}, author = {Shafeeq, S and Pannanusorn, S and Elsharabasy, Y and Ramírez-Zavala, B and Morschhäuser, J and Römling, U}, title = {Impact of manganese on biofilm formation and cell morphology of Candida parapsilosis clinical isolates with different biofilm forming abilities.}, journal = {FEMS yeast research}, volume = {}, number = {}, pages = {}, doi = {10.1093/femsyr/foz057}, pmid = {31403663}, issn = {1567-1364}, abstract = {The commensal species Candida parapsilosis is an emerging human pathogen that has the ability to form biofilms. In this study, we explored the impact of the divalent cations cobalt (Co2+), copper (Cu2+), iron (Fe3+), manganese (Mn2+), nickel (Ni2+) and zinc (Zn2+) on biofilm formation of clinical isolates of C. parapsilosis with no, low and high biofilm-forming abilities at 30 and 37°C. All strains beside one isolate showed a concentration dependent enhancement of biofilm formation at 30°C in the presence of Mn2+ with a maximum at 2 mM. The biofilm forming ability of no- and low-biofilm forming isolates was more than two-fold enhanced in the presence of 2 mM Mn2+, while the effect in high biofilm forming isolate was significantly less pronounced. Of note, cells in the biofilms of no- and low-biofilm forming strains differentiated into yeast and pseudohyphal cells similar in morphology to high biofilm formers. The biofilm transcriptional activator BCR1 has a dual developmental role in the absence and presence of 2 mM Mn2+ as it promoted biofilm formation of no biofilm forming strains, and, surprisingly, suppressed cells of no biofilm forming strains to develop into pseudohyphae and/or hyphae. Thus, environmental conditions can significantly affect the amount of biofilm formation and cell morphology of C. parapsilosis with Mn2+ to overcome developmental blocks to trigger biofilm formation and to partially relieve BCR1 suppressed cell differentiation.}, } @article {pmid31402901, year = {2019}, author = {van Vugt, TAG and Arts, JJ and Geurts, JAP}, title = {Antibiotic-Loaded Polymethylmethacrylate Beads and Spacers in Treatment of Orthopedic Infections and the Role of Biofilm Formation.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1626}, doi = {10.3389/fmicb.2019.01626}, pmid = {31402901}, issn = {1664-302X}, abstract = {Polymethylmethacrylate (PMMA) also referred as (acrylic) bone cement is a non-degradable biomaterial that has been used in clinical orthopedic practice for several decades. PMMA can be used in a plain formulation, but is often used in an antibiotic-loaded formulation in (primary and revision) arthroplasty and in treatment of orthopedic infections as prosthetic joint infections (PJI) and chronic osteomyelitis. In treatment of PJIs antibiotic-loaded PMMA is often used as a carrier material for local antibiotic delivery in addition to treatment with systemic antibiotics. In this case, the antibiotic-loaded PMMA is often used as a spacer or as a bead chain. Since the introduction of PMMA as an antibiotic carrier there is a tremendous amount of scientific and clinical papers published, which studied numerous different aspects of antibiotic-loaded PMMA. This paper will review the research regarding basic principles of antibiotic-loaded PMMA as mechanism of action, antibiotic-release capacities, choice of antibiotics and influences on mechanical properties of PMMA. Subsequently, concerns regarding the application of antibiotic-loaded PMMA, biofilm formation, antibiotic resistance and local or systemic toxicity will be discussed. In addition to these subjects, the role of antibiotic loaded PMMA in clinical treatment of PJIs and chronic osteomyelitis is discussed in the final part of this paper.}, } @article {pmid31402749, year = {2019}, author = {Krantz, GP and Lucas, K and Wunderlich, EL and Hoang, LT and Avci, R and Siuzdak, G and Fields, MW}, title = {Bulk phase resource ratio alters carbon steel corrosion rates and endogenously produced extracellular electron transfer mediators in a sulfate-reducing biofilm.}, journal = {Biofouling}, volume = {}, number = {}, pages = {1-15}, doi = {10.1080/08927014.2019.1646731}, pmid = {31402749}, issn = {1029-2454}, abstract = {Desulfovibrio alaskensis G20 biofilms were cultivated on 316 steel, 1018 steel, or borosilicate glass under steady-state conditions in electron-acceptor limiting (EAL) and electron-donor limiting (EDL) conditions with lactate and sulfate in a defined medium. Increased corrosion was observed on 1018 steel under EDL conditions compared to 316 steel, and biofilms on 1018 carbon steel under the EDL condition had at least twofold higher corrosion rates compared to the EAL condition. Protecting the 1018 metal coupon from biofilm colonization significantly reduced corrosion, suggesting that the corrosion mechanism was enhanced through attachment between the material and the biofilm. Metabolomic mass spectrometry analyses demonstrated an increase in a flavin-like molecule under the 1018 EDL condition and sulfonates under the 1018 EAL condition. These data indicate the importance of S-cycling under the EAL condition, and that the EDL is associated with increased biocorrosion via indirect extracellular electron transfer mediated by endogenously produced flavin-like molecules.}, } @article {pmid31402466, year = {2019}, author = {Balasundararajan, V and Dananjeyan, B}, title = {Occurrence of diversified N-acyl homoserine lactone mediated biofilm-forming bacteria in rice rhizoplane.}, journal = {Journal of basic microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1002/jobm.201900202}, pmid = {31402466}, issn = {1521-4028}, support = {5-5/2014 - TS VII//Ministry of Human Resource Development, New Delhi, India/ ; }, abstract = {Quorum sensing (QS)-mediated biofilm-forming rhizobacteria are indispensable due to their competitiveness in the crop rhizosphere. In the present work, we have reported on the occurrence of diversified bacterial species capable of producing N-acyl homoserine lactone (AHL) as the QS signal in the roots of a rice plant grown under field conditions. The AHL-producing bacteria were directly isolated from the rice root by the biosensor reporter (Chromobacterium violaceum CV026) overlay method and characterized for biofilm production by the microtiter plate method. A total of 48 QS-positive bacterial isolates were purified from different aged (7, 20, 24, 26, and 36 days) rice seedlings. The in vitro biofilm production and genetic diversity as revealed by BOX-PCR fingerprinting showed high variability among the isolates. Most of the best biofilm-forming isolates produced a N-butyryl dl-homoserine lactone (a C4-AHL type) signal in the medium. The 16S ribosomal RNA (rRNA) gene sequence of these putative elite isolates identified that they were close to Aeromonas hydrophila (QS7-4; QS36-2), A. enteropelongenes (QS20-8), A. veronii (QS36-3), Enterobacter sp. (QS20-11), Klebsiella pneumoniae (QS24-6), Kosakonia cowanii (QS24-21), Providentia rettigeri (QS24-2), Sphingomonas aquatilis (QS24-17), and Pseudomonas sihuiensis (QS24-20). These strains profusely colonized the rice root upon inoculation and formed biofilms on the surface of the root under gnotobiotic conditions. Developing inoculants from these strains would ensure competitive colonization on the rhizoplane of the crop through their biofilm and thereby improve plant growth and health.}, } @article {pmid31279761, year = {2019}, author = {Parvin, F and Hu, H and Whiteley, GS and Glasbey, T and Vickery, K}, title = {Difficulty in removing biofilm from dry surfaces.}, journal = {The Journal of hospital infection}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.jhin.2019.07.005}, pmid = {31279761}, issn = {1532-2939}, abstract = {Cleaning is fundamental to infection control. This report demonstrates that a Staphylococcus aureus biofilm is significantly more difficult to remove than dried planktonic bacteria. A single wiping action removed >99.9% (>3 log10) of dried planktonic bacteria, whereas only 1.4 log10 of biofilm (96.66%) was removed by 50 wiping actions with a standardized wiping process.}, } @article {pmid31401655, year = {2019}, author = {Bajoul Kakahi, F and Ly, S and Tarayre, C and Deschaume, O and Bartic, C and Wagner, P and Compère, P and Derdelinckx, G and Blecker, C and Delvigne, F}, title = {Modulation of fungal biofilm physiology and secondary product formation based on physico-chemical surface properties.}, journal = {Bioprocess and biosystems engineering}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00449-019-02187-6}, pmid = {31401655}, issn = {1615-7605}, abstract = {Relative to the amount of knowledge concerning bacterial biofilms, little is known about the impact of physico-chemical properties of support material on fungal biofilm adhesion and physiology. In the field of industrial fermentation, large-scale production of low-cost fungal secondary product is a challenging area of research. In the present work, the effect of physico-chemical surface properties of five different materials (Teflon, glass, Viton™ rubber, silicon rubber, and stainless steel) on the production of class II hydrophobins (HFBI and HFBII) from Trichoderma reesei (HFB2a-2) and Trichoderma harzianum) was evaluated. Two culture systems (shake flask and drip flow reactor (DFR)) were used in this study to promote biomass growth and the production of hydrophobins. Furthermore, the effect of physico-chemical surface properties (hydrophobicity, surface energy) and surface texture (roughness) of support material on the initial colonization and attachment of the fungal biofilm was evaluated. Maximum biofilm productivity was obtained using Viton™ rubber for T. reesei and Viton™ rubber and stainless steel as support materials for T. harzianum. Scanning electron microscope (SEM) revealed that fungal biofilm adhesion was higher on the rough hydrophobic Viton rubber surface as compared to the smooth hydrophobic Teflon surface. Initial colonization initiated because of surface irregularities and holes in the material as hyphal filaments. Moreover, compared to traditional submerged fermentation, a significant increase in biofilm productivity for both strains (T. reesei, T. harzianum) in all five materials was obtained.}, } @article {pmid31401462, year = {2019}, author = {Czuban, M and Wulsten, D and Wang, L and Di Luca, M and Trampuz, A}, title = {Release of different amphotericin B formulations from PMMA bone cements and their activity against Candida biofilm.}, journal = {Colloids and surfaces. B, Biointerfaces}, volume = {183}, number = {}, pages = {110406}, doi = {10.1016/j.colsurfb.2019.110406}, pmid = {31401462}, issn = {1873-4367}, abstract = {Amphotericin B is used for local delivery from polymethylmethacrylate to treat fungal prosthetic joint infections. The optimal amphotericin B formulation and the influence of different poragens in the bone cements are unknown. To investigate the necessary amount of amphotericin B in the bone cement to prevent Candida biofilm several amphotericin B formulations were studied: non-liposomal and liposomal with or without poragen gentamicin. For the non-liposomal formulation, standard bile salt, the sodium deoxycholate, was used and additionally N-methyl-D-glucamine/palmitate was applied. The activity of the released amphotericin B was tested against C. albicans, C. glabrata, C. parapsilosis and C. krusei biofilms with application of the isothermal calorimeter and standard microbiological methods. Compressive strength was measured before and after antifungal elution from the cements. There is less aggregated N-methyl-D-glucamine/palmitate amphotericin B released but its antifungal activity is equivalent with the deoxycholate amphotericin B. The minimum quantity of antifungal preventing the Candida biofilm formation is 12.5 mg in gram of polymer powder for both non-liposomal formulations. The addition of gentamicin reduced the release of sodium deoxycholate amphotericin B. Gentamicin can be added to N-methyl-D-glucamine/palmitate amphotericin B in order to boost the antifungal release. When using liposomal amphotericin B more drug is released. All amphotericin B formulations were active against Candida biofilms. Although compressive strength slightly decreased, the obtained values were above the level of strength recommended for the implant fixation. The finding of this work might be beneficial for the treatment of the prosthetic joint infections caused by Candida spp.}, } @article {pmid31400984, year = {2019}, author = {Ionescu, A and Brambilla, E and Hahnel, S}, title = {Does recharging dental restorative materials with fluoride influence biofilm formation?.}, journal = {Dental materials : official publication of the Academy of Dental Materials}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.dental.2019.07.019}, pmid = {31400984}, issn = {1879-0097}, abstract = {OBJECTIVES: To investigate the influence of recharging dental restorative materials with fluoride on biofilm formation.

METHODS: Specimens produced from a high-viscosity glass ionomer cement (HVGIC), a resin-modified glass ionomer cement (RMGIC), and a resin-based composite (RBC) were randomly allotted to incubation in artificial saliva either for one week (AS-1), for five weeks (AS-5), for five weeks including twice/day brushing with 1450ppm NaF toothpaste (AS-5-brush), or one-time exposition to 5000ppm NaF after five weeks of incubation (AS-5-exp). Human enamel was used as reference. Surface roughness and the release of fluoride from the specimens was determined; biofilm formation was simulated using mono- or multispecies microbiological models and analysed employing an MTT-based approach and confocal laser-scanning microscopy.

RESULTS: Monospecies biofilm formation was significantly reduced on HVGIC in comparison to RMGIC and RBC. It was also reduced on HVGIC and enamel after treatment with fluoride in groups AS-5-brush and AS-5-exp in comparison to AS-5. These effects were particularly pronounced after 24h, and less pronounced after 48h of biofilm formation. In the multispecies microbiological model, similar observations were identified for HVGIC, while for enamel a significant reduction in biofilm formation was observed in groups AS-5-brush and AS-5-exp. No significant effect of fluoride treatments was identified for RMGIC and RBC, regardless of the microbiological model applied.

SIGNIFICANCE: These data indicate that biofilm formation on the surfaces of a glass ionomer cement and enamel can be relevantly influenced by treatment with fluoride. Enamel may serve as a fluoride reservoir which requires regular recharge.}, } @article {pmid31400892, year = {2019}, author = {Vasileiou, NGC and Chatzopoulos, DC and Cripps, PJ and Ioannidi, KS and Gougoulis, DA and Chouzouris, TM and Lianou, DT and Gonzalez-Valerio, TC and Vallverdu, RG and Argyros, S and Cesio, M and Font, I and Mavrogianni, VS and Petinaki, E and Fthenakis, GC}, title = {Evaluation of efficacy of a biofilm-embedded bacteria-based vaccine against staphylococcal mastitis in sheep-A randomized, placebo-controlled field study.}, journal = {Journal of dairy science}, volume = {}, number = {}, pages = {}, doi = {10.3168/jds.2019-16287}, pmid = {31400892}, issn = {1525-3198}, abstract = {Our objective was to evaluate the efficacy of a vaccine against staphylococcal mastitis in 5 dairy sheep farms, with 316 ewes in the vaccinated (V) group and 307 in the control (C) group studied throughout a lactation period. Two administrations of the vaccine were performed during the last stage of gestation of ewes. Starting 15 d after lambing and at monthly intervals thereafter, up to 9 milk samplings were performed for bacteriological and cytological examinations. Staphylococcal isolates recovered were examined for biofilm formation. Blood samples were collected for measurement of IgG poly-N-acetylglucosamine-specific antibodies. The most frequently isolated bacteria were staphylococci: 56.4 and 76.1%, respectively, of total isolates recovered from ewes of group V and C, respectively; staphylococci as causal agents of mastitis were isolated less frequently from V (5.3%) than in ewes in C (10.3%). Among mastitis-associated staphylococcal isolates recovered from V ewes, a smaller proportion was biofilm-forming than among ones from C: 53.2% versus 74.9% of isolates; biofilm-forming staphylococci as causal agents of mastitis were isolated less frequently from ewes in group V (2.3%) than in ewes in group C (6.0%). Anti-poly-N-acetylglucosamine-specific antibody values increased in V ewes and were higher than in C; a greater proportion of ewes with low antibody titers developed staphylococcal mastitis (41.4%) than of V ewes with high antibody titers (17.0%). Incidence risk of mastitis, staphylococcal mastitis, and biofilm-associated staphylococcal mastitis was smaller in V than in C: 36.7, 17.1, and 8.0% versus 44.3, 30.9, and 18.9%, respectively. The first case of staphylococcal mastitis occurred later in V than in C: 3rd versus 2nd sampling point. Overall, efficacy of the vaccine was 44.6% for staphylococcal mastitis, 57.7% for biofilm-associated staphylococcal mastitis, 33.1% for staphylococcal intramammary infection, and 51.5% for biofilm-associated staphylococcal intramammary infection. Nevertheless, vaccination should not be the only means for controlling mastitis; other udder health management measures should be included therein to improve control of the infection.}, } @article {pmid31400863, year = {2019}, author = {Hans, S and Fatima, Z and Hameed, S}, title = {Retrograde signaling disruption influences ABC superfamily transporter, ergosterol and chitin levels along with biofilm formation in Candida albicans.}, journal = {Journal de mycologie medicale}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.mycmed.2019.07.003}, pmid = {31400863}, issn = {1773-0449}, abstract = {OBJECTIVE: The rise in fungal infections is alarming due to emergence of multidrug drug resistance (MDR). Hence elucidating novel drug targets to circumvent the problem of MDR warrants immediate attention. This study analyzes the effect of retrograde (RTG) signaling disruption on major MDR mechanisms and virulence of the human pathogenic fungal species Candida albicans.

MATERIAL AND METHODS: Drug transporter activity was measured by rhodamine 6G (R6G) efflux. Membrane damage was studied by propidium iodide intake and ergosterol level determination. Cell wall effect was estimated by quantifying chitin levels and cell sedimentation rate. Biofilm formation was visualized by calcoflour white and crystal violet staining and measured by dry mass and MTT assay. Cell adherence to buccal epithelial cell was determined by trypan blue staining and MTT assay. Virulence was studied using nematode model Caenorhabditis elegans.

RESULT: We demonstrated that mutant of transcription factor CaRTG3 leads to impaired efflux activity of ATP Binding Cassette (ABC) superfamily multidrug transporters. We further uncover that rtg3 mutant exhibited a disrupted membrane, decreased ergosterol levels and increased chitin content. Furthermore, RTG signaling disruption leads to inhibited biofilm formation and cell adherence to buccal epithelial cells. Lastly, rtg3 mutant displayed a reduced infectivity in C. elegans illustrating its vulnerability as antifungal target. Interestingly, all the abrogated phenotypes could be rescued in the revertant strain of rtg3 mutant.

CONCLUSION: Present study establishes a link between RTG signaling, drug efflux and biofilm formation and validates CaRTG3 as antifungal target. Intricate studies are needed to further understand and exploit this therapeutic opportunity.}, } @article {pmid31400688, year = {2019}, author = {Li, H and Zhou, L and Lin, H and Zhang, W and Xia, S}, title = {Nitrate effects on perchlorate reduction in a H2/CO2-based biofilm.}, journal = {The Science of the total environment}, volume = {694}, number = {}, pages = {133564}, doi = {10.1016/j.scitotenv.2019.07.370}, pmid = {31400688}, issn = {1879-1026}, abstract = {The H2/CO2-based membrane biofilm reactor (H2/CO2-MBfR) that effectively combines microporous diffusions of H2 and CO2 is efficient in removing perchlorate (ClO4-). Nitrate (NO3-) is a common oxidized contaminant frequently coexists with ClO4- in water, with the NO3- concentration in most ClO4--contaminated waters being several orders of magnitude higher than ClO4-. Determining the effect of NO3- on ClO4- reduction is a critical issue in practice. The ClO4- reduction performance, biofilm microbial community and influencing mechanism were investigated under a series of feed NO3- loadings in this work. ClO4- reduction was slightly promoted when NO3--N levels were <10 mg/L and inhibited at higher NO3--N levels. Denitrification competed more strongly for H2 than ClO4- reduction, regardless of H2 availability. A higher NO3--N loading was a strong driving force to change the biofilm microbial community. Betaproteobacteria were the dominant bacteria at all stages, and the biofilm reactor was enriched in Methyloversatilis and Zoogloea (31.9-56.5% and 10.6-25.8%, respectively). Changes in the relative amounts of Methyloversatilis and Zoogloea coincided with changes in the ClO4- fluxes and removal efficiencies and the relative abundances of nitrogen cycle functional genes. These results suggest that Methyloversatilis and Zoogloea likely follow independent reduction mechanisms for ClO4- removal.}, } @article {pmid31398534, year = {2019}, author = {Dieser, SA and Fessia, AS and Zanotti, AR and Raspanti, CG and Odierno, LM}, title = {Fibronectin and laminin induce biofilm formation by Streptococcus uberis and decrease its penicillin susceptibility.}, journal = {Microbial pathogenesis}, volume = {}, number = {}, pages = {103652}, doi = {10.1016/j.micpath.2019.103652}, pmid = {31398534}, issn = {1096-1208}, abstract = {The aim of this study was to determine the effect of fibronectin and laminin on the in vitro biofilm formation by Streptococcus uberis and the susceptibility to penicillin under planktonic and biofilm growth conditions. We observed that a high percentage (76.5%) of the S. uberis isolates was weak biofilm producers in Todd Hewitt Broth (THB). A high percentage of moderate (38.2%) or strong (53%) biofilm producers was observed in THB supplemented with laminin or fibronectin, respectively. All S. uberis isolates growing as planktonic cells were sensitive to penicillin. Minimum biofilm inhibitory concentrations (MBICs) were ranging between 0.25 and 2 μg/ml, whereas minimum biofilm eradication concentrations (MBECs) ranging from 8 to 256 μg/ml. These results show that biofilm-growing S. uberis cells required higher concentrations of the antibiotic than those needed to inhibit planktonic cells. Similar MBICs of penicillin were obtained when S. uberis cells growing in THB supplemented or not with laminin or fibronectin, whereas the MBECs markedly increased when one of two proteins were added to culture medium compared with the medium without proteins. To the best of our knowledge, this is the first report of decreased susceptibility to penicillin likely related to a higher production of biofilms stimulated by laminin or fibronectin. Therapeutic failures of penicillin to treat S. uberis infections may be due to biofilm formation.}, } @article {pmid31398514, year = {2019}, author = {Shin, NR and Yi, YJ and Choi, JS}, title = {Hand motor functions on the presence of red fluorescent dental biofilm in older community-dwelling Koreans.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.08.010}, pmid = {31398514}, issn = {1873-1597}, abstract = {BACKGROUND: The Quantitative Light-induced Fluorescence-Digital (QLF-D) system visualizes old and mature dental biofilm as red fluorescence. Risk factors for poor oral hygiene have been identified, however, few studies have evaluated the relationship between mature dental biofilm and hand motor functions. This study aimed to investigate the effects of two important manual motor functions for object manipulation -handgrip strength and manual dexterity- on the presence of red fluorescent dental biofilm in older community-dwelling Koreans using QLF-D, an optical device that reveals dental biofilm.

METHODS: This cross-sectional study included 70 Korean participants aged ≥65 years, all of whom completed questionnaires and were tested for handgrip strength and manual dexterity. In total, 840 dental surfaces were photographed using QLF-D, and ΔR20 values, which reflect mature dental biofilm accumulation, were calculated. The t-test was performed to analyze the differences in the △R20 values according to sociodemographic characteristics, health-related characteristics and hand motor functions, while multiple linear regression analysis was used to investigate the effects of hand motor functions on the △R20 values.

RESULTS: Multivariate regression analysis revealed that handgrip strength (β = -0.294) was the factor most strongly affecting mature dental biofilm accumulation (ΔR20), followed by tooth-brushing time (β = -0.262) and manual dexterity (β = -0.241).

CONCLUSIONS: Reductions in handgrip strength and manual dexterity were independent risk factors for pathogenic dental biofilm accumulation. The results of this investigation suggest that programs designed to prevent the decline, as well as improve, handgrip strength and manual dexterity might improve the oral hygiene of older adults.}, } @article {pmid31398473, year = {2019}, author = {Arenas-Vivo, A and Amariei, G and Aguado, S and Rosal, R and Horcajada, P}, title = {An Ag-loaded photoactive nano-Metal Organic Framework as a promising biofilm treatment.}, journal = {Acta biomaterialia}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.actbio.2019.08.011}, pmid = {31398473}, issn = {1878-7568}, abstract = {Surface biofilm inhibition is still currently a considerable challenge. Among other organisms, Staphylococcus aureus is notable for its ability to form a strong biofilm with proved resistance to chemotherapy. Contamination of high-touch surfaces with S. aureus biofilm not only promotes disease spread but also generates tremendous health-associated costs. Therefore, development of new bactericidal and antiadhesive surface coatings is a priority. Considering that metal-organic frameworks (MOFs) have recently emerged as promising antibacterial agents, we originally report here the synthesis of a multi-active silver-containing nanoscaled MOF composite as a potential surface coating against S. aureus biofilm owing to a triple effect: intrinsic bactericide activity of the MOF, biocidal character of silver nanoparticles (AgNPs), and photoactivity after UVA irradiation. AgNPs were successfully entrapped within the benchmarked nanoscaled porous photoactive titanium(IV) aminoterephthalate MIL-125(Ti)NH2 using a simple and efficient impregnation-reduction method. After complete characterization of the composite thin film, its antibacterial and anti-adherent properties were fully evaluated. After UVA irradiation, the composite coating exhibited relevant bacterial inhibition and detachment, improved ligand-to-cluster charge transfer, and steady controlled delivery of Ag+. These promising results establish the potential of this composite as an active coating for biofilm treatment on high-touch surfaces (e.g., surgical devices, door knobs, and rail bars). STATEMENT OF SIGNIFICANCE: Surface contamination due to bacterial biofilm formation is still a demanding issue, as it causes severe disease spread. One possible solution is the development of antifouling and antibacterial surface coatings. In this work, we originally propose the use of photoactive metal-organic frameworks (MOFs) for biofilm treatment. The novelty of this work relies on the following: i) the treatment of strongly contaminated surfaces, as previous studies with MOFs have exclusively addressed biofilm prevention; ii) this pioneering work reports both antiadherent effect, which removes the biofilm, and bacterial inhibition; iii) our original successful strategy has never been proposed thus far, involving the multi-active combination of 1) intrinsic antibacterial effect of a photoactive titanium-based nanoMOF, 2) immobilization of biocide silver nanoparticles, and 3) improved anti-bioadherent effect upon irradiation of the composite coating.}, } @article {pmid31398188, year = {2019}, author = {Rai, LS and Singha, R and Sanchez, H and Chakraborty, T and Chand, B and Bachellier-Bassi, S and Chowdhury, S and d'Enfert, C and Andes, DR and Sanyal, K}, title = {The Candida albicans biofilm gene circuit modulated at the chromatin level by a recent molecular histone innovation.}, journal = {PLoS biology}, volume = {17}, number = {8}, pages = {e3000422}, doi = {10.1371/journal.pbio.3000422}, pmid = {31398188}, issn = {1545-7885}, abstract = {Histone H3 and its variants regulate gene expression but the latter are absent in most ascomycetous fungi. Here, we report the identification of a variant histone H3, which we have designated H3VCTG because of its exclusive presence in the CTG clade of ascomycetes, including Candida albicans, a human pathogen. C. albicans grows both as single yeast cells and hyphal filaments in the planktonic mode of growth. It also forms a three-dimensional biofilm structure in the host as well as on human catheter materials under suitable conditions. H3VCTG null (hht1/hht1) cells of C. albicans are viable but produce more robust biofilms than wild-type cells in both in vitro and in vivo conditions. Indeed, a comparative transcriptome analysis of planktonic and biofilm cells reveals that the biofilm circuitry is significantly altered in H3VCTG null cells. H3VCTG binds more efficiently to the promoters of many biofilm-related genes in the planktonic cells than during biofilm growth, whereas the binding of the core canonical histone H3 on the corresponding promoters largely remains unchanged. Furthermore, biofilm defects associated with master regulators, namely, biofilm and cell wall regulator 1 (Bcr1), transposon enhancement control 1 (Tec1), and non-dityrosine 80 (Ndt80), are significantly rescued in cells lacking H3VCTG. The occupancy of the transcription factor Bcr1 at its cognate promoter binding sites was found to be enhanced in the absence of H3VCTG in the planktonic form of growth resulting in enhanced transcription of biofilm-specific genes. Further, we demonstrate that co-occurrence of valine and serine at the 31st and 32nd positions in H3VCTG, respectively, is essential for its function. Taken together, we show that even in a unicellular organism, differential gene expression patterns are modulated by the relative occupancy of the specific histone H3 type at the chromatin level.}, } @article {pmid31397415, year = {2019}, author = {Sampaio, GG and Leódido, G and Gonçalves, LM and Benini Paschoal, MA}, title = {In vitro antimicrobial potential of infant mouthwashes against streptococcus mutans biofilm: A preliminary study.}, journal = {Indian journal of dental research : official publication of Indian Society for Dental Research}, volume = {30}, number = {3}, pages = {399-402}, doi = {10.4103/ijdr.IJDR_500_17}, pmid = {31397415}, issn = {1998-3603}, abstract = {Background: Children and teenagers accumulate dental plaque easily due to immature motor coordination present at this specific age. Thus, chemical solutions such as mouthwashes are used for biofilm control. The widespread use of mouthwash could potentially change the oral environment though there is no evidence of its effects on the biofilm.

Aim: The present study aimed to investigate the in vitro antimicrobial potential of infant mouthwashes on mature Streptococcus mutans biofilm.

Methods: The susceptibility of S. mutans biofilm UA 159 (ATCC700610) to infant mouthwashes was tested with childrens mouthwashes containing the following active agents: G1-cetylpyridinium chloride, G2-xylitol and triclosan and G3-Malva sylvestris and xylitol. Phosphage-buffered saline (PBS) was used at the negative control (G4). In this study, cariogenic biofilm was exposed once a day for one minute to the mouthwashes over a period of five days. Following this, an aliquot of each mouthwash used was seeded in brain heart infusion (BHI) agar and then incubated at 37°C, 5% CO2 for 48 h. The results were expressed as colony-forming units (CFU) and converted into log10. The results were submitted to ANOVA and Tukey's test at 5%.

Results: It was observed 7.75, 7.66, and 7.49 CFUlog10 values to G1, G2, and G3, respectively, with 9.53 CFUlog10 value to G4. Accordingly, all studied mouthwashes showed no significant statistical difference between them but with statistically significant bacterial reduction in comparison to control group.

Conclusion: Infant mouthwashes presented a highly significant antimicrobial effect on cariogenic biofilm in an in vitro model, which raises concern when used by a young population.}, } @article {pmid31397177, year = {2019}, author = {Acquaviva, R and D'Angeli, F and Malfa, GA and Ronsisvalle, S and Garozzo, A and Stivala, A and Ragusa, S and Nicolosi, D and Salmeri, M and Genovese, C}, title = {Antibacterial and anti-biofilm activities of walnut pellicle extract (Juglans regia L.) against coagulase-negative staphylococci.}, journal = {Natural product research}, volume = {}, number = {}, pages = {1-6}, doi = {10.1080/14786419.2019.1650352}, pmid = {31397177}, issn = {1478-6427}, abstract = {Juglans regia L. (common walnut) is a deciduous tree belonging to Juglandaceae family. Since ancient time, walnut was widely used in traditional medicine for its antioxidant, antidiabetic, antimicrobial, anti-inflammatory, anti-atherogenic and liver-protective effects. In this work, the antibacterial and anti-biofilm activities of walnuts pellicle extract against coagulase-negative staphylococci were evaluated. Qualitative chemical analysis was performed by the thin layer chromatography. UPLC-Ms/Ms was used to identify the chemical composition of J. regia extract. The total flavonoid and phenolic contents were determined by the Aluminium chloride and Folin-Ciocalteu methods, respectively. The extract showed antibacterial activity with MIC ranging from 3.60 to 461.75 µg/ml and MBC ranging from 461.75 to >461.75 µg/ml. Furthermore, it significantly reduced biofilm biomass and cell viability in a dose-dependent manner. Biological activities of J. regia extract may be due to its high flavonoid and phenolic contents. The obtained results are promising and they deserve further scientific investigations.}, } @article {pmid31396394, year = {2019}, author = {Cameron, LC and Bonis, B and Phan, CQ and Kent, LA and Lee, AK and Hunter, RC}, title = {A putative enoyl-CoA hydratase contributes to biofilm formation and the antibiotic tolerance of Achromobacter xylosoxidans.}, journal = {NPJ biofilms and microbiomes}, volume = {5}, number = {}, pages = {20}, doi = {10.1038/s41522-019-0093-6}, pmid = {31396394}, issn = {2055-5008}, abstract = {Achromobacter xylosoxidans has attracted increasing attention as an emerging pathogen in patients with cystic fibrosis. Intrinsic resistance to several classes of antimicrobials and the ability to form robust biofilms in vivo contribute to the clinical manifestations of persistent A. xylosoxidans infection. Still, much of A. xylosoxidans biofilm formation remains uncharacterized due to the scarcity of existing genetic tools. Here we demonstrate a promising genetic system for use in A. xylosoxidans; generating a transposon mutant library which was then used to identify genes involved in biofilm development in vitro. We further described the effects of one of the genes found in the mutagenesis screen, encoding a putative enoyl-CoA hydratase, on biofilm structure and tolerance to antimicrobials. Through additional analysis, we find that a fatty acid signaling compound is essential to A. xylosoxidans biofilm ultrastructure and maintenance. This work describes methods for the genetic manipulation of A. xylosoxidans and demonstrated their use to improve our understanding of A. xylosoxidans pathophysiology.}, } @article {pmid31396193, year = {2019}, author = {Woodburn, KW and Jaynes, JM and Clemens, LE}, title = {Evaluation of the Antimicrobial Peptide, RP557, for the Broad-Spectrum Treatment of Wound Pathogens and Biofilm.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1688}, doi = {10.3389/fmicb.2019.01688}, pmid = {31396193}, issn = {1664-302X}, abstract = {The relentless growth of multidrug resistance and generation of recalcitrant biofilm are major obstacles in treating wounds, particularly in austere military environments where broad-spectrum pathogen coverage is needed. Designed antimicrobial peptides (dAMPs) are constructed analogs of naturally occurring AMPs that provide the first line of defense in many organisms. RP557 is a dAMP resulting from iterative rational chemical structural analoging with endogenous AMPs, human cathelicidin LL-37 and Tachyplesin 1 and the synthetic D2A21 used as structural benchmarks. RP557 possesses broad spectrum activity against Gram-positive and Gram-negative bacteria and fungi, including recalcitrant biofilm with substantial selective killing over bacterial cells compared to mammalian cells. RP557 did not induce resistance following chronic passages of Pseudomonas aeruginosa and Staphylococcus aureus at subinhibitory concentrations, whereas concurrently run conventional antibiotics, gentamycin, and clindamycin, did. Furthermore, RP557 was able to subsequently eliminate the generated gentamycin resistant P. aeruginosa and clindamycin resistant S. aureus strains without requiring an increase in minimum inhibitory concentration (MIC) concentrations. RP557 was evaluated further in a MRSA murine wound abrasion infection model with a topical application of 0.2% RP557, completely eliminating infection. If these preclinical results are translated into the clinical setting, RP557 may become crucial for the empirical broad-spectrum treatment of wound pathogens, so that infections can be reduced to a preventable complication of combat-related injuries.}, } @article {pmid31396166, year = {2019}, author = {Yan, S and Wu, G}, title = {Can Biofilm Be Reversed Through Quorum Sensing in Pseudomonas aeruginosa?.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1582}, doi = {10.3389/fmicb.2019.01582}, pmid = {31396166}, issn = {1664-302X}, abstract = {Pseudomonas aeruginosa is a Gram-negative bacterium causing diseases in plants, animals, and humans, and its drug resistance is a major concern in medical care. Biofilms play an important role in P. aeruginosa drug resistance. Three factors are most important to induce biofilm: quorum sensing (QS), bis-(3'-5')-cyclic diguanosine monophosphate (c-di-GMP), and small RNAs (sRNAs). P. aeruginosa has its own specific QS system (PQS) besides two common QS systems, LasI-LasR and RhlI-RhlR, in bacteria. PQS is interesting not only because there is a negative regulation from RhlR to pqsR but also because the null mutation in PQS leads to a reduced biofilm formation. Furthermore, P. aeruginosa dispersed cells have physiological features that are distinct between the planktonic cells and biofilm cells. In response to a low concentration of c-di-GMP, P. aeruginosa cells can disperse from the biofilms to become planktonic cells. These raise an interesting hypothesis of whether biofilm can be reversed through the QS mechanism in P. aeruginosa. Although a single factor is certainly not sufficient to prevent the biofilm formation, it necessarily explores such possibility. In this hypothesis, the literature is analyzed to determine the negative regulation pathways, and then the transcriptomic data are analyzed to determine whether this hypothesis is workable or not. Unexpectedly, the transcriptomic data reveal a negative regulation between lasI and psqR. Also, the individual cases from transcriptomic data demonstrate the negative regulations of PQS with laslI, laslR, rhlI, and rhlR under different experiments. Based on our analyses, possible strategies to reverse biofilm formation are proposed and their clinic implications are addressed.}, } @article {pmid31394187, year = {2019}, author = {Barrios-Gumiel, A and Sanchez-Nieves, J and Pérez-Serrano, J and Gómez, R and Javier de la Mata, F}, title = {PEGylated AgNP covered with cationic carbosilane dendrons to enhance antibacterial and inhibition of biofilm properties.}, journal = {International journal of pharmaceutics}, volume = {}, number = {}, pages = {118591}, doi = {10.1016/j.ijpharm.2019.118591}, pmid = {31394187}, issn = {1873-3476}, abstract = {This work focuses on preparation of silver nanoparticles (AgNP) covered with cationic carbosilane dendrons and poly(ethylene glycol) (PEG). It is well known that AgNP and cationic carbosilane dendritic systems present antibacterial properties. On the other hand, PEG ligand provides antifouling properties and improved biocompatibility. Hence, combination of both ligands, carbosilane dendrons and PEG, on the AgNP surface can be a way to improve antibacterial capacity of AgNP. The new family of heterofunctionalized AgNP has been directly synthesized using silver precursor and cationic carbosilane dendrons and PEG ligands containing a thiol moiety. AgNP were characterized by TEM, TGA, UV, 1H NMR, DLS, Z potential, XRD. The antibacterial capacity of these systems was evaluated against E. coli and S. aureus. The results confirmed the influence of both silver core and cationic carbosilane dendrons on the activity of these systems. The behaviour obtained for PEGylated systems were slightly lower than for non-PEGylated AgNP. However, hemolysis assays demonstrated that this decrease was compensated for by the greater biocompatibility. To more completely characterize the improvements of PEGylation on dendronized AgNP, one non-PEGylated and one PEGylated AgNP were tested for resistance in a planktonic state. Both AgNPs barely affected the minimum inhibitory concentration (MIC) whereas reference antibiotics generated significant resistance. In addition, relevant improvement in biofilm inhibition was achieved by dendronized AgNP after PEGylation.}, } @article {pmid31393795, year = {2019}, author = {Fronzo, C}, title = {An early, biofilm-focused wound management approach.}, journal = {Journal of wound care}, volume = {28}, number = {8}, pages = {524-526}, doi = {10.12968/jowc.2019.28.8.524}, pmid = {31393795}, issn = {0969-0700}, abstract = {Wound care experts at the 2019 EWMA conference described the need to adopt biofilm-based wound care, the case for silver dressings, the importance of early intervention and the benefits of effective antibiofilm technologies. Camila Fronzo, JWC chief sub editor, summarises the main points.}, } @article {pmid31392229, year = {2019}, author = {Abbaszadeh, A and Tehmasebi-Foolad, A and Rajabzadeh, A and Beigi-Brojeni, N and Zarei, L}, title = {Effects of Chitosan/Nano Selenium Biofilm on Infected Wound Healing in Rats; An Experimental Study.}, journal = {Bulletin of emergency and trauma}, volume = {7}, number = {3}, pages = {284-291}, doi = {10.29252/beat-0703012}, pmid = {31392229}, issn = {2322-2522}, abstract = {Objective: The present study was aimed at assessment of effect of application of Chitosan/Nano Selenium biofilm on infected wound healing in rats.

Methods: Sixty-eight male Wistar rats were randomized into four groups of 17 animals each. In group I (Normal) the wounds were created with no infection. In group II (MRSA), the wounds were infected with methicillin resistant Staphylococcus aureus(MRSA). In group III (MRSA/CHIT), animals with infected wounds were dressed with chitosan biofilm only. In group IV (MRSA/CHIT/NS), animals with infected wounds were dressed with Chitosan/Nano Selenium biofilm.

Results: There were significant differences in comparisons of group IV and other groups, particularly in terms of cellular infiltration and neovascularization. During the study period, scores for neovascularization was significantly higher in group IV rats than other groups (P<0.05). Polymorphonuclear (PMN) and mononuclear (MNC) cell count and fibroblast cell proliferation in group IV were significantly higher than those of other experimental groups (P<0.05).

Conclusion: Chitosan/Nano Selenium biofilm resulted in significant improvement in histopathological indices in full thickness infected wound healing.}, } @article {pmid31391891, year = {2019}, author = {Cox, KE and Melander, C}, title = {Anti-biofilm activity of quinazoline derivatives against Mycobacterium smegmatis.}, journal = {MedChemComm}, volume = {10}, number = {7}, pages = {1177-1179}, doi = {10.1039/c9md00156e}, pmid = {31391891}, issn = {2040-2511}, abstract = {Bacteria employ a number of mechanisms to resist the effects of antibiotics, including the formation of biofilms. We explored the anti-biofilm capabilities of a library of compounds based upon a 2-aminoquinazoline (2-AQ) scaffold against Mycobacterium smegmatis. This study resulted in the identification of 2-AQ derivatives with biofilm inhibition activity against M. smegmatis.}, } @article {pmid31390848, year = {2019}, author = {Pennone, V and Sanz-Gaitero, M and O'Connor, P and Coffey, A and Jordan, K and van Raaij, MJ and McAuliffe, O}, title = {Inhibition of L. monocytogenes Biofilm Formation by the Amidase Domain of the Phage vB_LmoS_293 Endolysin.}, journal = {Viruses}, volume = {11}, number = {8}, pages = {}, doi = {10.3390/v11080722}, pmid = {31390848}, issn = {1999-4915}, support = {14/F/881//Food Institutional Research Measure/ ; }, abstract = {Listeria monocytogenes is a ubiquitous Gram-positive bacterium that is a major concern for food business operators because of its pathogenicity and ability to form biofilms in food production environments. Bacteriophages (phages) have been evaluated as biocontrol agents for L. monocytogenes in a number of studies and, indeed, certain phages have been approved for use as anti-listerial agents in food processing environments (ListShield and PhageGuard Listex). Endolysins are proteins produced by phages in the host cell. They cleave the peptidoglycan cell wall, thus allowing release of progeny phage into the environment. In this study, the amidase domain of the phage vB_LmoS_293 endolysin (293-amidase) was cloned and expressed in Escherichia. coli(E. coli). Muralytic activity at different concentrations, pH and temperature values, lytic spectrum and activity against biofilms was determined for the purified 293-amidase protein. The results showed activity on autoclaved cells at three different temperatures (20 °C, 37 °C and 50 °C), with a wider specificity (L. monocytogenes 473 and 3099, a serotype 4b and serogroup 1/2b-3b-7, respectively) compared to the phage itself, which targets only L. monocytogenes serotypes 4b and 4e. The protein also inhibits biofilm formation on abiotic surfaces. These results show the potential of using recombinant antimicrobial proteins against pathogens in the food production environment.}, } @article {pmid31389671, year = {2019}, author = {Martínez-García, S and Ortega-Peña, S and De Haro-Cruz, MJ and Aguilera-Arreola, MG and Alcántar-Curiel, MD and Betanzos-Cabrera, G and Jan-Roblero, J and Pérez-Tapia, SM and Rodríguez-Martínez, S and Cancino-Diaz, ME and Cancino-Diaz, JC}, title = {Non-biofilm-forming commensal Staphylococcus epidermidis isolates produce biofilm in the presence of trypsin.}, journal = {MicrobiologyOpen}, volume = {}, number = {}, pages = {e906}, doi = {10.1002/mbo3.906}, pmid = {31389671}, issn = {2045-8827}, support = {269242//Consejo Nacional de Ciencia y Tecnología (CONACyT)/ ; 20181167//SIP-Instituto Politécnico Nacional Mexico/ ; //Instituto Politécnico Nacional fellowships/ ; //Sistema Nacional de Investigadores, CONACyT/ ; //CONACyT/ ; 247489//PDCPN/ ; IN220613//Program UNAM-DGAPA-PAPIIT/ ; }, abstract = {Epidemiological studies comparing clinical and commensal Staphylococcus epidermidis isolates suggest that biofilm formation is a discriminant biomarker. A study showed that four non-biofilm-forming clinical S. epidermidis isolates could form an induced biofilm by trypsin treatment, suggesting that S. epidermidis can form biofilms in a protease-independent way and in a trypsin-induced way. In this study, the trypsin capacity to induce biofilm formation was evaluated in non-biofilm-forming S. epidermidis isolates (n = 133) in order to support this mechanism and to establish the importance of total biofilms (meaning the sum of protease-independent biofilm and trypsin-induced biofilm). Staphylococcus epidermidis isolates from ocular infections (OI; n = 24), prosthetic joint infections (PJI; n = 64), and healthy skin (HS-1; n = 100) were screened for protease-independent biofilm formation according to Christensen's method. The result was that there are significant differences (p < .0001) between clinical (43.2%) and commensal (17%) protease-independent biofilm producers. Meanwhile, non-biofilm-forming isolates were treated with trypsin, and biofilm formation was evaluated by the same method. The number of commensal trypsin-induced biofilm producers significantly increased from 17% to 79%. In contrast, clinical isolates increased from 43.2% to 72.7%. The comparison between clinical and commensal total biofilm yielded no significant differences (p = .392). A similar result was found when different isolation sources were compared (OI vs. HS-1 and PJI vs. HS-1). The genotype icaA- /aap+ was associated with the trypsin-induced biofilm phenotype; however, no correlation was observed between aap mRNA expression and the level of trypsin-induced biofilm phenotype. Studying another group of commensal S. epidermidis non-biofilm-forming isolates (HS-2; n = 139) from different body sites, it was found that 70 isolates (60.3%) formed trypsin-induced biofilms. In conclusion, trypsin is capable of inducing biofilm production in non-biofilm-forming commensal S. epidermidis isolates with the icaA- /aap+ genotype, and there is no significant difference in total biofilms when comparing clinical and commensal isolates, suggesting that total biofilms are not a discriminant biomarker.}, } @article {pmid31388951, year = {2019}, author = {Bó, LG and Almeida, RM and Cardoso, CMM and Zavarize, DG and Brum, SS and Mendonça, ARV}, title = {Acetylsalicylic acid biosorption onto fungal-bacterial biofilm supported on activated carbons: an investigation via batch and fixed-bed experiments.}, journal = {Environmental science and pollution research international}, volume = {}, number = {}, pages = {}, doi = {10.1007/s11356-019-06075-0}, pmid = {31388951}, issn = {1614-7499}, abstract = {This study reports on acetylsalicylic acid (ASA) biosorption onto fungal-bacterial biofilm supported on two types of activated carbons (one commercial type made of coconut fibers, CAC, and one other manufactured from fruit rinds of Hymenaea stigonocarpa Mart., HYAC, which after biofilm inoculation, they were named CAC-b and HYAC-b), via batch and fixed-bed experiments. These materials were characterized by BET Specific Surface Area and Scanning Electronic Microscopy (SEM). Biosorption onto HYAC-b was 57.2% higher than HYAC. Despite presenting the highest biosorption capacity over time (qt = 85.4 ± 0.82 mg g-1), CAC-b had a lower increase in efficiency (32.4%) compared to CAC. Kinetic data from the biosorption experiments responded well to the pseudo-first-order model thus suggests the predominance of physisorption, while without biofilm presence, there was a better agreement with the pseudo-second-order model, suggesting chemisorption. The possible interaction mechanism of ASA to biofilm was attributed to ionic forces between the drug in anionic form and eventual presence of cationic by-products of the biologically active surface metabolism. Biosorption equilibrium data responded better to the Sips model and CAC-b presented the highest biosorption capacity (qe = 292.4 ± 2.01 mg g-1). A combination of faster volumetric flow rates, higher inlet concentrations and shorter beds accelerated the breakthrough time of ASA biosorption in the fixed-bed experiments. These operational conditions affected C/Co ratio in the following magnitude order: volumetric flow rate < inlet concentration < bed height. Breakthrough data responded better to the modified dose-response model compared to Thomas and Yoon-Nelson models.}, } @article {pmid31385644, year = {2019}, author = {Quan, K and Zhang, Z and Chen, H and Ren, X and Ren, Y and Peterson, BW and van der Mei, HC and Busscher, HJ}, title = {Artificial Channels in an Infectious Biofilm Created by Magnetic Nanoparticles Enhanced Bacterial Killing by Antibiotics.}, journal = {Small (Weinheim an der Bergstrasse, Germany)}, volume = {}, number = {}, pages = {e1902313}, doi = {10.1002/smll.201902313}, pmid = {31385644}, issn = {1613-6829}, support = {2016YFC1100402//National Key Research and Development Program of China/ ; 21334004//National Natural Science Foundation of China/ ; 11574222//National Natural Science Foundation of China/ ; 21522404//National Natural Science Foundation of China/ ; //UMCG/ ; }, abstract = {The poor penetrability of many biofilms contributes to the recalcitrance of infectious biofilms to antimicrobial treatment. Here, a new application for the use of magnetic nanoparticles in nanomedicine to create artificial channels in infectious biofilms to enhance antimicrobial penetration and bacterial killing is proposed. Staphylococcus aureus biofilms are exposed to magnetic-iron-oxide nanoparticles (MIONPs), while magnetically forcing MIONP movement through the biofilm. Confocal laser scanning microscopy demonstrates artificial channel digging perpendicular to the substratum surface. Artificial channel digging significantly (4-6-fold) enhances biofilm penetration and bacterial killing efficacy by gentamicin in two S. aureus strains with and without the ability to produce extracellular polymeric substances. Herewith, this work provides a simple, new, and easy way to enhance the eradication of infectious biofilms using MIONPs combined with clinically applied antibiotic therapies.}, } @article {pmid31384892, year = {2019}, author = {He, ZY and Zhou, W and Huang, ZW and Liang, JP and Jiang, W}, title = {[The effect of Streptococcus mutans luxS gene on mixed-species biofilm communities].}, journal = {Shanghai kou qiang yi xue = Shanghai journal of stomatology}, volume = {28}, number = {2}, pages = {113-117}, pmid = {31384892}, issn = {1006-7248}, abstract = {PURPOSE: To evaluate the effect of S.mutans luxS gene on mixed-species biofilms communities.

METHODS: Biofilms were formed by S. mutans (wild type strain, its luxS overexpression strain and luxS knockout strain) and Lactobacillus acidophilus (ATCC4356) with a ratio of 1:1 at 37℃ for 4 h, 14 h and 24 h. MTT assay was used to detect the quantification of the biofilms formed. The structures of biofilms were observed under confocal laser scanning microscopy after 24 h, and expression of biofilm-related genes (ftf, smu630, brpA, gbpB, gtfB, vicR, comDE and relA) was investigated by real-time PCR. Statistical analysis was performed with SPSS17.0 software package.

RESULTS: The results showed that biofilm formed by S. mutans(wild type strain, its luxS overexpression strain and luxS knockout strain) and L.acidophilus after 14 h were 0.481±0.024, 0.591±0.023 and 0.279±0.019, respectively. The same findings were present after 24 h, the biofilm formed by S.mutans overexpression strain with L.acidophilus was higher than wild type strain, and the biofilm formed by knockout strain significantly decreased; but there was no significant difference at 4 h time points. CLSM images revealed that both S.mutans overexpression strain and its wild type strain tended to aggregate into distinct clusters and dense structures, whereas the luxS knockout strain appeared relatively sparse. Compared with wild type strain, all of the genes examined were upregulated in the biofilms formed by the overexpression strain, and were downregulated in the biofilms formed by the luxS mutant strain in mixed-species biofilm.

CONCLUSIONS: S.mutans luxS gene can affect mixed-species biofilm formation with L.acidophilus, which provides evidences for further study.}, } @article {pmid31382580, year = {2019}, author = {Cattò, C and Cappitelli, F}, title = {Testing Anti-Biofilm Polymeric Surfaces: Where to Start?.}, journal = {International journal of molecular sciences}, volume = {20}, number = {15}, pages = {}, doi = {10.3390/ijms20153794}, pmid = {31382580}, issn = {1422-0067}, abstract = {Present day awareness of biofilm colonization on polymeric surfaces has prompted the scientific community to develop an ever-increasing number of new materials with anti-biofilm features. However, compared to the large amount of work put into discovering potent biofilm inhibitors, only a small number of papers deal with their validation, a critical step in the translation of research into practical applications. This is due to the lack of standardized testing methods and/or of well-controlled in vivo studies that show biofilm prevention on polymeric surfaces; furthermore, there has been little correlation with the reduced incidence of material deterioration. Here an overview of the most common methods for studying biofilms and for testing the anti-biofilm properties of new surfaces is provided.}, } @article {pmid31382523, year = {2019}, author = {Karampoula, F and Doulgeraki, AI and Fotiadis, C and Tampakaki, A and Nychas, GE}, title = {Monitoring Biofilm Formation and Microbial Interactions that May Occur During a Salmonella Contamination Incident across the Network of a Water Bottling Plant.}, journal = {Microorganisms}, volume = {7}, number = {8}, pages = {}, doi = {10.3390/microorganisms7080236}, pmid = {31382523}, issn = {2076-2607}, support = {380229//European Social Fund/ ; 548//Education and Lifelong Learning/ ; }, abstract = {The present study aims to monitor the ability of Salmonella to colonize and compete as a member of the mixed species biofilm within key points at a water bottling plant, in case of a contamination incident with this major foodborne pathogen. To achieve this goal, bacterial communities throughout the production line were collected and their identities were investigated by microbial counts and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). These bacterial communities alone or along with constructed Salmonellaenterica serovar Typhimurium (ST) fluorescence-based bioreporters were left to form a biofilm on stainless steel for 6 days at 20 °C. ST bioreporters were constructed by introducing plasmids expressing EYFP (enhanced yellow fluorescent protein) fusions of the genes csgB, csrA, sspH2, and fliD into ST 14028S. The bead vortexing-plate counting method was applied for the enumeration of the biofilm population, while the behavior of the bioreporters was evaluated by fluorescence microscopy. From a set of 16 samples that were collected from the plant, species of Citrobacter, Staphylococcus, Pseudomonas, Bacillus, and Exiguobacterium were identified. The presence of these indigenous bacteria neither inhibited nor enhanced the biofilm formation of ST in mixed bacterial communities (p > 0.05). Furthermore, the csrA-based bioreporter was shown to be induced in multispecies biofilms with Citrobacter. In conclusion, this study enhanced our knowledge of bacterial interactions occurring within a biofilm in a water bottling plant.}, } @article {pmid31382160, year = {2019}, author = {Martins, ML and Monteiro, ASN and Guimarães, JEC and Guimarães, MBCT and da Silva, RF and Cabral, LM and Farah, A and dePaula, J and Romanos, MTV and Maia, LC and Cavalcanti, YW and Fonseca-Gonçalves, A}, title = {Cytotoxic and antibacterial effect of a red propolis mouthwash, with or without fluoride, on the growth of a cariogenic biofilm.}, journal = {Archives of oral biology}, volume = {107}, number = {}, pages = {104512}, doi = {10.1016/j.archoralbio.2019.104512}, pmid = {31382160}, issn = {1879-1506}, abstract = {OBJECTIVE: To evaluatein vitro the antibacterial activity, the antibiofilm effect and the cytotoxic potential of mouthwashes containing Brazilian red propolis with or without fluoride.

METHODS: The minimum inhibitory and bactericidal concentrations (MIC and MBC) against S. mutans, S. sanguinis, S. salivarius and L. casei were determined for RPE mouthwashes. A cariogenic biofilm with the aforementioned bacteria was formed over cellulose membrane disks (N = 30, 13 mm), which were submitted for 1 min to the following mouthwashes: plain mouthwash base; 0.05% NaF; 0.8% RPE; 0.8% RPE + 0.05% NaF and 0.12% chlorhexidine (CHX). The bacterial viability and the production of extracellular polysaccharide (EPS) were measured. Cytotoxic potential of the mouthwashes was also evaluated. For bacterial viability and EPS production, Mann-Withney and one-way ANOVA tests were performed followed by Tukey, with results considered significant when p ≤ 0.05.

RESULTS: MIC and MBC values of RPE mouthwashes ranged from 7.44 to 29.76 mg/mL and from 7.44 to ≥59.52 mg/mL, respectively, presenting better action against S. salivarius. RPE mouthwashes showed 44% of viable cells after 1 min of contact with fibroblasts. RPE (7.74) had the greatest reduction of viable total microorganisms and did not differ from the RPE + NaF (7.95) (p = 0.292). CHX (7.54) was the most effective in reducing Streptococcus spp, but did not differ from RPE (p = 0.521) and RPE + NaF (p = 0.238). There was no difference between the treatments regarding EPS production.

CONCLUSION: RPE and RPE + NaF mouthwash showed similar antibacterial activity, toxicity level and antibiofilm effect compared to CHX.}, } @article {pmid31380192, year = {2019}, author = {Lei, W and Bruchmann, J and Rüping, JL and Levkin, PA and Schwartz, T}, title = {Biofilm Bridges Forming Structural Networks on Patterned Lubricant-Infused Surfaces.}, journal = {Advanced science (Weinheim, Baden-Wurttemberg, Germany)}, volume = {6}, number = {13}, pages = {1900519}, doi = {10.1002/advs.201900519}, pmid = {31380192}, issn = {2198-3844}, abstract = {Despite many decades of research, biofilm architecture and spreading mechanisms are still not clear because of the heterogenous 3D structure within biofilms. Here, patterned "slippery" lubricant-infused porous surfaces are utilized to study biofilm structure of Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Staphylococcus aureus. It is found that bacteria are able to spread over bacteria-repellent lubricant-infused regions by using a mechanism, termed "biofilm bridges". Here, it is demonstrated that bacteria use bridges to form interconnected networks between distant biofilm colonies. Detailed structure of bridges shows a spatial distribution of bacteria with an accumulation of respiratory active bacteria and biomass in the bridges. The core-shell structure of bridges formed by two-species mixed population is illustrated. It is demonstrated that eDNA and nutrients have a strong effect on biofilm bridges formation. Thus, it is believed that biofilm bridging is important to reveal the structure and communication within biofilms.}, } @article {pmid31379772, year = {2019}, author = {Josse, J and Valour, F and Maali, Y and Diot, A and Batailler, C and Ferry, T and Laurent, F}, title = {Interaction Between Staphylococcal Biofilm and Bone: How Does the Presence of Biofilm Promote Prosthesis Loosening?.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1602}, doi = {10.3389/fmicb.2019.01602}, pmid = {31379772}, issn = {1664-302X}, abstract = {With the aging of population, the number of indications for total joint replacement is continuously increasing. However, prosthesis loosening can happen and is related to two major mechanisms: (1) aseptic loosening due to prosthesis micromotion and/or corrosion and release of wear particles from the different components of the implanted material and (2) septic loosening due to chronic prosthetic joint infection (PJI). The "aseptic" character of prosthesis loosening has been challenged over the years, especially considering that bacteria can persist in biofilms and be overlooked during diagnosis. Histological studies on periprosthetic tissue samples reported that macrophages are the principle cells associated with aseptic loosening due to wear debris. They produce cytokines and favor an inflammatory environment that induces formation and activation of osteoclasts, leading to bone resorption and periprosthetic osteolysis. In PJIs, the presence of infiltrates of polymorphonuclear neutrophils is a major criterion for histological diagnosis. Neutrophils are colocalized with osteoclasts and zones of osteolysis. A similar inflammatory environment also develops, leading to bone resorption through osteoclasts. Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus lugdunensis are the main staphylococci observed in PJIs. They share the common feature to form biofilm. For S. aureus and S. epidermidis, the interaction between biofilm and immunes cells (macrophages and polymorphonuclear neutrophils) differs regarding the species. Indeed, the composition of extracellular matrix of biofilm seems to impact the interaction with immune cells. Recent papers also reported the major role of myeloid-derived suppressor cells in biofilm-associated PJIs with S. aureus. These cells prevent lymphocyte infiltration and facilitate biofilm persistence. Moreover, the role of T lymphocytes is still unclear and potentially underestimates. In this review, after introducing the cellular mechanism of aseptic and septic loosening, we will focus on the interrelationships between staphylococcal biofilm, immune cells, and bone cells.}, } @article {pmid31378149, year = {2019}, author = {Wang, W and Nemati, M}, title = {Co-biodegradation of naphthenic acids in anoxic denitrifying biofilm reactors.}, journal = {Environmental technology}, volume = {}, number = {}, pages = {1-17}, doi = {10.1080/09593330.2019.1650122}, pmid = {31378149}, issn = {1479-487X}, abstract = {Anoxic co-biodegradation of linear and cyclic naphthenic acids (NAs) namely octanoic acid, trans-4-methyl-1-cyclohexane carboxylic acid (trans-4MCHCA), cis- and trans-4-methyl-1-cyclohexane-acetic acids (cis-4MCHAA and trans-4MCHAA) was investigated in denitrifying biofilm reactors. In all evaluated compositions, co-biodegradation of NAs was coupled to denitrification, with octanoic acid showing the fastest biodegradation rate (1180.4 mg L-1 h-1 at loading rate of 1180.4 mg L-1 h-1), followed by trans-4MCHCA (398.1 mg L-1 h-1 at loading rate of 435.8 mg L-1 h-1), trans-4MCHAA (25.7 mg L-1 h-1 at loading rate of 221.7 mg L-1 h-1), and cis-4MCHAA (5.3 mg L-1 h-1 at loading rate of 16.9 mg L-1 h-1). Biodegradation of octanoic acid and trans-4MCHCA were not influenced by the presence of recalcitrant NAs (cis- and trans-4MCHAA). Co-biodegradation of cis- and trans-4MCHAA with octanoic acid, trans-4MCHCA, or their combination enhanced the biodegradability of these recalcitrant NAs, with the positive impact being more pronounced for trans-4MCHCA. Finally anoxic co-biodegradation of NAs under denitrifying conditions proceeded at rates that were faster than the aerobic rates obtained in similar mixtures. Anoxic biodegradation, therefore, is an effective alternative for in situ treatment of oil sands process water in anoxic stabilization ponds amended with nitrate, or as an ex situ treatment approach in denitrifying bioreactors whereby the cost and technical challenges of aeration are eliminated.}, } @article {pmid31376667, year = {2019}, author = {Li, X and Wang, X and Lee, DJ and Yan, WM}, title = {Highly heterogeneous interior structure of biofilm wastewater for enhanced pollutant removals.}, journal = {Bioresource technology}, volume = {291}, number = {}, pages = {121919}, doi = {10.1016/j.biortech.2019.121919}, pmid = {31376667}, issn = {1873-2976}, abstract = {Biofilm processes are widely used in wastewater treatment. The biofilm has highly heterogeneous interior structure, which can significantly affect the transport processes and the biological reactions over the biofilm. This study for the first time detailed the complicated velocity and concentration fields of substrate in a real biofilm structure. With a real biofilm interior being profiled and meshed to numerical solutions, the flow-through mode has significant distortion of inflow velocity fields and concentration distributions, which lead to enhanced biological reactions at regimes nearby major pores. Conversely, the crossflow mode depends weakly on the biofilm interior structure. The uniform biofilm model fails to describe the real biofilm processes. Future research needs based on real biofilm structures were discussed.}, } @article {pmid31376126, year = {2019}, author = {Kumari, S and Das, S}, title = {Expression of metallothionein encoding gene bmtA in biofilm-forming marine bacterium Pseudomonas aeruginosa N6P6 and understanding its involvement in Pb(II) resistance and bioremediation.}, journal = {Environmental science and pollution research international}, volume = {}, number = {}, pages = {}, doi = {10.1007/s11356-019-05916-2}, pmid = {31376126}, issn = {1614-7499}, support = {BT/PR14998/GBD/27/279/2010//Department of Biotechnology , Ministry of Science and Technology/ ; }, abstract = {The genetic basis and biochemical aspects of heavy metal endurance abilities have been precisely studied in planktonic bacteria; however, in nature, bacteria mostly grows as surface-attached communities called biofilms. A hallmark trait of biofilm is increased resistance to heavy metals compared with the resistance of planktonic bacteria. A proposed mechanism that contributes to this increased resistance is the enhanced expression of metal-resistant genes. bmtA gene coding for metallothionein protein is one such metal-resistant gene found in many bacterial spp. In the present study, lead (Pb) remediation potential of a biofilm-forming marine bacterium Pseudomonas aeruginosa N6P6 was explored. Biofilm-forming marine bacterium P. aeruginosa N6P6 possess bmtA gene and shows resistance towards many heavy metals, i.e., Pb, Cd, Hg, Cr, and Zn. The expression of metallothionein encoding gene bmtA is significantly high in 48-h-old biofilm culture (11. 4 fold) followed by 24-h-old biofilm culture of P. aeruginosa N6P6 (4.7 fold) (P < 0.05). However, in the case of planktonically grown culture of P. aeruginosa N6P6, the highest expression of bmtA gene was observed in 24-h-old culture. The expression of bmtA also increased significantly with increase in Pb concentration up to 800 ppm. CSLM analysis indicated significant reduction in the raw integrated density of biofilm-associated lipids and polysaccharides (PS) of P. aeruginosa N6P6 biofilm grown in Pb (sub-lethal concentration)-amended medium (P < 0.05), whereas no significant reduction was observed in the raw integrated density of EPS-associated protein. The role of bmtA gene as Pb(II)-resistant determinant was characterized by overexpressing the bmtA gene derived from P. aeruginosa N6P6 in Escherichia coli BL21(DE3). ESI-MS and SDS-PAGE analyses validated the presence of 11.5-kDa MT protein isolated from Pb(II)-induced recombinant E. coli BL21(DE3) harboring bmtA gene.}, } @article {pmid31375964, year = {2019}, author = {Fonseca, DL and Bassin, JP}, title = {Investigating the most appropriate methods for attached solids determination in moving-bed biofilm reactors.}, journal = {Bioprocess and biosystems engineering}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00449-019-02182-x}, pmid = {31375964}, issn = {1615-7605}, abstract = {Moving-bed biofilm reactors (MBBR) have been employed worldwide as an efficient technology for the treatment of a diverse set of wastewaters. Although the attached biomass represents the major fraction of solids in MBBR systems, there is still no standard for its reliable quantification. An extensive literature review indicated that several methods for attached biomass assessment are applied, hindering the comparability of results issued from different studies. Therefore, the most reported methods for biofilm quantification in the MBBR literature were compared using three different carriers. The results revealed that the performance of each method was biased depending on the carrier type and shape. Moreover, differences in total attached solids (TAS) concentrations varied from 13% up to more than 90%, depending on the employed method for a given carrier. Overall, direct weighing of the carrier containing the biofilm, accounting for the clean carrier weight, and manual extraction of the biofilm, preceded or not by sonication for at least 15 min, were the most suitable techniques for assessing TAS and the volatile/total solids ratio in non-porous medias, respectively. The results here presented may be used as a frame of reference for standardization of the methods for assessing the biofilm mass in MBBR carriers.}, } @article {pmid31374264, year = {2019}, author = {Sherly Carolyn, J and Selva Raj, D and Malaikozhundan, B and Govindarajan, M and Alharbi, NS and Kadaikunnan, S and Khaled, JM and Al-Anbr, MN and Alobaidi, AS and Vaseeharan, B}, title = {Anti-cancer, anti-biofilm, and anti-inflammatory properties of Hen's albumen: a photodynamic approach.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.07.026}, pmid = {31374264}, issn = {1873-1597}, abstract = {The albumen plays a major role in the protection of eggs against microorganisms. It contains an arsenal of natural antimicrobial molecules and antibacterial proteins, including the well-known ovotransferrin and lysozyme, which exert their activities against a range of bacteria. In the present study, the hen's albumen extract treated with the dried insect body of blister beetle M. pustulata was assessed for antibacterial, antibiofilm, anti-inflammatory and anti-proliferative activity. The zone of inhibition against Gram positive E. faecalis and S. aureus was 10.8 mm and 12.1 mm respectively at 100 µg mL-1. However, it was 13.6 mm and 15.3 mm for Gram negative P. aeruginosa and P. vulgaris respectively. The biofilm of tested bacteria was significantly inhibited at 100 µg mL-1. The hydrophobicity of bacterial biofilms was considerably condensed after treatment with the hen's albumen extracts at 100 µg mL-1. The anti-inflammatory activity of hen's albumen extracts was confirmed by the inhibition of cyclooxygenase (COX) enzyme to 84.91% at 100 μg mL-1 with the relative IC50 of 8.26 μg mL-1. The albumen extract effectively inhibited the viability (23.61%) of HepG2 hepatic cancer cells at 100 µg mL-1. The anti-proliferative activity of the albumen extracts was further revealed by the induction of HepG2 apoptotic cell morphology. This study concludes that the hen's albumen extract treated with M. pustulata is a natural therapeutic agent to treat biofilm associated clinical bacteria, inflammations and human hepatic cancer cells.}, } @article {pmid31373891, year = {2019}, author = {Bottino, MA and Pereira, S and Amaral, M and Milhan, N and Pereira, CA and Camargo, S and Carvalho, A and Melo, RM}, title = {Streptococcus mutans Biofilm Formation and Cell Viability on Polymer-infiltrated Ceramic and Yttria-stabilized Polycrystalline Zirconium Dioxide Ceramic.}, journal = {Operative dentistry}, volume = {}, number = {}, pages = {}, doi = {10.2341/18-278-L}, pmid = {31373891}, issn = {1559-2863}, abstract = {OBJECTIVE: The aim of this study was to investigate the biofilm formation and cell viability of a polymer-infiltrated ceramic (PIC) and an yttria-stabilized polycrystalline zirconium dioxide ceramic (Y-TZP). The null hypothesis was that there would be no difference in biofilm formation and cell viability between the materials.

METHODS AND MATERIALS: Streptococcus mutans biofilm was analyzed with scanning electron microscopy (SEM), confocal laser scanning microscopy, and colony counting (colony-forming units/mL). The cell viability (fibroblasts) of both materials was measured with 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium) (MTT) test. Roughness measurements were also performed.

RESULTS: The PIC displayed higher roughness but showed similar colony-forming units and biovolume values to those of Y-TZP. SEM showed a higher amount of adhered fibroblasts on the PIC surface on the first day and similar amounts on both materials after seven days. Moreover, the materials were biocompatible with human fibroblasts.

CONCLUSION: PIC and Y-TZP are biocompatible and present the same characteristics for biofilm formation; therefore, they are indicated for indirect restorations and implant abutments.}, } @article {pmid31373035, year = {2019}, author = {Simkins, JW and Stewart, PS and Codd, SL and Seymour, JD}, title = {Non-invasive imaging of oxygen concentration in a complex in vitro biofilm infection model using 19 F MRI: Persistence of an oxygen sink despite prolonged antibiotic therapy.}, journal = {Magnetic resonance in medicine}, volume = {}, number = {}, pages = {}, doi = {10.1002/mrm.27888}, pmid = {31373035}, issn = {1522-2594}, support = {R01GM109452/NIH HHS/National Institutes of Health/United States ; //National Science Foundation./ ; }, abstract = {PURPOSE: Oxygen availability is a critical determinant of microbial biofilm activity and antibiotic susceptibility. However, measuring oxygen gradients in these systems remains difficult, with the standard microelectrode approach being both invasive and limited to single-point measurement. The goal of the study was to develop a 19 F MRI approach for 2D oxygen mapping in biofilm systems and to visualize oxygen consumption behavior in real time during antibiotic therapy.

METHODS: Oxygen-sensing beads were created by encapsulating an emulsion of oxygen-sensing fluorocarbon into alginate gel. Escherichia coli biofilms were grown in and on the alginate matrix, which was contained inside a packed bed column subjected to nutrient flow, mimicking the complex porous structure of human wound tissue, and subjected to antibiotic challenge.

RESULTS: The linear relationship between 19 F spin-lattice relaxation rate R1 and local oxygen concentration permitted noninvasive spatial mapping of oxygen distribution in real time over the course of biofilm growth and subsequent antibiotic challenge. This technique was used to visualize persistence of microbial oxygen respiration during continuous gentamicin administration, providing a time series of complete spatial maps detailing the continued bacterial utilization of oxygen during prolonged chemotherapy in an in vitro biofilm model with complex spatial structure.

CONCLUSIONS: Antibiotic exposure temporarily causes oxygen consumption to enter a pseudosteady state wherein oxygen distribution becomes fixed; oxygen sink expansion resumes quickly after antibiotic clearance. This technique may provide valuable information for future investigations of biofilms by permitting the study of complex geometries (typical of in vivo biofilms) and facilitating noninvasive oxygen measurement.}, } @article {pmid31372943, year = {2019}, author = {Ansari, FA and Ahmad, I}, title = {Isolation, functional characterization and efficacy of biofilm-forming rhizobacteria under abiotic stress conditions.}, journal = {Antonie van Leeuwenhoek}, volume = {}, number = {}, pages = {}, doi = {10.1007/s10482-019-01306-3}, pmid = {31372943}, issn = {1572-9699}, abstract = {Abiotic stresses such as salinity, drought and excessive heat are associated with significant loss of crop productivity globally, and require effective strategies for their reduction or tolerance. Biofilm-forming rhizobacteria, which harbor multifarious plant growth promoting traits and tolerance to abiotic stress, are believed to benefit plant health and production even under environmental stresses. The primary objective of this study was to investigate indigenous biofilm-forming rhizobacteria (Pseudomonas spp., Bacillus sp., Pantoea sp., Brevibacterium sp. and Acinetobacter sp.) for their functional diversity relevant to plant growth promoting activities, biofilm development and tolerance to abiotic stress conditions. The most promising isolates among FAP1, FAP2, FAP3, FAP4, FAP5, FAP10, FAB1, FAB3 and FAA1 were selected. Rhizobacteria exhibited high tolerance to salinity (1.5 M NaCl) and drought stress (up to 55% PEG-6000) conditions in vitro. The isolates demonstrated varying levels of PGP activities (IAA production and phosphate solubilization), biofilm development, and production of alginate and exopolysaccharides in the presence of salinity, drought stress and elevated temperature. Further efficacy of the isolates was demonstrated by inoculating to wheat (Triticum aestivum L.) plants in greenhouse conditions under both normal and drought stress for up to 30 days inoculation. The plant growth potential of the isolates was in the order of FAP3 > FAB3 > FAB1 > FAP10 > FAP5 > FAP4 > FAA1 > FAP2 > FAP1. The present study resulted in successful selection of promising PGPR as identified by 16S rRNA gene sequence analysis. Field study is needed to evaluate their relative performance in both 'normal' and stressed environments in order to be exploited for plant stress management.}, } @article {pmid31371744, year = {2019}, author = {Stępień-Pyśniak, D and Hauschild, T and Kosikowska, U and Dec, M and Urban-Chmiel, R}, title = {Biofilm formation capacity and presence of virulence factors among commensal Enterococcus spp. from wild birds.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {11204}, doi = {10.1038/s41598-019-47602-w}, pmid = {31371744}, issn = {2045-2322}, abstract = {Enterococci are opportunistic pathogens that can form biofilms during infections and many virulence determinants are involved in this process. Although the virulence factors are often analysed in Enterococcus spp. from humans and food animals, little is known about gut enterococcal isolates from wild birds. Therefore, the determination of virulence factors among enterococci isolated from wild birds may provide new information about a possible source of infection for humans and animals or vice versa via the environment. We analysed different phenotypic and genotypic traits in enterococci from wild birds related to potential virulence in humans and animals and to evaluate biofilm formation and its relationship to virulence genes. The E. faecalis isolates were characterised by greater frequency of biofilm formation in BHI than E. faecium. There was a correlation between hydrophobicity and biofilm formation in BHI broth in E. faecalis. None of the isolates was haemolytic. The presence of some adhesion and gelatinase genes was detected in biofilm-positive isolates. The enterococcal pathogenic factors (esp, hyl, and cyl operon genes) did not seem to be necessary or sufficient for production of biofilm by analysed bacteria. Enterococcus species isolated from wild birds should be considered as a possible source of some virulence determinants.}, } @article {pmid31370119, year = {2019}, author = {Song, YJ and Yu, HH and Kim, YJ and Lee, NK and Paik, HD}, title = {Anti-biofilm Activity of Grapefruit Seed Extract against Staphylococcus aureus and Escherichia coli.}, journal = {Journal of microbiology and biotechnology}, volume = {}, number = {}, pages = {}, doi = {10.1041/jmb.1905.05022}, pmid = {31370119}, issn = {1738-8872}, abstract = {Grapefruit seed extract (GSE) is a safe and effective preservative that is used widely in the food industry. However, there are few studies addressing the anti-biofilm effect of GSE. In this study, the anti-biofilm effect of GSE was investigated against biofilm-forming strains of Staphylococcus aureus and Escherichia coli. The GSE minimum inhibitory concentration (MIC) for S. aureus and E. coli were 25 μg/ml and 250 μg/ml, respectively. To investigate biofilm inhibition and degradation effect, crystal violet assay and stainless-steel were used. Biofilm formation rates of four strains (S. aureus 7, and S. aureus 8, E. coli ATCC 25922, and E. coli O157:H4 FRIK 125) were 55.8%, 70.2%, 55.4%, and 20.6% at 1/2 × MIC of GSE, respectively. The degradation effect of GSE on biofilms attached to stainless-steel coupons was observed (≥1 log CFU/coupon) after exposure to concentrations above the MIC for all strains and 1/2 × MIC for S. aureus 7. In addition, the specific mechanisms of this anti-biofilm effect were investigated by evaluating hydrophobicity, auto-aggregation, exopolysaccharide (EPS) production rate, and motility. Significant changes in EPS production rate and motility were observed in both S. aureus and E. coli in the presence of GSE, while changes in hydrophobicity were observed only in E. coli. No relationship was seen between auto-aggregation and biofilm formation. Therefore, our results suggest that GSE might be used as an anti-biofilm agent that is effective against S. aureus and E. coli.}, } @article {pmid31368074, year = {2019}, author = {Zhou, JH and Yu, HC and Ye, KQ and Wang, HY and Ruan, YJ and Yu, JM}, title = {Optimized aeration strategies for nitrogen removal efficiency: application of end gas recirculation aeration in the fixed bed biofilm reactor.}, journal = {Environmental science and pollution research international}, volume = {}, number = {}, pages = {}, doi = {10.1007/s11356-019-06050-9}, pmid = {31368074}, issn = {1614-7499}, support = {51708499//National Natural Science Foundation of China/ ; 21576241//National Natural Science Foundation of China/ ; 21776262//National Natural Science Foundation of China/ ; 20180533B03//Hangzhou Agricultural and Social Development Research Program/ ; }, abstract = {Aeration strategy played an important role in reactor performance. In this study, when superficial upflow air velocity (SAV) decreased from 0.16 to 0.08 cm s-1, low dissolved oxygen concentration (DO) of 2.0 mg L-1 occurred in reactor. The required depth for anoxic microenvironment in biofilm decreased from 902.3 to 525.9 μm, which enhanced the growth of denitrifying bacteria and total nitrogen (TN) removal efficiency. However, decreasing aeration intensity resulted in insufficient hydraulic shear stress, which led to weak biofilm matrix structure. Mass biofilm detachment and reactor deterioration then occurred after 87 days of operation. An end gas recirculation aeration strategy was proposed to separately manipulate DO and aeration intensity. Low DO and high aeration intensity were simultaneously achieved, which enhanced the metabolism of denitrifying bacteria (such as Flavobacterium sp., Pseudorhodobacter sp., and Dok59 sp.) and EPS-producing bacteria (such as Zoogloea sp. and Rhodobacter sp.). Consequently, high TN removal performance (82.1 ± 2.7%) and stable biofilm structure were achieved.}, } @article {pmid31366707, year = {2019}, author = {Brown, JR and Jurcisek, J and Lakhani, V and Snedden, A and Ray, WC and Mokrzan, EM and Bakaletz, LO and Das, J}, title = {In Silico Modeling of Biofilm Formation by Nontypeable Haemophilus influenzae In Vivo.}, journal = {mSphere}, volume = {4}, number = {4}, pages = {}, doi = {10.1128/mSphere.00254-19}, pmid = {31366707}, issn = {2379-5042}, abstract = {Biofilms formed by nontypeable Haemophilus influenzae (NTHI) bacteria play an important role in multiple respiratory tract diseases. Visual inspection of the morphology of biofilms formed during chronic infections shows distinct differences from biofilms formed in vitro To better understand these differences, we analyzed images of NTHI biofilms formed in the middle ears of Chinchilla lanigera and developed an in silico agent-based model of the formation of NTHI biofilms in vivo We found that, as in vitro, NTHI bacteria are organized in self-similar patterns; however, the sizes of NTHI clusters in vivo are more than 10-fold smaller than their in vitro counterparts. The agent-based model reproduced these patterns and suggested that smaller clusters occur due to elimination of planktonic NTHI cells by the host responses. Estimation of model parameters by fitting simulation results to imaging data showed that the effects of several processes in the model change during the course of the infection.IMPORTANCE Multiple respiratory illnesses are associated with formation of biofilms within the human airway by NTHI. However, a substantial amount of our understanding of the mechanisms that underlie NTHI biofilm formation is obtained from in vitro studies. Our in silico model that describes biofilm formation by NTHI within the middle ears of Chinchilla lanigera will help isolate processes potentially responsible for the differences between the morphologies of biofilms formed in vivo versus those formed in vitro Thus, the in silico model can be used to glean mechanisms that underlie biofilm formation in vivo and connect those mechanisms to those obtained from in vitro experiments. The in silico model developed here can be extended to investigate potential roles of specific host responses (e.g., mucociliary clearance) on NTHI biofilm formation in vivo The developed computational tools can also be used to analyze and describe biofilm formation by other bacterial species in vivo.}, } @article {pmid31366705, year = {2019}, author = {Kean, R and Ramage, G}, title = {Combined Antifungal Resistance and Biofilm Tolerance: the Global Threat of Candida auris.}, journal = {mSphere}, volume = {4}, number = {4}, pages = {}, doi = {10.1128/mSphere.00458-19}, pmid = {31366705}, issn = {2379-5042}, abstract = {The enigmatic yeast Candida auris has emerged over the last decade and rapidly penetrated our consciousness. The global threat from this multidrug-resistant yeast has generated a call to arms from within the medical mycology community. Over the past decade, our understanding of how this yeast has spread globally, its clinical importance, and how it tolerates and resists antifungal agents has expanded. This review highlights the clinical importance of antifungal resistance in C. auris and explores our current understanding of the mechanisms associated with azole, polyene, and echinocandin resistance. We also discuss the impact of phenotypic tolerance, with particular emphasis on biofilm-mediated resistance, and present new pipelines of antifungal drugs that promise new hope in the management of C. auris infection.}, } @article {pmid31366076, year = {2019}, author = {Ghensi, P and Bettio, E and Maniglio, D and Bonomi, E and Piccoli, F and Gross, S and Caciagli, P and Segata, N and Nollo, G and Tessarolo, F}, title = {Dental Implants with Anti-Biofilm Properties: A Pilot Study for Developing a New Sericin-Based Coating.}, journal = {Materials (Basel, Switzerland)}, volume = {12}, number = {15}, pages = {}, doi = {10.3390/ma12152429}, pmid = {31366076}, issn = {1996-1944}, support = {Prot. 24/2015//SIdP (Italian Society of Periodontology and Implantology)/ ; }, abstract = {AIM: several strategies have been tested in recent years to prevent bacterial colonization of dental implants. Sericin, one of the two main silk proteins, possesses relevant biological activities and also literature reports about its potential antibacterial properties, but results are discordant and not yet definitive. The aim of this study was to evaluate the effectiveness of different experimental protocols in order to obtain a sericin-based coating on medical grade titanium (Ti) able to reduce microbial adhesion to the dental implant surface.

MATERIALS AND METHODS: different strategies for covalent bonding of sericin to Ti were pursued throughout a multi-step procedure on Ti-6Al-4V disks. The surface of grade 5 Ti was initially immersed in NaOH solution to obtain the exposure of functional -OH groups. Two different silanization strategies were then tested using aminopropyltriethoxysilane (APTES). Eventually, the bonding between silanized Ti-6Al-4V and sericin was obtained with two different crosslinking processes: glutaraldehyde (GLU) or carbodiimide/N-Hydroxy-succinimide (EDC/NHS). Micro-morphological and compositional analyses were performed on the samples at each intermediate step to assess the most effective coating strategy able to optimize the silanization and bioconjugation processes. Microbiological tests on the coated Ti-6Al-4V disks were conducted in vitro using a standard biofilm producer strain of Staphylococcus aureus (ATCC 6538) to quantify the inhibition of microbial biofilm formation (anti-biofilm efficacy) at 24 hours.

RESULTS: both silanization techniques resulted in a significant increase of silicon (Si) on the Ti-6Al-4V surfaces etched with NaOH. Differences were found between GLU and EDC/NHS bioconjugation strategies in terms of composition, surface micro-morphology and anti-biofilm efficacy. Ti-6Al-4V samples coated with GLU-bound sericin after silanization obtained via vapor phase deposition proved that this technique is the most convenient and effective coating strategy, resulting in a bacterial inhibition of about 53% in respect to the uncoated Ti-6Al-4V disks.

CONCLUSIONS: The coating with glutaraldehyde-bound sericin after silanization in the vapor phase showed promising bacterial inhibition values with a significant reduction of S. aureus biofilm. Further studies including higher number of replicates and more peri-implant-relevant microorganisms are needed to evaluate the applicability of this experimental protocol to dental implants.}, } @article {pmid31364079, year = {2019}, author = {Lora-Tamayo, J and Murillo, O and Ariza, J}, title = {Clinical Use of Colistin in Biofilm-Associated Infections.}, journal = {Advances in experimental medicine and biology}, volume = {1145}, number = {}, pages = {181-195}, doi = {10.1007/978-3-030-16373-0_13}, pmid = {31364079}, issn = {0065-2598}, abstract = {Biofilm is an adaptive bacterial strategy whereby microorganisms become encased in a complex glycoproteic matrix. The low concentration of oxygen and nutrients in this environment leads to heterogeneous phenotypic changes in the bacteria, with antimicrobial tolerance being of paramount importance. As with other antibiotics, the activity of colistin is impaired by biofilm-embedded bacteria. Therefore, the recommendation for administering high doses in combination with a second drug, indicated for planktonic infections, remains valid in this setting. Notably, colistin has activity against metabolically inactive biofilm-embedded cells located in the inner layers of the biofilm structure. This is opposite and complementary to the activity of other antimicrobials that are able to kill metabolically active cells in the outer layers of the biofilm. Several experimental models have shown a higher activity of colistin when used in combination with other agents, and have reported that this can avoid the emergence of colistin-resistant subpopulations. Most experience of colistin in biofilm-associated infections comes from patients with cystic fibrosis, where the use of nebulized colistin allows high concentrations to reach the site of the infection. However, limited clinical experience is available in other scenarios, such as osteoarticular infections or device-related central nervous system infections caused by multi-drug resistant microorganisms. In the latter scenario, the use of intraventricular or intrathecal colistin also permits high local concentrations and good clinical results. Overall, the efficacy of intravenous colistin seems to be poor, but its association with a second antimicrobial significantly increases the response rate. Given its activity against inner bioflm-embedded cells, its possible role in combination with other antibiotics, beyond last-line therapy situations, should be further explored.}, } @article {pmid31363870, year = {2019}, author = {Piotrowski, M and Wultańska, D and Obuch-Woszczatyński, P and Pituch, H}, title = {Fructooligosaccharides and mannose affect Clostridium difficile adhesion and biofilm formation in a concentration-dependent manner.}, journal = {European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1007/s10096-019-03635-7}, pmid = {31363870}, issn = {1435-4373}, support = {UMO:2017/25/N/NZ6/01763//Narodowe Centrum Nauki/ ; }, abstract = {The aim of this study was to investigate the effects that prebiotic and candidates for prebiotics on Clostridium difficile strains to adhere to various human epithelial cell lines and to compare the adhesive properties of specific C. difficile strains. We also sought to examine the effect of different concentrations of fructooligosaccharides and mannose on the formation of biofilms by C. difficile strains. The influence of cellobiose, fructooligosaccharides, inulin, mannose, and raffinose on the adherence properties of various C. difficile strains, including motile 630, non-motile M120, and 10 clinical motile ribotype 027 strains, to non-mucous secreting HT-29, mucous secreting HT-29 MXT, and CCD 841 CoN cells lines. The most effective prebiotics were used in biofilm formation assays. We demonstrated that all C. difficile strains adhered to all cell lines. However, the C. difficile M120 non-motile strain was statistically more likely to adhere to all three cell lines (CFU median, 40) compared to the motile strains (CFU median, 3; p < 0.001). Furthermore, among the carbohydrates examined, only fructooligosaccharides and mannose were found to significantly decrease adhesion (p < 0.001) of C. difficile strains. Alternatively, using a biofilm assay, we observed, via confocal laser scanning microscopy, that sub-inhibitory concentrations (1%) of fructooligosaccharides and mannose functioned to increase biofilm formation by C. difficile. We demonstrated that specific prebiotics and candidate prebiotics exhibit varying anti-adhesive properties towards C. difficile in vitro and that treatment with sub-inhibitory concentrations of prebiotics can cause an increase in biofilm formation by C. difficile.}, } @article {pmid31363032, year = {2019}, author = {Orazi, G and Ruoff, KL and O'Toole, GA}, title = {Pseudomonas aeruginosa Increases the Sensitivity of Biofilm-Grown Staphylococcus aureus to Membrane-Targeting Antiseptics and Antibiotics.}, journal = {mBio}, volume = {10}, number = {4}, pages = {}, doi = {10.1128/mBio.01501-19}, pmid = {31363032}, issn = {2150-7511}, abstract = {Pseudomonas aeruginosa and Staphylococcus aureus often cause chronic, recalcitrant infections in large part due to their ability to form biofilms. The biofilm mode of growth enables these organisms to withstand antibacterial insults that would effectively eliminate their planktonic counterparts. We found that P. aeruginosa supernatant increased the sensitivity of S. aureus biofilms to multiple antimicrobial compounds, including fluoroquinolones and membrane-targeting antibacterial agents, including the antiseptic chloroxylenol. Treatment of S. aureus with the antiseptic chloroxylenol alone did not decrease biofilm cell viability; however, the combination of chloroxylenol and P. aeruginosa supernatant led to a 4-log reduction in S. aureus biofilm viability compared to exposure to chloroxylenol alone. We found that the P. aeruginosa-produced small molecule 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO) is responsible for the observed heightened sensitivity of S. aureus to chloroxylenol. Similarly, HQNO increased the susceptibility of S. aureus biofilms to other compounds, including both traditional and nontraditional antibiotics, which permeabilize bacterial membranes. Genetic and phenotypic studies support a model whereby HQNO causes an increase in S. aureus membrane fluidity, thereby improving the efficacy of membrane-targeting antiseptics and antibiotics. Importantly, our data show that P. aeruginosa exoproducts can enhance the ability of various antimicrobial agents to kill biofilm populations of S. aureus that are typically difficult to eradicate. Finally, our discovery that altering membrane fluidity shifts antimicrobial sensitivity profiles of bacterial biofilms may guide new approaches to target persistent infections, such as those commonly found in respiratory tract infections and in chronic wounds.IMPORTANCE The thick mucus in the airways of cystic fibrosis (CF) patients predisposes them to frequent, polymicrobial respiratory infections. Pseudomonas aeruginosa and Staphylococcus aureus are frequently coisolated from the airways of individuals with CF, as well as from diabetic foot ulcers and other wounds. Both organisms form biofilms, which are notoriously difficult to eradicate and promote chronic infection. In this study, we have shown that P. aeruginosa-secreted factors can increase the efficacy of compounds that alone have little or no bactericidal activity against S. aureus biofilms. In particular, we discovered that P. aeruginosa exoproducts can potentiate the antistaphylococcal activity of phenol-based antiseptics and other membrane-active drugs. Our findings illustrate that polymicrobial interactions can dramatically increase antibacterial efficacy in vitro and suggest that altering membrane physiology promotes the ability of certain drugs to kill bacterial biofilms-knowledge that may provide a path for the discovery of new biofilm-targeting antimicrobial strategies.}, } @article {pmid31362660, year = {2019}, author = {Jain, N and Mansuri, A}, title = {Stopping the Unstoppable: Unconventional methods to prevent biofilm growth.}, journal = {Current drug discovery technologies}, volume = {}, number = {}, pages = {}, doi = {10.2174/1570163816666190726153441}, pmid = {31362660}, issn = {1875-6220}, abstract = {Biofilms are consortia of microorganisms encased in extracellular matrix that protect cells from adverse conditions. A biofilm matrix is typically composed of extracellular DNA, cellulose and proteinaceous amyloid fibers. The matrix aids in adhesion to abiotic and biotic surface including medical devices and host tissues. Presence of biofilm makes bacteria more resilient and non-responsive to most current treatment regimes at disposal. Therefore, biofilm-associated infections are serious threat in hospital settings and pose a huge burden on economy. Inhibition of matrix components (cellulose and/or amyloid formation) has emerged as a lucrative alternative strategy to cure biofilm-related infections and combat antibiotic resistance. Here we review the current and emerging therapeutic interventions to mitigate persistent infections due to biofilms. The successful implementation of these interventions will have a huge impact on alleviating the current financial burden on healthcare services.}, } @article {pmid31362602, year = {2019}, author = {Hirayama, S and Nojima, N and Furukawa, S and Ogihara, H and Morinaga, Y}, title = {Steric microstructure of mixed-species biofilm formed by interaction between Lactobacillus plantarum ML11-11 and Saccharomyces cerevisiae.}, journal = {Bioscience, biotechnology, and biochemistry}, volume = {}, number = {}, pages = {1-4}, doi = {10.1080/09168451.2019.1649978}, pmid = {31362602}, issn = {1347-6947}, abstract = {The mixed-species biofilm of Lactobacillus plantarum ML11-11 (LAB) and yeast had a double-layered structure with the ground layer composed of LAB cells, and the upper layer composed of coaggregates of LAB and yeast cells. The ability of LAB to adhere to both, the solid surface and the yeast cells, enabled the formation and maintenance of the biofilm as an ecosystem for LAB and yeast.}, } @article {pmid31362224, year = {2019}, author = {Ashkanani, A and Almomani, F and Khraisheh, M and Bhosale, R and Tawalbeh, M and AlJaml, K}, title = {Bio-carrier and operating temperature effect on ammonia removal from secondary wastewater effluents using moving bed biofilm reactor (MBBR).}, journal = {The Science of the total environment}, volume = {693}, number = {}, pages = {133425}, doi = {10.1016/j.scitotenv.2019.07.231}, pmid = {31362224}, issn = {1879-1026}, abstract = {This study investigates the impact of bio-carriers' surface area and shape, wastewater chemistry and operating temperature on ammonia removal from real wastewater effluents using Moving bed biofilm reactors (MBBRs) operated with three different AnoxKaldness bio-carriers (K3, K5, and M). The study concludes the surface area loading rate, specific surface area, and shape of bio-carrier affect ammonia removal under real conditions. MBBR kinetics and sensitivity for temperature changes were affected by bio-carrier type. High surface area bio-carriers resulted in low ammonia removal and bio-carrier clogging. Significant ammonia removals of 1.420 ± 0.06 and 1.103 ± 0.06 g - N/m2. d were achieved by K3(As = 500 m2/m3) at 35 and 20 °C, respectively. Lower removals were obtained by high surface area bio-carrier K5 (1.123 ± 0.06 and 0.920 ± 0.06 g - N/m2. d) and M (0.456 ± 0.05 and 0.295 ± 0.05 g - N/m2. d) at 35 and 20 °C, respectively. Theta model successfully represents ammonia removal kinetics with θ values of 1.12, 1.06 and 1.13 for bio-carrier K3, K5 and M respectively. MBBR technology is a feasible choice for treatment of real wastewater effluents containing high ammonia concentrations.}, } @article {pmid31362109, year = {2019}, author = {Sayar, F and Chiniforush, N and Bahador, A and Etemadi, A and Akhondi, N and Azimi, C}, title = {Efficacy of antimicrobial photodynamic therapy for elimination of Aggregatibacter actinomycetemcomitans biofilm on Laser-Lok titanium discs.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.07.012}, pmid = {31362109}, issn = {1873-1597}, abstract = {BACKGROUND: Antimicrobial Photodynamic therapy (aPDT) is a novel modality suggested for treatment of peri-implantitis. This study aimed to assess the effect of aPDT with toluidine blue (TBO) and indocyanine green (ICG) and 635 nm and 808 nm diode laser on Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) biofilm formed on Laser-Lok titanium discs.

MATERIALS AND METHODS: Eighty sterile Laser-Lok titanium discs were inoculated with A. actinomycetemcomitans to form biofilm and were randomly divided into 8 groups (n = 10) of control, chlorhexidine (CHX), TBO, ICG, 635 nm diode laser with 220 mW power, 808 nm diode laser with 250 mW power, 100 µg/mL TBO+635 nm diode laser and ICG+808 nm diode laser. Number of colony forming units (CFUs) on the surface of each disc was counted after the intervention. Data were analyzed using the Kruskal-Wallis test.

RESULTS: Significant differences were noted in colony count among the eight groups after the intervention (P = 0.001). Pairwise comparisons with adjusted P value test showed that aPDT with TBO+635 nm laser and ICG+808 nm laser caused significant reduction of bacterial biofilm compared to the control group (P = 0.0001). TBO alone caused significant reduction of biofilm compared to the control group (P = 0.004). No other significant differences were noted (P > 0.05).

CONCLUSION: Within the limitations of this study, the results showed that PDT is a potential modality for decontamination of implant surface and reduction of A. actinomycetemcomitans biofilm in vitro. In this study, aPDT with TBO+635 nm diode laser and ICG+808 nm diode laser decreased the bacterial load on titanium discs.}, } @article {pmid31360725, year = {2019}, author = {Leonhard, M and Zatorska, B and Moser, D and Schneider-Stickler, B}, title = {Growth Media for Mixed Multispecies Oropharyngeal Biofilm Compositions on Silicone.}, journal = {BioMed research international}, volume = {2019}, number = {}, pages = {8051270}, doi = {10.1155/2019/8051270}, pmid = {31360725}, issn = {2314-6141}, abstract = {Aims: Microbial colonization of silicone voice prostheses by bacteria and Candida species limits the device lifetime of modern voice prostheses in laryngectomized patients. Thus, research focuses on biofilm inhibitive properties of novel materials, coatings, and surface enhancements. Goal of this in vitro study was the evaluation of seven commonly used growth media to simulate growth of mixed oropharyngeal species as mesoscale biofilms on prosthetic silicone for future research purposes.

Methods and Results: Yeast Peptone Dextrose medium (YPD), Yeast Nitrogen Base medium (YNB), M199 medium, Spider medium, RPMI 1640 medium, Tryptic Soy Broth (TSB), and Fetal Bovine Serum (FBS) were used to culture combined mixed Candida strains and mixed bacterial-fungal compositions on silicone over the period of 22 days. The biofilm surface spread and the microscopic growth showed variations from in vivo biofilms depending on the microbial composition and growth medium.

Conclusion: YPD and FBS prove to support continuous in vitro growth of mixed bacterial-fungal oropharyngeal biofilms deposits over weeks as needed for longterm in vitro testing with oropharyngeal biofilm compositions.

The study provides data on culture conditions for mixed multispecies biofilm compositions that can be used for future prosthesis designs.}, } @article {pmid31357945, year = {2019}, author = {Ramos, JN and Souza, C and Faria, YV and da Silva, EC and Veras, JFC and Baio, PVP and Seabra, SH and de Oliveira Moreira, L and Hirata Júnior, R and Mattos-Guaraldi, AL and Vieira, VV}, title = {Bloodstream and catheter-related infections due to different clones of multidrug-resistant and biofilm producer Corynebacterium striatum.}, journal = {BMC infectious diseases}, volume = {19}, number = {1}, pages = {672}, doi = {10.1186/s12879-019-4294-7}, pmid = {31357945}, issn = {1471-2334}, abstract = {BACKGROUND: Corynebacterium striatum is an emerging multidrug-resistant (MDR) pathogen associated with immunocompromised and chronically ill patients, as well as nosocomial outbreaks. In this study, we characterized 23 MDR C. striatum isolated of bloodstream and catheter-related infections from a hospital of Rio de Janeiro.

METHODS: C. striatum isolates were identified by 16S rRNA and rpoB genes sequencing. The dissemination of these isolates was accomplished by pulsed-field gel electrophoresis (PFGE). All isolates were submitted to antimicrobial susceptibility testing by disk diffusion and by minimum inhibitory concentration using E-test strips methods. Antimicrobial resistance genes were detected by polymerase chain reaction. Quantitative tests were performed on four different abiotic surfaces and the ability to produce biofilm on the surface of polyurethane and silicone catheter was also demonstrated by scanning electron microscopy.

RESULTS: Eleven PFGE profiles were found. The PFGE profile I was the most frequently observed among isolates. Five different MDR profiles were found and all PFGE profile I isolates presented susceptibility only to tetracycline, vancomycin, linezolid and daptomycin. Only the multidrug-susceptible isolate did not show mutations in the quinolone-resistance determinant region (QRDR) of the gyrA gene and was negative in the search of genes encoding antibiotic resistance. The other 22 isolates were positive to resistance genes to aminoglycoside, macrolides/lincosamides and chloramphenicol and showed mutations in the QRDR of the gyrA gene. Scanning electron microscopy illustrated the ability of MDR blood isolate partaker of the epidemic clone (PFGE profile I) to produce mature biofilm on the surface of polyurethane and silicone catheter.

CONCLUSIONS: Genotyping analysis by PFGE revealed the permanence of the MDR PFGE profile I in the nosocomial environment. Other new PFGE profiles emerged as etiologic agents of invasive infections. However, the MDR PFGE profile I was also found predominant among patients with hematogenic infections. The high level of multidrug resistance associated with biofilm formation capacity observed in MDR C. striatum is a case of concern.}, } @article {pmid31357240, year = {2019}, author = {Feng, G and Cheng, Y and Worobo, RW and Borca-Tasciuc, DA and Moraru, CI}, title = {Nanoporous anodic alumina reduces Staphylococcus biofilm formation.}, journal = {Letters in applied microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1111/lam.13201}, pmid = {31357240}, issn = {1472-765X}, abstract = {Staphylococcus epidermidis and Staphylococcus aureus, two bacterial strains commonly associated with biofilm-related medical infections and food poisoning, can rapidly colonize biotic and abiotic surfaces. The present study investigates the ability of anodic alumina surfaces with nanoporous surface topography to minimize the attachment and biofilm formation mediated by these pathogenic bacterial strains. Early attachment and subsequent biofilm development were retarded on surfaces with nanopores of 15-25 nm in diameter compared to surfaces with 50-100 nm pore diameter and nanosmooth surfaces. After 30 min of incubation in nutritive media, the biomass accumulation per unit surface area was 2·93 ± 1·72 μm3 μm-2 for the 15 nm, 3·49 ± 1·97 μm3 μm-2 for the 25 nm, as compared to 14·04 ± 6·39 μm3 μm-2 for the nanosmooth, 11·88 ± 9·72 μm3 μm-2 for the 50 nm, and 12·09 ± 11·84 μm3 μm-2 for the 100 nm surfaces, respectively. These findings suggest that anodic alumina with small size nanoscale pores could reduce the incidence of staphylococcal biofilms and infections, and shows promise as a material for a variety of medical applications and food contact surfaces. This article is protected by copyright. All rights reserved.}, } @article {pmid31356873, year = {2019}, author = {Ham Lee, H and Del Pozzo, J and Salamanca, SA and Hernandez, H and Martinez, LR}, title = {Reduced phagocytosis and killing of Cryptococcus neoformans biofilm-derived cells by J774.16 macrophages is associated with fungal capsular production and surface modification.}, journal = {Fungal genetics and biology : FG & B}, volume = {}, number = {}, pages = {103258}, doi = {10.1016/j.fgb.2019.103258}, pmid = {31356873}, issn = {1096-0937}, abstract = {Cryptococcus neoformans is an opportunistic encapsulated pathogen that causes life-threatening meningoencephalitis in individuals with immunosuppression. We compared the interactions of C. neoformans planktonic and biofilm-derived cells with J774.16 macrophage-like cells. Planktonic cells are more phagocytized and killed by J774.16 cells than biofilm-derived fungal cells. Biofilm-derived cryptococci possess larger capsule size and release significantly more capsular polysaccharide than planktonic cells in culture. Biofilm-derived fungi exhibited upregulation of genes involved in capsular production. Capsular-specific monoclonal antibody 18B7 demonstrated differential binding to the surface of planktonic and biofilm-derived cryptococci providing a plausible strategy for fungal evasion of macrophages and persistence. Future studies are necessary to elucidate how C. neoformans biofilm-derived cells regulate their virulence factors when interacting with cells of the immune system.}, } @article {pmid31355999, year = {2019}, author = {Chuang, PJ and Swaminathan, V and Pavlovsky, L and Marquez-Catral, L and Jones, D and Song, L}, title = {Negative Influence of Biofilm on CoCrMo Corrosion.}, journal = {Journal of biomedical materials research. Part A}, volume = {}, number = {}, pages = {}, doi = {10.1002/jbm.a.36761}, pmid = {31355999}, issn = {1552-4965}, abstract = {Minimal studies exist investigating biofilm-induced corrosion of orthopaedic implants. This study investigates potential contributions of Pseudomonas aeruginosa and Staphylococcus aureus biofilms on corrosion resistance of CoCrMo under static and fretting conditions. Biofilms were cultured on CoCrMo coupons for either 4 weeks (static culture) or 6 days (fretting culture; pin-on-disc with a Ti6Al4V hemispherical tip pin). Morphology of biofilms and corrosion of coupon surfaces were analyzed via SEM. Open circuit potential and electrochemical impedance spectroscopy measurements were collected for corrosion performance evaluation. Results showed no visible corrosion on coupon surfaces in static culture which suggests these biofilms alone do not induce severe corrosion under the conditions of this study. However, electrochemical data showed biofilm presence lowered coupon electrochemical impedance in static and fretting cultures, suggesting resistive and capacitive characteristics of the metal oxide-biofilm-media interface were altered. Under fretting, the P. aeruginosa group exhibited a distinct damage morphology and Co:Cr:Mo ratio within the wear scar when compared with S. aureus and the bacteria-free control. These differences suggest the presence of P. aeruginosa biofilms may negatively impact corrosion resistance at the fretting interface. Taken together these results demonstrate biofilms can contribute to implant corrosion by influencing the electrochemical impedance of implant metal surfaces. This article is protected by copyright. All rights reserved.}, } @article {pmid31354823, year = {2019}, author = {Cunha, EJ and Auersvald, CM and Deliberador, TM and Gonzaga, CC and Esteban Florez, FL and Correr, GM and Storrer, CLM}, title = {Effects of Active Oxygen Toothpaste in Supragingival Biofilm Reduction: A Randomized Controlled Clinical Trial.}, journal = {International journal of dentistry}, volume = {2019}, number = {}, pages = {3938214}, doi = {10.1155/2019/3938214}, pmid = {31354823}, issn = {1687-8728}, abstract = {Gingivitis is still considered a major risk factor for the occurrence and progression of periodontal disease. The aim of the present study was to compare the long-term (1, 12, and 18 weeks) antiplaque and antigingivitis efficacies of two commercially available toothpastes, Colgate Total® (CT) and BlueM® (BM), against attached supragingival dental plaque and gingival inflammation in an experimental gingivitis model. A parallel double-blinded randomized clinical trial including 39 dental students who refrained from all plaque control methods (manual or chemical) for 7 days was conducted. After the establishment of clinical gingivitis, participants were randomized into two experimental groups (CT and BM). Plaque index (PI) and gingival index (GI) were then calculated according to Turesky's modified Quigley and Hein index. Participants were assessed in four time periods (preclinical trial phase (W -1), gingivitis phase (W0), one week (W1), twelve weeks (W12), and eighteen weeks (W18)). Participants' stimulated saliva was collected and cultured (either aerobically or anaerobically, 37°C, 48 hours) in each time period (W -1, W0, W1, W12, and W18) for the count of viable colonies. Obtained data were analyzed using 2-way ANOVA and Tukey's test (α = 0.05). No significant differences were found (p > 0.05) between experimental groups at W -1. Significant differences between groups were observed at W0 (p < 0.05) for the parameter time period, but not for the interaction between parameters (time period ∗ toothpastes). Lower bacterial counts were observed in both groups after one week of toothbrushing; however, no significant differences were found between investigated dentifrices. Intra- and intergroup comparisons revealed that significant differences were not found (p > 0.05) between dentifrices at W1, W12, and W18 for both GI and PI. The present study demonstrated that toothpastes containing active oxygen and lactoferrin (BM) have comparable antiplaque and antigingivitis efficacies with triclosan-containing toothpastes (CT).}, } @article {pmid31354319, year = {2019}, author = {Abd El-Baky, RM and Sandle, T and John, J and Abuo-Rahma, GEA and Hetta, HF}, title = {A novel mechanism of action of ketoconazole: inhibition of the NorA efflux pump system and biofilm formation in multidrug-resistant Staphylococcus aureus.}, journal = {Infection and drug resistance}, volume = {12}, number = {}, pages = {1703-1718}, doi = {10.2147/IDR.S201124}, pmid = {31354319}, issn = {1178-6973}, abstract = {Background: The rapid emergence of antimicrobial resistance among Gram-positive organisms, especially staphylococci, has become a serious clinical challenge. Efflux machinery and biofilm formation are considered two of the main causes of antimicrobial resistance and therapy failure. Aim: Our study aims to evaluate the antibiofilm and efflux pump inhibitory activity of the antifungal ketoconazole against multidrug-resistant (MDR) Staphylococcus aureus. Methods: Ketoconazole was tested for its effect on the following: minimum inhibitory concentrations (MICs) of ciprofloxacin, norfloxacin, levofloxacin, and ethidium bromide (EtBr) by the broth microdilution method, the efflux of EtBr by NorA-positive MDR S. aureus, and the relative expression of NorA, NorB, and NorC efflux pump genes. Docking studies of ketoconazole were performed using 1PW4 (glycerol-3-phosphate transporter from Escherichia coli which was the representative structure from the major facilitator superfamily). Results: Ketoconazole significantly decreased the MICs of levofloxacin, ciprofloxacin, norfloxacin, and EtBr (a substrate for efflux pump) by 8 to 1024-fold (P<0.01) and decreased the efflux of EtBr. Furthermore, a time-kill assay revealed that combinations of levofloxacin with ketoconazole or carbonyl cyanide m-chlorophenylhydrazone showed no growth for the tested strains after 24 h in comparison to the effect of levofloxacin alone. Docking studies and the ability of ketoconazole to diminish the relative expression of NorA gene in comparison to control (untreated strains) confirmed its action as an efflux pump inhibitor. Conclusion: The findings showed that the antifungal ketoconazole has no antibacterial activity but can potentiate the activity of the fluroquinolones against MDR S. aureus via inhibiting efflux pump and biofilm formation in vitro.}, } @article {pmid31352165, year = {2019}, author = {Riegler, P and Bieringer, E and Chrusciel, T and Stärz, M and Löwe, H and Weuster-Botz, D}, title = {Continuous conversion of CO2/H2 with Clostridium aceticum in biofilm reactors.}, journal = {Bioresource technology}, volume = {291}, number = {}, pages = {121760}, doi = {10.1016/j.biortech.2019.121760}, pmid = {31352165}, issn = {1873-2976}, abstract = {A lab-scale stirred-tank bioreactor was reversibly retrofitted to a packed-bed and a trickle-bed biofilm reactor to study and compare the conversion of CO2/H2 with immobilised Clostridiumaceticum. The biofilm reactors were characterised and their functionality confirmed. Up to 8.6 g of C. aceticum were immobilised onto 300 g sintered ceramic carrier material, proving biofilm formation to be a robust means for cell retention of C. aceticum. Continuous CO2/H2-fermentation studies were performed with both biofilm reactor configurations as function of dilution rates, partial gas pressures and gas flow rates. The experiments showed that in the packed-bed biofilm reactor, the acetate space-time yield was independent of the dilution rate, because of low H2 gas-liquid mass transfer rates (≤17 mmol H2 L-1 h-1). The continuous operation of the trickle-bed biofilm reactor increased the gas-liquid mass transfer rates to up to 56 mmol H2 L-1 h-1. Consequently, the acetate space-time yield of up to 14 mmol acetate L-1 h-1 was improved 3-fold at hydrogen conversions of up to 96%.}, } @article {pmid31351106, year = {2019}, author = {Bautista-Hernández, LA and Gómez-Olivares, JL and Buentello-Volante, B and Dominguez-Lopez, A and Garfias, Y and Acosta-García, MC and Calvillo-Medina, RP and Bautista-de Lucio, VM}, title = {Negative interaction of Staphylococcus aureus on Fusarium falciforme growth ocular isolates in an in vitro mixed biofilm.}, journal = {Microbial pathogenesis}, volume = {}, number = {}, pages = {103644}, doi = {10.1016/j.micpath.2019.103644}, pmid = {31351106}, issn = {1096-1208}, abstract = {The interactions between prokaryotes and eukaryotes are abundant in nature. These microorganisms also interact in the human body. Fungal-bacteria interactions are present in many diseases. In this study, we evaluated the microbial interaction of Fusarium falciforme and Staphylococcus aureus developing mixed biofilm in vitro. When both microorganisms grew up together the mixed biofilm biomass decreased than F. falciforme monobiofilm biomass. S. aureus was able to interact and form aggregates over the mycelium and conidia surface of F. falciforme. Our results suggest that S. aureus could bind to colloidal chitin. On another hand, the supernatants from S. aureus biofilm and S. aureus-F. falciforme presented an antifungal effect over F. falciforme biofilm formation. Finally we found that the pH had an inhibitory effect over fungal biofilm formation. We concluded that S. aureus can affect the F. falciforme growth negatively in mixed biofilm involving factors like pH, supernatants compounds, anchor to chitin, and bacterial viability.}, } @article {pmid31350606, year = {2019}, author = {Schopf, A and Delatolla, R and Kirkwood, KM}, title = {Partial nitritation at elevated loading rates: design curves and biofilm characteristics.}, journal = {Bioprocess and biosystems engineering}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00449-019-02177-8}, pmid = {31350606}, issn = {1615-7605}, support = {497995-2017//Natural Sciences and Engineering Research Council of Canada/ ; }, abstract = {There is a need to develop low operational intensity, cost-effective, and small-footprint systems to treat wastewater. Partial nitritation has been studied using a variety of control strategies, however, a gap in passive operation is evident. This research investigates the use of elevated loading rates as a strategy for achieving low operational intensity partial nitritation in a moving bed biofilm reactor (MBBR) system. The effects of loading rates on nitrification kinetics and biofilm characteristics were determined at elevated, steady dissolved oxygen concentrations between 5.5 and 7.0 mg O2/L and ambient temperatures between 19 and 21 °C. Four elevated loading rates (3, 4, 5 and 6.5 g NH4+-N/m2 days) were tested with a distinct shift in kinetics being observed towards nitritation at elevated loadings. Complete partial nitritation (100% nitrite production) was achieved at 6.5 g NH4+-N/m2 days, likely due to thick biofilm (572 µm) and elevated NH4+-N load, which resulted in suppression of nitrite oxidation.}, } @article {pmid31349525, year = {2019}, author = {Ismail, NA and Amin, KAM and Majid, FAA and Razali, MH}, title = {Gellan gum incorporating titanium dioxide nanoparticles biofilm as wound dressing: Physicochemical, mechanical, antibacterial properties and wound healing studies.}, journal = {Materials science & engineering. C, Materials for biological applications}, volume = {103}, number = {}, pages = {109770}, doi = {10.1016/j.msec.2019.109770}, pmid = {31349525}, issn = {1873-0191}, abstract = {In this work, the potential of titanium dioxide nanoparticles incorporated gellan gum (GG + TiO2-NPs) biofilm as wound dressing material was investigated. The GG + TiO2-NPs biofilm was prepared via evaporative casting technique and was characterized using FTIR, XRD, and SEM to study their physiochemical properties. The mechanical properties, swelling and water vapor transmission rate (WVTR) of biofilm was determined to comply with an ideal wound dressing material. In vitro and in vivo wound healing studies was carried out to evaluate the performance of GG + TiO2-NPs biofilm. In vitro wound healing was studied on 3 T3 mouse fibroblast cells for cell viability, cell proliferation, and scratch assay. The acridine orange/propidium iodide (AO/PI) staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were used to evaluate the viability of cell and cell proliferation. Cell migration assay was analyzed using Essen BioScience IncuCyteTM Zoom system. In vivo wound healing via open excision wounds model on Sprague Dawley rat was studied within 14 days. The FT-IR spectra of GG + TiO2-NPs biofilm show main bands assigned to OH stretching, OH deformation, and TiO stretching modes. XRD pattern of GG + TiO2-NPs biofilm suggesting that TiO2-NPs was successfully incorporated in biofilm and well distributed on the surface as proved by SEM analysis. The GG + TiO2-NPs biofilm shows higher mechanical strength and swelling (3.76 ± 0.11 MPa and 1061 ± 6%) as compared to pure GG film (3.32 ± 0.08 Mpa and 902 ± 6%), respectively. GG + TiO2-NPs biofilm shows good antibacterial properties as 9 ± 0.25 mm and 11 ± 0.06 mm exhibition zone was observed against Staphylococcus aureus and Escherichia coli bacteria, respectively. While no exhibition zone was obtained for pure GG biofilm. GG + TiO2-NPs biofilm also demonstrated better cell-to-cell interaction properties, as it's promoted cell proliferation and cell migration to accelerate open excision wound healing on Sprague Dawley rat. The wound treated with GG + TiO2-NPs biofilm was healed within 14 days, on the other hand, the wound is still can be seen when it was treated with GG. However, GG and GG + TiO2-NPs biofilm show no cytotoxicity effects on mouse fibroblast cells.}, } @article {pmid31349520, year = {2019}, author = {Vögeling, H and Plenagl, N and Seitz, BS and Duse, L and Pinnapireddy, SR and Dayyoub, E and Jedelska, J and Brüßler, J and Bakowsky, U}, title = {Synergistic effects of ultrasound and photodynamic therapy leading to biofilm eradication on polyurethane catheter surfaces modified with hypericin nanoformulations.}, journal = {Materials science & engineering. C, Materials for biological applications}, volume = {103}, number = {}, pages = {109749}, doi = {10.1016/j.msec.2019.109749}, pmid = {31349520}, issn = {1873-0191}, abstract = {Catheter related infections are causing one third of all blood stream infections. The mortality of those infections is very high and the gold standard for catheter related blood stream infections (CR-BSI) is still the removal of the catheter and systemic antibiotic therapy. There already exist some approaches to prevent the biofilm formation on catheter material, which are far from ideal. A new strategy to prevent bacterial colonization on catheter surfaces is the application of photodynamic therapy (PDT). Therefor the surface has to be modified with substances that can be activated by light, leading to the production of cell toxic reactive oxygen species (ROS). Only small concentrations of the so called photosensitizer (PS) are necessary, avoiding side effects in human therapy. Furthermore, there is no resistance development in PDT. In this study polyurethane (PUR) surfaces were coated with hypericin nanoformulations, leading to 4.3 log10 reduction in bacterial growth in vitro. The effect could be enhanced by the application of ultrasound. The combination of PDT with ultrasound therapy led to a synergistic effect resulting in a 6.8 log10 reduction of viable counts. This minimal invasive method requires only an optical fibre inserted in the catheter lumen and an ultrasound device. Thus the implementation in daily clinical practice is very simple.}, } @article {pmid31349502, year = {2019}, author = {Torres-Rêgo, M and Gláucia-Silva, F and Rocha Soares, KS and de Souza, LBFC and Damasceno, IZ and Santos-Silva, ED and Lacerda, AF and Chaves, GM and Silva-Júnior, AAD and Fernandes-Pedrosa, MF}, title = {Biodegradable cross-linked chitosan nanoparticles improve anti-Candida and anti-biofilm activity of TistH, a peptide identified in the venom gland of the Tityus stigmurus scorpion.}, journal = {Materials science & engineering. C, Materials for biological applications}, volume = {103}, number = {}, pages = {109830}, doi = {10.1016/j.msec.2019.109830}, pmid = {31349502}, issn = {1873-0191}, abstract = {Among several bioactive peptides identified from the venom glands of the Tityus stigmurus scorpion, one peptide with hypotensive action (TistH, Tityus stigmurus Hypotensin) showed multifunctional and biotechnological applications. The maximum efficacy of this class of compounds can be achieved by immobilizing it in specific and suitable biomaterials or suitable carriers. In this study, distinct entrapment methods of TistH in chitosan nanoparticles was tested using its incorporation (CN-TistH-Inc) or adsorption (CN-TistH-Ads) methods by ionotropic gelification. Physico-chemical properties as well as biocompatibility and antifungal efficacy were assessed for different samples. Atomic force microscopy and field emission gun scanning electronic microscopy images associated with particle size measurements demonstrated that the two methods induced cationic spherical, small (< 160 nm), and narrow-sized (PdI about 0.3) nanoparticles, even after peptide loading greater than 96.5%, which was confirmed using Fourier transform infrared spectroscopy. The colloidal suspensions showed to be stable for 8 weeks and were able to induce the desired slow in vitro peptide release. Cytotoxicity assays performed in normal cells originated from murine macrophages (RAW 264.7) and kidneys of African green monkeys (Vero E6) suggested biocompatibility of samples. The CN-TistH-Inc and CN-TistH-Ads showed a minimal inhibitory concentration of 89.2 μg.mL-1 against Candida albicans, 11.1 μg.mL-1 for C. parapsilosis and C. tropicalis, confirmed by minimum fungicidal concentrations assay. Moreover, the TistH-loaded cross-linked chitosan nanoparticles significantly reduced the biofilm formation of clinical yeast sepsis of C. tropicalis and C. krusei, as well as clinical yeasts of vulvovaginal candidiasis of C. albicans. In this approach, biodegradable nanocarriers prepared using simple and reproducible methods demonstrated the ability to deliver the TistH peptide from T. stigmurus and improve its antifungal efficacy.}, } @article {pmid31349480, year = {2019}, author = {Hasan, N and Cao, J and Lee, J and Naeem, M and Hlaing, SP and Kim, J and Jung, Y and Lee, BL and Yoo, JW}, title = {PEI/NONOates-doped PLGA nanoparticles for eradicating methicillin-resistant Staphylococcus aureus biofilm in diabetic wounds via binding to the biofilm matrix.}, journal = {Materials science & engineering. C, Materials for biological applications}, volume = {103}, number = {}, pages = {109741}, doi = {10.1016/j.msec.2019.109741}, pmid = {31349480}, issn = {1873-0191}, abstract = {Wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) biofilm represent a high risk in patients with diabetes. Nitric oxide (NO) has shown promise in dispersing biofilm and wound healing. For an effective treatment of MRSA biofilm-infected wounds, however, NO needs to be supplied to the biofilm matrix in a sustainable manner due to a short half-life and limited diffusion distance of NO. In this study, polyethylenimine/diazeniumdiolate (PEI/NONOate)-doped PLGA nanoparticles (PLGA-PEI/NO NPs) with an ability to bind to the biofilm matrix are developed to facilitate the NO delivery to MRSA biofilm-infected wound. In simulated wound fluid, PLGA-PEI/NO NPs show an extended NO release over 4 days. PLGA-PEI/NO NPs firmly bind to the MRSA biofilm matrix, resulting in a greatly enhanced anti-biofilm activity. Moreover, PLGA-PEI/NO NPs accelerate healing of MRSA biofilm-infected wounds in diabetic mice along with complete biofilm dispersal and reduced bacterial burden. These results suggest that the biofilm-binding NO-releasing NPs represent a promising NO delivery system for the treatments of biofilm-infected chronic wounds.}, } @article {pmid31349180, year = {2019}, author = {di Biase, A and Kowalski, MS and Devlin, TR and Oleszkiewicz, JA}, title = {Moving bed biofilm reactor technology in municipal wastewater treatment: A review.}, journal = {Journal of environmental management}, volume = {247}, number = {}, pages = {849-866}, doi = {10.1016/j.jenvman.2019.06.053}, pmid = {31349180}, issn = {1095-8630}, abstract = {The review encompasses the development of municipal wastewater treatment process using MBBR from early stages, established application, and recent advancements. An overview of main drivers leading to the MBBR technology development over its early stage is discussed. Biocarriers types and features together with biofilm development and role of extracellular polymeric substances (EPS) are presented, ultimately, addressing the challenge in decreasing startup time required for full operation. Furthermore, the review investigates the state of the art of MBBR technology for nutrient removal (i.e., COD and BOD, nitrogen and phosphorus) through process functionality and configuration of established (e.g., IFAS) and under development (e.g. PN/A) applications. Reactor operational characteristics such as filling fractions, mixing properties, dissolved oxygen requirements, and loading rates are presented and related to full scale examples. Current literature discussing the most recent studies on MBBR capability in reduction and removal of chemicals of emerging concern (CEC) released is presented. Ultimately, high rate carbon and nitrogen removal through A/B stage process are examined in its main operational parameters and its application towards energy neutrality suggesting novel MBBR application to further reduce energy requirements and plant footprint.}, } @article {pmid31347191, year = {2019}, author = {Kannan, S and Krishnamoorthy, G and Kulanthaiyesu, A and Marudhamuthu, M}, title = {Effect of biosurfactant derived from Vibrio natriegens MK3 against Vibrio harveyi biofilm and virulence.}, journal = {Journal of basic microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1002/jobm.201800706}, pmid = {31347191}, issn = {1521-4028}, support = {//Department of Biotechnology, Interdisciplinary Programme in Life Sciences/ ; //University Grants Commission (UGC-NFOBC)/ ; }, abstract = {Vibrio harveyi is a marine luminous pathogen, which causes biofilm-mediated infections, pressures the search for an innovative alternate approach to strive against vibriosis in aquaculture. This study anticipated to explore the effect of glycolipid biosurfactant as an antipathogenic against V. harveyi to control vibriosis. In this study, 27 bacterial strains were isolated from marine soil sediments. Out of these, 11 strains exhibited surfactant activity and the strain MK3 showed high emulsification index. The potent strain was identified as Vibrio natriegens and named as V. natriegens MK3. The extracted biosurfactant was purified using high-performance liquid chromatography and it was efficient to decrease the surface tension of the growth medium up to 21 mN/m. The functional group and composition of the biosurfactant were determined by Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy spectral studies and the nature of the biosurfactant was identified as glycolipid. The surfactant was capable of reducing the biofilm formation, bioluminescence, extracellular polysaccharide synthesis, and quorum sensing in marine shrimp pathogen V. harveyi. The antagonistic effect of biosurfactant was evaluated against V. harveyi-infected brine shrimp Artemia salina. This study reveals that biosurfactant can be considered for the management of biofilm-related aquatic infections.}, } @article {pmid31346374, year = {2019}, author = {Listiana-Kriswandini, I and Budi-Rahardjo, M and Soesilawati, P and Prisca-Suciadi, A}, title = {Detection of Candida albicans biofilm proteins induced by glucose, lactose, soy protein, and iron.}, journal = {Journal of clinical and experimental dentistry}, volume = {11}, number = {6}, pages = {e542-e546}, doi = {10.4317/jced.55787}, pmid = {31346374}, issn = {1989-5488}, abstract = {Background: Oral candidiasis is one of the most common fungal infections, which attack the mucosa of the oral cavity. These lesions are mostly caused by the fungal species Candida albicans. Candida albicans is included in the normal oral microorganisms that are opportunistic pathogens, and its presence is quite large, which can reach 75% of the total oral fungal population. Research on specific proteins of Candida biofilm can be an alternative to early prevention of oral infections such as Oral Candidiasis. This biofilm protein can be used as a reference in making kits to detect the presence of microbes that cause infectious diseases. The purpose of this study was to determine molecular weight of Candida albicans biofilm protein induced by 5% glucose, 5% lactose, soy protein, and 5% iron.

Material and Methods: This experimental laboratory study used SDS-PAGE electrophoresis to determine the molecular weight of Candida albicans biofilm proteins induced by glucose 5%, lactose 5%, soy protein, and iron 5%.

Results: Biofilm induced by 5% glucose shows four protein bands: 71,6 kDa; 56,1 kDa; 49,7 kDa; and 41 kDa. Biofilm induced by 5% lactose shows seven protein bands: 71 kDa; 61,2 kDa; 57,7 kDa; 55,3 kDa; 48,9 kDa; 39,5 kDa; and 29,8 kDa. Biofilm induced by soy protein shows one protein band: 49,4 kDa. Biofilm induced by 5% iron shows one protein band: 51,1 kDa.

Conclusions: Candida albicans biofilm induced by 5% glucose has four protein band candidates, 5% lactose has seven candidates of protein band, and soy protein and 5% iron each has a candidate of protein band, which can be used as a target for the detection of oral Candidiasis. Key words:Biofilm protein, Candida albicans, molecular weight, oral candidiasis.}, } @article {pmid31345229, year = {2019}, author = {Besser, M and Terberger, J and Weber, L and Ghebremedhin, B and Naumova, EA and Arnold, WH and Stuermer, EK}, title = {Impact of probiotics on pathogen survival in an innovative human plasma biofilm model (hpBIOM).}, journal = {Journal of translational medicine}, volume = {17}, number = {1}, pages = {243}, doi = {10.1186/s12967-019-1990-4}, pmid = {31345229}, issn = {1479-5876}, support = {IFF2018-61//University of Witten/Herdecke/ ; }, abstract = {BACKGROUND: Despite of medical advances, the number of patients suffering on non-healing chronic wounds is still increasing. This fact is attended by physical and emotional distress and an economic load. The majority of chronic wounds are infected of harmful microbials in a protecting extracellular matrix. These biofilms inhibit wound healing. Biofilm-growing bacteria developed unique survival properties, which still challenge the appropriate wound therapy. The present in-vitro biofilm models are not suitable for translational research. By means of a novel in-vivo like human plasma biofilm model (hpBIOM), this study systematically analysed the influence of 3 probiotics on the survival of five clinically relevant pathogenic microorganisms.

METHODS: Human plasma was used to produce the innovate biofilm. Pathogenic microorganisms were administered to the plasma. By stimulating the production of a fibrin scaffold, stable coagula-like discs with integrated pathogens were produced. The five clinically relevant pathogens P. aeruginosa, S. aureus, S. epidermidis, E. faecium and C. albicans were challenged to the probiotics L. plantarum, B. lactis and S. cerevisiae. The probiotics were administered on top of the biofilm and the survival was quantified after 4 h and 24 h of incubation. For statistics, two-way ANOVA with post-hoc Tukey's HSD test was applied. P-value > 0.05 was considered to be significant.

RESULTS: SEM micrographs depicted the pathogens on the surface of the fibrin scaffold, arranged in close proximity and produced the glycocalyx. The application of probiotics induced different growth-reducing capacities towards the pathogens. B. lactis and S. cerevisiae showed slight bacteria-reducing properties. The survival of C. albicans was not affected at all. The most antimicrobial activity was detected after the treatment with L. plantarum.

CONCLUSIONS: This study successfully reproduced a novel human biofilm model, which provides a human wound milieu and individual immune competence. The success of bacteriotherapy is dependent on the strain combination, the number of probiotics and the activity of the immune cells. The eradicating effect of L. plantarum on P. aeruginosa should be emphasized.}, } @article {pmid31344909, year = {2019}, author = {Zhang, T and Ying, D and Qi, M and Li, X and Fu, L and Sun, X and Wang, L and Zhou, Y}, title = {Anti-Biofilm Property of Bioactive Upconversion Nanocomposites Containing Chlorin e6 against Periodontal Pathogens.}, journal = {Molecules (Basel, Switzerland)}, volume = {24}, number = {15}, pages = {}, doi = {10.3390/molecules24152692}, pmid = {31344909}, issn = {1420-3049}, support = {81570983//National Natural Science Foundation of China/ ; 20180414030GH//International Cooperation Project of Science and Technology Development Jilin Province/ ; }, abstract = {Photodynamic therapy (PDT) based periodontal disease treatment has received extensive attention. However, the deep tissue location of periodontal plaque makes the conventional PDT encounter a bottleneck. Herein, upconversion fluorescent nanomaterial with near-infrared light excitation was introduced into the treatment of periodontal disease, overcoming the limited tissue penetration depth of visible light in PDT. Photosensitizer Ce6 molecules were combined with upconversion nanoparticles (UCNPs) NaYF4:Yb,Er with a novel strategy. The hydrophobic UCNPs were modified with amphiphilic silane, utilizing the hydrophobic chain of the silane to bind to the hydrophobic groups of the UCNPs through a hydrophobic-hydrophobic interaction, and the Ce6 molecules were loaded in this hydrophobic layer. This achieves both the conversion of the hydrophobic to the hydrophilic surface and the loading of the oily photosensitizer molecules. Because the excitation position of the Ce6 molecule is in the red region, Mn ions were doped to enhance red light, and thus the improved PDT function. This Ce6 loaded UCNPs composites with efficient red upconversion luminescence show remarkable bacteriological therapeutic effect on Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum and the corresponding biofilms under 980 nm irradiation, indicating a high application prospect in the treatment of periodontal diseases.}, } @article {pmid31344638, year = {2019}, author = {Jensen, MB and Strübing, D and de Jonge, N and Nielsen, JL and Ottosen, LDM and Koch, K and Kofoed, MVW}, title = {Stick or leave - Pushing methanogens to biofilm formation for ex situ biomethanation.}, journal = {Bioresource technology}, volume = {291}, number = {}, pages = {121784}, doi = {10.1016/j.biortech.2019.121784}, pmid = {31344638}, issn = {1873-2976}, abstract = {Biomethanation exploits the ability of methanogenic archaea to convert CO2 and renewable H2 from electrolysis to biomethane. Biofilm reactors are promising for biomethanation scale-up due to high CH4 productivity and low energy input for H2 gas-liquid mass transfer. Effects of operational conditions on biofilm dynamics remain largely uncharacterized but may increase reactor potentials further. This study investigated the effect of hydraulic retention time (HRT) on methanogenic biofilm activity and composition. Commercial carriers floating in liquid were exposed to H2/CO2 for 87 days with the liquid phase being subject to either 18 hours, 10 days, or 20 days HRT. Methanogenic biofilms were dominated by hydrogenotrophic methanogens, but biofilm CH4 productivity was enhanced at 18 hours HRT due to wash-out of competing planktonic species, which otherwise hampered proliferation of biofilm biomass at long HRT. It is suggested that high-rate biofilm reactors can increase methanogenic biofilm activity by minimizing the liquid's H2 exposure.}, } @article {pmid31344634, year = {2019}, author = {Song, T and Li, S and Jin, J and Yin, Z and Lu, Y and Bao, M and Li, Y}, title = {Enhanced hydrolyzed polyacrylamide removal from water by an aerobic biofilm reactor-ozone reactor-aerobic biofilm reactor hybrid treatment system: Performance, key enzymes and functional microorganisms.}, journal = {Bioresource technology}, volume = {291}, number = {}, pages = {121811}, doi = {10.1016/j.biortech.2019.121811}, pmid = {31344634}, issn = {1873-2976}, abstract = {Degradation of hydrolyzed polyacrylamide-containing (HPAM-containing) wastewater was investigated in a lab-scale aerobic-ozonic-aerobic hybrid treatment system. When the HPAM concentration was 500 mg L-1 and the ozone dose was 25 g O3/g TOC, the HPAM removal rate reached 90.79%. Experimental results obtained from gel permeation chromatography (GPC) and rheometer indicated that the refractory HPAM was decomposed into small-molecule compounds. High performance liquid chromatography (HPLC) analysis showed that there was no acrylamide (AM) in the effluent of the system. Microbial communities in two aerobic biofilm reactors (ABRs) were analyzed by Illumina MiSeq Sequencing, which indicated that norank_f_Cytophagaceae, Meiothermus, Bacillus, etc. were keystone functional bacterial genera and Methanobacterium, norank_p_Bathyarchaeota, norank_c_Marine_Group_Ⅰ, etc. were dominant functional archaeal groups. To our knowledge, this is the first study to treat HPAM-containing wastewater using an aerobic-ozonic-aerobic hybrid process. Good removal efficiencies and presence of functional microorganisms demonstrated that the hybrid treatment system was practical for treating HPAM-containing wastewater.}, } @article {pmid31342619, year = {2019}, author = {Sivadon, P and Barnier, C and Urios, L and Grimaud, R}, title = {Biofilm formation as a microbial strategy to assimilate particulate substrates.}, journal = {Environmental microbiology reports}, volume = {}, number = {}, pages = {}, doi = {10.1111/1758-2229.12785}, pmid = {31342619}, issn = {1758-2229}, abstract = {In most ecosystems, a large part of the organic carbon is not solubilized in the water phase. Rather, it occurs as particles made of aggregated hydrophobic and/or polymeric natural or man-made organic compounds. These particulate substrates are degraded by extracellular digestion/solubilization implemented by heterotrophic bacteria that form biofilms on them. Organic particle-degrading biofilms are widespread and have been observed in aquatic and terrestrial natural ecosystems, in polluted and man-driven environments and in the digestive tracts of animals. They have central ecological functions as they are major players in carbon recycling and pollution removal. The aim of this review is to highlight bacterial adhesion and biofilm formation as central mechanisms to exploit the nutritive potential of organic particles. It focuses on the mechanisms that allow access and assimilation of nondissolved organic carbon, and considers the advantage provided by biofilms for gaining a net benefit from feeding on particulate substrates. Cooperative and competitive interactions taking place in biofilms feeding on particulate substrates are also discussed. This article is protected by copyright. All rights reserved.}, } @article {pmid31341834, year = {2019}, author = {Gawish, S and Abbass, A and Abaza, A}, title = {Occurrence and biofilm forming ability of Pseudomonas aeruginosa in the water output of dental unit waterlines in a dental center in Alexandria, Egypt.}, journal = {Germs}, volume = {9}, number = {2}, pages = {71-80}, doi = {10.18683/germs.2019.1160}, pmid = {31341834}, issn = {2248-2997}, abstract = {Introduction: Dental unit waterlines (DUWLs) are notorious for being contaminated with different bacterial species including the opportunistic pathogen Pseudomonas aeruginosa which poses a risk to patients and professionals. This work aimed at studying the occurrence and biofilm-forming ability (BFA) of P. aeruginosa in the output of DUWLs in a dental center in Egypt.

Methods: Water samples were collected from the outlets of the high-speed hand piece, the air/water syringe and the cup filler waterlines. Bacteriological analysis included heterotrophic plate count (HPC), isolation and identification of P. aeruginosa and determination of the antimicrobial susceptibility and the BFA of the isolates by tissue culture plate (TCP) method and tube method (TM).

Results: The average concentration of HPC bacteria in the output of the 3 DUWLs was 2.9×104 CFU/μL where 88.3% of the samples exceeded the Egyptian standards for drinking water (<50 CFU L). P. aeruginosa was isolated from nine cup filler samples (which had a water source different from the other waterlines). The isolates were sensitive to all tested antimicrobials. Of these nine isolates, 6, 5 and 4 were positive for BFA by TCP, modified TCP and TM, respectively.

Conclusions: More stringent measures are required to ensure safer dental water; as the majority of studied samples exceeded the required HPC bacterial limit and P. aeruginosa isolates were detected. P. aeruginosa isolates from DUWLs may not be as resistant to antibiotics as what is reported in the literature about clinical isolates. Some P. aeruginosa isolates can colonize DUWLs despite their inability to form biofilms in experimental testing.}, } @article {pmid31341833, year = {2019}, author = {Ahmed, DM and Messih, MAWA and Ibrahim, NH and Meabed, MH and Abdel-Salam, SM}, title = {Frequency of icaA and icaD determinants and biofilm formation among coagulase-negative staphylococci associated with nasal carriage in neonatal intensive care units.}, journal = {Germs}, volume = {9}, number = {2}, pages = {61-70}, doi = {10.18683/germs.2019.1159}, pmid = {31341833}, issn = {2248-2997}, abstract = {Introduction: Nasal colonization with coagulase-negative staphylococci (CoNS) may be a preliminary risk factor for systemic infection. The aim of this study was to assess the frequency of ica A and D genes and biofilm formation among hospital-acquired nasal colonizing CoNS strains isolated from neonates in the neonatal intensive care units (NICUs). Antibiotic sensitivity patterns and some relevant risk factors were estimated.

Methods: This study assessed nasal colonization with CoNS among neonates at days one and three of admission to NICUs of Beni-Suef University Hospital and Beni-Suef General Hospital from November 2015 to May 2016. The isolates were screened and identified; susceptibility testing was performed. Biofilm formation was examined using the Congo red agar method. Isolates identified as CoNS were tested by polymerase chain reaction (PCR) for the presence of mecA and icaA and icaD genes.

Results: A total of 340 nasal swabs were collected from 170 neonates. The incidence of nasal colonization with CoNS was 50%. The species most frequently isolated were S. haemolyticus and S. epidermidis. Multidrug resistance (MDR) was detected in 86% of isolates. It was found that there was a strong association between the presence of mecA gene and phenotypic resistance to methicillin and also the presence of the icaA gene and biofilm formation.

Conclusions: Neonates admitted to NICUs can become reservoirs for CoNS strains, leading to potential dissemination of MDR strains into the community.}, } @article {pmid31340580, year = {2019}, author = {Bessa, LJ and Manickchand, JR and Eaton, P and Leite, JRSA and Brand, GD and Gameiro, P}, title = {Intragenic Antimicrobial Peptide Hs02 Hampers the Proliferation of Single- and Dual-Species Biofilms of P. aeruginosa and S. aureus: A Promising Agent for Mitigation of Biofilm-Associated Infections.}, journal = {International journal of molecular sciences}, volume = {20}, number = {14}, pages = {}, doi = {10.3390/ijms20143604}, pmid = {31340580}, issn = {1422-0067}, support = {UID/QUI/50006/2019//FCT/MCTES through national funds/ ; 0193.000866/2015//FAP-DF/ ; }, abstract = {Pseudomonas aeruginosa and Staphylococcus aureus are two major pathogens involved in a large variety of infections. Their co-occurrence in the same site of infection has been frequently reported and is linked to enhanced virulence and difficulty of treatment. Herein, the antimicrobial and antibiofilm activities of an intragenic antimicrobial peptide (IAP), named Hs02, which was uncovered from the human unconventional myosin 1H protein, were investigated against several P. aeruginosa and S. aureus strains, including multidrug-resistant (MDR) isolates. The antibiofilm activity was evaluated on single- and dual-species biofilms of P. aeruginosa and S. aureus. Moreover, the effect of peptide Hs02 on the membrane fluidity of the strains was assessed through Laurdan generalized polarization (GP). Minimum inhibitory concentration (MIC) values of peptide Hs02 ranged from 2 to 16 μg/mL against all strains and MDR isolates. Though Hs02 was not able to hamper biofilm formation by some strains at sub-MIC values, it clearly affected 24 h preformed biofilms, especially by reducing the viability of the bacterial cells within the single- and dual-species biofilms, as shown by confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) images. Laurdan GP values showed that Hs02 induces membrane rigidification in both P. aeruginosa and S. aureus. Peptide Hs02 can potentially be a lead for further improvement as an antibiofilm agent.}, } @article {pmid31340472, year = {2019}, author = {Al-Bakri, AG and Mahmoud, NN}, title = {Photothermal-Induced Antibacterial Activity of Gold Nanorods Loaded into Polymeric Hydrogel against Pseudomonas aeruginosa Biofilm.}, journal = {Molecules (Basel, Switzerland)}, volume = {24}, number = {14}, pages = {}, doi = {10.3390/molecules24142661}, pmid = {31340472}, issn = {1420-3049}, support = {1820-1104//the Deanship of Scientific Research at The University of Jordan/ ; 2017-2016/64/04//Deanship of Scientific Research and Graduate Studies at Al-Zaytoonah University of Jordan/ ; 3/2017//Abdul Hameed Shoman Foundation, Amman, Jordan/ ; }, abstract = {In this study, the photothermal-induced bactericidal activity of phospholipid-decorated gold nanorods (DSPE-AuNR) suspension against Pseudomonas aeruginosa planktonic and biofilm cultures was investigated. We found that the treatment of planktonic culture of Pseudomonas aeruginosa with DSPE-AuNR suspension (0.25-0.03 nM) followed by a continuous laser beam exposure resulted in ~6 log cycle reduction of the bacterial viable count in comparison to the control. The percentage reduction of Pseudomonas aeruginosa biofilm viable count was ~2.5-6.0 log cycle upon laser excitation with different concentrations of DSPE-AuNR as compared to the control. The photothermal ablation activity of DSPE-AuNR (0.125 nM) loaded into poloxamer 407 hydrogel against Pseudomonas aeruginosa biofilm resulted in ~4.5-5 log cycle reduction in the biofilm viable count compared to the control. Moreover, transmission electron microscope (TEM) images of the photothermally-treated bacteria revealed a significant change in the bacterial shape and lysis of the bacterial cell membrane in comparison to the untreated bacteria. Furthermore, the results revealed that continuous and pulse laser beam modes effected a comparable photothermal-induced bactericidal activity. Therefore, it can be concluded that phospholipid-coated gold nanorods present a promising nanoplatform to eradicate Pseudomonas aeruginosa biofilm responsible for common skin diseases.}, } @article {pmid31338728, year = {2019}, author = {Zaatout, N and Ayachi, A and Kecha, M}, title = {Epidemiological investigation of subclinical bovine mastitis in Algeria and molecular characterization of biofilm-forming Staphylococcus aureus.}, journal = {Tropical animal health and production}, volume = {}, number = {}, pages = {}, doi = {10.1007/s11250-019-02015-9}, pmid = {31338728}, issn = {1573-7438}, abstract = {Thirty dairy farms were selected for this study; the first objective of our study was to investigate the prevalence of subclinical bovine mastitis (SCM) in Eastern Algeria, from 600 lactating cows, and to identify potential risk factors associated with the occurrence of bovine mastitis and bacteria isolation using logistic regression. The second objective was to evaluate biofilm formation capacity and detect biofilm-associated genes of S. aureus, isolated from SCM cases. Molecular typing was investigated by spa typing. The prevalence of mastitis at cow and quarter level was 37.66% (226/600) and 27.17% (555/2042), respectively. Stage of lactation, cow breed, milk production, and the study area were factors associated with SCM. In addition, the most frequent pathogens isolated from mastitic milk were coagulase-negative staphylococci (CNS), E. coli, and S. aureus. The study area was highly associated with SCM caused by S. aureus; cows from Setif province were 18 times more affected with SCM caused by S. aureus compared to cows from Batna province (OR = 18.6, 95%CI 2.038-171.2), but were less affected with SCM caused by CNS isolates (OR = 0.17, 95%CI 0.033-0.868). Moreover, cows with milk production less than 10 L per day increased (p < 0.05) the prevalence of mastitis caused by E. coli. All the S. aureus isolates had biofilm-forming ability, and 41.66% of isolates were positive for adhesion genes (icaA, icaD, fbnA, and clfA). This study, therefore, warrants the need for improving sanitary measures and strict hygienic measures, and presents the first insight into biofilm-forming ability of S. aureus strains causing mastitis in dairy herds in Algeria, which will help in tracking the evolution of epidemic strains responsible for causing bovine mastitis.}, } @article {pmid31338076, year = {2019}, author = {Alviz-Gazitua, P and Fuentes-Alburquenque, S and Rojas, LA and Turner, RJ and Guiliani, N and Seeger, M}, title = {The Response of Cupriavidus metallidurans CH34 to Cadmium Involves Inhibition of the Initiation of Biofilm Formation, Decrease in Intracellular c-di-GMP Levels, and a Novel Metal Regulated Phosphodiesterase.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1499}, doi = {10.3389/fmicb.2019.01499}, pmid = {31338076}, issn = {1664-302X}, abstract = {Cadmium is a highly toxic heavy metal for biological systems. Cupriavidus metallidurans CH34 is a model strain to study heavy metal resistance and bioremediation as it is able to deal with high heavy metal concentrations. Biofilm formation by bacteria is mediated by the second messenger bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP). The aim of this study was to characterize the response of C. metallidurans CH34 planktonic and biofilm cells to cadmium including their c-di-GMP regulatory pathway. Inhibition of the initiation of biofilm formation and EPS production by C. metallidurans CH34 correlates with increased concentration of cadmium. Planktonic and biofilm cells showed similar tolerance to cadmium. During exposure to cadmium an acute decrease of c-di-GMP levels in planktonic and biofilm cells was observed. Transcription analysis by RT-qPCR showed that cadmium exposure to planktonic and biofilm cells induced the expression of the urf2 gene and the mercuric reductase encoding merA gene, which belong to the Tn501/Tn21 mer operon. After exposure to cadmium, the cadA gene involved in cadmium resistance was equally upregulated in both lifestyles. Bioinformatic analysis and complementation assays indicated that the protein encoded by the urf2 gene is a functional phosphodiesterase (PDE) involved in the c-di-GMP metabolism. We propose to rename the urf2 gene as mrp gene for metal regulated PDE. An increase of the second messenger c-di-GMP content by the heterologous expression of the constitutively active diguanylate cyclase PleD correlated with an increase in biofilm formation and cadmium susceptibility. These results indicate that the response to cadmium in C. metallidurans CH34 inhibits the initiation of biofilm lifestyle and involves a decrease in c-di-GMP levels and a novel metal regulated PDE.}, } @article {pmid31336660, year = {2019}, author = {Cadena, M and Kelman, T and Marco, ML and Pitesky, M}, title = {Understanding Antimicrobial Resistance (AMR) Profiles of Salmonella Biofilm and Planktonic Bacteria Challenged with Disinfectants Commonly Used During Poultry Processing.}, journal = {Foods (Basel, Switzerland)}, volume = {8}, number = {7}, pages = {}, doi = {10.3390/foods8070275}, pmid = {31336660}, issn = {2304-8158}, abstract = {Foodborne pathogens such as Salmonella that survive cleaning and disinfection during poultry processing are a public health concern because pathogens that survive disinfectants have greater potential to exhibit resistance to antibiotics and disinfectants after their initial disinfectant challenge. While the mechanisms conferring antimicrobial resistance (AMR) after exposure to disinfectants is complex, understanding the effects of disinfectants on Salmonella in both their planktonic and biofilm states is becoming increasingly important, as AMR and disinfectant tolerant bacteria are becoming more prevalent in the food chain. This review examines the modes of action of various types of disinfectants commonly used during poultry processing (quaternary ammonium, organic acids, chlorine, alkaline detergents) and the mechanisms that may confer tolerance to disinfectants and cross-protection to antibiotics. The goal of this review article is to characterize the AMR profiles of Salmonella in both their planktonic and biofilm state that have been challenged with hexadecylpyridinium chloride (HDP), peracetic acid (PAA), sodium hypochlorite (SHY) and trisodium phosphate (TSP) in order to understand the risk of these disinfectants inducing AMR in surviving bacteria that may enter the food chain.}, } @article {pmid31336253, year = {2019}, author = {Tian, Z and Liu, R and Zhang, H and Yang, M and Zhang, Y}, title = {Developmental dynamics of antibiotic resistome in aerobic biofilm microbiota treating wastewater under stepwise increasing tigecycline concentrations.}, journal = {Environment international}, volume = {131}, number = {}, pages = {105008}, doi = {10.1016/j.envint.2019.105008}, pmid = {31336253}, issn = {1873-6750}, abstract = {This study aimed to investigate the impact of tigecycline, the third generation tetracycline, on the antibiotic resistance development in environmental microbiota. Two biological contact oxidation reactors containing aerobic biofilm microbiota were constructed, one of which was constantly fed with synthetic wastewater spiked with increasing concentrations of tigecycline (0 to 25 mg/L) under a hydrolytic retention time of 24 h. Over a period of 636 days, chemical oxygen demand removal over 90% and complete nitrification were achieved for both the control and tigecycline-exposed reactors, and effluent tigecycline concentrations in the tigecycline-exposed system were always <0.051 mg/L. Significant increases (p < 0.01) in resistome abundance and resistant bacteria ratio were detected at a tigecycline dose of 10 and 25 mg/L, respectively, revealed by metagenomic sequencing and culture-based method. The increase of resistome in the tigecycline system was mainly attributed to the enrichment of tetX, one cooperative tetracycline degrading gene. Partial canonical correspondence analysis showed that the change of resistome was mainly driven by bacterial community shift (vertical pathway). Network and genome binning analyses further suggested that the proliferation of Flavobacterium harboring tetX contributed to a relatively low community-wide resistance development in the aerobic biofilm microbiota under tigecycline selection by reducing the antibiotic concentration. This work provides scientific bases for the management and evaluation of the resistance risk induced by this novel antibiotic.}, } @article {pmid31336203, year = {2019}, author = {Chávez-Andrade, GM and Tanomaru-Filho, M and Basso Bernardi, MI and de Toledo Leonardo, R and Faria, G and Guerreiro-Tanomaru, JM}, title = {Antimicrobial and biofilm anti-adhesion activities of silver nanoparticles and farnesol against endodontic microorganisms for possible application in root canal treatment.}, journal = {Archives of oral biology}, volume = {107}, number = {}, pages = {104481}, doi = {10.1016/j.archoralbio.2019.104481}, pmid = {31336203}, issn = {1879-1506}, abstract = {OBJECTIVE: This study aimed to evaluate the antimicrobial and biofilm anti-adhesion activities of poly(vinyl alcohol)-coated silver nanoparticles (AgNPs-PVA) and farnesol against Enterococcus faecalis, Candida albicans or Pseudomonas aeruginosa.

DESIGN: Minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) of the solutions, as well as the effect on the biofilm biomass were evaluated. The biofilm anti-adhesion activity was evaluated using bovine root dentine treated with the solutions after 3 min of contact and analyzed by scanning electron microscopy (SEM) and by colony-forming units per milliliter (CFU mL-1) counting. Data were analyzed using ANOVA and Tukey's, the paired Student's t-test or Kruskal-Wallis and Dunn's tests (α = 0.05).

RESULTS: The MIC and MMC values (MIC/MMC) of the AgNPs-PVA and farnesol against E. faecalis were 42.5/50 μM and 0.85/1.0%, respectively. For C. albicans, the values were 27.5/37.5 μM and 1.75/2.5%; and for P. aeruginosa, 32.5/32.5 μM and 2.5/2.75%, respectively. Both solutions showed reduced biofilm biomass (p < 0.05). SEM analysis showed that dentine blocks treated with both solutions had lower biofilm formation than the control (saline), except for C. albicans. In the CFU mL-1 counting, biofilm cells were viable in the all groups in comparison with control (p > 0.05).

CONCLUSIONS: AgNPs-PVA and farnesol showed antimicrobial and biofilm anti-adhesion activities, as well as potential for use as coadjuvant in endodontic treatment, and may be an option as auxiliary procedure for root canal disinfection or to inhibit biofilm formation.}, } @article {pmid31335442, year = {2019}, author = {Munro, APS and Highmore, CJ and Webb, JS and Faust, SN}, title = {Diagnosis and treatment of biofilm infections in children.}, journal = {Current opinion in infectious diseases}, volume = {}, number = {}, pages = {}, doi = {10.1097/QCO.0000000000000582}, pmid = {31335442}, issn = {1473-6527}, abstract = {PURPOSE OF REVIEW: Biofilm-associated infections cause difficulties in the management of childhood chronic infections and other diseases, due to the invasive nature of interventions which are often necessary for definitive management. Despite their importance, there are challenges in diagnosing biofilm infections and gaps in clinicians' understanding regarding the significance of biofilms.

RECENT FINDINGS: Many chronic infections associated with biofilms remain difficult or impossible to eradicate with conventional therapy. Surgical intervention, implant removal or long-term intermittent or suppressive antimicrobial therapy may be required. There are still significant challenges in detecting biofilms which presents a barrier in clinical practice and research. Novel therapies to disrupt biofilms are currently under investigation, which may help reduce the impact of antimicrobial resistance.

SUMMARY: Biofilm-associated infection should be considered wherever there is clinical concern for an infection affecting prosthetic material, where there is a predisposing condition such as suppurative lung disease; or in the setting of chronic or relapsing infections which may be culture negative. New diagnostic methods for detecting biofilms are a research priority for both clinical diagnosis and the ability to conduct high quality clinical trials of novel antibiofilm interventions.}, } @article {pmid31335187, year = {2019}, author = {Devivilla, S and Lekshmi, M and Kumar, SH and Valappil, RK and Roy, SD and Nayak, BB}, title = {Effect of Sodium Hypochlorite on Biofilm-Forming Ability of Histamine-Producing Bacteria Isolated from Fish.}, journal = {Journal of food protection}, volume = {82}, number = {8}, pages = {1417-1422}, doi = {10.4315/0362-028X.JFP-19-101}, pmid = {31335187}, issn = {1944-9097}, abstract = {Histamine poisoning occurs when temperature-abused marine fish containing elevated levels of histamine are consumed. Histamine-producing bacteria found in fish can colonize processing surfaces and form biofilms. In this study, the biofilm-forming abilities of histamine-producing bacteria from Indian mackerel (Rastrelliger kanagurta) and the effect of hypochlorite treatment on biofilm formation were studied. The isolates of this study produced histamine in the range of 471 to 2,126 ppm. The histidine decarboxylase gene hdc was detected in all isolates producing histamine except in one strain each of Psychrobacter pulmonis and Proteus vulgaris. All isolates tested in this study produced moderate biofilms under control conditions, whereas exposure to 1 and 3 ppm of sodium hypochlorite significantly enhanced biofilm formation. However, exposure to 5 ppm of sodium hypochlorite showed an inhibitory effect on biofilm formation by all the isolates except Klebsiella variicola. The results of this study suggest that histamine-producing bacteria can form stable biofilms and that this activity may be enhanced by the application of low levels of sodium hypochlorite, a phenomenon that might influence the persistence of histamine-producing bacteria in fish processing areas.}, } @article {pmid31332872, year = {2019}, author = {Wang, Y and Du, Z and Liu, Y and Wang, H and Xu, F and Liu, B and Zheng, Z}, title = {The Nitrogen Removal and Sludge Reduction Performance of a Multi-stage anoxic/oxic (A/O) Biofilm Reactor.}, journal = {Water environment research : a research publication of the Water Environment Federation}, volume = {}, number = {}, pages = {}, doi = {10.1002/wer.1188}, pmid = {31332872}, issn = {1554-7531}, abstract = {To overcome the problems of high excess sludge yield and poor nitrogen removal efficiency in traditional biological treatment processes, a multi-stage A/O biofilm reactor was developed by combining the multi-stage A/O process with novel floating spherical carriers, resulting in repeated coupling of anoxic and aerobic environments. Results showed that the system achieved COD, NH4+ -N, and TN removal efficiencies of 93.8%, 84.5%, and 75.7%, respectively, with average effluent concentrations lower than : 29.8 COD mg/L,4.3 NH4+ -N mg/L, and 13.2 TN mg/L. The observed sludge yield was 0.139 g MLSS/g COD, which was lower than that of the conventional activated sludge process. Microbial analysis showed that the community structure and cell morphology of microorganisms changed greatly with alternating aerobic-anoxic condition; High-throughput sequencing results proved that functional microorganisms can be enriched on the surface of the carries and therefore improved the nitrogen removal efficiency and meanwhile minimize the sludge yield within the system. This article is protected by copyright. All rights reserved.}, } @article {pmid31331112, year = {2019}, author = {Glasenapp, Y and Cattò, C and Villa, F and Saracchi, M and Cappitelli, F and Papenbrock, J}, title = {Promoting Beneficial and Inhibiting Undesirable Biofilm Formation with Mangrove Extracts.}, journal = {International journal of molecular sciences}, volume = {20}, number = {14}, pages = {}, doi = {10.3390/ijms20143549}, pmid = {31331112}, issn = {1422-0067}, support = {57265315//MIUR-DAAD Joint Mobility Program/ ; }, abstract = {The extracts of two mangrove species, Bruguieracylindrica and Lagunculariaracemosa, have been analyzed at sub-lethal concentrations for their potential to modulate biofilm cycles (i.e., adhesion, maturation, and detachment) on a bacterium, yeast, and filamentous fungus. Methanolic leaf extracts were also characterized, and MS/MS analysis has been used to identify the major compounds. In this study, we showed the following. (i) Adhesion was reduced up to 85.4% in all the models except for E. coli, where adhesion was promoted up to 5.10-fold. (ii) Both the sum and ratio of extracellular polysaccharides and proteins in mature biofilm were increased up to 2.5-fold and 2.6-fold in comparison to the negative control, respectively. Additionally, a shift toward a major production of exopolysaccharides was found coupled with a major production of both intracellular and extracellular reactive oxygen species. (iii) Lastly, detachment was generally promoted. In general, the L.racemosa extract had a higher bioactivity at lower concentrations than the B.cylindrica extract. Overall, our data showed a reduction in cells/conidia adhesion under B.cylindrica and L.racemosa exposure, followed by an increase of exopolysaccharides during biofilm maturation and a variable effect on biofilm dispersal. In conclusion, extracts either inhibited or enhanced biofilm development, and this effect depended on both the microbial taxon and biofilm formation step.}, } @article {pmid31330991, year = {2019}, author = {Vitale, M and Galluzzo, P and Buffa, PG and Carlino, E and Spezia, O and Alduina, R}, title = {Comparison of Antibiotic Resistance Profile and Biofilm Production of Staphylococcus aureus Isolates Derived from Human Specimens and Animal-Derived Samples.}, journal = {Antibiotics (Basel, Switzerland)}, volume = {8}, number = {3}, pages = {}, doi = {10.3390/antibiotics8030097}, pmid = {31330991}, issn = {2079-6382}, support = {Fondo Finalizzato alla Ricerca//Università degli Studi di Palermo/ ; IZS SI 13/15 RC//Italian Ministry of Health/ ; IZS SI 08/16 RC//Italian Ministry of Health/ ; }, abstract = {BACKGROUND: The diffusion of antimicrobial resistance is a significant concern for public health worldwide. Staphylococcus aureus represents a paradigm microorganism for antibiotic resistance in that resistant strains appear within a decade after the introduction of new antibiotics.

METHODS: Fourteen S. aureus isolates from human specimens and twenty-one from samples of animal origin, were compared for their antimicrobial resistance and biofilm capability. In addition, they were characterized at the molecular level to detect the antimicrobial resistance mecA gene and genes related with enterotoxin, toxin, and biofilm production.

RESULTS: Both phenotypic and molecular analysis showed main differences among human- and animal-derived isolates. Among the human-derived isolates, more multidrug-resistant isolates were detected and mecA gene, enterotoxin, and toxin genes were more prevalent. Different genes involved in biofilm production were detected with bap present only in animal-derived isolates and sasC present in both isolates, however, with a higher prevalence in the human-derived isolates. Biofilm capability was higher in human-derived isolates mainly associated to the sasC gene.

CONCLUSIONS: The overall results indicate that human S. aureus isolates are more virulent and resistant than the isolates of animal origin randomly selected with no infection anamnesis. This study confirms that selection for more virulent and resistant S. aureus strains is related to the clinical practice.}, } @article {pmid31330825, year = {2019}, author = {Ly, S and Bajoul Kakahi, F and Mith, H and Phat, C and Fifani, B and Kenne, T and Fauconnier, ML and Delvigne, F}, title = {Engineering Synthetic Microbial Communities through a Selective Biofilm Cultivation Device for the Production of Fermented Beverages.}, journal = {Microorganisms}, volume = {7}, number = {7}, pages = {}, doi = {10.3390/microorganisms7070206}, pmid = {31330825}, issn = {2076-2607}, abstract = {Production of Cambodian rice wine involves complex microbial consortia. Indeed, previous studies focused on traditional microbial starters used for this product revealed that three microbial strains with complementary metabolic activities are required for an effective fermentation, i.e., filamentous fungi (Rhizopus oryzae), yeast (Saccharomycescerevisiae), and lactic acid bacteria (Lactobacillusplantarum). Modulating the ratio between these three key players led to significant differences, not only in terms of ethanol and organic acid production, but also on the profile of volatile compounds, in comparison with natural communities. However, we observed that using an equal ratio of spores/cells of the three microbial strains during inoculation led to flavor profile and ethanol yield close to that obtained through the use of natural communities. Compartmentalization of metabolic tasks through the use of a biofilm cultivation device allows further improvement of the whole fermentation process, notably by increasing the amount of key components of the aroma profile of the fermented beverage (i.e., mainly phenylethyl alcohol, isobutyl alcohol, isoamyl alcohol, and 2-methyl-butanol) and reducing the amount of off-flavor compounds. This study is a step forward in our understanding of interkingdom microbial interactions with strong application potential in food biotechnology.}, } @article {pmid31330262, year = {2019}, author = {Yu, M and Wang, X and Ling, F and Wang, H and Zhang, P and Shao, S}, title = {Atractylodes lancea volatile oils attenuated helicobacter pylori NCTC11637 growth and biofilm.}, journal = {Microbial pathogenesis}, volume = {135}, number = {}, pages = {103641}, doi = {10.1016/j.micpath.2019.103641}, pmid = {31330262}, issn = {1096-1208}, abstract = {Atractylodes lancea is a traditional Chinese perennial herb, which has been used for treating gastrointestinal diseases in traditional medicine. The aim of this study was to investigate the effect of Atractylodes lancea volatile oils on the planktonic growth and biofilm formation of Helicobacter pylori (H. pylori). Firstly, the minimal inhibitory concentration (MIC) of the volatile oils against H. pylori were determined using broth dilution method. SPSS17.0 was used to account 50% inhibiting concentration (IC50). Moreover, the anti-biofilm activity of the volatile oils was determined by crystal violet measurement and fluorescence microscope. Finally, gastric epithelial cells (GES-1 cells) were co-incubated with H. pylori with or without volatile oils treated. Real-time PCR and western blot were performed to detect the translocation of virulence factor Cag A. We found that Atractylodes lancea volatile oils inhibited the growth of H. pylori in a concentration dependent manner. The MIC and IC50 of volatile oils against H. pylori were 7.5 mg/mL and 2.181 mg/mL respectively. Fluorescence microscopy and crystal violet measurement indicated that volatile oils at sub-MIC concentration could reduce biofilm formation of H. pylori. In addition, volatile oils decreased the translocation of Cag A and reduced inflammatory cytokine IL-8 in GES-1 cells. Our results suggested that Atractylodes lancea volatile oils could be a potential compound of a novel class of H. pylori inhibitors with anti-H. pylori effects.}, } @article {pmid31329599, year = {2019}, author = {Lachica, MRCT and Anutrakunchai, C and Prajaneh, S and Nazmi, K and Bolscher, JGM and Taweechaisupapong, S}, title = {Synergistic effects of LFchimera and antibiotic against planktonic and biofilm form of Aggregatibacter actinomycetemcomitans.}, journal = {PloS one}, volume = {14}, number = {7}, pages = {e0217205}, doi = {10.1371/journal.pone.0217205}, pmid = {31329599}, issn = {1932-6203}, abstract = {Adjunctive use of antibiotics in periodontal treatment have limitations and disadvantages including bacterial resistance. Antimicrobial peptides (AMPs) are potential new agents that can combat bacterial infection. In this study, antimicrobial activity of different concentrations of conventional antibiotics minocycline (MH), doxycycline (DOX), and antimicrobial peptides LL-37, LL-31, Lactoferrin chimera (LFchimera) and Innate Defense Regulator Peptide 1018 (IDR-1018) against Aggregatibacter actinomycetemcomitans ATCC 43718 were determined using colony culturing assay. Subsequently, in vitro activity of the most effective drug and peptide combination was evaluated by checkerboard technique. Impact of the drug and peptide co-administration on biofilm at different stages, i.e., during adhesion and 1-day old biofilm was compared to each of the agents used alone. Results revealed that the killing effects of all AMPs range from 13-100%. In contrast, MH and DOX at 1 and 5 μM showed no killing activity and instead stimulated growth of bacteria. DOX has better killing activity than MH. LFchimera displayed the strongest killing amongst the peptides. Checkerboard technique revealed that combining DOX and LFchimera yielded synergism. Confocal laser scanning microscopy further showed that the combination of DOX and LFchimera caused significant reduction of bacterial adhesion and reduction of biomass, average biofilm thickness and substratum biofilm coverage of 1-day old biofilm compared to DOX and LFchimera alone. In conclusion, LFchimera alone and in combination with DOX exhibited strong antibacterial and anti-biofilm property against A. actinomycetemcomitans. The findings suggest that LFchimera should be considered for development as a new potential therapeutic agent that may be used as an adjunctive treatment for periodontitis.}, } @article {pmid31329200, year = {2019}, author = {Kwon, HY and Kim, JY and Liu, X and Lee, JY and Yam, JKH and Dahl Hultqvist, L and Xu, W and Rybtke, M and Tolker-Nielsen, T and Heo, W and Kim, JJ and Kang, NY and Joo, T and Yang, L and Park, SJ and Givskov, M and Chang, YT}, title = {Visualizing biofilm by targeting eDNA with long wavelength probe CDr15.}, journal = {Biomaterials science}, volume = {}, number = {}, pages = {}, doi = {10.1039/c9bm00152b}, pmid = {31329200}, issn = {2047-4849}, abstract = {Detection of the biofilm of bacteria would be a counter strategy to detect hidden bacteria in their camouflage. Through unbiased screening of bacteria biofilm, we discovered a long wavelength probe CDr15 with extracellular DNA as the molecular target. CDr15 revealed a real-time geometric distribution of eDNA in a 3D bacterial colony.}, } @article {pmid31328358, year = {2019}, author = {Qiu, H and Pu, F and Liu, Z and Deng, Q and Sun, P and Ren, J and Qu, X}, title = {Depriving Bacterial Adhesion-Related Molecule to Inhibit Biofilm Formation Using CeO2 -Decorated Metal-Organic Frameworks.}, journal = {Small (Weinheim an der Bergstrasse, Germany)}, volume = {}, number = {}, pages = {e1902522}, doi = {10.1002/smll.201902522}, pmid = {31328358}, issn = {1613-6829}, support = {21871249//National Natural Science Foundation of China/ ; 21673223//National Natural Science Foundation of China/ ; 21431007//National Natural Science Foundation of China/ ; 21533008//National Natural Science Foundation of China/ ; 21820102009//National Natural Science Foundation of China/ ; //Key Program of Frontier of Sciences/ ; QYZDJ-SSW-SLH052//CAS/ ; }, abstract = {The formation of bacterial biofilm is one of the causes of antimicrobial resistance, often leading to persistent infections and a high fatality rate. Therefore, there is an urgent need to develop novel and effective strategies to inhibit biofilm formation. Adenosine triphosphate (ATP) plays an important role in bacterial adhesion and biofilm formation through stimulating cell lysis and extracellular DNA (eDNA) release. Herein, a simple and robust strategy for inhibiting biofilm formation is developed using CeO2 -decorated porphyrin-based metal-organic frameworks (MOFs). The function of extracellular ATP (eATP) can be inhibited by CeO2 nanoparticles, leading to the disruption of the initial adhesion of bacteria. Furthermore, planktonic bacteria can be killed by cytotoxic reactive oxygen species (ROS) generated by MOFs. As a consequence, the synergic effect of eATP deprivation and ROS generation presents excellent capacity to prevent biofilm formation, which may provide a new direction for designing flexible and effective biofilm-inhibiting systems.}, } @article {pmid31328252, year = {2019}, author = {Bazzoli, A and Plateau, J and Turney, A}, title = {Improvement of microbial ecosystem in livestock animal environment: concept of positive biofilm using an example in swine farrowing.}, journal = {Australian veterinary journal}, volume = {}, number = {}, pages = {}, doi = {10.1111/avj.12808}, pmid = {31328252}, issn = {1751-0813}, } @article {pmid31326562, year = {2019}, author = {Sowndarya, J and Farisa Banu, S and Madhura, G and Yuvalakshmi, P and Rubini, D and Bandeira Junior, G and Baldisserotto, B and Vadivel, V and Nithyanand, P}, title = {Agro food by-products and essential oil constituents curtail virulence and biofilm of Vibrio harveyi.}, journal = {Microbial pathogenesis}, volume = {135}, number = {}, pages = {103633}, doi = {10.1016/j.micpath.2019.103633}, pmid = {31326562}, issn = {1096-1208}, abstract = {Vibrio harveyi causes severe loss to the aquaculture industry due to its virulence, which is mediated by Quorum sensing (QS) and biofilm formation. In the current study, we have explored the anti-virulent properties and biofilm disruption ability of luteolin (extracted from coconut shell) and linalool against this important aquaculture pathogen. HPLC analysis of the methanolic extract of coconut shells revealed a single major peak which matched to the standard luteolin which was further elucidated by NMR studies. Further, luteolin and linalool were screened for their ability to inhibit biofilms and various quorum sensing mediated virulence factors of V. harveyi. The Minimum Inhibitory Concentration (MIC) of the two compounds was determined and the sub-inhibitory concentrations of the compounds were able to inhibit biofilm formation. Both the compounds disrupted about 60-70% mature biofilms, which was also visually observed by light microscopy. Both linalool and luteolin exhibited a significant reduction in the production of EPS and alginate in the biofilms matrix of V. harveyi which was confirmed by Scanning Electron Microscopy (SEM). Both compounds inhibited the swarming and swimming motility, the crucial quorum sensing (QS) mediated virulence of V. harveyi. The present study shows the presence of valuable polyphenolic compound like luteolin in coconut shells that are discarded as a waste. From the present study we envisage that luteolin and linalool can serve as potent anti-virulent agents to combat QS mediated infections against aquaculture pathogens.}, } @article {pmid31325779, year = {2019}, author = {Borah, SN and Sen, S and Goswami, L and Bora, A and Pakshirajan, K and Deka, S}, title = {Rice based distillers dried grains with solubles as a low cost substrate for the production of a novel rhamnolipid biosurfactant having anti-biofilm activity against Candida tropicalis.}, journal = {Colloids and surfaces. B, Biointerfaces}, volume = {182}, number = {}, pages = {110358}, doi = {10.1016/j.colsurfb.2019.110358}, pmid = {31325779}, issn = {1873-4367}, abstract = {In this study, rhamnolipid (RL) production by Pseudomonas aeruginosa SS14 utilizing rice based Distillers Dried Grains with Solubles (rDDGS) as the sole carbon source was evaluated and the production parameters were optimized using response surface methodology. Highest RL (RL-rDDGS) yield was 14.87 g/L in a culture medium containing 12% (w/v) rDDGS and 11% (v/v) inoculum concentration after 48 h of fermentation at 35 °C. RL-rDDGS was produced as a mixture of mono and di-RL congeners with four novel homologues Rha-C18:2, Rha-C19, Rha-C9, and Rha-Rha-C19. The RL reduced the surface tension of water to 34.8 mN/m at a critical micelle concentration (CMC) value of 100 mg/L, exhibited high stability at a wide range of pH (6-12), heating time (0-120 min), and salinity (2-12% NaCl). Furthermore, RL-rDDGS demonstrated appreciable biofilm disruptive property against Candida tropicalis. This is the first report on the usage of rDDGS for sustainable and low cost production of RL.}, } @article {pmid31324055, year = {2019}, author = {Shi, Z and Dittoe, DK and Feye, KM and Kogut, M and Ricke, SC}, title = {Short Communication: Preliminary Differences Identified in Genes Responsible for Biofilm Formation in Poultry Isolates of Salmonella enterica Heidelberg, Enteritidis, and Kentucky.}, journal = {Microorganisms}, volume = {7}, number = {7}, pages = {}, doi = {10.3390/microorganisms7070196}, pmid = {31324055}, issn = {2076-2607}, abstract = {Salmonella enterica is one of the most prevalent foodborne pathogens. The large quantity of serovar types results in the colonization of a large spectrum of hosts, with different environmental conditions and hazards. The aim of this study was to evaluate the differences in gene expression (bcsA and csgD) of Salmonella enterica serovars Heidelberg, Kentucky, and Enteritidis during biofilm formation using quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Overall, there appeared to be differences in expression between the different serovars with high variation between strains. These data are important as they demonstrate considerable variability in gene expression between serovars and strains of poultry isolates of Salmonella enterica.}, } @article {pmid31323790, year = {2019}, author = {Carvalho, DB and Fox, EGP and Santos, DGD and Sousa, JS and Freire, DMG and Nogueira, FCS and Domont, GB and Castilho, LVA and Machado, EA}, title = {Fire Ant Venom Alkaloids Inhibit Biofilm Formation.}, journal = {Toxins}, volume = {11}, number = {7}, pages = {}, doi = {10.3390/toxins11070420}, pmid = {31323790}, issn = {2072-6651}, support = {150895/2010-0//Conselho Nacional de Desenvolvimento Científico e Tecnológico/ ; }, abstract = {Biofilm formation on exposed surfaces is a serious issue for the food industry and medical health facilities. There are many proposed strategies to delay, reduce, or even eliminate biofilm formation on surfaces. The present study focuses on the applicability of fire ant venom alkaloids (aka 'solenopsins', from Solenopsis invicta) tested on polystyrene and stainless steel surfaces relative to the adhesion and biofilm-formation by the bacterium Pseudomonas fluorescens. Conditioning with solenopsins demonstrates significant reduction of bacterial adhesion. Inhibition rates were 62.7% on polystyrene and 59.0% on stainless steel surfaces. In addition, solenopsins drastically reduced cell populations already growing on conditioned surfaces. Contrary to assumptions by previous authors, solenopsins tested negative for amphipathic properties, thus understanding the mechanisms behind the observed effects still relies on further investigation.}, } @article {pmid31323501, year = {2019}, author = {Morgan-Sagastume, F and Jacobsson, S and Olsson, LE and Carlsson, M and Gyllenhammar, M and Sárvári Horváth, I}, title = {Anaerobic treatment of oil-contaminated wastewater with methane production using anaerobic moving bed biofilm reactors.}, journal = {Water research}, volume = {163}, number = {}, pages = {114851}, doi = {10.1016/j.watres.2019.07.018}, pmid = {31323501}, issn = {1879-2448}, abstract = {Oil-contaminated wastewaters are generally treated by a combination of physico-chemical and biological methods. Interest in the anaerobic treatment of oily wastewaters has increased since it complements aerobic treatment and produces energy in the form of methane. The objectives of this study were to characterise the anaerobic process spontaneously occurring in a full-scale storage tank at a facility treating waste oil and oil-contaminated effluents, and to evaluate the applicability of an anaerobic moving bed biofilm reactor (AnMBBR) and an anaerobic contact reactor (ACR) for treating the oil contaminated wastewater feeding the storage tank. Three lab-scale reactors were operated in parallel over 465 days: one mesophilic and one thermophilic AnMBBR, and one thermophilic ACR. The wastewater had a high strength with an average chemical oxygen demand (COD) of 36 g/L with a soluble fraction of 80%. The BOD7/COD ratios varied between 0.1 and 0.5, indicating low aerobic degradability. However, biomethane potential tests indicated some level of anaerobic degradability with methane yields between 150 and 200 NmL/gCOD. The full-scale storage tank operated at low organic loading rates (0.35-0.43 kgCOD/m3d), and long hydraulic retention times (HRT = 83-104 d). In comparison, the AnMBBRs achieved similar COD reductions (60%) as the full-scale tank but at a much shorter HRT of 30 d. Similar efficiency could only be reached at longer HRTs (43 d) in the ACR due to low biomass levels resulting from poor sludge settleability. The methane yield was higher (210 NmLCH4/COD removed) in the AnMBBR operated at 37 °C, compared to the other reactors working at 50 °C (180 NmLCH4/COD removed). This reactor also maintained a higher COD removal (67%) at an increased OLR of 1.1 kgCOD/m3d than the AnMBBR at 50 °C. The microbial composition of the biomass from the full-scale tank and the laboratory reactors provided evidence for the conversion of oil-contaminated wastewater into methane with a relatively high abundance of hydrogenotrophic methanogens.}, } @article {pmid31323469, year = {2019}, author = {Qi, X and Liu, P and Liang, P and Hao, W and Li, M and Huang, X}, title = {Dual-signal-biosensor based on luminescent bacteria biofilm for real-time online alert of Cu(II) shock.}, journal = {Biosensors & bioelectronics}, volume = {142}, number = {}, pages = {111500}, doi = {10.1016/j.bios.2019.111500}, pmid = {31323469}, issn = {1873-4235}, abstract = {The development of real-time online warning system for toxicity materials is important to ensure the safety of water supply. This study for the first time constructs luminescent bacteria (Vibrio fischeri) biofilm to deliver both electrical and optical real-time response for Cu(II) toxic shock in a bioelectrochemical system (BES) sensor. Compared to biocathode, bioanode was more suitable as sensitive elements. With three tested concentrations of Cu(II), i.e., 1 mg/L, 3 mg/L and 6 mg/L, electrical signals were raised. But optical signal failed to respond to the lowest concentration, suggesting that electrical signal then was produced by chemical reaction of Cu(II) on the electrode surface. For 3 mg/L and 6 mg/L Cu(II) shock, more rapid optical signals were observed than electrical signal, indicating that both the biofilm's surface and inner was affected. In addition, high concentration of Cu(II) toxic as 6 mg/L caused irreversible damage in the biosensor as there were great fluctuation in the recovery curve and large recovery ratio up to -10.39% for optical signal. These results provided a comparison between optical and electrical signals simultaneously produced by a biosensor and visual evidences for better understanding of the toxicity process in the biosensor.}, } @article {pmid31323449, year = {2019}, author = {Li, D and Chen, S and Dou, H and Wu, W and Liu, Q and Zhang, L and Shen, Y and Shu, G and Yuan, Z and Lin, J and Zhang, W and Peng, G and Zhong, Z and Yin, L and Fu, H}, title = {Preparation of cefquinome sulfate cationic proliposome and evaluation of its efficacy on Staphylococcus aureus biofilm.}, journal = {Colloids and surfaces. B, Biointerfaces}, volume = {182}, number = {}, pages = {110323}, doi = {10.1016/j.colsurfb.2019.06.053}, pmid = {31323449}, issn = {1873-4367}, abstract = {Staphylococcus aureus (S. aureus) has the propensity to form biofilms, which eventually cause antibiotic resistance and treatment failure. Cefquinome sulfate (CS) is an animal-specific antibacterial agent for S. aureus infection. In this work, CS cationic proliposomes (CSCPs) were prepared by solid-dispersion method combined with effervescent hydration to eradicate bacterial biofilm and improve the antibacterial effect of the drug. CSCPs were readily dispersed in water, thereby forming CS cationic liposomes (CSCLs) as a white, uniform suspension. The CSCLs had an encapsulation efficiency (EE) of 63.21%, a drug loading of 4.04%, an average particle size of 201.5 nm, and a positive zeta-potential of 65.29 mV. In vitro release studies showed that CSCLs had good sustained-release behavior. The CS and CSCL minimal inhibitory concentration (MIC) of S. aureus type culture strain were 1 and 0.48 g/mL, respectively. The eradication effect of CS on bacterial biofilm (BBF) was relatively weak during culture in drug-containing medium for 8 h-24 h. However, the CSCL eradication effect on BBF increased gradually, and the clearance rate of CSCLs on BBF was about twice that of CS. The clearance rate reached 81.30% with 2.5 × MIC in 24 h. All these results indicated that CSCLs can significantly improve the eradication effect of cefquinome on biofilm to inhibit bacterial growth.}, } @article {pmid31323072, year = {2019}, author = {, }, title = {Correction: Circuit diversification in a biofilm regulatory network.}, journal = {PLoS pathogens}, volume = {15}, number = {7}, pages = {e1007966}, doi = {10.1371/journal.ppat.1007966}, pmid = {31323072}, issn = {1553-7374}, abstract = {[This corrects the article DOI: 10.1371/journal.ppat.1007787.].}, } @article {pmid31321751, year = {2019}, author = {Černáková, L and Light, C and Salehi, B and Rogel-Castillo, C and Victoriano, M and Martorell, M and Sharifi-Rad, J and Martins, N and Rodrigues, CF}, title = {Novel Therapies for Biofilm-Based Candida spp. Infections.}, journal = {Advances in experimental medicine and biology}, volume = {}, number = {}, pages = {}, doi = {10.1007/5584_2019_400}, pmid = {31321751}, issn = {0065-2598}, abstract = {The presence of fungal infections continue to grow worldwide, mostly in immunosuppressed patients, and in individuals with continued antimicrobial treatments. Candida spp. are the most common yeasts involved in these disorders, being associated with a high rate of antifungal resistance and an increased ability to form biofilms, which make the treatment of these infections difficult. This review aims to present and discuss the main biofilm-related infections cause by several Candida spp. and novel therapies that are currently available in the clinical, scientific and academic environment. New drugs with promising antifungal activity, natural approaches (e.g. probiotics, essential oils, plant extracts, honey) and a final consideration on alternative methodologies, such as photodynamic therapy are presented and discussed.}, } @article {pmid31321337, year = {2019}, author = {Pakshir, K and Sheykhi, S and Zomorodian, K and Nouraei, H and Zare Shahrabadi, Z}, title = {Evaluation of biofilm formation in the homozygous and heterozygous strains of vaginal Candida albicans isolates.}, journal = {Current medical mycology}, volume = {5}, number = {2}, pages = {37-40}, doi = {10.18502/cmm.5.2.1160}, pmid = {31321337}, issn = {2423-3439}, abstract = {Background and Purpose: Candida albicans is one of the most opportunistic yeasts around the world. This species has two heterozygous and homozygous strains at hyphal wall protein 1 (hwp1) gene locus. A simple method for the discrimination of these two strains is the amplification of HWP1 gene. Regarding this, the aim of this study was to discriminate C. albicans heterozygous and homozygous strains via the amplification of hwp1 gene and evaluation of biofilm formation between the strains.

Materials and Methods: A total of 60 homozygous (n=30) and heterozygous (n=30) strains were discriminated among 126 C. albicans vaginal isolates by the amplification of HWP1 gene, using specific primers. The evaluation of biofilm formation was accomplished using the visual method.

Results: According to the results, the homozygous and heterozygous strains produced one and two DNA fragments, respectively. The frequency of homozygous strains among the C. albicans vaginal isolates was 76.2%. Biofilm formation activity in the heterozygous strains was more than that in the homozygous strains. However, statistical analysis showed no significant difference between the strains in terms of biofilm formation.

Conclusion: As the findings indicated, the frequency of the heterozygous strains in C. albicans was lower than that of the homozygous strains. Both of the strains could form biofilm in the different ranges of severity. High activity of biofilm formation in heterozygous strains may set the ground for its pathogenicity.}, } @article {pmid31320183, year = {2019}, author = {Lee, MJ and Kwon, JS and Kim, JY and Ryu, JH and Seo, JY and Jang, S and Kim, KM and Hwang, CJ and Choi, SH}, title = {Bioactive resin-based composite with surface pre-reacted glass-ionomer filler and zwitterionic material to prevent the formation of multi-species biofilm.}, journal = {Dental materials : official publication of the Academy of Dental Materials}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.dental.2019.06.004}, pmid = {31320183}, issn = {1879-0097}, abstract = {OBJECTIVE: This study evaluated the synergetic effect between surface pre-reacted glass-ionomer (SPRG) filler and 2-methacryloyloxyethyl phosphorylcholine (MPC), for inhibiting multi-species biofilm formation, while maintaining or even improving the original beneficial features of SPRG-filled resin-based composite (RBC).

METHODS: MPC (1.5-10wt%) was incorporated into commercial SPRG-filled RBC. Then, the inherent properties of RBC, and ion release and acid-neutralising properties associated with SPRG were investigated. Further, protein adsorptions and bacterial adhesion and viability on the SPRG-filled RBC surfaces were studied using four kinds of oral bacteria; Streptococcus mutans, Actinomyces naeslundii, Veillonella parvula, and Porphyromonas gingivalis. Finally, the thickness and biomass of the human saliva-derived biofilm model cultured on test and control samples were analysed.

RESULTS: Addition of MPC content resulted in decreased flexural strength and wettability of SPRG-filled RBC. SPRG-filled RBC released significantly higher amounts of multiple ions as contents of MPC increased. Meanwhile, SPRG-filled RBC with 5-wt% MPC significantly improved acid-neutralising properties than those of other test and control samples (P<0.001). SPRG-filled RBC with 3wt% MPC significantly reduced the amount of adsorbed bovine serum albumin and proteins from the brain heart infusion medium as compared to the control (P<0.01). A similar trend was observed in the attachment of four types of bacteria and multi-species biofilm (P<0.01).

SIGNIFICANCE: Despite limitation in terms of deteriorations of some physical properties, addition of 3% MPC to SPRG-filled RBC leads to inhibition of the attachment of multi-species bacteria on its surface, as well as inhibition of biofilm growth. Moreover, the original important bioactive features of SPRG-filled RBC such as ion release and acid neutralisations are either maintained or improved upon adding MPC.}, } @article {pmid31319827, year = {2019}, author = {Ahmed, AA and Salih, FA}, title = {Quercus infectoria gall extracts reduce quorum sensing-controlled virulence factors production and biofilm formation in Pseudomonas aeruginosa recovered from burn wounds.}, journal = {BMC complementary and alternative medicine}, volume = {19}, number = {1}, pages = {177}, doi = {10.1186/s12906-019-2594-5}, pmid = {31319827}, issn = {1472-6882}, abstract = {BACKGROUND: Quercus gall extracts' ability to kill pathogens in vitro and even removal of chronic drug-resistant infections has been reported by several studies. The current investigation is focused on the action of extracts of Quercus infectoria gall in their sub-inhibitory concentrations on the corresponding bacterial behaviours instead of killing them.

METHODS: The effect of gall extracts on the quorum sensing (QS) associated virulence of multiple drug resistant Pseudomonas aeruginosa recovered from burns wounds was studied. The influence of different extracts on the production of bacterial virulence and biofilm, and expression of the genes encoding quorum sensing and exotoxin A were investigated. Quorum sensing is a crucial regulator of virulence and biofilm development in Pseudomonas aeruginosa and other medical related microbes.

RESULTS: Experiments to characterise and quantify Q. infectoria gall extracts impact on the quorum sensing networks of P.aeruginosa revealed that the expression of las, rhl, and exotoxin A (ETA) genes levels including the associated virulence were reduced by the extracts at their subinhibitory concentrations.

CONCLUSIONS: The obtained results indicated that extracts of Q. infectoria galls fight infections either by their inhibitory constituents, which vigorously eradicate cells or by disruption of the pathogens quorum sensing system through weakening the virulence and bacterial coordination.}, } @article {pmid31319670, year = {2019}, author = {Balasubramanian, S and Aubin-Tam, ME and Meyer, AS}, title = {3D Printing for the Fabrication of Biofilm-Based Functional Living Materials.}, journal = {ACS synthetic biology}, volume = {8}, number = {7}, pages = {1564-1567}, doi = {10.1021/acssynbio.9b00192}, pmid = {31319670}, issn = {2161-5063}, abstract = {Bacterial biofilms are three-dimensional networks of cells entangled in a self-generated extracellular polymeric matrix composed of proteins, lipids, polysaccharides, and nucleic acids. Biofilms can establish themselves on virtually any accessible surface and lead to varying impacts ranging from infectious diseases to degradation of toxic chemicals. Biofilms exhibit high mechanical stiffness and are inherently tolerant to adverse conditions including the presence of antibiotics, pollutants, detergents, high temperature, changes in pH, etc. These features make biofilms resilient, which is beneficial for applications in dynamic environments such as bioleaching, bioremediation, materials production, and wastewater purification. We have recently described an easy and cost-effective method for 3D printing of bacteria and have extended this technology for 3D printing of genetically engineered Escherichia coli biofilms. Our 3D printing platform exploits simple alginate chemistry for printing of a bacteria-alginate bioink mixture onto calcium-containing agar surfaces, resulting in the formation of bacteria-encapsulating hydrogels with varying geometries. Bacteria in these hydrogels remain intact, spatially patterned, and viable for several days. Printing of engineered bacteria to produce inducible biofilms leads to formation of multilayered three-dimensional structures that can tolerate harsh chemical treatments. Synthetic biology and material science approaches provide the opportunity to append a wide range of useful functionalities to these 3D-printed biofilms. In this article, we describe the wide range of future applications possible for applying functional 3D-printed biofilms to the construction of living biofilm-derived materials in a large-scale and environmentally stable manner.}, } @article {pmid31319057, year = {2019}, author = {Narayana, JL and Mishra, B and Lushnikova, T and Golla, RM and Wang, G}, title = {Modulation of antimicrobial potency of human cathelicidin peptides against the ESKAPE pathogens and in vivo efficacy in a murine catheter-associated biofilm model.}, journal = {Biochimica et biophysica acta. Biomembranes}, volume = {1861}, number = {9}, pages = {1592-1602}, doi = {10.1016/j.bbamem.2019.07.012}, pmid = {31319057}, issn = {1879-2642}, abstract = {Antimicrobial peptides are essential components of innate immune systems that protect hosts from infection. They are also useful candidates for developing a new generation of antibiotics to fight antibiotic-resistant pathogens. Human innate immune peptide LL-37 can inhibit biofilm formation, but suffers from high cost due to a long peptide length and rapid protease degradation. To improve the peptide, we previously identified the major active region and changed the peptide backbone structure. This study designed two families of new peptides by altering peptide side chains. Interestingly, these peptides displayed differential potency against various ESKAPE pathogens in vitro and substantially reduced hemolysis. Further potency test in vivo revealed that 17tF-W eliminated the burden of methicillin-resistant Staphylococcus aureus (MRSA) USA300 in both mouse-embedded catheters and their surrounding tissues. In addition, peptide treatment suppressed the level of chemokine TNFα, and boosted the levels of chemokines MCP-1, IL-17A and IL-10 in the surrounding tissues of the infected catheter embedded in mice. In conclusion, we have designed a set of new LL-37 peptides with varying antimicrobial activities, opening the door to potential topical treatment of infections involving different drug-resistant pathogens.}, } @article {pmid31318574, year = {2019}, author = {Patel, KK and Surekha, DB and Tripathi, M and Anjum, MM and Muthu, MS and Tilak, R and Agrawal, AK and Singh, S}, title = {Antibiofilm Potential of Silver Sulfadiazine-Loaded Nanoparticle Formulations: A Study on the Effect of DNase-I on Microbial Biofilm and Wound Healing Activity.}, journal = {Molecular pharmaceutics}, volume = {}, number = {}, pages = {}, doi = {10.1021/acs.molpharmaceut.9b00527}, pmid = {31318574}, issn = {1543-8392}, abstract = {Biofilm resistance is one of the severe complications associated with chronic wound infections, which impose extreme microbial tolerance against antibiotic therapy. Interestingly, deoxyribonuclease-I (DNase-I) has been empirically proved to be efficacious in improving the antibiotic susceptibility against biofilm-associated infections. DNase-I hydrolyzes the extracellular DNA, a key component of the biofilm responsible for the cell adhesion and strength. Moreover, silver sulfadiazine, a frontline therapy in burn wound infections, exhibits delayed wound healing due to fibroblast toxicity. In this study, a chitosan gel loaded with solid lipid nanoparticles of silver sulfadiazine (SSD-SLNs) and supplemented with DNase-I has been developed to reduce the fibroblast cytotoxicity and overcome the biofilm-imposed resistance. The extensive optimization using the Box-Behnken design (BBD) resulted in the formation of SSD-SLNs with a smooth surface as confirmed by scanning electron microscopy and controlled release (83%) for up to 24 h. The compatibility between the SSD and other formulation excipients was confirmed by Fourier transform infrared, differential scanning calorimetry, and powder X-ray diffraction studies. Developed SSD-SLNs in combination with DNase-I inhibited around 96.8% of biofilm of Pseudomonas aeruginosa as compared to SSD with DNase-I (82.9%). In line with our hypothesis, SSD-SLNs were found to be less toxic (cell viability 90.3 ± 3.8% at 100 μg/mL) in comparison with SSD (Cell viability 76.9 ± 4.2%) against human dermal fibroblast cell line. Eventually, the results of the in vivo wound healing study showed complete wound healing after 21 days' treatment with SSD-SLNs along with DNase-I, whereas marketed formulations SSD and SSD-LSNs showed incomplete healing after 21 days. Data in hand suggest that the combination of SSD-SLNs with DNase-I is an effective treatment strategy against the biofilm-associated wound infections and accelerates wound healing.}, } @article {pmid31318043, year = {2019}, author = {Alsahhaf, A and Al-Aali, KA and Alshagroud, RS and Alshiddi, IF and Alrahlah, A and Abduljabbar, T and Javed, F and Vohra, F}, title = {Comparison of yeasts species in the subgingival oral biofilm of type 2-diabetic and non-diabetic individuals with peri-implantitis.}, journal = {Journal of periodontology}, volume = {}, number = {}, pages = {}, doi = {10.1002/JPER.19-0091}, pmid = {31318043}, issn = {1943-3670}, abstract = {BACKGROUND: There are no studies that have investigated the presence of yeasts in the subgingival oral biofilm (OB) of type-2 diabetic and non-diabetic patients with peri-implantitis. The aim was to assess the presence of yeasts in the subgingival OB of type-2 diabetic and non-diabetic patients with peri-implantitis.

MATERIALS AND METHODS: Type-2 diabetic individuals with peri-implantitis (Group-A), non-diabetic individuals with peri-implantitis (Group-B) and non-diabetic individuals without peri-implantitis (Group-C) were included. Life style related and demographic data was collected using a questionnaire and hemoglobin A1c levels were measured. Peri-implant plaque-index (PI), bleeding-on-probing (BOP) and probing-depth (PD) were evaluated and crestal bone loss (CBL) were measured. Subgingival OB samples were collected, and oral yeasts species were identified using ChromAgar medium. Level of significance was set at P < 0.05.

RESULTS: The mean age of individuals in groups A (n = 43), B (n = 41) and C (n = 42) were 55.6 ± 6.4, 54.6 ± 4.5 and 57.1 ± 3.3 years, respectively. The mean HbA1c levels were higher in Group-A (P < 0.01) than groups B and C. Peri-implant PI (P < 0.01), BOP (P < 0.01), PD (P < 0.01) and CBL (P < 0.01) were significantly higher in Group-A compared with patients in groups B and C. Peri-implant PI (P < 0.05), BOP (P < 0.05), PD (P < 0.05) and CBL (P < 0.05) were significantly higher among patients in Group-B compared with Group-C. Subgingival yeasts were more often isolated from the OB of patients in groups A (74.4%) and B (46.3%) than Group-C (7.1%). The most common yeast species identified in all groups was Candida albicans (C. albicans). The CFU/ml for subgingival yeasts were higher in Group-A than groups B (P < 0.01) and C (P < 0.01). The CFU/ml for subgingival yeasts were higher in Group-B than Group-C (P < 0.01).

CONCLUSION: Candida species (predominantly C. albicans) were more often present in the subgingival OB of type-2 diabetic and non-diabetic patients with peri-implantitis than systemically healthy individuals without peri-implant diseases. This article is protected by copyright. All rights reserved.}, } @article {pmid31315967, year = {2019}, author = {Sherman, E and Bayles, K and Moormeier, D and Endres, J and Wei, T}, title = {Observations of Shear Stress Effects on Staphylococcus aureus Biofilm Formation.}, journal = {mSphere}, volume = {4}, number = {4}, pages = {}, doi = {10.1128/mSphere.00372-19}, pmid = {31315967}, issn = {2379-5042}, abstract = {Staphylococcus aureus bacteria form biofilms and distinctive microcolony or "tower" structures that facilitate their ability to tolerate antibiotic treatment and to spread within the human body. The formation of microcolonies, which break off, get carried downstream, and serve to initiate biofilms in other parts of the body, is of particular interest here. It is known that flow conditions play a role in the development, dispersion, and propagation of biofilms in general. The influence of flow on microcolony formation and, ultimately, what factors lead to microcolony development are, however, not well understood. The hypothesis being examined is that microcolony structures form within a specific range of levels of shear stress. In this study, laminar shear flow over a range of 0.15 to 1.5 dynes/cm2 was examined. It was found that microcolony structures form in a narrow range of shear stresses around 0.6 dynes/cm2 Further, measurements of cell density as a function of space and time showed that shear dependence can be observed hours before microcolonies form. This is significant because, among other physiologic flows, this is the same shear stress found in large veins in the human vasculature, which, along with catheters of similar diameters and flow rates, may therefore play a critical role in biofilm development and subsequent spreading of infections throughout the body.IMPORTANCE It is well known that flow plays an important role in the formation, transportation, and dispersion of Staphylococcus aureus biofilms. What was heretofore not known was that the formation of tower structures in these biofilms is strongly shear stress dependent; there is, in fact, a narrow range of shear stresses in which the phenomenon occurs. This work quantifies the observed shear dependence in terms of cell growth, distribution, and fluid mechanics. It represents an important first step in opening up a line of questioning as to the interaction of fluid forces and their influence on the dynamics of tower formation, break-off, and transportation in biofilms by identifying the parameter space in which this phenomenon occurs. We have also introduced state-of-the-art flow measurement techniques to address this problem.}, } @article {pmid31315572, year = {2019}, author = {Zeighami, H and Valadkhani, F and Shapouri, R and Samadi, E and Haghi, F}, title = {Virulence characteristics of multidrug resistant biofilm forming Acinetobacter baumannii isolated from intensive care unit patients.}, journal = {BMC infectious diseases}, volume = {19}, number = {1}, pages = {629}, doi = {10.1186/s12879-019-4272-0}, pmid = {31315572}, issn = {1471-2334}, abstract = {BACKGROUND: Nosocomial infections and persistence of multidrug resistant biofilm forming Acinetobacter baumannii in hospitals has made it as a serious problem in healthcare settings worldwide.

METHODS: A total of 100 A. baumannii clinical isolates from immunocompromised patients hospitalized in ICU were investigated for biofilm formation, the presence of biofilm related genes (bap, ompA, csuE, fimH, epsA, blaPER-1, bfmS, ptk, pgaB, csgA, kpsMII), integron characterization and molecular typing based on REP-PCR.

RESULTS: All isolates were resistant to three or more categories of antibiotics and considered as multidrug resistant (MDR). A total of 32 isolates were resistant to all tested antibiotics and 91% were extensively drug-resistance (XDR). All isolates were able to produce biofilm and 58% of isolates showed strong ability to biofilm formation. All strong biofilm forming A. baumannii isolates were XDR. All A. baumannii isolates carried at least one biofilm related gene. The most prevalent gene was csuE (100%), followed by pgaB (98%), epsA and ptk (95%), bfmS (92%) and ompA (81%). 98% of isolates carried more than 4 biofilm related genes, simultaneously. Class I integron (67%) was more frequent in comparison with class II (10%) (P < 0.05). The REP-PCR patterns were classified as 8 types (A-H) and 21 subtypes. The A1 (23%) and C1 (15%) clusters were the most prevalent among A. baumannii isolates (P < 0.05). According to the REP-PCR patterns, 23% of all isolates had a clonal relatedness.

CONCLUSION: Our study revealed the high frequency of biofilm forming XDR A. baumannii in ICU patients, with a high prevalence of biofilm related genes of csuE and pgaB. It seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of XDR A. baumannii in our country.}, } @article {pmid31314663, year = {2019}, author = {Sianglum, W and Muangngam, K and Joycharat, N and Voravuthikunchai, SP}, title = {Mechanism of Action and Biofilm Inhibitory Activity of Lupinifolin Against Multidrug-Resistant Enterococcal Clinical Isolates.}, journal = {Microbial drug resistance (Larchmont, N.Y.)}, volume = {}, number = {}, pages = {}, doi = {10.1089/mdr.2018.0391}, pmid = {31314663}, issn = {1931-8448}, abstract = {The treatment of enterococcal infections is becoming more difficult because of multidrug resistance (MDR). Lupinifolin, a prenylated flavonoid isolated from Albizia myriophylla Benth., showed a potent antimicrobial activity against enterococci. The aim of this study was to investigate antibacterial activity and action of lupinifolin against MDR enterococcal clinical isolates. Antibacterial properties of lupinifolin against 21 MDR isolates were assessed using broth microdilution method and time-kill assay. To study mode of action of lupinifolin on the isolates, propidium iodide intensity, salt tolerance assay, and electron microscopic analyses were performed. Antibiofilm formation activity of lupinifolin was conducted using crytal violet assay. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration values of lupinifolin against the isolates ranged between 0.5 and 2.0 μg/mL and between 2 and 16 μg/mL, respectively. Lupinifolin at 2MIC and 4MIC inhibited the bacterial growth >2 log colony-forming units (CFU)/mL at 2 hr incubation by time-kill analysis. The compound increased membrane permeability and caused loss of salt tolerance. SEM and TEM micrographs revealed pronounced morphological and ultrastructural changes in the treated bacteria. Crystal violet staining showed the antibiofilm-producing activity of lupinifolin against four MDR enterococci. This study suggested that lupinifolin is an essential antimicrobial agent that could be useful for the treatment of MDR enterococcal infections.}, } @article {pmid31313963, year = {2019}, author = {Khelissa, SO and Abdallah, M and Jama, C and Barras, A and Chihib, NE}, title = {Comparative Study on the Impact of Growth Conditions on the Physiology and the Virulence of Pseudomonas aeruginosa Biofilm and Planktonic Cells.}, journal = {Journal of food protection}, volume = {82}, number = {8}, pages = {1357-1363}, doi = {10.4315/0362-028X.JFP-18-565}, pmid = {31313963}, issn = {1944-9097}, abstract = {The aim of the present work was to study and compare the effect of growth temperature (20, 30, and 37°C) and surface type (stainless steel and polycarbonate) on the production of virulence factors, such as proteases and siderophores, and the risk of surface contamination associated with Pseudomonas aeruginosa biofilm and planktonic cells. The increase of growth temperature from 20 to 37°C increased (approximately twofold) the electronegative charge and the hydrophobicity of the P. aeruginosa biofilm cell surface. P. aeruginosa biofilm cell adhesion to stainless steel and polycarbonate was 5- and 1.5-fold higher than their planktonic counterparts at 20 and 30°C, respectively. The increase of growth temperature from 20 to 37°C increased the production of proteases (twofold) and siderophores (twofold) and the cytotoxicity (up to 30-fold) against the HeLa cell line in the supernatants of P. aeruginosa planktonic and biofilm cultures. This study also highlighted that biofilm and planktonic P. aeruginosa cells exhibited distinct physiological properties with respect to the production of virulence factors and the cytotoxicity against the Hela cell line. Therefore, effective disinfection procedures should be adapted to inactivate bacteria detached from biofilms.}, } @article {pmid31312343, year = {2019}, author = {Wei, Q and Zhang, Z and Luo, J and Kong, J and Ding, Y and Chen, Y and Wang, K}, title = {Insulin treatment enhances pseudomonas aeruginosa biofilm formation by increasing intracellular cyclic di-GMP levels, leading to chronic wound infection and delayed wound healing.}, journal = {American journal of translational research}, volume = {11}, number = {6}, pages = {3261-3279}, pmid = {31312343}, issn = {1943-8141}, abstract = {Diabetes-related infections have become challenging and important public health problems in China and around the world. P. aeruginosa plays an important role in diabetic foot infections. As a gram-negative opportunistic pathogen, P. aeruginosa causes recurrent and refractory infections that are characterized by biofilm formation. Previous studies have demonstrated that biofilm-challenged wounds typically take longer to heal than non-biofilm-challenged normal wounds in diabetic mouse models. In the present study, we sought to explore the mechanism via which insulin treatment affects cyclic di-GMP signaling in P. aeruginosa-infected chronic wounds in db/db diabetic mice. We found that the wounds of diabetic mice healed more slowly than those of nondiabetic mice. Moreover, wound healing in diabetic mice treated with insulin exhibited a considerable delay. Peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH) was used to detect biofilms on P. aeruginosa-infected wound tissues. Increased intracellular c-di-GMP levels promoted biofilm formation in wound tissues from nondiabetic mice. Greater biofilm formation was observed in the wounds of insulin-treated diabetic mice than in the wounds of untreated diabetic mice or nondiabetic mice, in both the PAO1/plac-yhjH- and PAO1-infected groups. Quantitative RT-PCR indicated that upon infection with PAO1/Plac-yhjH (the low c-di-GMP expression strain), the expression of IL-4 RNA was significantly higher in diabetic mice treated with insulin than in untreated diabetic mice or nondiabetic mice at each observation time point. Peak expression of IFN-γ occurred earlier in diabetic mice treated with insulin than in untreated diabetic mice with each of the experimental strains. Finally, P. aeruginosa harboring the plasmid pCdrA: gfps was used as a reporter strain to monitor c-di-GMP levels. We found that insulin could promote biofilm formation by increasing intracellular c-di-GMP levels in vitro. Taken together, these data demonstrate that insulin treatment increases intracellular c-di-GMP levels, promotes biofilm formation and prolongs the inflammation period during the healing of infected wounds, resulting in delayed wound healing.}, } @article {pmid31311139, year = {2019}, author = {Nóbrega, V and Faria, M and Quintana, A and Kaufmann, M and Ferreira, A and Cordeiro, N}, title = {From a Basic Microalga and an Acetic Acid Bacterium Cellulose Producer to a Living Symbiotic Biofilm.}, journal = {Materials (Basel, Switzerland)}, volume = {12}, number = {14}, pages = {}, doi = {10.3390/ma12142275}, pmid = {31311139}, issn = {1996-1944}, support = {REBECA (MAC/1.1a/060)//European Territorial Cooperation Programme PCT-MAC 2014-2020/ ; M1420-01-0145-FEDER-000001//Oceanic Observatory of Madeira/ ; }, abstract = {Bacterial cellulose (BC) has recently been the subject of a considerable amount of research, not only for its environmentally friendly biosynthesis, but also for its high potential in areas such as biomedicine or biomaterials. A symbiotic relationship between a photosynthetic microalga, Chlamydomonas debaryana, and a cellulose producer bacterium, Komagataeibacter saccharivorans, was established in order to obtain a viable and active biofilm. The effect of the growth media composition ratio on the produced living material was investigated, as well as the microalgae biomass quantity, temperature, and incubation time. The optimal temperature for higher symbiotic biofilm production was 30 °C with an incubation period of 14 days. The high microalgae presence, 0.75% w/v, and 60:40 HS:BG-11 medium (v/v) induced a biofilm microalgae incorporation rate of 85%. The obtained results report, for the first time, a successful symbiotic interaction developed in situ between an alkaline photosynthetic microalga and an acetic acid bacterium. These results are promising and open a new window to BC living biofilm applications in medical fields that have not yet been explored.}, } @article {pmid31310825, year = {2019}, author = {Cusicanqui Méndez, DA and Gutierrez, E and Campos Chaves Lamarque, G and Lopes Rizzato, V and Afonso Rabelo Buzalaf, M and Andrade Moreira Machado, MA and Cruvinel, T}, title = {The effectiveness of curcumin-mediated antimicrobial photodynamic therapy depends on pre-irradiation and biofilm growth times.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.07.011}, pmid = {31310825}, issn = {1873-1597}, abstract = {BACKGROUND: The aim of this study was to determine the influence of distinct pre-irradiation times (PIT) of curcumin on the effectiveness of the antimicrobial photodynamic therapy (aPDT) against intact dentin caries biofilms grown for 3 or 5 days.

METHODS: The microcosm biofilms grew on non-fluorescent glass blocks immersed in McBain medium with 1% sucrose, using microaerophilic conditions at 37 °C for 3 or 5 days. The biofilms were treated by the association of 600 µmol.L-1 curcumin using different pre-irradiation times (1, 2 or 5 min) combined with 0 or 75 J.cm-2 blue LED. Then, the vitality of biofilms was determined by confocal scanning laser microscopy (CSLM), after being stained with the mixture of ethidium bromide and fluorescein diacetate. Statistical analysis was performed by two-way ANOVA and post-hoc Tukey tests, after arcsine transformation (P < 0,05).

RESULTS: In comparison to control, curcumin alone (PIT = 5 min) and all combinations of curcumin and LED reduced significantly the vitality of 3-day biofilms. Distinctly, only curcumin plus LED using PITs of 2 or 5 min were effective in reducing the vitality of 5-day biofilms.

CONCLUSION: Curcumin-mediated aPDT significantly decreased the vitality of intact dentin caries microcosms grown during 3 or 5 days, although successful treatments of 5-day biofilms required longer PITs in comparison to their counterparts.}, } @article {pmid31303882, year = {2019}, author = {Bahari, M and Ebrahimi Chaharom, ME and Daneshpooy, M and Gholizadeh, S and Pashayi, H}, title = {Effect of bleaching protocols on surface roughness and biofilm formation on silorane-based composite resin.}, journal = {Dental research journal}, volume = {16}, number = {4}, pages = {264-270}, pmid = {31303882}, issn = {1735-3327}, abstract = {Background: Knowledge about the effect of bleaching on behavior of composite resins is important to find a suitable composite resin for restoration of teeth undergoing bleaching. This study aimed to assess the effect of different bleaching protocols on surface roughness and biofilm formation on a silorane-based composite resin.

Materials and Methods: In this in vitro experimental study, 60 silorane-based composite resin samples measuring 3 mm in thickness and 6 mm in diameter were fabricated and polished. They were then randomly divided into four groups (n = 15). In Group 1, samples were stored in distilled water as control. Samples in Groups 2, 3, and 4 were subjected to bleaching with 15% carbamide peroxide, 35% hydrogen peroxide, and 35% hydrogen peroxide activated by light, respectively. Surface roughness was measured using a profilometer. Streptococcus mutans cultured in brain-heart infusion broth was used for the assessment of biofilm formation on the samples. The bacterial colonies were counted using the pure-plate technique. Data were analyzed using one-way ANOVA and post hoc Tukey's tests. Regression model was used to assess the association between surface roughness and biofilm formation (P < 0.05).

Results: The mean surface roughness of the four groups was not significantly different (P = 0.11); however, a significant difference was noted in the mean biofilm formation among the groups (P = 0.00).

Conclusion: Bleaching decreased biofilm formation. The lowest biofilm formation was noted in the group subjected to light-activated 35% hydrogen peroxide. Increased surface roughness enhanced biofilm formation to a certain level; excessive roughness did not increase biofilm formation.}, } @article {pmid31303772, year = {2019}, author = {Farajzadeh Sheikh, A and Asareh Zadegan Dezfuli, A and Navidifar, T and Fard, SS and Dehdashtian, M}, title = {Association between biofilm formation, structure and antibiotic resistance in Staphylococcus epidermidis isolated from neonatal septicemia in southwest Iran.}, journal = {Infection and drug resistance}, volume = {12}, number = {}, pages = {1771-1782}, doi = {10.2147/IDR.S204432}, pmid = {31303772}, issn = {1178-6973}, abstract = {Background:Staphylococcus epidermidis has emerged as the pathogen from neonatal septicemia. Antibiotic resistance and the capability of biofilm formation make these infections much harder to treat. Hence, the aim of this study was to investigate the association between biofilm formation, structure and antibiotic resistance in S. epidermidis isolated from neonatal septicemia. Methods: Overall, 65 S. epidermidis isolates were recovered from blood cultures of neonatal septicemia. Antibiotic resistance pattern and the biofilm production were determined using phenotypic methods. The presence of ica operon, the bhp, the aap genes and SCCmec types were screened using PCR. Results: Most S.epidermidis isolates were resistant to erythromycin, while all isolates were sensitive to linezolid and vancomycin. Fifty-three percent of S.epidermidis isolates were resistant to methicillin. SCCmec types II was found commonly among methicillin-resistant S. epidermidis (MRSE) strains. The biofilm formation was observed in 65% of S.epidermidis isolates and the majority have polysaccharide matrix. icaA and icaD genes were found in 40% and 19% of isolates. Twenty-three isolates (62%) produced dissolvable polysaccharide intercellular adhesion (PIA)-dependent biofilms in SM after growth in TSB with NaCl and 14 (37%) isolates produced dissolvable protein-dependent biofilms in PK after growth in TSB with glucose. Three isolates (62%) produced dissolvable polysaccharide intercellular adhesion. Conclusion: Our data indicate the high rates of antibiotic resistance and the capability of biofilm formation among S. epidermidis isolates. Hence, the transmission of these strains can cause an increased risk of serious nosocomial infections.}, } @article {pmid31302463, year = {2019}, author = {Zhang, Q and Zhang, L and Li, Z and Zhang, L and Li, D}, title = {Enhancement of fipronil degradation with eliminating its toxicity in a microbial fuel cell and the catabolic versatility of anodic biofilm.}, journal = {Bioresource technology}, volume = {290}, number = {}, pages = {121723}, doi = {10.1016/j.biortech.2019.121723}, pmid = {31302463}, issn = {1873-2976}, abstract = {The degradation of fipronil was investigated in microbial fuel cells (MFCs). Almost 79% of 30 mg/L fipronil was rapidly degraded within 12 h by MFC biofilm. Based on the constructed quadratic polynomial model, a maximum fipronil degradation rate of 94.22% could be theoretically achieved at pH of 7.01, 33.39 °C, and the initial fipronil concentration 74 mg/L after incubation for 72 h. The high acute toxicity of fipronil toward zebrafish was largely eliminated after degradation by the MFC. In addition, the MFC biofilm showed catabolic versatility to 4-chloronitrobenzene, sulfanilamide, fluoroglycofen, and azoxystrobin. The microbial community analysis revealed that the functional bacteria Sphaerochaeta, Pseudomonas, Azospirillum, Azoarcus, and Chryseobacterium were major predominant bacteria in the anodic biofilm. Therefore, the MFC offers a promising approach in treating the environmental contaminants due to its abilities of energy capture from waste substances and catabolic versatility to different organic compounds.}, } @article {pmid31300852, year = {2019}, author = {Zara, G and Bou Zeidan, M and Fancello, F and Sanna, ML and Mannazzu, I and Budroni, M and Zara, S}, title = {The administration of L-cysteine and L-arginine inhibits biofilm formation in wild-type biofilm-forming yeast by modulating FLO11 gene expression.}, journal = {Applied microbiology and biotechnology}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00253-019-09996-5}, pmid = {31300852}, issn = {1432-0614}, abstract = {Microbial biofilms are undesired in food manufacturing, drinking water distribution systems, and clinical realms. Yeast biofilms are particularly problematic because of the strong capacity of yeast cells to adhere to abiotic surfaces, cells, and tissues. Novel approaches have been developed over recent years to prevent the establishment of microbial biofilms, such as through the use of small molecules with inhibiting and dispersing properties. Here, we studied the inhibitory activity of 11 different amino acids on the biofilm formation ability of three wild-type Saccharomyces cerevisiae strains and the reference strain ∑1278b. Subsequent evaluation of different concentrations of the two most effective amino acids, namely, arginine and cysteine, revealed that they acted in different ways. Arginine prevented biofilm formation by reducing FLO11 gene expression; its addition did not affect cell viability and was even found to enhance cell metabolism (vitality marker) as determined by phenotype microarray (PM) analysis. On the contrary, the addition of cysteine reduced both cell viability and vitality as well as FLO11 expression. Thus, the use of cysteine and arginine as agents against biofilm formation can be diversified depending on the most desired action towards yeast growth.}, } @article {pmid31300301, year = {2019}, author = {Uribe-García, A and Paniagua-Contreras, GL and Monroy-Pérez, E and Bustos-Martínez, J and Hamdan-Partida, A and Garzón, J and Alanís, J and Quezada, R and Vaca-Paniagua, F and Vaca, S}, title = {Frequency and expression of genes involved in adhesion and biofilm formation in Staphylococcus aureus strains isolated from periodontal lesions.}, journal = {Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.jmii.2019.05.010}, pmid = {31300301}, issn = {1995-9133}, abstract = {BACKGROUND/PURPOSE: The aim of this study was to characterize the Staphylococcus aureus strains isolated from periodontal lesions of patients, to determine the expression of genes involved in cell adhesion upon their infection of human epithelial cells using an in vitro model, its biofilm formation, and its resistance to antibiotics.

METHODS: S. aureus was analysed by PCR, Kirby-Bauer, and pulsed-field gel electrophoresis (PFGE), measuring gene expression by real-time PCR after infection of human cells in vitro.

RESULTS: S. aureus was identified in 18.6% (50/268) of the samples. All strains (n = 50) possessed the virulence genes spa (Staphylococcal protein A), coa (coagulase), and icaAB (intercellular adhesin); 96% (n = 48) possessed clfB (clumping factor B), and 88% (n = 44) possessed ebps (elastin-binding protein) and sdrD (serine aspartate repeat protein D). All strains were resistant to methicillin, ampicillin, dicloxacillin, cefotaxime, and penicillin, and were multidrug resistant to 6-12 antibiotics. PFGE analysis showed 37 different pulsed-field types and most strains (60.4%) had a unique pulsed-field type. Twenty-four distinct combinations of virulence genes and antibiotic-resistant phenotypes were identified.

CONCLUSION: Although S. aureus has been considered a transient member of the oral microbiota, our results indicate a high-level expression of virulence genes and multidrug resistance in the strains isolated from periodontal lesions. These strains might complicate the successful treatment of the disease.}, } @article {pmid31300167, year = {2019}, author = {Zhang, K and Lyu, L and Yao, S and Kang, T and Ma, Y and Pan, Y and Chang, M and Wang, Y and Furukawa, K and Zhu, T}, title = {Effects of vibration on anammox-enriched biofilm in a high-loaded upflow reactor.}, journal = {The Science of the total environment}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.scitotenv.2019.06.082}, pmid = {31300167}, issn = {1879-1026}, abstract = {An upflow biofilm reactor was operated for 211 days to investigate the effects of vibration on anammox treatment performance. With vibration, the highest nitrogen removal rates (20 kg-N·m-3·d-1) were obtained on day 180. Since the vibration could directly applied on the biofilm, it could release the dinitrogen gas accumulated in the biofilm timely and reduce the internal mass transfer resistance sharply. The specific anammox activity increased by more than 3 times with a higher vibration intensity. Meanwhile, the unique random motion caused by mechanical vibration promotes the production of extracellular proteins. Moreover, the VSS reached 20.97 g·L-1 which was 1.6 times higher than the control reactor. Such enrichment method resulted in a hard and thick anammox biofilm with a special granular morphology, and the nitrite tolerance concentration could reach 500 mg-N·L-1. Operated with an adequate vibration intensity could maintain the biofilm thickness and conducive to improve the stability of the reactor. In addition, this technique also allowed the microorganisms inside the biofilm and those on the surface to reach the same culture conditions. Base on the batch experiments, intermittent vibration caused a decrease in energy consumption from about 7.757 (kW·h)·(kg-N)-1 in group 0-Lv7(60-60) to 0.912 (kW·h)·(kg-N)-1 in group 0-Lv7(5-60). Compared to the internal recycle without vibration, the energy consumption fell by a slice over 65%. Furthermore, the high-throughput sequencing results showed that the relative abundance of Candidatus Kuenenia in reactor 1 increased from 13.2% to 43.9%.}, } @article {pmid31299899, year = {2019}, author = {Azmi, K and Qrei, W and Abdeen, Z}, title = {Screening of genes encoding adhesion factors and biofilm production in methicillin resistant strains of Staphylococcus aureus isolated from Palestinian patients.}, journal = {BMC genomics}, volume = {20}, number = {1}, pages = {578}, doi = {10.1186/s12864-019-5929-1}, pmid = {31299899}, issn = {1471-2164}, support = {(M33-014).//Merck/ ; }, abstract = {BACKGROUND: Intercellular adhesion and biofilm production by Staphylococcus aureus makes these bacteria resistant to antimicrobial therapy. Here, Methicillin-resistant Staphylococcus aureus (MRSA) strains were characterized and the prevalence of genes encoding adhesion factors and biofilm formation was determined.

RESULTS: All 248 MRSA isolates identified by cefoxitin disc diffusion were positive for the mecA gene. SCCmec-IV was the most frequently detected genotype (92.7%) and SCCmec-IVa was also very prevalent (84.3%). The quantitative microtiter plate assay showed that all the isolates were able to produce biofilm with levels ranging from high (21%) to moderate (46.4%) to low (32.7%). All the strains possessed the icaD/icaA genes and produced biofilm (P < 0.05). None of the isolates possessed the bap gene. Furthermore, 94.8% of the isolates were positive for eno, 80.2% for clfA and for clfB, 78.2% for fnbA, 76.2% for ebps, 62.2% for fib, 39.9% for cna and 29.0% for fnbB. Also, nearly 69.8% of the isolates were positive for the gene sarA. All four agr groups were present: agr group 1 was predominant with 39.5%; agr group 3. agr group 2 and 3 strains carried more toxin-producing genes, and frequently produced more toxin. Sixty-six (26.6%) of the strains were multidrug resistant. All were vancomycin sensitive. Agr group I is more resistant to ciprofloxacin and gentamicin while agr group III is more resistant to erythromycin. Maximum sensitivity was to gentamicin and SXT, and they could be considered drugs of choice for controlling MRSA mediated infections in this region.

CONCLUSIONS: Biofilm development in MRSA might be an ica dependent and one needs to investigate the involvement of other global regulators, agr and sarA, and their contribution to the biofilm phenotype, as the high rate of biofilm production among the studied strains of S. aureus.}, } @article {pmid31297368, year = {2019}, author = {Nichols, D and Pimentel, MB and Borges, FTP and Hyoju, SK and Teymour, F and Hong, SH and Zaborina, OY and Alverdy, JC and Papavasiliou, G}, title = {Sustained Release of Phosphates From Hydrogel Nanoparticles Suppresses Bacterial Collagenase and Biofilm Formation in vitro.}, journal = {Frontiers in bioengineering and biotechnology}, volume = {7}, number = {}, pages = {153}, doi = {10.3389/fbioe.2019.00153}, pmid = {31297368}, issn = {2296-4185}, support = {R01 GM062344/GM/NIGMS NIH HHS/United States ; R21 AI124037/AI/NIAID NIH HHS/United States ; }, abstract = {Intestinal disease or surgical intervention results in local changes in tissue and host-derived factors triggering bacterial virulence. A key phenotype involved in impaired tissue healing is increased bacterial collagenase expression which degrades intestinal collagen. Antibiotic administration is ineffective in addressing this issue as it inadvertently eliminates normal flora while allowing pathogenic bacteria to "bloom" and acquire antibiotic resistance. Compounds that could attenuate collagenase production while allowing commensal bacteria to proliferate normally would offer major advantages without the risk of the emergence of resistance. We have previously shown that intestinal phosphate depletion in the surgically stressed host is a major cue that triggers P. aeruginosa virulence which is suppressed under phosphate abundant conditions. Recent findings indicate that orally administered polyphosphate, hexametaphosphate, (PPi) suppresses collagenase, and biofilm production of P. aeruginosa and S. marcescens in animal models of intestinal injury but does not attenuate E. faecalis induced collagenolytic activity (Hyoju et al., 2017). Systemic administration of phosphates, however, is susceptible to rapid clearance. Given the diversity of collagenase producing bacteria and the variation of phosphate metabolism among microbial species, a combination therapy involving different phosphate compounds may be required to attenuate pathogenic phenotypes. To address these barriers, we present a drug delivery approach for sustained release of phosphates from poly(ethylene) glycol (PEG) hydrogel nanoparticles. The efficacy of monophosphate (Pi)- and PPi-loaded NPs (NP-Pi and NP-PPi, respectively) and a combination treatment (NP-Pi + NP-PPi) in mitigating collagenase and biofilm production of gram-positive and gram-negative pathogens expressing high collagenolytic activity was investigated. NP-PPi was found to significantly decrease collagenase and biofilm production of S. marcescens and P. aeruginosa. Treatment with either NP-Pi or NP-Pi + NP-PPi resulted in more prominent decreases in E. faecalis collagenase compared to NP-PPi alone. The combination treatment was also found to significantly reduce P. aeruginosa collagenase production. Finally, significant attenuation in biofilm dispersal was observed with NP-PPi or NP-Pi + NP-PPi treatment across all test pathogens. These findings suggest that sustained release of different forms of phosphate confers protection against gram-positive and gram-negative pathogens, thereby providing a promising treatment to attenuate expression of tissue-disruptive bacterial phenotypes without eradicating protective flora over the course of intestinal healing.}, } @article {pmid31297098, year = {2019}, author = {Friedlander, A and Nir, S and Reches, M and Shemesh, M}, title = {Preventing Biofilm Formation by Dairy-Associated Bacteria Using Peptide-Coated Surfaces.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1405}, doi = {10.3389/fmicb.2019.01405}, pmid = {31297098}, issn = {1664-302X}, abstract = {Biofilm-forming bacteria, which colonize the surfaces of equipment in the dairy industry, may adversely affect the safety and quality of the milk and its products. Despite numerous efforts to combat biofilm formation, there is still no effective technological means to thoroughly solve the biofilm problem in the dairy industry. Here, we introduced peptide-based coating in order to modify the physical properties of the stainless steel surface by affecting its availability for bacterial adhesion. We found that the coated surface displays a notable decrease in the ability of bacterial cells to attach and to subsequently form biofilm by Gram-positive Bacillus licheniformis and Gram-negative Pseudomonas aeruginosa. Furthermore, the coated surface retained its anti-biofilm ability following its exposure to raw milk. Importantly, the modified surface did not affect the milk coagulation process or its nutritious properties and quality. Overall, this anti-biofilm approach may serve as an attractive solution for the dairy industry in its struggle against bacterial contamination.}, } @article {pmid31297021, year = {2019}, author = {Al-Yousef, HM and Sheikh, IA}, title = {β-Sitosterol derived compound from onion husks non-polar fraction reduces quorum sensing controlled virulence and biofilm production.}, journal = {Saudi pharmaceutical journal : SPJ : the official publication of the Saudi Pharmaceutical Society}, volume = {27}, number = {5}, pages = {664-672}, doi = {10.1016/j.jsps.2019.04.001}, pmid = {31297021}, issn = {1319-0164}, abstract = {Quorum sensing is an important regulatory factor of P. aeruginosa virulence induction such as BF, motility, formations of proteases, pyocyanin, and some toxins. The aim of the current study is to detect the effect of the pet.ether extract from onion husk and compound drive from it on quorum sensing and virulence formations of P. aeruginosa. Quorum sensing inhibiting effect of the pet.ether extract of onion husk and a compound drive from it, was evaluated by C. violaceum reporter using dilution method as well as an antioxidant by using DPPH. The efficacious of: Quorum sensing inhibiting on pet.ether fraction and compound derived from it, were investigated for their activities toward biofilm and pyocyanin synthesis as well as motility from P. aeruginosa. The pet.ether fraction and compound derived from it of onion husk exhibited potent antimicrobial, antioxidant and Quorum sensing inhibiting effects. The pet.ether fraction and compound derived from it possesses significant reduction on pyocyanin and biofilm induction of P. aeruginosa. Moreover, they significantly inhibited swimming motilities of P. aeruginosa. For the first time, our study showed the medical importance of Allium cepa L. as antimicrobial, antioxidant as well as Quorum sensing inhibiting and virulence suppressors of P. aeruginosa. Thus, these might emphasized on Allium cepa L as a natural source for attenuating toxins of the Pseudomonas.}, } @article {pmid31295074, year = {2019}, author = {Carter, MJ and Myntti, MF}, title = {Cost-utility of a biofilm-disrupting gel versus standard of care in chronic wounds: a Markov microsimulation model based on a randomised controlled trial.}, journal = {Journal of wound care}, volume = {28}, number = {Sup7}, pages = {S24-S38}, doi = {10.12968/jowc.2019.28.Sup7.S24}, pmid = {31295074}, issn = {0969-0700}, abstract = {OBJECTIVE: Analyse the cost-effectiveness and treatment outcomes of debridement (standard of care) plus BlastX, a biofilm-disrupting wound gel (group 1) or a triple-antibiotic, maximum-strength ointment (group 2), comparing a subset of patients who had not healed at four weeks using the ointment crossed-over to the biofilm-disrupting gel (group 3).

METHODS: A series of Markov microsimulation models were built using health states of an unhealed non-infected ulcer, healed ulcer, and infected non-healed ulcer and absorbing states of dead or amputation. All patients started with unhealed non-infected ulcers at cycle 0. Complications and healing rates were based on a randomised controlled trial (RCT). Costs were incurred by patients for procedures at outpatient wound care clinics and hospitals (if complications occurred) and were in the form of Medicare allowable charges. Quality-adjusted life years (QALYs) were computed using literature utility values. Incremental cost-effectiveness ratios (ICERs) were calculated for group 1 versus group 2, and group 3 versus group 2. One-way, multi-way and probabilistic sensitivity analysis (PSA) was conducted.

RESULTS: After one year, the base case ICER was $8794 per QALY for group 1 versus group 2, and $21,566 per QALY for group 3 versus group 2. Product cost and amputation rates had the most influence in one-way sensitivity analysis. PSA showed that the majority of costs were higher for group 1 but effectiveness values were always higher than for group 2. Average product use of 3.1ml per application represented 9.4% of the total group 1 cost (average $24.52 per application/$822.50 per group 1 patient). The biofilm-disrupting gel group performed substantially better than the current cost-effectiveness benchmarks, $8794 versus $50,000, respectively. Furthermore, when biofilm-disrupting gel treatment was delayed, as in group 3, the ICER outcomes were less substantial but it did remain cost-effective, suggesting the added benefits of immediate use of biofilm-disrupting gel. Also, when product cost assumptions used in the study were halved (Wolcott study usage), the model indicates important reductions in ICER to $966/QALY when comparing group 1 with group 2. It should be noted that product cost can hypothetically be affected not only by direct product purchase costs, but also by application intervals and technique. This suggests additional opportunities exist to optimise these parameters, maximising wound healing efficacy while providing significant cost savings to the payer.

CONCLUSION: The addition of the biofilm-disrupting gel treatment to standard of care is likely to be cost-effective in the treatment of chronic wounds but when delayed by as little as 9-12 weeks the ICER is still far less than current cost-effectiveness benchmarks. The implication for payers and decision-makers is that biofilm-disrupting gel should be used as a first-line therapy at the first clinic visit rather than waiting as it substantially decreases cost-utility.}, } @article {pmid31294965, year = {2019}, author = {Alizadeh, S and Abdul Rahim, A and Guo, B and Hawari, J and Ghoshal, S and Comeau, Y}, title = {Impacts of Continuous Inflow of Low Concentrations of Silver Nanoparticles on Biological Performance and Microbial Communities of Aerobic Heterotrophic Wastewater Biofilm.}, journal = {Environmental science & technology}, volume = {}, number = {}, pages = {}, doi = {10.1021/acs.est.9b01214}, pmid = {31294965}, issn = {1520-5851}, abstract = {Attached-growth wastewater processes are currently used in water resource recovery facilities (WRRFs) for required upgrades due to an increase in influent loading or to reach more stringent discharge criteria. Yet, the distribution and long-term inhibitory effects of silver nanoparticles (AgNPs) in attached-growth biological wastewater processes and their impact on involved microbial communities are poorly understood at relevant, low concentrations. Retention, distribution, and long-term inhibitory effect of polyvinylpyrrolidone (PVP)-coated AgNPs were evaluated in bench-scale moving bed biofilm reactors (MBBRs), achieving soluble organic matter removal, over a 64 day exposure to nominal concentrations of 10 and 100 μg/L. Distributions of continuously added AgNPs were characterized in the influent, bioreactor, and effluent of MBBRs using single particle inductively coupled plasma mass spectroscopy (spICP-MS). Aerobic heterotrophic biofilms in MBBRs demonstrated limited retention capacity for AgNPs over long-term exposure, with release of AgNPs, and Ag-rich biofilm sloughed from the carriers. Continuous exposure to both influent AgNP concentrations significantly decreased soluble chemical oxygen demand (SCOD) removal efficiency (11% to 31%) and reduced biofilm viability (8% to 30%). Specific activities of both intracellular dehydrogenase (DHA) and extracellular α-glucosidase (α-Glu) and protease (PRO) enzymes were significantly inhibited (8% to 39%) with an observed NP dose-dependent intracellular reactive oxygen species (ROS) production and shift in biofilm microbial community composition by day 64. Our results indicated that long-term exposure to AgNPs in biofilm processes at environmentally relevant concentrations can impact the treatment process stability and the quality of the discharged effluent.}, } @article {pmid31294223, year = {2018}, author = {Xaxiri, NA and Nikouli, E and Berillis, P and Kormas, KA}, title = {Bacterial biofilm development during experimental degradation of Melicertus kerathurus exoskeleton in seawater.}, journal = {AIMS microbiology}, volume = {4}, number = {3}, pages = {397-412}, doi = {10.3934/microbiol.2018.3.397}, pmid = {31294223}, issn = {2471-1888}, abstract = {Chitinolytic bacteria are widespread in marine and terrestrial environment, and this is rather a reflection of their principle growth substrate's ubiquity, chitin, in our planet. In this paper, we investigated the development of naturally occurring bacterial biofilms on the exoskeleton of the shrimp Melicertus kerathurus during its degradation in sea water. During a 12-day experiment with exoskeleton fragments in batch cultures containing only sea water as the growth medium at 18 °C in darkness, we analysed the formation and succession of biofilms by scanning electron microscopy and 16S rRNA gene diversity by next generation sequencing. Bacteria belonging to the γ- and α-Proteobacteria and Bacteroidetes showed marked (less or more than 10%) changes in their relative abundance from the beginning of the experiment. These bacterial taxa related to known chitinolytic bacteria were the Pseudolateromonas porphyrae, Halomonasaquamarina, Reinekea aestuarii, Colwellia asteriadis and Vibrio crassostreae. These bacteria could be considered as appropriate candidates for the degradation of chitinous crustacean waste from the seafood industry as they dominated in the biofilms developed on the shrimp's exoskeleton in natural sea water with no added substrates and the degradation of the shrimp exoskeleton was also evidenced.}, } @article {pmid31294028, year = {2019}, author = {Coelho, C and Gougeon, RD and Perepelkine, L and Alexandre, H and Guzzo, J and Weidmann, S}, title = {Chemical Transfers Occurring Through Oenococcus oeni Biofilm in Different Enological Conditions.}, journal = {Frontiers in nutrition}, volume = {6}, number = {}, pages = {95}, doi = {10.3389/fnut.2019.00095}, pmid = {31294028}, issn = {2296-861X}, abstract = {Chardonnay wine malolactic fermentations were carried out to evaluate the chemical transfers occurring at the wood/wine interface in the presence of two different bacterial lifestyles. To do this, Oenococcus oeni was inoculated into must and wine in its planktonic and biofilm lifestyles, whether adhering or not to oak chips, leading to three distinct enological conditions: (i) post-alcoholic fermentation inoculation in wine in the absence of oak chips, (ii) post-alcoholic fermentation inoculation in wine in the presence of oak chips, and (iii) co-inoculation of both Saccharomyces cerevisiae and O. oeni directly in Chardonnay musts in the presence of oak chips. Classical microbiological and physico-chemical parameters analyzed during the fermentation processes confirmed that alcoholic fermentation was completed identically regardless of the enological conditions, and that once O. oeni had acquired a biofilm lifestyle in the presence or absence of oak, malolactic fermentation occurred faster and with better reproducibility compared to planktonic lifestyles. Analyses of volatile components (higher alcohols and wood aromas) and non-volatile components (Chardonnay grape polyphenols) carried out in the resulting wines revealed chemical differences, particularly when bacterial biofilms were present at the wood interface. This study revealed the non-specific trapping activity of biofilm networks in the presence of wood and grape compounds regardless of the enological conditions. Changes of concentrations in higher alcohols reflected the fermentation bioactivity of bacterial biofilms on wood surfaces. These chemical transfers were statistically validated by an untargeted approach using Excitation Emission Matrices of Fluorescence combined with multivariate analysis to discriminate innovative enological practices during winemaking and to provide winemakers with an optical tool for validating the biological and chemical differentiations occurring in wine that result from their decisions.}, } @article {pmid31293539, year = {2019}, author = {Schiffer, C and Hilgarth, M and Ehrmann, M and Vogel, RF}, title = {Bap and Cell Surface Hydrophobicity Are Important Factors in Staphylococcus xylosus Biofilm Formation.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1387}, doi = {10.3389/fmicb.2019.01387}, pmid = {31293539}, issn = {1664-302X}, abstract = {Staphylococcus (S.) xylosus is a coagulase-negative Staphylococcus species naturally present in food of animal origin with a previously described potential for biofilm formation. In this study we characterized biofilm formation of five selected strains isolated from raw fermented dry sausages, upon different growth conditions. Four strains exhibited a biofilm positive phenotype with strain-dependent intensities. Biofilm formation of S. xylosus was influenced by the addition of glucose, sodium chloride and lactate to the growth medium, respectively. It was further dependent on strain-specific cell surface properties. Three strains exhibited hydrophobic and two hydrophilic cell surface properties. The biofilm positive hydrophilic strain TMW 2.1523 adhered significantly better to hydrophilic than to hydrophobic supports, whereas the differences in adherence to hydrophobic versus hydrophilic supports were not as distinct for the hydrophobic strains TMW 2.1023, TMW 2.1323, and TMW 2.1521. Comparative genomics enabled prediction of functional biofilm-related genes and link these to phenotypic variations. While a wide range of biofilm associated factors/genes previously described for S. aureus and S. epidermidis were absent in the genomes of the five strains analyzed, they all possess the gene encoding biofilm associated protein Bap. The only biofilm negative strain TMW 2.1602 showed a mutation in the bap sequence. This study demonstrates that Bap and surface hydrophobicity are important factors in S. xylosus biofilm formation with potential impact on the assertiveness of a starter strain against autochthonous staphylococci by competitive exclusion during raw sausage fermentation.}, } @article {pmid31293528, year = {2019}, author = {Ranjith, K and Ramchiary, J and Prakash, JSS and Arunasri, K and Sharma, S and Shivaji, S}, title = {Gene Targets in Ocular Pathogenic Escherichia coli for Mitigation of Biofilm Formation to Overcome Antibiotic Resistance.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1308}, doi = {10.3389/fmicb.2019.01308}, pmid = {31293528}, issn = {1664-302X}, abstract = {The present work is an attempt to establish the functionality of genes involved in biofilm formation and antibiotic resistance in an ocular strain of Escherichia coli (L-1216/2010) which was isolated and characterized from the Vitreous fluid of a patient with Endophthalmitis. For this purpose, seven separate gene-specific knockout mutants were generated by homologous recombination in ocular E. coli. The genes that were mutated included three transmembrane genes ytfR (ABC transporter ATP-binding protein), mdtO (multidrug efflux system) and tolA (inner membrane protein), ryfA coding for non-coding RNA and three metabolic genes mhpA (3-3-hydroxyphenylpropionate 1,2-dioxygenase), mhpB (2,3-di hydroxyphenylpropionate 1,2-dioxygenase), and bdcR (regulatory gene of bdcA). Mutants were validated by sequencing and Reverse transcription-PCR and monitored for biofilm formation by XTT method and confocal microscopy. The antibiotic susceptibility of the mutants was also ascertained. The results indicated that biofilm formation was inhibited in five mutants (ΔbdcR, ΔmhpA, ΔmhpB, ΔryfA, and ΔtolA) and the thickness of biofilm reduced from 17.2 μm in the wildtype to 1.5 to 4.8 μm in the mutants. Mutants ΔytfR and ΔmdtO retained the potential to form biofilm. Complementation of the mutants with the wild type gene restored biofilm formation potential in all mutants except in ΔmhpB. The 5 mutants which lost their ability to form biofilm (ΔbdcR, ΔmhpA, ΔmhpB, ΔtolA, and ΔryfA) did not exhibit any change in their susceptibility to Ceftazidime, Cefuroxime, Ciprofloxacin, Gentamicin, Cefotaxime, Sulfamethoxazole, Imipenem, Erythromycin, and Streptomycin in the planktonic phase compared to wild type ocular E. coli. But ΔmdtO was the only mutant with altered MIC to Sulfamethoxazole, Imipenem, Erythromycin, and Streptomycin both in the planktonic and biofilm phase. This is the first report demonstrating the involvement of the metabolic genes mhpA and mhpB and bdcR (regulatory gene of bdcA) in biofilm formation in ocular E. coli. In addition we provide evidence that tolA and ryfA are required for biofilm formation while ytfR and mdtO are not required. Mitigation of biofilm formation to overcome antibiotic resistance could be achieved by targeting the genes bdcR, mhpA, mhpB, ryfA, and tolA.}, } @article {pmid31293526, year = {2019}, author = {Gannesen, AV and Zdorovenko, EL and Botchkova, EA and Hardouin, J and Massier, S and Kopitsyn, DS and Gorbachevskii, MV and Kadykova, AA and Shashkov, AS and Zhurina, MV and Netrusov, AI and Knirel, YA and Plakunov, VK and Feuilloley, MGJ}, title = {Composition of the Biofilm Matrix of Cutibacterium acnes Acneic Strain RT5.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1284}, doi = {10.3389/fmicb.2019.01284}, pmid = {31293526}, issn = {1664-302X}, abstract = {In skin, Cutibacterium acnes (former Propionibacterium acnes) can behave as an opportunistic pathogen, depending on the strain and environmental conditions. Acneic strains of C. acnes form biofilms inside skin-gland hollows, inducing inflammation and skin disorders. The essential exogenous products of C. acnes accumulate in the extracellular matrix of the biofilm, conferring essential bacterial functions to this structure. However, little is known about the actual composition of the biofilm matrix of C. acnes. Here, we developed a new technique for the extraction of the biofilm matrix of Gram-positive bacteria without the use of chemical or enzymatic digestion, known to be a source of artifacts. Our method is based on the physical separation of the cells and matrix of sonicated biofilms by ultracentrifugation through a CsCl gradient. Biofilms were grown on the surface of cellulose acetate filters, and the biomass was collected without contamination by the growth medium. The biofilm matrix of the acneic C. acnes RT5 strain appears to consist mainly of polysaccharides. The following is the ratio of the main matrix components: 62.6% polysaccharides, 9.6% proteins, 4.0% DNA, and 23.8% other compounds (porphyrins precursors and other). The chemical structure of the major polysaccharide was determined using a nuclear magnetic resonance technique, the formula being →6)-α-D-Galp-(1→4)-β-D-ManpNAc3NAcA-(1→6)-α-D-Glcp-(1→4)-β-D-ManpNAc3NAcA-(1→3)-β-GalpNAc-(1→. We detected 447 proteins in the matrix, of which the most abundant were the chaperonin GroL, the elongation factors EF-Tu and EF-G, several enzymes of glycolysis, and proteins of unknown function. The matrix also contained more than 20 hydrolases of various substrata, pathogenicity factors, and many intracellular proteins and enzymes. We also performed surface-enhanced Raman spectroscopy analysis of the C. acnes RT5 matrix for the first time, providing the surface-enhanced Raman scattering (SERS) profiles of the C. acnes RT5 biofilm matrix and biofilm biomass. The difference between the matrix and biofilm biomass spectra showed successful matrix extraction rather than simply the presence of cell debris after sonication. These data show the complexity of the biofilm matrix composition and should be essential for the development of new anti-C. acnes biofilms and potential antibiofilm drugs.}, } @article {pmid31292867, year = {2019}, author = {Calapez, AR and Elias, CL and Almeida, SFP and Brito, AG and Feio, MJ}, title = {Sewage contamination under water scarcity effects on stream biota: biofilm, grazers, and their interaction.}, journal = {Environmental science and pollution research international}, volume = {}, number = {}, pages = {}, doi = {10.1007/s11356-019-05876-7}, pmid = {31292867}, issn = {1614-7499}, support = {PD\BD\52510\2014//Fundação para a Ciência e a Tecnologia/ ; UID/MAR/04292/2013//Fundação para a Ciência e a Tecnologia/ ; UID/GEO/04035/2013//Fundação para a Ciência e a Tecnologia/ ; }, abstract = {One of the most common anthropogenic impacts on river ecosystems is the effluent discharge from wastewater treatment plants. The effects of this contamination on stream biota may be intensified in Mediterranean climate regions, which comprise a drought period that leads to flow reduction, and ultimately to stagnant pools. To assess individual and combined effects of flow stagnation and sewage contamination, biofilm and gastropod grazers were used in a 5-week experiment with artificial channels to test two flow velocity treatments (stagnant flow/basal flow) and two levels of organic contamination using artificial sewage (no sewage input/sewage input). Stressors' effects were determined on biofilm total biomass and chlorophyll (Chl) content, on oxygen consumption and growth rate of the grazers (Theodoxus fluviatilis), and on the interaction grazer-biofilm given by grazer's feeding activity (i.e., biofilm consumption rate). The single effect of sewage induced an increase in biofilm biomass and Chl-a content, simultaneously increasing both grazers' oxygen consumption and their feeding activity. Diatoms showed a higher sensitivity to flow stagnation, resulting in a lower content of Chl-c. Combined stressors interacted antagonistically for biofilm total biomass, Chl-b contents, and grazers's feeding rate. The effect of sewage increasing biofilm biomass and grazing activity was reduced by the presence of flow stagnation (antagonist factor). Our findings suggest that sewage contamination has a direct effect on the functional response of primary producers and an indirect effect on primary consumers, and this effect is influenced by water flow stagnation.}, } @article {pmid31291096, year = {2019}, author = {Wang, M and Shi, J and Mao, H and Sun, Z and Guo, S and Guo, J and Yan, F}, title = {Fluorescent Imidazolium-Type Poly(ionic liquid)s for Bacterial Imaging and Biofilm Inhibition.}, journal = {Biomacromolecules}, volume = {}, number = {}, pages = {}, doi = {10.1021/acs.biomac.9b00741}, pmid = {31291096}, issn = {1526-4602}, abstract = {Fluorescent imidazolium-type poly(ionic liquid)s (PIL)s were synthesized by anion exchange of bromide (Br-) in poly(3-butyl-1-vinylimidazolium bromide) (PIL-Br) with a fluorescent anion, namely, 3-(4-(1,2,2-triphenylvinyl)phenoxy)propane-1-sulfonate (TPESO3-). Such an anion exchange provided antibacterial PILs with aggregation-induced emission (AIE) properties that simultaneously kill and image bacteria. These fluorescence and antibacterial properties could be regulated by controlling the Br-/TPESO3- ratio. The fluorescence intensity increases as this ratio increases, while the antibacterial property exhibits an opposite trend. Moreover, the AIE-type PILs are useful for fluorescently imaging dead bacteria (macroscopically and microscopically) and could effectively inhibit biofilm growth. This study provided a convenient method to obtain fluorescent PILs with adjustable antibacterial and imaging properties.}, } @article {pmid31290732, year = {2019}, author = {Süß, M and De Visscher, A}, title = {Effect of diffusion limitation and substrate inhibition on steady states of a biofilm reactor treating a single pollutant.}, journal = {Journal of the Air & Waste Management Association (1995)}, volume = {}, number = {}, pages = {}, doi = {10.1080/10962247.2019.1631904}, pmid = {31290732}, issn = {2162-2906}, abstract = {The occurrence of multiple steady states in a toluene biodegrading, diffusion-limited biofilm under aerobic conditions was investigated by computer models: one steady-state, and one nonsteady-state. Two stable and one unstable intermediate steady-state were identified in a narrow set of combinations of parameters values. The nonsteady-state model predicts conditions that evolve to a steady state that is within 0.02-1% of the solution of the steady-state model, depending on the number of grid points used, confirming the algorithms are valid. Multiple steady states occur if, 1) a biofilm is exposed to a constant gas-phase pollution concentration, which exceeds or undershoots a certain threshold, 2) in a narrow range of parameter values and 3) provided that the pollutant degradation follows Haldane kinetics. Such a biofilm displays half-saturation (i.e., Michaelis-Menten)-like apparent ('falsified') kinetics from a concentration range starting at zero up to the occurrence of a second steady state. Multiple steady states and falsified kinetics can negatively affect a biofilter and the experimental determination of kinetic parameters, respectively.}, } @article {pmid31289312, year = {2019}, author = {Lim, ES and Koo, OK and Kim, MJ and Kim, JS}, title = {Bio-enzymes for inhibition and elimination of Escherichia coli O157:H7 biofilm and their synergistic effect with sodium hypochlorite.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {9920}, doi = {10.1038/s41598-019-46363-w}, pmid = {31289312}, issn = {2045-2322}, abstract = {Escherichia coli O157:H7 is one of the most important pathogens worldwide. In this study, three different kinds of enzymes, DNase I, proteinase K and cellulase were evaluated for inhibitory or degrading activity against E. coli O157:H7 biofilm by targeting extracellular DNA, proteins, and cellulose, respectively. The cell number of biofilms formed under proteinase K resulted in a 2.43 log CFU/cm2 reduction with an additional synergistic 3.72 log CFU/cm2 reduction after NaClO post-treatment, while no significant reduction occurred with NaClO treatment alone. It suggests that protein degradation could be a good way to control the biofilm effectively. In preformed biofilms, all enzymes showed a significant reduction of 16.4-36.7% in biofilm matrix in 10-fold diluted media (p < 0.05). The sequential treatment with proteinase K, cellulase, and NaClO showed a significantly higher synergistic inactivation of 2.83 log CFU/cm2 compared to 1.58 log CFU/cm2 in the sequence of cellulase, proteinase K, and NaClO (p < 0.05). It suggests that the sequence of multiple enzymes can make a significant difference in the susceptibility of biofilms to NaClO. This study indicates that the combination of extracellular polymeric substance-degrading enzymes with NaClO could be useful for the efficient control of E. coli O157:H7 biofilms.}, } @article {pmid31288972, year = {2019}, author = {Tsai, MH and Liang, YH and Chen, CL and Chiu, CH}, title = {Characterization of Salmonella resistance to bile during biofilm formation.}, journal = {Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.jmii.2019.06.003}, pmid = {31288972}, issn = {1995-9133}, abstract = {BACKGROUND: Non-typhoid Salmonella infection may present as acute gastroenteritis or chronic infection, primarily in the bile-rich gallbladder. Biofilm formation is a mechanism of bile resistance in Salmonella. Our aim was to determine how Salmonella utilizes bile as a signal, and to study the relevance of the interaction between the PhoP-PhoQ two-component system and cyclic diguanosine monophosphate (c-di-GMP) signaling to biofilm formation.

METHODS: Two-dimensional (2-D) gel electrophoresis was used to identify genes required for Salmonella biofilm formation in bile. Quantitative real-time PCR (qRT-PCR) was used to clarify the role of the PhoP-PhoQ two-component system and its interaction with genes involved in the c-di-GMP network during biofilm formation.

RESULTS: Our result revealed that Salmonella mutants with incomplete outer membrane (△ompA), defective flagella (△flgE), or incomplete PhoP-PhoQ two-component system (△phoP), were unable to develop complete biofilms in the presence of bile. Moreover, PhoP-PhoQ two-component system-related Salmonella mutants (△phoP, △phoQ, △phoP△phoQ) had lower expression of c-di-GMP related genes (csgD, adrA) than the wild-type Salmonella strain had in the bile environment.

CONCLUSION: Salmonella may sense and respond to bile through the PhoP-PhoQ two-component system during biofilm formation. Furthermore, the PhoP-PhoQ two-component system might activate regulators of the c-di-GMP signaling network.}, } @article {pmid31288325, year = {2019}, author = {Wu, F and Li, MC and Sun, CC and Liu, Y and Wu, LG}, title = {[Influence of environmental factors on the two-species biofilm formed by Streptococcus oligofermentans and Streptococcus mutans].}, journal = {Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology}, volume = {54}, number = {7}, pages = {456-462}, doi = {10.3760/cma.j.issn.1002-0098.2019.07.005}, pmid = {31288325}, issn = {1002-0098}, abstract = {Objective: To study the influence of environmental factors on the two-species biofilm formed by the combinations of Streptococcus oligofermentans (So) with Streptococcus mutans (Sm) and Streptococcus sanguinis (Ss) with Sm so as to evaluate the role of So in maintaining the microecological balance of the oral cavity. Methods: Single-and two-species biofilms were grown on saliva-coated surfaces (glass tube and 96-well plate). Colony-counting method and safranin staining method were used to measure the biofilms formed under various oxygen conditions (aerobic and anaerobic), sucrose conditions (0%, 1% and 5% sucrose concentrations) and pH conditions (5.5, 6.0, 6.5, 7.0, 7.5 and 8.0). Results: Comparing the numbers of Sm in two co-cultures under various conditions, Sm counts in So+Sm group [(7.70±2.46)×10(8) CFU/ml] were significantly lower than those in Ss+Sm group [(9.00±1.13)×10(8) CFU/ml] in aerobic environment (P<0.05). Sm counts in So+Sm group [(2.80±0.52)×10(8) CFU/ml] were also significantly lower than those in the Ss+Sm group [(4.00±1.25)×10(8) CFU/ml] in anaerobic environment (P<0.05). The Sm counts in So+Sm group [(8.90±0.82)×10(8) CFU/ml] were significantly higher than those in Ss+Sm group [(7.50±1.73)×10(8) CFU/ml] in 0% sucrose environment (P<0.05). The Sm counts in So+Sm group [(5.70±2.94)×10(8) CFU/ml] were significantly lower than those in Ss+Sm group [(10.30±3.21) ×10(8) CFU/ml] in 1% sucrose environment (P<0.05). The Sm counts in So+Sm group [(6.10±1.71)×10(8) CFU/ml] were also significantly lower than those in Ss+Sm group [(7.40±1.20)×10(8) CFU/ml] in 5% sucrose environment (P<0.05). The Sm counts in So+Sm group [(3.50±1.50)×10(8) CFU/ml] were significantly lower than those in Ss+Sm group [(10.70±2.80)×10(8) CFU/ml] in pH7.0 environment (P<0.05). Comparing the formation of biofilm after 24 h cultivation, the Sm counts in So+Sm group were significantly lower than those in Ss+Sm group both in aerobic and anaerobic environments (P<0.05). The Sm counts in So+Sm group were significantly higher than those in Ss+Sm group in 0% sucrose environment (P<0.05). The Sm counts in So+Sm group were significantly lower than those in Ss+Sm group in 1% and 5% sucrose and pH 7.0 environments (P<0.05). Both So and Ss had no inhibitory effect on Sm in pH5.5 and pH8.0 environments. Conclusions: In the in vitro two-species co-culture systems, So showed stronger inhibitory effects than Ss on Sm and its inhibitory ability might influenced by various environmental factors.}, } @article {pmid31287946, year = {2019}, author = {Xiang, Z and Li, Z and Ren, Z and Zeng, J and Peng, X and Li, Y and Li, J}, title = {EzrA, a cell shape regulator contributing to biofilm formation and competitiveness in Streptococcus mutans.}, journal = {Molecular oral microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1111/omi.12264}, pmid = {31287946}, issn = {2041-1014}, support = {//National Key Technologies R&D Program of the Twelve Five-year Plan/ ; 2012BAI07B03//Ministry of Science and Technology of China/ ; 81371135//National Natural Science Foundation of China/ ; 31870065//National Natural Science Foundation of China/ ; }, abstract = {Bacterial cell division is initiated by tubulin homologue FtsZ that assembles into a ring structure at mid-cell to facilitate cytokinesis. EzrA has been identified to be implicated in FtsZ-ring dynamics and cell wall biosynthesis during cell division of Bacillus subtilis and Staphylococcus aureus, the model rod and cocci. However, its role in pathogenic streptococci remains largely unknown. Here, the role of EzrA was investigated in Streptococcus mutans, the primary etiological agent of human dental caries, by constructing an ezrA in-frame deletion mutant. Our data showed that the ezrA mutant was slow-growing with a shortened length and extended width round cell shape compared to the wild type, indicating a delay in cell division with abnormalities of peptidoglycan biosynthesis. Additionally, FtsZ irregularly localized in dividing ezrA mutant cells forming angled division planes, potentially contributing to an aberrant cell shape. Furthermore, investigation using single-species cariogenic biofilm model revealed that deletion of ezrA resulted in defective biofilm formation with less extracellular polysaccharides and altered three-dimensional biofilm architecture. Unexpectedly, in a dual-species ecological model, the ezrA mutant exhibited substantially lower tolerance for H2 O2 and reduced competitiveness against one commensal species, Streptococcus sanguinis. Taken together, these results demonstrate that EzrA plays a key role in regulating cell division and maintaining a normal morphology in S. mutans and is required for its robust biofilm formation/interspecies competition. Therefore, EzrA protein represents a potential therapeutic target in the development of drugs controlling dental caries and other biofilm-related diseases.}, } @article {pmid31287831, year = {2019}, author = {Ryser, S and Tenorio, E and Estellés, A and Kauvar, LM}, title = {Human antibody repertoire frequently includes antibodies to a bacterial biofilm associated protein.}, journal = {PloS one}, volume = {14}, number = {7}, pages = {e0219256}, doi = {10.1371/journal.pone.0219256}, pmid = {31287831}, issn = {1932-6203}, support = {SB1 AI120425/AI/NIAID NIH HHS/United States ; }, abstract = {We have previously described a native human monoclonal antibody, TRL1068, that disrupts bacterial biofilms by extracting from the biofilm matrix key scaffolding proteins in the DNABII family, which are present in both gram positive and gram negative bacterial species. The antibiotic resistant sessile bacteria released from the biofilm then revert to the antibiotic sensitive planktonic state. Qualitative resensitization to antibiotics has been demonstrated in three rodent models of acute infections. We report here the surprising discovery that antibodies against the target family were found in all twenty healthy humans surveyed, albeit at a low level requiring a sensitive single B-cell assay for detection. We have cloned 21 such antibodies. Aside from TRL1068, only one (TRL1330) has all the biochemical properties believed necessary for pharmacological efficacy (broad spectrum epitope specificity and high affinity). We suggest that the other anti-DNABII antibodies, while not necessarily curative, reflect an immune response at some point in the donor's history to these components of biofilms. Such an immune response could reflect exposure to bacterial reservoirs that have been previously described in chronic non-healing wounds, periodontal disease, chronic obstructive pulmonary disease, colorectal cancer, rheumatoid arthritis, and atherosclerotic artery explants. The detection of anti-DNABII antibodies in all twenty surveyed donors with no active infection suggests that bacterial biofilm reservoirs may be present periodically in most healthy individuals. Biofilms routinely shed bacteria, creating a continuous low level inflammatory stimulus. Since chronic subclinical inflammation is thought to contribute to most aging-related diseases, suppression of bacterial biofilm has potential value in delaying age-related pathology.}, } @article {pmid31286367, year = {2019}, author = {Dong, QY and Wang, Z and Shi, LD and Lai, CY and Zhao, HP}, title = {Anaerobic methane oxidation coupled to chromate reduction in a methane-based membrane biofilm batch reactor.}, journal = {Environmental science and pollution research international}, volume = {}, number = {}, pages = {}, doi = {10.1007/s11356-019-05709-7}, pmid = {31286367}, issn = {1614-7499}, support = {21577123, 51878596//National Natural Science Foundation of China/ ; LR17B070001//Natural Science Funds for Distinguished Young Scholar of Zhejiang Province/ ; }, abstract = {Chromate can be reduced by methanotrophs in a membrane biofilm reactor (MBfR). In this study, we cultivated a Cr(VI)-reducing biofilm in a methane (CH4)-based membrane biofilm batch reactor (MBBR) under anaerobic conditions. The Cr(VI) reduction rate increased to 0.28 mg/L day when the chromate concentration was ≤ 2.2 mg/L but declined sharply to 0.01 mg/L day when the Cr(VI) concentration increased to 6 mg/L. Isotope tracing experiments showed that part of the 13C-labeled CH4 was transformed to 13CO2, suggesting that the biofilm may reduce Cr(VI) by anaerobic methane oxidation (AnMO). Microbial community analysis showed that a methanogen, i.e., Methanobacterium, dominated in the biofilm, suggesting that this genus is probably capable of carrying out AnMO. The abundance of Methylomonas, an aerobic methanotroph, decreased significantly, while Meiothermus, a potential chromate-reducing bacterium, was enriched in the biofilm. Overall, the results showed that the anaerobic environment inhibited the activity of aerobic methanotrophs while promoting AnMO bacterial enrichment, and high Cr(VI) loading reduced Cr(VI) flux by inhibiting the methane oxidation process.}, } @article {pmid31286118, year = {2019}, author = {Menini, M and Setti, P and Dellepiane, E and Zunino, P and Pera, P and Pesce, P}, title = {Comparison of biofilm removal using glycine air polishing versus sodium bicarbonate air polishing or hand instrumentation on full-arch fixed implant rehabilitations: a split-mouth study.}, journal = {Quintessence international (Berlin, Germany : 1985)}, volume = {}, number = {}, pages = {2-10}, doi = {10.3290/j.qi.a42704}, pmid = {31286118}, issn = {1936-7163}, abstract = {OBJECTIVES: To compare the cleaning efficacy of glycine air polishing against two different professional oral hygiene techniques on implants supporting full-arch fixed prostheses.

METHOD AND MATERIALS: Thirty patients with a total of 32 implant fixed full-arch rehabilitations in the maxilla and/or mandible (134 implants) were included. After the removal of the screw-retained prostheses, baseline peri-implant spontaneous bleeding (SB), Plaque Index (PI), probing depth (PD), and bleeding on probing (BOP) were recorded (T0). Three oral hygiene treatments were assigned randomly following a split-mouth method: all the patients received glycine air polishing (G) in one side of the arch (n = 32), and sodium bicarbonate air polishing (B) (n = 16) or manual scaling with carbon-fiber curette (C) (n = 16) was performed in the opposite side. After the hygiene procedures, PI and SB were recorded and patient's comfort degree towards the three techniques was analyzed by questionnaires using a rating scale from 1 to 5 (T1).

RESULTS: PI reduction was significantly higher for G (T0, 2.88 ± 1.37; T1, 0.04 ± 0.21) and B (T0, 3.13 ± 1.34; T1, 0.0 ± 0.0) as compared with C (T0, 2.15 ± 1.46; T1, 0.44 ± 0.7) (P < .001). B reported the highest mean value of SB (T0, 0.0 ± 0.0; T1, 3.42 ± 0.75) compared with G (T0, 0.05 ± 0.21; T1, 1.60 ± 1.05) and C (T0, 0.07 ± 0.24; T1, 0.73 ± 0.91) (P < .001). A significant difference in comfort mean score was found between G (4.8 ± 0.5) and B (3.5 ± 1.7) (P = .014), no difference between G and C (4.7 ± 0.7) (P = .38).

CONCLUSION: Professional oral hygiene on implants using glycine air polishing showed high levels of both cleaning efficacy and patients' acceptance.}, } @article {pmid31284975, year = {2019}, author = {Merino, L and Trejo, FM and De Antoni, G and Golowczyc, MA}, title = {Lactobacillus strains inhibit biofilm formation of Salmonella sp. isolates from poultry.}, journal = {Food research international (Ottawa, Ont.)}, volume = {123}, number = {}, pages = {258-265}, doi = {10.1016/j.foodres.2019.04.067}, pmid = {31284975}, issn = {1873-7145}, abstract = {Lactic acid bacteria (LAB) exert a strong antagonistic activity against many microorganisms including food spoilage organisms and may be used as an alternative to control biofilm formation of pathogens in food industries. The objective of this work was to investigate the ability of fifteen Salmonella strains isolated from poultry environment to form biofilms on different surfaces. In addition, the effect of Lactobacillus kefiri strains 8321 and 83113 and Lactobacillus plantarum 83114 and their surface proteins on biofilm development of Salmonella Enteritidis 115 was studied. The relationship between surface properties of bacteria (hydrophobicity, autoaggregation and coaggregation with lactobacilli) and biofilm formation was also investigated. Most of Salmonella strains were hydrophilic and five strains were moderately hydrophobic. In general, Salmonella strains showed high aggregation abilities (27-54%). S. Enteritidis 106 and S. Typhimurium 102 and 108 showed the highest percentages of autoaggregation. All Salmonella strains tested showed aggregation abilities with the three lactobacilli studied, but the percentage of coaggregation proved to be strain-specific. When comparing stainless steel, glass and polystyrene surfaces, higher levels of biofilm formation occurred on polystyrene plate than on glass surfaces or stainless steel. S. Enteritidis 115 exhibited the greatest attachment to polyestyrene surface. The preincubation or coincubation with the three lactobacilli strains significantly reduced (about 1 log CFU/ml of reduction) the ability of S. Enteritidis 115 to form biofilm compared to the control without lactobacilli. These results were confirmed by confocal microscopy. In the same way, when surface proteins extracted from lactobacilli strains were preincubated or coincubated with S. Enteritidis 115, biofilm formation of this strain was significantly decreased compared to the control. The results obtained showed that these Lactobacillus strains and their surface proteins can be used as alternatives for control of biofilm formation by Salmonella in the poultry industry.}, } @article {pmid31284940, year = {2019}, author = {Rajkumari, J and Borkotoky, S and Reddy, D and Mohanty, SK and Kumavath, R and Murali, A and Suchiang, K and Busi, S}, title = {Anti-quorum sensing and anti-biofilm activity of 5-hydroxymethylfurfural against Pseudomonas aeruginosa PAO1: Insights from in vitro, in vivo and in silico studies.}, journal = {Microbiological research}, volume = {226}, number = {}, pages = {19-26}, doi = {10.1016/j.micres.2019.05.001}, pmid = {31284940}, issn = {1618-0623}, abstract = {Pseudomonas aeruginosa is one of the most common pathogens associated with nosocomial infections and a great concern to immunocompromised individuals especially in the cases of cystic fibrosis, AIDS and burn wounds. The pathogenicity of P. aeruginosa is largely directed by the quorum sensing (QS) system. Hence, QS may be considered an important therapeutic target to combat P. aeruginosa infections. The anti-quorum sensing and anti-biofilm efficacy of aromatic aldehyde, 5-hydroxymethylfurfural (5-HMF) against P. aeruginosa PAO1 were assessed. At the sub-inhibitory concentration, 5-HMF suppressed the production of QS-controlled virulence phenotypes and biofilm formation in P. aeruginosa. It was also able to significantly enhance the survival rate of C. elegans infected with P. aeruginosa. The in silico studies revealed that 5-HMF could serve as a competitive inhibitor for the auto-inducer molecules as it exhibited a strong affinity for the regulatory proteins of the QS-circuits i.e. LasR and RhlR. In addition, a significant down-regulation in the expression of QS-related genes was observed suggesting the ability of 5-HMF in mitigating the pathogenicity of P. aeruginosa.}, } @article {pmid31284905, year = {2019}, author = {Li, L and Yan, G and Wang, H and Chu, Z and Li, Z and Ling, Y and Wu, T}, title = {Denitrification and microbial community in MBBR using A. donax as carbon source and biofilm carriers for reverse osmosis concentrate treatment.}, journal = {Journal of environmental sciences (China)}, volume = {84}, number = {}, pages = {133-143}, doi = {10.1016/j.jes.2019.04.030}, pmid = {31284905}, issn = {1001-0742}, abstract = {In this study, raw Arundo donax (A. donax) pieces were applied as carbon source and biofilm carriers for denitrification in a lab-scale moving bed biofilm reactor (MBBR) for the treatment of reverse osmosis concentrate gathered from local wastewater reuse plant. At stable phase (about 60 days), efficient denitrification performance was obtained with 73.2% ± 19.5% NO3--N average removal and 8.10 ± 3.45 g N/(m3·day) NO3--N average volumetric removal rate. Mass balance analysis showed that 4.84 g A. donax was required to remove 1 g TN. Quantitative real-time PCR analysis results showed that the copy numbers of 16S r-RNA, narG, nirS, nosZ and anammox gene of carrier biofilm and suspended activated sludge in the declination phase (BF2 and AS2) were lower than those of samples in the stable phase (BF1 and AS1), and relatively higher copy numbers of nirS and nirK genes with lower abundance of narG and nosZ genes were observed. High-throughput sequencing analysis was conducted for BF2 and AS2, and similar dominant phyla and classes with different abundance were obtained. The class Gammaproteobacteria affiliated with the phylum Proteobacteria was the most dominant microbial community in both BF2 (52.6%) and AS2 (41.7%). The PICRUSt prediction results indicated that 33 predictive specific genes were related to denitrification process, and the relative abundance of 18 predictive specific genes in BF2 were higher than those in AS2.}, } @article {pmid31284195, year = {2019}, author = {Lu, L and Wang, B and Zhang, Y and Xia, L and An, D and Li, H}, title = {Identification and nitrogen removal characteristics of Thauera sp. FDN-01 and application in sequencing batch biofilm reactor.}, journal = {The Science of the total environment}, volume = {690}, number = {}, pages = {61-69}, doi = {10.1016/j.scitotenv.2019.06.453}, pmid = {31284195}, issn = {1879-1026}, abstract = {A strain FDN-01 was isolated from the sequencing batch biofilm reactor (SBBR) which was seeded with wasted activated sludge from a municipal wastewater treatment plant in Shanghai. Bacterium FDN-01 was identified as Thauera sp., and Genbank Sequence_ID was KY393097. By comparing inorganic total nitrogen (TN) removal efficiency by strain FDN-01 under different conditions, the optimal initial pH, carbon source and the ratio of carbon to nitrogen were 7.5, sodium succinate and 4.0, respectively. Inorganic TN removal efficiency was 93% within 3 d while the concentration of nitrate was 100 mg/L, and the type of substrates affected extracellular polymeric substances (EPS) production and the ratio of protein to polysaccharide in the EPS. Further investigation for the application of strain FDN-01 in the SBBRs showed that anoxic ammonia oxidation occurred at room temperature, and the removal efficiencies of inorganic TN were noticeably enhanced by the augmentation of bacterium FDN-01 back into the SBBR. This study provided a promising method of TN removal requiring less carbon source in the wastewater.}, } @article {pmid31284075, year = {2019}, author = {Cabrini Carmello, J and Alves, F and Basso, FG and de Souza Costa, CA and Tedesco, AC and Lucas Primo, F and de Oliveira Mima, EG and Pavarina, AC}, title = {Antimicrobial photodynamic therapy reduces adhesion capacity and biofilm formation of Candida albicans from induced oral candidiasis in mice.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.06.010}, pmid = {31284075}, issn = {1873-1597}, abstract = {BACKGROUND: Antimicrobial photodynamic therapy (aPDT) has been considered an alternative therapeutic modality for the treatment of Candida infections. However, most studies are focused mainly on microorganism's inactivation efficiency. Here, we evaluated the efficacy of aPDT mediated by chloro-aluminum phthalocyanine encapsulated in cationic nanoemulsions (ClAlP-NE) to treat oral candidiasis in vivo and its effect on the virulence factors of Candida albicans.

METHODS: For this, mice were immunosuppressed and inoculated with C. albicans to produce oral candidiasis. aPDT and Nystatin were applied for 5 successive sessions. Next, the microbiological evaluation was determined (CFU/ml) and the analyses of virulence factors (adhesion capacity and biofilm formation) were performed. Data were analyzed by Two-way ANOVA (α = 0.05).

RESULTS: aPDT was as effective as Nystatin reducing 1.4 and 2.0 log10 of the cell viability (p ≤ 0.0001), respectively. Both treatments reduced the adhesion capacity and biofilm formation of C. albicans (p ≤ 0.0001) CONCLUSION: : ClAlP-NE-mediated aPDT was effective in reducing the virulence factors of C. albicans and also to treat induced oral candidiasis in mice.}, } @article {pmid31283996, year = {2019}, author = {Palaniraj, S and Murugesan, R and Narayan, S}, title = {Chlorogenic acid- loaded calcium phosphate chitosan nanogel as biofilm degradative materials.}, journal = {The international journal of biochemistry & cell biology}, volume = {114}, number = {}, pages = {105566}, doi = {10.1016/j.biocel.2019.105566}, pmid = {31283996}, issn = {1878-5875}, abstract = {This work describes an effort to develop an antimicrobial agent (chlorogenic acid - CGA) loaded porous nanogel based on calcium phosphate-chitosan (CaPNP@Chi) nanogel with biofilm degradative properties and has potential applications in restorative dentistry. The nanogel was prepared by ionic gelation of calcium phosphate nanoparticles and chitosan in the ratio of 1.25: 1. Chlorogenic acid was loaded to the nanoparticles as an ethanolic solution and the encapsulation efficiency determined by chromatographic techniques. The particle size and morphology of CaPNP@Chi and CaPNP@Chi@CGA was determined by dynamic light scattering and scanning electron microscopic techniques. The minimum inhibitory concentration against S. aureus and K. pneumoniae was determined through the well diffusion method. The biofilm formation and biofilm decay were studied through staining assays. The toxicity, if any of the nanogel was assessed by MTT assay against HaCaT cells. All data were statistically analyzed. The composite had a CGA encapsulation efficiency of 70% and was thermally stable up to 124 °C. The zone of inhibition was found to be 18.7 mm ± 0.6 against S. aureus. CaPNP@Chi@CGA showed a 68% increase in biofilm degradation when compared with the untreated group. Results obtained in this study suggest that the positively charged nanogel interacted with the bacterial cell membrane and brought about the disruption of the cell membrane. Also, CaPNP@Chi@CGA was observed to be nontoxic up to 40 μg/mL to HaCaT cells. These results support the potential of CaPNP@Chi@CGA nanogel for biofilm degradation and its application as filling material in restorative dentistry.}, } @article {pmid31282384, year = {2019}, author = {Meroni, G and Zamarian, V and Prussiani, C and Bronzo, V and Lecchi, C and Martino, PA and Ceciliani, F}, title = {The bovine acute phase protein α1-acid glycoprotein (AGP) can disrupt Staphylococcus aureus biofilm.}, journal = {Veterinary microbiology}, volume = {235}, number = {}, pages = {93-100}, doi = {10.1016/j.vetmic.2019.06.007}, pmid = {31282384}, issn = {1873-2542}, abstract = {Staphylococcus aureus biofilm-related infections are of clinical concern due to the capability of bacterial colonies to adapt to a hostile environment. The present study investigated the capability of the acute phase protein alpha 1-acid glycoprotein (AGP) to a) disrupt already established S. aureus biofilm and b) interfere with the biofilm de novo production by using Microtiter Plate assay (MtP) on field strains isolated from infected quarters by assessing. The present study also investigated whether AGP could interfere with the expression of bacterial genes related to biofilm formation (icaA, icaD, icaB, and icaC) and adhesive virulence determinants (fnbA, fnbB, clfA, clfB, fib, ebps, eno) by quantitative real-time PCR (qPCR). The results provided the evidence that AGP could disrupt the biofilm structure only when it was already developed, but could not prevent the de novo biofilm formation. Moreover, AGP could interfere with the expression levels of genes involved in biofilm formation in a dose- and strain-dependent way, by upregulating, or downregulating, icaABC genes and fnbB, respectively. The results presented in this study provide new insights about the direct antibacterial activity of AGP in bovine milk. It remains to be demonstrated the molecular bases of AGP mechanism of action, in particular for what concerns the scarce capability to interact with the de novo formation of biofilm.}, } @article {pmid31282211, year = {2019}, author = {Wongkaewkhiaw, S and Taweechaisupapong, S and Anutrakunchai, C and Nazmi, K and Bolscher, JGM and Wongratanacheewin, S and Kanthawong, S}, title = {D-LL-31 in combination with ceftazidime synergistically enhances bactericidal activity and biofilm destruction in Burkholderia pseudomallei.}, journal = {Biofouling}, volume = {}, number = {}, pages = {1-12}, doi = {10.1080/08927014.2019.1632835}, pmid = {31282211}, issn = {1029-2454}, abstract = {Melioidosis is a severe disease caused by Burkholderia pseudomallei. The biofilm of B. pseudomallei acquires resistance to several antibiotics and may be related to relapse in melioidosis patients. Here, the killing activity of antimicrobial peptides (LL-37, LL-31) and the D-enantiomers (D-LL-37, D-LL-31) in combination with ceftazidime (CAZ) against B. pseudomallei 1026b, H777 and a biofilm mutant M10, derived from H777 grown under biofilm-stimulating conditions was observed. Using static conditions, D-LL-31 exhibited the strongest killing activity against the three isolates in a dose-dependent manner. IC50 values for D-LL-31 ranged from 1 to 6 µM, for isolates M10, H777, and 1026b, respectively. Moreover, D-LL-31 combined with CAZ synergistically decreased the IC50 values of the peptide and antibiotic and caused also disruption of biofilms of B. pseudomallei 1026b under flow conditions. Thus a combination of D-LL-31 and CAZ may enhance the efficacy of the currently used antibiotic treatments against B. pseudomallei.}, } @article {pmid31282200, year = {2019}, author = {Maquera Huacho, PM and Rodriguez Herrero, E and Verspecht, T and Pauwels, M and Marcantonio, E and Palomari Spolidorio, DM and Teughels, W}, title = {Terpinen-4-ol and carvacrol affect multi-species biofilm composition.}, journal = {Biofouling}, volume = {}, number = {}, pages = {1-12}, doi = {10.1080/08927014.2019.1630386}, pmid = {31282200}, issn = {1029-2454}, abstract = {The aim of this study was to investigate the cytotoxic activity and inhibitory effect of terpinen-4-ol (T4ol) and carvacrol against single- and multi-species biofilms. The toxicity of each compound was tested on oral keratinocytes and evaluated by XTT assay. Inhibition and eradication of single-species biofilms were analyzed by crystal violet assay and the effect on multi-species biofilm composition was evaluated by qPCR. T4ol and carvacrol did not affect the epithelial cell viability, in contrast to chlorhexidine, which showed a high cytotoxic effect. Inhibition and eradication of single-species biofilms treated with T4ol and carvacrol were observed. The same inhibitory effect was observed for multi-species biofilms, especially on periodontal pathogens. In conclusion, specific concentrations of T4ol and carvacrol without toxicity towards the epithelial cells reduced the numbers of periodontal pathogens in single- and multi-species biofilms.}, } @article {pmid31280338, year = {2019}, author = {Wang, X and Shen, X and Wang, Z and Kong, Y}, title = {Viscoelasticity variation in a biofilm-mediated Bacillus subtilis suspension induced by adding polyethylene glycol.}, journal = {European biophysics journal : EBJ}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00249-019-01385-0}, pmid = {31280338}, issn = {1432-1017}, support = {11772047//National Natural Science Foundation of China/ ; 11620101001//Key international collaborating Project from National Natural Science Foundation of China/ ; }, abstract = {Recent experiments show that synthetic polymers can influence the degree of microbial aggregation and the rheological properties of bacterial suspensions, the study of which can help us control biofilm formation. In this article, we add polyethylene glycol (PEG) with various molecular weights and concentrations into two types Bacillus subtilis cell cultures, Luria Broth (LB) and Minimal Salts glutamate glycerol (MSgg), respectively. We first observe cell clusters in cell suspensions with various concentrations of PEG, and measure cluster size in both static and dynamic fluid environments. We find that cells gather together into big clusters and most of the cells are arranged longitudinally; and the large cell clusters are divided into smaller aggregates under fluid shear. We then use a rheometer to measure the viscoelastic properties of various cell cultures, to represent the degree of aggregation of the bacterial suspensions. We find the storage modulus, the loss modulus and the viscosity of bacterial suspensions not only depend on the cell aggregation but also depend on the directionality of cellular motion.}, } @article {pmid31280150, year = {2019}, author = {Zakaria, BS and Lin, L and Dhar, BR}, title = {Shift of biofilm and suspended bacterial communities with changes in anode potential in a microbial electrolysis cell treating primary sludge.}, journal = {The Science of the total environment}, volume = {689}, number = {}, pages = {691-699}, doi = {10.1016/j.scitotenv.2019.06.519}, pmid = {31280150}, issn = {1879-1026}, abstract = {This study, for the first time, documented microbial community shifts in response to the changes in anode potential in a microbial electrolysis cell (MEC) operated with primary sludge. At an anode potential of -0.4 V vs. Ag/AgCl, the MEC showed COD and VSS removal efficiencies of 73 ± 1% and 75 ± 2%, respectively. The volumetric current density and specific hydrogen production rate were 23 ± 1.2 A/m3, and 145 ± 4.1 L/m3-d, respectively. The anodic microbial community was consisted of various fermentative/hydrolytic bacteria (e.g., Bacteroides and Dysgonomonas) and anode-respiring bacteria (Geobacter), while different hydrolytic/fermentative bacteria were abundant in suspension. The MEC showed substantially inferior performance along with a higher accumulation of various volatile fatty acids when the anode potential was switched to more positive values (0 V and +0.4 V). Both biofilms and suspended communities were also shifted when the anode potential was changed. Notably, at +0.4 V, Geobacter genus entirely disappeared from the biofilms, while Paludibacter species (known fermentative bacteria) were selectively enriched in biofilms. Also, the relative abundance of genus Bacteroides (known hydrolytic bacteria) substantially decreased in both biofilms and suspension, which was correlated with the inferior hydrolysis of VSS. Quantitative comparison of biofilms and suspended microbial communities at different anode potentials revealed a sharp decrease in bacterial cell numbers in anode biofilms after changing anode potential from -0.4 V to +0.4 V. By contrast, bacterial cell numbers in suspension were slightly decreased. Collectively, these results provide new insights into the role of anode potential in shaping key microbial players associated with hydrolysis/fermentation and anodic respiration processes when MECs are operated with real biowastes.}, } @article {pmid31279340, year = {2019}, author = {Velsko, IM and Fellows Yates, JA and Aron, F and Hagan, RW and Frantz, LAF and Loe, L and Martinez, JBR and Chaves, E and Gosden, C and Larson, G and Warinner, C}, title = {Microbial differences between dental plaque and historic dental calculus are related to oral biofilm maturation stage.}, journal = {Microbiome}, volume = {7}, number = {1}, pages = {102}, doi = {10.1186/s40168-019-0717-3}, pmid = {31279340}, issn = {2049-2618}, support = {143/108//John Fell Fund, University of Oxford/ ; BCS-1516633//National Science Foundation (US)/ ; }, abstract = {BACKGROUND: Dental calculus, calcified oral plaque biofilm, contains microbial and host biomolecules that can be used to study historic microbiome communities and host responses. Dental calculus does not typically accumulate as much today as historically, and clinical oral microbiome research studies focus primarily on living dental plaque biofilm. However, plaque and calculus reflect different conditions of the oral biofilm, and the differences in microbial characteristics between the sample types have not yet been systematically explored. Here, we compare the microbial profiles of modern dental plaque, modern dental calculus, and historic dental calculus to establish expected differences between these substrates.

RESULTS: Metagenomic data was generated from modern and historic calculus samples, and dental plaque metagenomic data was downloaded from the Human Microbiome Project. Microbial composition and functional profile were assessed. Metaproteomic data was obtained from a subset of historic calculus samples. Comparisons between microbial, protein, and metabolomic profiles revealed distinct taxonomic and metabolic functional profiles between plaque, modern calculus, and historic calculus, but not between calculus collected from healthy teeth and periodontal disease-affected teeth. Species co-exclusion was related to biofilm environment. Proteomic profiling revealed that healthy tooth samples contain low levels of bacterial virulence proteins and a robust innate immune response. Correlations between proteomic and metabolomic profiles suggest co-preservation of bacterial lipid membranes and membrane-associated proteins.

CONCLUSIONS: Overall, we find that there are systematic microbial differences between plaque and calculus related to biofilm physiology, and recognizing these differences is important for accurate data interpretation in studies comparing dental plaque and calculus.}, } @article {pmid31279321, year = {2019}, author = {Shi, J and Han, Y and Xu, C and Han, H}, title = {Enhanced biodegradation of coal gasification wastewater with anaerobic biofilm on polyurethane (PU), powdered activated carbon (PAC), and biochar.}, journal = {Bioresource technology}, volume = {289}, number = {}, pages = {121487}, doi = {10.1016/j.biortech.2019.121487}, pmid = {31279321}, issn = {1873-2976}, abstract = {The primary objective was to explore the feasibility of anaerobic biofilm on polyurethane (PU), powdered activated carbon (PAC), and biochar in strengthening anaerobic degradation of phenolic compounds and selected nitrogen heterocyclic compounds (NHCs) in coal gasification wastewater (CGW). When total phenols (TPh) was less than 300 mg/L, PAC-based biofilm was more efficient. Whereas, when the TPh concentration was more than 450 mg/L, PU-based biofilm performed the optimal degradation efficiency. Furthermore, microbial community structure analysis showed that PAC and biochar had little effect on the microbial community structure after 120 days of operation, while the addition of PU could lead to the enrichment of Giesbergeria, Caldisericum, Thauera, Methanolinea, and Methanoregula.}, } @article {pmid31279316, year = {2019}, author = {Cui, YX and Guo, G and Ekama, GA and Deng, YF and Chui, HK and Chen, GH and Wu, D}, title = {Elucidating the biofilm properties and biokinetics of a sulfur-oxidizing moving-bed biofilm for mainstream nitrogen removal.}, journal = {Water research}, volume = {162}, number = {}, pages = {246-257}, doi = {10.1016/j.watres.2019.02.061}, pmid = {31279316}, issn = {1879-2448}, abstract = {The sulfide-oxidizing autotrophic denitrification (SOAD) process offers a feasible alternative to mainstream heterotrophic denitrification in treating domestic sewage with insufficient organics. Previously SOAD has been successfully applied in a moving-bed biofilm reactor (MBBR). However, the biofilm properties and biokinetics are still not thoroughly understood. The present study was therefore designed to investigate these features of sulfur-oxidizing biofilms (SOBfs) cultivated in a lab-scale MBBR under stable operation for over a year. The biofilms developed were 160 μm thick, had an uneven and porous surface on which elemental sulfur (S0) accumulated, and the SOB biomass was highly diverse. The bioprocess kinetics were evaluated through 12 batch experiments. The results were interpreted by adopting a two-step sulfide oxidation model (sulfide→S0 and S0→ sulfate) with all specific rates having a linear regression coefficient of R2 > 0.9. Moreover, the inhibitory kinetic analysis revealed that 1) the maximum treatment capacity (about 480 mg S/(m2·h) and 80 mg N/(m2·h)) was observed at low sulfide level (40 mg S/L), while higher sulfide level (60-150 mg S/L) showed increasing inhibition on the oxidation of both sulfide and sulfur and denitrification. 2) The denitritation activity decreased by up to 43% when free nitrous acid reached a maximum of 8.6 μg N/L, whereas the oxidation of sulfide and sulfur did not have any significant effect. Interestingly, two physiologically diverse SOB groups were found in this special biofilm. The mechanisms of the cooperation and competition for electron donors and acceptors between these two SOB clades are proposed. The results of this study greatly enhance our understanding of the design and optimization of SOAD-MBBR for mainstream nitrogen removal.}, } @article {pmid31278701, year = {2019}, author = {Liaqat, I and Liaqat, M and Tahir, HM and Haq, I and Ali, NM and Arshad, M and Arshad, N}, title = {Motility effects biofilm formation in Pseudomonas aeruginosa and Enterobacter cloacae.}, journal = {Pakistan journal of pharmaceutical sciences}, volume = {32}, number = {3}, pages = {927-932}, pmid = {31278701}, issn = {1011-601X}, abstract = {Chronic infections caused by gram negative bacteria are the mains reasons to have morbidity and death in patients, despite using high doses of antibiotics applied to cure diseases producing by them. This study was designed to identify the role of flagella in biofilm formation Ten pure strains were collected from our lab. Morphological variation and motility assays led us to study two strains in detail. They were characterized biochemically, physiologically and genetically. Biofilm formation analysis was performed using test tube assay, congo red assay and liquid-interface coverslip assay. In order to disrupt flagella of studied strains, blending was induced for 5, 10 and 15 minutes followed by centrifugation and observing motility using motility test. Biofilm quantification of wild type (parental) and blended strains was done using test tube and liquid interface coverslip assays. 16S rRNA sequencing identified strains as Pseudomonas aeroginosa and Enterobacter cloacae. Significant biofilm formation (p>0.05) by was observed after 72 and 18 hours using test tube and liquid-interface coverslip assays respectively. Flagellar disruption showed that 15 minutes blending caused significant reduction in both strains, hence demonstrated that flagellar mediated motility could be a potent strategy to stabilize aggregate and invest resources for biofilm formation in P. aeruginosa and E. cloacae.}, } @article {pmid31278369, year = {2019}, author = {Hou, J and Wang, C and Rozenbaum, RT and Gusnaniar, N and de Jong, ED and Woudstra, W and Geertsema-Doornbusch, GI and Atema-Smit, J and Sjollema, J and Ren, Y and Busscher, HJ and van der Mei, HC}, title = {Bacterial Density and Biofilm Structure Determined by Optical Coherence Tomography.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {9794}, doi = {10.1038/s41598-019-46196-7}, pmid = {31278369}, issn = {2045-2322}, abstract = {Optical-coherence-tomography (OCT) is a non-destructive tool for biofilm imaging, not requiring staining, and used to measure biofilm thickness and putative comparison of biofilm structure based on signal intensity distributions in OCT-images. Quantitative comparison of biofilm signal intensities in OCT-images, is difficult due to the auto-scaling applied in OCT-instruments to ensure optimal quality of individual images. Here, we developed a method to eliminate the influence of auto-scaling in order to allow quantitative comparison of biofilm densities in different images. Auto- and re-scaled signal intensities could be qualitatively interpreted in line with biofilm characteristics for single and multi-species biofilms of different strains and species (cocci and rod-shaped organisms), demonstrating qualitative validity of auto- and re-scaling analyses. However, specific features of pseudomonas and oral multi-species biofilms were more prominently expressed after re-scaling. Quantitative validation was obtained by relating average auto- and re-scaled signal intensities across biofilm images with volumetric-bacterial-densities in biofilms, independently obtained using enumeration of bacterial numbers per unit biofilm volume. The signal intensities in auto-scaled biofilm images did not significantly relate with volumetric-bacterial-densities, whereas re-scaled intensities in images of biofilms of widely different strains and species increased linearly with independently determined volumetric-bacterial-densities in the biofilms. Herewith, the proposed re-scaling of signal intensity distributions in OCT-images significantly enhances the possibilities of biofilm imaging using OCT.}, } @article {pmid31277901, year = {2019}, author = {Cameron, R and Claudia, E and Ping, W and Erin, S and Ruparel, NB}, title = {Effect of a Residual Biofilm on Release of Transforming Growth Factor β1 from Dentin.}, journal = {Journal of endodontics}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.joen.2019.05.004}, pmid = {31277901}, issn = {1878-3554}, abstract = {INTRODUCTION: Several studies have reported regeneration of the pulp-dentin complex when treating noninfected root canal systems. However, current protocols applied to infected root canal systems are much less predictable for the formation of dentin. Converging lines of evidence implicate residual biofilm as an important factor for these variable histologic outcomes. Here we studied the effect of a residual polymicrobial biofilm on the release of transforming growth factor beta 1 (TGF-β1) from dentin. We hypothesized that the presence of bacterial biofilm attenuates the release of bioactive molecules from dentin.

METHODS: Using bacteria commonly found in infected immature teeth, we developed a multispecies biofilm in an organotypic root canal model. Root segments were then subjected to various irrigation or intracanal medicament protocols. Subsequently, the release of TGF-β1 from dentin was measured using the enzyme-linked immunosorbent assay.

RESULTS: Our data show that sterile root segments released greater amounts of TGF-β1 when conditioned with 17% EDTA alone (P < .001) or with the combination of 1.5% sodium hypochlorite and 17% EDTA (P < .05) compared with root segments infected with the multispecies biofilm. Similar results were also observed with the intracanal medicament protocol. Sterile root segments medicated with various concentrations of triple antibiotic paste and full-strength calcium hydroxide released greater amounts of TGF-β1 when compared with their infected counterparts.

CONCLUSIONS: This is the first study to report the detrimental effects of a residual biofilm on dentin conditioning and, therefore, the release of growth factors critical for regenerative procedures.}, } @article {pmid31276938, year = {2019}, author = {Huang, Y and Thompson, T and Wang, Y and Yu, Q and Zhu, L and Xu, X and Wen, ZT and Townsend, JA}, title = {Analysis of cariogenic potential of alternative milk beverages by in vitro Streptococcus mutans biofilm model and ex vivo caries model.}, journal = {Archives of oral biology}, volume = {105}, number = {}, pages = {52-58}, doi = {10.1016/j.archoralbio.2019.05.033}, pmid = {31276938}, issn = {1879-1506}, support = {R01 DE019452/DE/NIDCR NIH HHS/United States ; R01 DE026782/DE/NIDCR NIH HHS/United States ; }, abstract = {OBJECTIVE: To evaluate the potential of various alternative milk beverages to support bacterial biofilm formation and acid production and cause unbalanced demineralization.

DESIGN: in vitro assays were used to examine the ability of the beverages to support Streptococcus mutans' biofilm formation and acid production from sugar fermentation and the capacity of the beverages to buffer pH changes. Biofilm formation was done using 96-well plate model. Acid production was measured using L-Lactate assay kit, and the buffering capacity was assessed by pH titration. For ex vivo caries model, enamel and dentine slabs and S. mutans biofilms were exposed to selected alternative milk beverages three times a day, 30 min each, and by the end of the experiments, slab's demineralization was assessed by loss of surface microhardness.

RESULTS: Of the alternative milk beverages tested in this study, Original Almond consistently supported the most S. mutans biofilms, followed by Chocolate Cashew Milk, while the least biofilms were measured with Unsweetened Flax Milk. The most acids and the lowest culture pH were measured with Toasted Coconut Almond Milk, while the least buffering capacity was measured with Unsweetened Coconut Milk. The results of ex vivo caries model showed that like Bovine Whole Milk, repeated exposure to Original Almond led to significant enamel and dentine slab demineralization, when compared to those exposed to saline as a control (P < 0.001).

CONCLUSIONS: These results further provide support that popular alternative milk beverages, especially those with supplemental sugars, are potentially cariogenic.}, } @article {pmid31275531, year = {2019}, author = {Schoilew, K and Ueffing, H and Dalpke, A and Wolff, B and Frese, C and Wolff, D and Boutin, S}, title = {Bacterial biofilm composition in healthy subjects with and without caries experience.}, journal = {Journal of oral microbiology}, volume = {11}, number = {1}, pages = {1633194}, doi = {10.1080/20002297.2019.1633194}, pmid = {31275531}, issn = {2000-2297}, abstract = {Objective:The composition of the oral microbiome differs distinctively between subjects with and without active caries. Still, caries research has mainly been focused on states of disease; aspects about how biofilm composition and structure maintain oral health still remain widely unclear. Therefore, the aim of the study was to compare the healthy oral microbiome of caries-free adult subjects with and without former caries experience using next generation sequencing methods. Methods: 46 samples were collected from subjects without any signs of untreated active caries. Samples of pooled supragingival plaque from 19 subjects without caries experience (NH; DMFT = 0) and 27 subjects with 'caries experience' (CE; DMFT > 0 [F(T)> 0; D(T)= 0]) were analyzed by 16S ribosomal RNA amplicon sequencing. Results: Subjects with caries experience did not exhibit a dramatically modified supragingival plaque microbiome. However, we observed a slight and significant modification between the two groups, validated by PERMANOVA (NH vs. CE: R2 0.04; p= 0.039). The composition of the microbiome of subjects with caries experience indicates a tendency to lower α-diversity and richness. Subjects without caries experience showed a significant higher evenness compared to patients with previous caries. LDA effect size (LEfSe) analysis demonstrated that the genus Haemophilus is significantly more frequent in patients with caries experience. For the group without caries experience LefSe analysis showed a set of 11 genera being significantly more frequent, including Corynebacterium, Fusobacterium, Capnocytophaga, Porphyromonas, Prevotella,and Leptotrichia.Conclusion: The analysis of the oral microbiome of subjects with and without caries experience indicates specific differences. With the presence of Corynebacterium and Fusobacterium subjects without caries experience exhibited more frequently organisms that are considered to be main actors in structural plaque formation and integration. The abundance of Corynebacterium might be interpreted as a signature for dental health.}, } @article {pmid31275529, year = {2019}, author = {Shany-Kdoshim, S and Polak, D and Houri-Haddad, Y and Feuerstein, O}, title = {Killing mechanism of bacteria within multi-species biofilm by blue light.}, journal = {Journal of oral microbiology}, volume = {11}, number = {1}, pages = {1628577}, doi = {10.1080/20002297.2019.1628577}, pmid = {31275529}, issn = {2000-2297}, abstract = {Objectives: The aim of the study was to characterize the immediate and delayed effects of non-coherent blue-light treatment on the composition and viability of an in vitro biofilm composed of anaerobic multispecies, as well as the mechanisms involved. Methods: A multispecies biofilm was constructed of Streptococcus sanguinis, Actinomyces naeslundii, Porphyromonas gingivalis and Fusobacterium nucleatum, test groups were exposed to blue light. The multispecies biofilm was explored with a newly developed method based on flow cytometry and confocal microscopy. The involvement of the paracrine pathway in the phototoxic mechanism was investigated by a crossover of the supernatants between mono-species P. gingivalis and F. nucleatum biofilms. Results: Blue light led to a reduction of about 50% in the viable pathogenic bacteria P. gingivalis and F. nucleatum, vs that in the non-exposed biofilm. Biofilm thickness was also reduced by 50%. The phototoxic effect of blue light on mono-species biofilm was observed in P. gingivalis, whereas F. nucleatum biofilm was unaffected. A lethal effect was obtained when the supernatant of P. gingivalis biofilm previously exposed to blue light was added to the F. nucleatum biofilm. The effect was circumvented by the addition of reactive oxygen species (ROS) scavengers to the supernatant. Conclusion: Blue-light has an impact on the bacterial composition and viability of the multispecies biofilm. The phototoxic effect of blue light on P. gingivalis in biofilm was induced directly and on F. nucleatum via ROS mediators of the paracrine pathway. This phenomenon may lead to a novel approach for 'replacement therapy,' resulting in a less periodonto-pathogenic biofilm.}, } @article {pmid31275267, year = {2019}, author = {Zhu, YL and Hou, HM and Zhang, GL and Wang, YF and Hao, HS}, title = {AHLs Regulate Biofilm Formation and Swimming Motility of Hafnia alvei H4.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1330}, doi = {10.3389/fmicb.2019.01330}, pmid = {31275267}, issn = {1664-302X}, abstract = {The aim of this study was to evaluate the role of N-acyl homoserine lactones (AHLs) in the regulation of swimming motility of Hafnia alvei H4 and its biofilm formation on 96-well plate, glass and stainless-steel surfaces. The luxI gene, which codes for an enzyme involved in AHL synthesis, was deleted to generate a luxI mutant (ΔluxI). The mutant produced no AHL, and the relative expression of the luxR gene was significantly (P < 0.05) decreased. In addition, qRT-PCR analysis showed that the relative expression of the luxR gene in ΔluxI was stimulated by the presence of exogenous AHLs (C4-HSL, C6-HSL, and 3-o-C8-HSL) added at concentrations ranging from of 50-250 μg/ml. Among the three AHLs, C6-HSL had the strongest effect. The ability of ΔluxI to form biofilm on 96-well plate, glass and stainless-steel surfaces was significantly reduced (P < 0.05) compared with the wild type (WT), but was increased when provided with 150 μg/ml C4-HSL, whereas C6-HSL and 3-o-C8-HSL had no effect. Scanning electron microscopy analysis of the biofilm revealed less bacteria adhering to the surface of stainless-steel and fewer filaments were found binding to the cells compared with the WT. Furthermore, ΔluxI also exhibited significant (P < 0.05) decrease in the expression of biofilm- and swimming motility-related genes, flgA, motA and cheA, consistent with the results observed for biofilm formation and swimming motility. Taken together, the results suggested that in H. alvei H4, C4-HSL may act as an important molecular signal through regulating the ability of the cells to form biofilm, as well as through regulating the swimming motility of the cell, and this could provide a new way to control these phenotypes of H. alvei in food processing.}, } @article {pmid31273528, year = {2019}, author = {Hasegawa, T and Takenaka, S and Ohsumi, T and Ida, T and Ohshima, H and Terao, Y and Naksagoon, T and Maeda, T and Noiri, Y}, title = {Effect of a novel glass ionomer cement containing fluoro-zinc-silicate fillers on biofilm formation and dentin ion incorporation.}, journal = {Clinical oral investigations}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00784-019-02991-0}, pmid = {31273528}, issn = {1436-3771}, support = {15H05021//Japan Society for the Promotion of Science/ ; None//GC Corporation/ ; }, abstract = {OBJECTIVES: This study is aimed at evaluating the effect of a new glass ionomer cement (GIC) containing fluoro-zinc-silicate fillers on biofilm formation and ion incorporation.

MATERIALS AND METHODS: Streptococcus mutans biofilms were developed on two GIC materials: Caredyne Restore (CD) and Fuji VII (FJ); and hydroxyapatite (HA) for 24 h at 37 °C using a flow cell system. The morphological structure and bacterial viability were analyzed using a confocal laser scanning microscopy. Bacterial adhesion during the initial 2 h was also assessed by viable cell counting. To study the ion incorporation, restored cavities prepared on the root surfaces of human incisors were subjected to the elemental mapping of the zinc and fluoride ions in the GIC-dentin interface using a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer.

RESULTS: Morphological observations revealed that biofilm formation in the CD group was remarkably inhibited compared with the HA and FJ groups, exhibiting sparse, thinner biofilm clusters. The microorganisms adhering to the CD group were significantly inhibited, revealing 2.9 ± 0.4 for CD, 4.9 ± 0.2 for FJ, and 5.4 ± 0.4 log colony-forming units (CFU) for HA. The CD zinc ion incorporation depth was 72.2 ± 8.0 μm. The fluoride penetration of CD was three times deeper than that of FJ; this difference was statistically significant (p < 0.05).

CONCLUSIONS: Enhanced by the incorporation of zinc and fluoride ions, the new GIC inhibited biofilm formation by interfering with bacterial adhesion.

CLINICAL RELEVANCE: A novel GIC comprised of fluoro-zinc-silicate fillers may improve clinical outcomes, such as root caries and minimally invasive dentistry.}, } @article {pmid31272369, year = {2019}, author = {Cai, W and De La Fuente, L and Arias, CR}, title = {Transcriptome analysis of the fish pathogen Flavobacterium columnare in biofilm suggests calcium role in pathogenesis.}, journal = {BMC microbiology}, volume = {19}, number = {1}, pages = {151}, doi = {10.1186/s12866-019-1533-4}, pmid = {31272369}, issn = {1471-2180}, support = {Internal Grant//Auburn University/ ; N/A//USDA-HATCH/ ; }, abstract = {BACKGROUND: Flavobacterium columnare is the causative agent of columnaris disease that affects cultured freshwater fishes worldwide. F. columnare easily colonizes surfaces by forming biofilm, which helps the pathogen resist antibiotic and disinfectant treatments. Previously, we had shown that increasing concentrations of calcium (Ca2+) promoted biofilm formation by F. columnare. The objective of this study was to further characterize the role of Ca2+ on biofilm formation and to compare the transcriptome profiles of planktonic and biofilm cells.

RESULTS: RNA-Seq analysis was conducted to identify genes that were differentially expressed between the following states: i) planktonic cells in control medium (P), ii) planktonic cells in calcium-enriched medium (P/Ca), and iii) biofilm cells in calcium-enriched medium (B/Ca). Overall, we identified 441 significant (FDR-adjusted p < 0.05, fold change > 2) differentially expressed genes (DEGs) between P and B/Ca samples; 112 significant DEGs between P/Ca and B/Ca samples, and 175 significant DEGs between P/Ca and P samples, corresponding to 15.87, 4.03 and 6.30% of the total protein-coding sequences, respectively. The significant DEGs fell into different functional categories including iron acquisition, oxidative stress response, extracellular protein secretion, and respiratory metabolism.

CONCLUSIONS: Our results posit Ca2+ as a critical signal in regulating bacterial surface adhesion and biofilm formation in F. columnare. Living in biofilm elicited a shift in several metabolic pathways that allowed the cells to cope with oxidative stress and nutrient starvation. In addition, Ca2+ supplementation induced the expression of putative virulence factors in F. columnare, such as extracellular protein secretion and iron acquisition.}, } @article {pmid31271350, year = {2019}, author = {Romera, D and Aguilera-Correa, JJ and Gadea, I and Viñuela-Sandoval, L and García-Rodríguez, J and Esteban, J}, title = {Candida auris: a comparison between planktonic and biofilm susceptibility to antifungal drugs.}, journal = {Journal of medical microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1099/jmm.0.001036}, pmid = {31271350}, issn = {1473-5644}, abstract = {INTRODUCTION: Candida auris is a pathogenic yeast that mainly affects immunosuppressed patients and those with implanted medical devices. This pathogen also displays elevated resistance to common antifungals and high survival and spreading capacities. Since no antifungal breakpoints have yet been defined for this pathogen, the data obtained here can be useful for further research concerning treatment or implementation of a prevention and disinfection protocol. Our aim was to study the antifungal resistance of C. auris to current antifungals in planktonic and sessile states. Using confocal laser scanning microscopy and viable biomass production, we demonstrated the ability of C. auris to develop a mature biofilm. We compared the minimal inhibitory concentration (MIC) and the minimal biofilm eradication concentration (MBEC) for the C. auris DSM 21092 strain plus two clinical isolates, and the results were compared with those obtained for Candida albicans and Candida parapsilosis, two species strongly linked to bloodstream infections and infections associated with biomaterials. We found that the clinical isolates of C. auris were resistant to fluconazole and sensitive to echinocandins and polyenes. The C. auris biofilms did not show susceptibility to any antifungal agent, showing MBECs that were up to 512-fold higher than the MICs. These findings highlight the importance of biofilm formation as a key factor underlying the resistance of this species to antifungals and suggest that the presence of implantable medical devices is one of the major risk factors in immunocompromised patients.}, } @article {pmid31271299, year = {2019}, author = {Pereira-Ribeiro, PM and Sued-Karam, BR and Faria, YV and Nogueira, BA and Colodette, SS and Fracalanzza, SE and Duarte, JL and Júnior, RH and Mattos-Guaraldi, AL}, title = {Influence of antibiotics on biofilm formation by different clones of nosocomial Staphylococcus haemolyticus.}, journal = {Future microbiology}, volume = {14}, number = {}, pages = {789-799}, doi = {10.2217/fmb-2018-0230}, pmid = {31271299}, issn = {1746-0921}, abstract = {Staphylococcus haemolyticus is the most common organism among clinical isolatesof methicillin-resistant staphylococci. Aim: This study evaluated the ability to produce biofilm with the presence of the antibiotics (1/4 minimum inhibitory concentrations) of S. haemolyticus strains isolated from blood culture. Methods: Clonal distribution was assessed in pulsed-field gel electrophoresis. PCR assays were performed to detect mecA, icaA, aap, atlE, atl, fbp genes. S. haemolyticus strains grown in the presence of the antibiotics were investigated for biofilm formation on glass, polystyrene and catheter surfaces. Results: Biofilm formation was independent of the presence of the icaA and mecA genes, pulsed-field gel electrophoresis type. Vancomycin, oxacillin, moxifloxacin, rifampicin, teicoplanin, tigecycline and linezolid did not inhibit biofilm formation on abiotic surfaces. Conclusion: This study demonstrated that the biofilm formation process is complex and may not be related to ica gene carriage. Furthermore, in this study the biofilm formation was increased in the presence of antimicrobial agents.}, } @article {pmid31269803, year = {2019}, author = {Yang, X and Zhang, Z and Huang, Z and Zhang, X and Li, D and Sun, L and You, J and Pan, X and Yang, H}, title = {A putative LysR-type transcriptional regulator inhibits biofilm synthesis in Pseudomonas aeruginosa.}, journal = {Biofouling}, volume = {}, number = {}, pages = {1-10}, doi = {10.1080/08927014.2019.1627337}, pmid = {31269803}, issn = {1029-2454}, abstract = {Biofilm formation is an important virulence factor which is controlled by complex regulatory circuits in Pseudomonas aeruginosa. In this work, a biofilm hyper-producing strain, P2-7, was selected from a collection of transposon insertion mutants in which the PA2121 gene was disrupted. PA2121 was predicted as a putative LysR-type regulator. Analyses showed that it was involved in early biofilm formation, mature biofilm development, and colony morphology. Quantitative measurements revealed that PA2121 repressed biosynthesis of extracellular polysaccharides (alginate, psl and pel). Furthermore, it was observed that PA2121 was self-regulated, highly expressed in the early phase of biofilm development, and subject to the negative regulation by a biofilm synthesis regulator SrpA that binds directly to the PA2121 gene promoter. Collectively, this study proposes that PA2121 is a novel biofilm synthesis repressor (BsrA) in P. aeruginosa.}, } @article {pmid31268675, year = {2019}, author = {Blanco-Cabra, N and Vega-Granados, K and Moya-Andérico, L and Vukomanovic, M and Parra, A and Álvarez de Cienfuegos, L and Torrents, E}, title = {Novel Oleanolic and Maslinic Acid Derivatives as a Promising Treatment against Bacterial Biofilm in Nosocomial Infections: An in Vitro and in Vivo Study.}, journal = {ACS infectious diseases}, volume = {}, number = {}, pages = {}, doi = {10.1021/acsinfecdis.9b00125}, pmid = {31268675}, issn = {2373-8227}, abstract = {Oleanolic acid (OA) and maslinic acid (MA) are pentacyclic triterpenic compounds that abound in industrial olive oil waste. These compounds have renowned antimicrobial properties and lack cytotoxicity in eukaryotic cells as well as resistance mechanisms in bacteria. Despite these advantages, their antimicrobial activity has only been tested in vitro, and derivatives improving this activity have not been reported. In this work, a set of 14 OA and MA C-28 amide derivatives have been synthesized. Two of these derivatives, MA-HDA and OA-HDA, increase the in vitro antimicrobial activity of the parent compounds while reducing their toxicity in most of the Gram-positive bacteria tested, including a methicillin-resistant Staphylococcus aureus-MRSA. MA-HDA also shows an enhanced in vivo efficacy in a Galleria mellonella invertebrate animal model of infection. A preliminary attempt to elucidate their mechanism of action revealed that these compounds are able to penetrate and damage the bacterial cell membrane. More significantly, their capacity to reduce antibiofilm formation in catheters has also been demonstrated in two sets of conditions: a static and a more challenged continuous-flow S. aureus biofilm.}, } @article {pmid31268665, year = {2019}, author = {Banerjee, P and Chanchal, and Jain, D}, title = {Sensor I Regulated ATPase Activity of FleQ Is Essential for Motility to Biofilm Transition in Pseudomonas aeruginosa.}, journal = {ACS chemical biology}, volume = {14}, number = {7}, pages = {1515-1527}, doi = {10.1021/acschembio.9b00255}, pmid = {31268665}, issn = {1554-8937}, abstract = {Members of the AAA+ (ATPase associated with various cellular activities) family of ATPases couple chemical energy derived from ATP hydrolysis for generation of mechanical force, resulting in conformational changes. The hydrolysis is brought about by highly conserved domains and motifs. The sensor I motif is critical for sensing and hydrolysis of the nucleotide. Pseudomonas aeruginosa FleQ is an ATPase that is a positive regulator of flagellar gene expression. We have determined the crystal structures of the ATPase domain of wild-type FleQ and sensor I mutants H287N and H287A in complex with ATPγS and Mg2+ to 2.4, 1.95, and 2.25 Å resolution, respectively. The structural data highlight the role of sensor I in regulating the ATPase activity. The in vitro and in vivo data demonstrate that the moderate ATPase activity of FleQ due to the presence of histidine in sensor I is essential for maintaining the monotrichous phenotype and for the rapid motility to biofilm transition.}, } @article {pmid31262835, year = {2019}, author = {Vogeleer, P and Vincent, AT and Chekabab, SM and Charette, SJ and Novikov, A and Caroff, M and Beaudry, F and Jacques, M and Harel, J}, title = {Regulation of waaH by PhoB during Pi starvation promotes biofilm formation by Escherichia coli O157:H7.}, journal = {Journal of bacteriology}, volume = {}, number = {}, pages = {}, doi = {10.1128/JB.00093-19}, pmid = {31262835}, issn = {1098-5530}, abstract = {In open environments such as water, enterohemorrhagic Escherichia coli O157:H7 responds to inorganic phosphate (Pi) starvation by inducing the Pho regulon controlled by PhoB. This activates the phosphate-specific transport (Pst) system that contains a high-affinity Pi transporter. In the Δpst mutant, PhoB is constitutively activated and regulates the expression of genes in the Pho regulon. Here we show that Pi starvation and deletion of the pst system enhances E. coli O157:H7 biofilm formation. Among differentially expressed genes of EDL933 grown in Pi starvation conditions and in the Δpst mutant, we have found that a member of the PhoB regulon, waaH, predicted to encode a glycosyltransferase, was highly expressed. Interestingly, WaaH contributed to biofilm formation of E. coli O157:H7 during both Pi starvation and in the Δpst mutant. In the Δpst mutant, the presence of waaH was associated with lipopolysaccharide (LPS) R3 core type modifications whereas in E. coli O157:H7, waaH overexpression had no effect on LPS structure during Pi starvation. Therefore, waaH participates to E. coli O157:H7 biofilm formation during Pi starvation but its biochemical role remains to be clarified. This study highlights the importance of the Pi-starvation stress response to biofilm formation, which may contribute to the persistence of E. coli O157:H7 in the environment.IMPORTANCE Enterohemorrhagic Escherichia coli O157:H7 is a human pathogen that causes bloody diarrhea that can result in renal failure. Outside of mammalian hosts E. coli O157:H7 survives for extended periods of time in nutrient-poor environments, likely as part of biofilms. In E. coli K-12, the levels of free extracellular inorganic phosphate (Pi) affect biofilm formation; however, it was unknown whether Pi influences biofilm formation by E. coli O157:H7. Our results show that upon Pi starvation, PhoB activates waaH expression, which favors biofilm formation by E. coli O157:H7. These findings suggest that WaaH might be a potential target to controlling biofilm formation. Altogether, our work demonstrates how adaptation to Pi starvation allows E. coli O157:H7 to occupy different ecological niches.}, } @article {pmid31261752, year = {2019}, author = {Riau, AK and Aung, TT and Setiawan, M and Yang, L and Yam, GHF and Beuerman, RW and Venkatraman, SS and Mehta, JS}, title = {Surface Immobilization of Nano-Silver on Polymeric Medical Devices to Prevent Bacterial Biofilm Formation.}, journal = {Pathogens (Basel, Switzerland)}, volume = {8}, number = {3}, pages = {}, doi = {10.3390/pathogens8030093}, pmid = {31261752}, issn = {2076-0817}, support = {KPFA/2018/0028//Duke-NUS Khoo Postdoctoral Fellowship Award grant/ ; (SHF/FG661P/2017)//SingHealth Foundation grant/ ; }, abstract = {: Bacterial biofilm on medical devices is difficult to eradicate. Many have capitalized the anti-infective capability of silver ions (Ag+) by incorporating nano-silver (nAg) in a biodegradable coating, which is then laid on polymeric medical devices. However, such coating can be subjected to premature dissolution, particularly in harsh diseased tissue microenvironment, leading to rapid nAg clearance. It stands to reason that impregnating nAg directly onto the device, at the surface, is a more ideal solution. We tested this concept for a corneal prosthesis by immobilizing nAg and nano-hydroxyapatite (nHAp) on poly(methyl methacrylate), and tested its biocompatibility with human stromal cells and antimicrobial performance against biofilm-forming pathogens, Pseudomonas aeruginosa and Staphylococcus aureus. Three different dual-functionalized substrates-high Ag (referred to as 75:25 HAp:Ag); intermediate Ag (95:5 HAp:Ag); and low Ag (99:1 HAp:Ag) were studied. The 75:25 HAp:Ag was effective in inhibiting biofilm formation, but was cytotoxic. The 95:5 HAp:Ag showed the best selectivity among the three substrates; it prevented biofilm formation of both pathogens and had excellent biocompatibility. The coating was also effective in eliminating non-adherent bacteria in the culture media. However, a 28-day incubation in artificial tear fluid revealed a ~40% reduction in Ag+ release, compared to freshly-coated substrates. The reduction affected the inhibition of S. aureus growth, but not the P. aeruginosa. Our findings suggest that Ag+ released from surface-immobilized nAg diminishes over time and becomes less effective in suppressing biofilm formation of Gram-positive bacteria, such as S. aureus. This advocates the coating, more as a protection against perioperative and early postoperative infections, and less as a long-term preventive solution.}, } @article {pmid31261727, year = {2019}, author = {Chew, SY and Ho, KL and Cheah, YK and Sandai, D and Brown, AJP and Than, LTL}, title = {Physiologically Relevant Alternative Carbon Sources Modulate Biofilm Formation, Cell Wall Architecture, and the Stress and Antifungal Resistance of Candida glabrata.}, journal = {International journal of molecular sciences}, volume = {20}, number = {13}, pages = {}, doi = {10.3390/ijms20133172}, pmid = {31261727}, issn = {1422-0067}, support = {01-01-14-1456FR//Ministry of Education, Malaysia/ ; }, abstract = {Flexibility in carbon metabolism is pivotal for the survival and propagation of many human fungal pathogens within host niches. Indeed, flexible carbon assimilation enhances pathogenicity and affects the immunogenicity of Candida albicans. Over the last decade, Candida glabrata has emerged as one of the most common and problematic causes of invasive candidiasis. Despite this, the links between carbon metabolism, fitness, and pathogenicity in C. glabrata are largely unexplored. Therefore, this study has investigated the impact of alternative carbon metabolism on the fitness and pathogenic attributes of C. glabrata. We confirm our previous observation that growth on carbon sources other than glucose, namely acetate, lactate, ethanol, or oleate, attenuates both the planktonic and biofilm growth of C. glabrata, but that biofilms are not significantly affected by growth on glycerol. We extend this by showing that C. glabrata cells grown on these alternative carbon sources undergo cell wall remodeling, which reduces the thickness of their β-glucan and chitin inner layer while increasing their outer mannan layer. Furthermore, alternative carbon sources modulated the oxidative stress resistance of C. glabrata as well as the resistance of C. glabrata to an antifungal drug. In short, key fitness and pathogenic attributes of C. glabrata are shown to be dependent on carbon source. This reaffirms the perspective that the nature of the carbon sources available within specific host niches is crucial for C. glabrata pathogenicity during infection.}, } @article {pmid31260476, year = {2019}, author = {Marini, E and Di Giulio, M and Ginestra, G and Magi, G and Di Lodovico, S and Marino, A and Facinelli, B and Cellini, L and Nostro, A}, title = {Efficacy of carvacrol against resistant rapidly growing mycobacteria in the planktonic and biofilm growth mode.}, journal = {PloS one}, volume = {14}, number = {7}, pages = {e0219038}, doi = {10.1371/journal.pone.0219038}, pmid = {31260476}, issn = {1932-6203}, abstract = {Rapidly growing mycobacteria (RGM) are environmental bacteria found worldwide with a propensity to produce skin and soft-tissue infections. Among them, the most clinically relevant species is Mycobacterium abscessus. Multiple resistance to antibiotics and the ability to form biofilm contributes considerably to the treatment failure. The search of novel anti-mycobacterial agents for the control of biofilm growth mode is crucial. The aim of the present study was to evaluate the activity of carvacrol (CAR) against planktonic and biofilm cells of resistant RGM strains. The susceptibility of RGM strains (n = 11) to antibiotics and CAR was assessed by MIC/MBC evaluation. The CAR activity was estimated by also vapour contact assay. The effect on biofilm formation and preformed biofilm was measured by evaluation of bacterial growth, biofilm biomass and biofilm metabolic activity. MIC values were equal to 64 μg/mL for most of RGM isolates (32-512 μg/mL), MBCs were 2-4 times higher than MICs, and MICs of vapours were lower (16 μg/mL for most RGM isolates) than MICs in liquid phase. Regarding the biofilm, CAR at concentrations of 1/2 × MIC and 1/4 × MIC showed a strong inhibition of biofilm formation (61-77%) and at concentration above the MIC (2-8 × MIC) produced significant inhibition of 4- and 8-day preformed biofilms. In conclusion, CAR could have a potential use, also in vapour phase, for the control of RGM.}, } @article {pmid31260250, year = {2019}, author = {Simcox, LJ and Pereira, RPA and Wellington, EMH and Macpherson, JV}, title = {Boron Doped Diamond as a Low Biofouling Material in Aquatic Environments: Assessment of Pseudomonas aeruginosa Biofilm Formation.}, journal = {ACS applied materials & interfaces}, volume = {11}, number = {28}, pages = {25024-25033}, doi = {10.1021/acsami.9b07245}, pmid = {31260250}, issn = {1944-8252}, abstract = {Boron doped diamond (BDD), given the robustness of the material, is becoming an electrode of choice for applications which require long-term electrochemical monitoring of analytes in aqueous environments. However, despite the extensive work in this area, there are no studies which directly assess the biofilm formation (biofouling) capabilities of the material, which is an essential consideration because biofouling often causes deterioration in the sensor performance. Pseudomonas aeruginosa is one of the most prevalent bacterial pathogens linked to water-related diseases, with a strong capacity for forming biofilms on surfaces that are exposed to aquatic environments. In this study, we comparatively evaluate the biofouling capabilities of oxygen-terminated (O-)BDD against materials commonly employed as either the packaging or sensing element in water quality sensors, with an aim to identify factors which control biofilm formation on BDD. We assess the monospecies biofilm formation of P. aeruginosa in two different growth media, Luria-Bertani, a high nutrient source and drinking water, a low nutrient source, at two different temperatures (20 and 37 °C). Multispecies biofilm formation is also investigated. The performance of O-BDD, when tested against all other materials, promotes the lowest extent of P. aeruginosa monospecies biofilm formation, even with corrections made for total surface area (roughness). Importantly, O-BDD shows the lowest water contact angle of all materials tested, that is, greatest hydrophilicity, strongly suggesting that for these bacterial species, the factors controlling the hydrophilicity of the surface are important in reducing bacterial adhesion. This was further proven by keeping the surface topography fixed and changing surface termination to hydrogen (H-), to produce a strongly hydrophobic surface. A noticeable increase in biofilm formation was found. Doping with boron also results in changes in hydrophobicity/hydrophilicity compared to the undoped counterpart, which in turn affects the bacterial growth. For practical electrochemical sensing applications in aquatic environments, this study highlights the extremely beneficial effects of employing smooth, O-terminated (hydrophilic) BDD electrodes.}, } @article {pmid31259174, year = {2019}, author = {Santos, T and Viala, D and Chambon, C and Esbelin, J and Hébraud, M}, title = {Listeria monocytogenes Biofilm Adaptation to Different Temperatures Seen Through Shotgun Proteomics.}, journal = {Frontiers in nutrition}, volume = {6}, number = {}, pages = {89}, doi = {10.3389/fnut.2019.00089}, pmid = {31259174}, issn = {2296-861X}, abstract = {Listeria monocytogenes is a foodborne pathogen that can cause invasive severe human illness (listeriosis) in susceptible patients. Most human listeriosis cases appear to be caused by consumption of refrigerated ready-to-eat foods. Although initial contamination levels in foods are usually low, the ability of these bacteria to survive and multiply at low temperatures allows it to reach levels high enough to cause disease. This study explores the set of proteins that might have an association with L. monocytogenes adaptation to different temperatures. Cultures were grown in biofilm, the most widespread mode of growth in natural and industrial realms. Protein extractions were performed from three different growth temperatures (10, 25, and 37°C) and two growth phases (early stage and mature biofilm). L. monocytogenes subproteomes were targeted using three extraction methods: trypsin-enzymatic shaving, biotin-labeling and cell fractionation. The different subproteomes obtained were separated and analyzed by shotgun proteomics using high-performance liquid chromatography combined with tandem mass spectrometry (LC-OrbiTrap LTQVelos, ThermoFisher Scientific). A total of 141 (biotinylation), 98 (shaving) and 910 (fractionation) proteins were identified. Throughout the 920 unique proteins identified, many are connected to basic cell functions, but some are linked with thermoregulation. We observed some noteworthy protein abundance shifts associated with the major adaptation to cold mechanisms present in L. monocytogenes, namely: the role of ribosomes and the stressosome with a higher abundance of the general stress protein Ctc (Rl25) and the general stress transcription factor sigma B (σB), changes in cell fluidity and motility seen by higher levels of foldase protein PrsA2 and flagellin (FlaA), the uptake of osmolytes with a higher abundance of glycine betaine (GbuB) and carnitine transporters (OpucA), and the relevance of the overexpression of chaperone proteins such as cold shock proteins (CspLA and Dps). As for 37°C, we observed a significantly higher percentage of proteins associated with transcriptional or translational activity present in higher abundance upon comparison with the colder settings. These contrasts of protein expression throughout several conditions will enrich databases and help to model the regulatory circuitry that drives adaptation of L. monocytogenes to environments.}, } @article {pmid31254829, year = {2019}, author = {Barreiro, P and González, P and Pozo-Antonio, JS}, title = {IR irradiation to remove a sub-aerial biofilm from granitic stones using two different laser systems: An Nd: YAG (1064 nm) and an Er:YAG (2940 nm).}, journal = {The Science of the total environment}, volume = {688}, number = {}, pages = {632-641}, doi = {10.1016/j.scitotenv.2019.06.306}, pmid = {31254829}, issn = {1879-1026}, abstract = {A sub-aerial biofilm (SAB) developed on a granite commonly found in the built cultural heritage of the NW Iberian Peninsula was extracted with 2 different IR irradiations using an Nd:YAG laser at 1064 nm and an Er:YAG laser at 2940 nm. The methodology was based on the application of only one scan in order to evaluate the effect of the laser cleaning operated by applying different consecutive laser scanning and the suitability of these lasers as quick tools. The aim of this comparative study was twofold. The first goal was to find the most satisfactory level of extraction by comparing the results obtained by the different laser sources (IR wavelengths). The other aim was to investigate the by-effects induced by both lasers on each granite-forming mineral. Evaluations were made using stereomicroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and scanning electron microscopy with energy-dispersive x-ray spectroscopy. The results were interpreted in terms of SAB extraction and damage induced on the granite. The results showed that the Nd:YAG laser achieved the most successful level of cleaning, because it extracted the most SAB, while causing the least amount of damage to the surfaces. Regardless of the fluence applied, the Er:YAG laser did not completely extract the SAB in only one scan; in addition, a more intense melting of biotite grains was found, producing amorphous fusion crusts and losing the distinction of the cleavage planes.}, } @article {pmid31254346, year = {2019}, author = {Gonçalves, B and Azevedo, NM and Henriques, M and Silva, S}, title = {Hormones modulate Candida vaginal isolates biofilm formation and decrease their susceptibility to azoles and hydrogen peroxide.}, journal = {Medical mycology}, volume = {}, number = {}, pages = {}, doi = {10.1093/mmy/myz070}, pmid = {31254346}, issn = {1460-2709}, abstract = {Vulvovaginal candidiasis (VVC) is an infection usually caused by Candida albicans and increasingly by Candida glabrata, which has an intrinsically high resistance to commonly used antifungals. Candida species possess virulence factors that contribute to VVC development, as the ability to form biofilms in vaginal walls and intrauterine devices. It is known that VVC is promoted by conditions that increase the hormones levels, during pregnancy, however, the effects of hormones on Candida cells are poorly studied, especially in C. glabrata. Thus, the influence of progesterone and β-estradiol, at normal cycle and pregnancy concentrations, on biofilm formation and resistance of C. albicans and C. glabrata vaginal isolates, was analyzed using acidic conditions (pH 4). Biofilms of C. albicans developed in the presence of hormones presented reduced biomass (up to 65%) and impaired cells ability to produce filamentous forms. On the other hand, C. glabrata presented high adaptation to the presence of hormones, which did not affect its biofilm formation. Additionally, hormones impaired the susceptibility of C. albicans and C. glabrata cells to azoles, with potential clinical significance in the presence of pregnancy hormone levels. A similar result was obtained for the susceptibility to hydrogen peroxide, a biological vaginal barrier against Candida growth. Overall, the results of this study suggest that hormones may act as environmental cues promoting Candida protection from vaginal defenses and harmful conditions, what may have implications in Candida vaginal pathogenicity and treatment of VVC, especially in C. glabrata infections due to its high adaptability to vaginal conditions.}, } @article {pmid31253082, year = {2019}, author = {Suryaletha, K and Narendrakumar, L and John, J and Radhakrishnan, MP and George, S and Thomas, S}, title = {Decoding the proteomic changes involved in the biofilm formation of Enterococcus faecalis SK460 to elucidate potential biofilm determinants.}, journal = {BMC microbiology}, volume = {19}, number = {1}, pages = {146}, doi = {10.1186/s12866-019-1527-2}, pmid = {31253082}, issn = {1471-2180}, support = {BT/PR15261/MED/29/994/2015//Department of Biotechnology, Govt. of India/ ; }, abstract = {BACKGROUND: Enterococcus faecalis is a major clinically relevant nosocomial bacterial pathogen frequently isolated from polymicrobial infections. The biofilm forming ability of E. faecalis attributes a key role in its virulence and drug resistance. Biofilm cells are phenotypically and metabolically different from their planktonic counterparts and many aspects involved in E. faecalis biofilm formation are yet to be elucidated. The strain E. faecalis SK460 used in the present study is esp (Enterococcal surface protein) and fsr (two-component signal transduction system) negative non-gelatinase producing strong biofilm former isolated from a chronic diabetic foot ulcer patient. We executed a label-free quantitative proteomic approach to elucidate the differential protein expression pattern at planktonic and biofilm stages of SK460 to come up with potential determinants associated with Enterococcal biofilm formation.

RESULTS: The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of proteomic data revealed that biofilm cells expressed higher levels of proteins which are associated with glycolysis, amino acid biosynthesis, biosynthesis of secondary metabolites, microbial metabolism in diverse environments and stress response factors. Besides these basic survival pathways, LuxS-mediated quorum sensing, arginine metabolism, rhamnose biosynthesis, pheromone and adhesion associated proteins were found to be upregulated during the biofilm transit from planktonic stages. The selected subsets were validated by quantitative real-time PCR. In silico functional interaction analysis revealed that the genes involved in upregulated pathways pose a close molecular interaction thereby coordinating the regulatory network to thrive as a biofilm community.

CONCLUSIONS: The present study describes the first report of the quantitative proteome analysis of an esp and fsr negative non gelatinase producing E. faecalis. Proteome analysis evidenced enhanced expression of glycolytic pathways, stress response factors, LuxS quorum signaling system, rhamnopolysaccharide synthesis and pheromone associated proteins in biofilm phenotype. We also pointed out the relevance of LuxS quorum sensing and pheromone associated proteins in the biofilm development of E. faecalis which lacks the Fsr quorum signaling system. These validated biofilm determinants can act as potential inhibiting targets in Enterococcal infections.}, } @article {pmid31252357, year = {2019}, author = {Shi, LD and Wang, M and Li, ZY and Lai, CY and Zhao, HP}, title = {Dissolved oxygen has no inhibition on methane oxidation coupled to selenate reduction in a membrane biofilm reactor.}, journal = {Chemosphere}, volume = {234}, number = {}, pages = {855-863}, doi = {10.1016/j.chemosphere.2019.06.138}, pmid = {31252357}, issn = {1879-1298}, abstract = {Methane oxidation coupled to selenate reduction has been suggested as a promising technology to bio-remediate selenium contaminated environments. However, the effect of dissolved oxygen (DO) on this process remained unclear. Here, we investigate the feasibility of selenate removal at two distinct DO concentrations. A membrane biofilm reactor (MBfR) was initially fed with ∼5 mg Se/L and then lowered to ∼1 mg Se/L of selenate, under anoxic condition containing ∼0.2 mg/L of influent DO. Selenate removal reached approximately 90% without selenite accumulation after one-month operation. Then 6-7 mg/L of DO was introduced and showed no apparent effect on selenate reduction in the subsequent operation. Electron microscopy suggested elevated oxygen exposure did not affect microbial shapes. 16S rDNA sequencing showed the aerobic methanotroph Methylocystis increased, while possible selenate reducers, Ignavibacterium and Bradyrhizobium, maintained stable after oxygen boost. Gene analysis indicated that nitrate/nitrite reductases positively correlated with selenate removal flux and were not remarkably affected by oxygen addition. Reversely, enzymes related with aerobic methane oxidation were obviously improved. This study provides a potential technology for selenate removal from oxygenated environments in a methane-based MBfR.}, } @article {pmid31251598, year = {2019}, author = {Jack, AA and Nordli, HR and Powell, LC and Farnell, DJJ and Pukstad, B and Rye, PD and Thomas, DW and Chinga-Carrasco, G and Hill, KE}, title = {Cellulose Nanofibril Formulations Incorporating a Low-Molecular-Weight Alginate Oligosaccharide Modify Bacterial Biofilm Development.}, journal = {Biomacromolecules}, volume = {}, number = {}, pages = {}, doi = {10.1021/acs.biomac.9b00522}, pmid = {31251598}, issn = {1526-4602}, abstract = {Cellulose nanofibrils (CNFs) from wood pulp are a renewable material possessing advantages for biomedical applications because of their customizable porosity, mechanical strength, translucency, and environmental biodegradability. Here, we investigated the growth of multispecies wound biofilms on CNF formulated as aerogels and films incorporating the low-molecular-weight alginate oligosaccharide OligoG CF-5/20 to evaluate their structural and antimicrobial properties. Overnight microbial cultures were adjusted to 2.8 × 109 colony-forming units (cfu) mL-1 in Mueller Hinton broth and growth rates of Pseudomonas aeruginosa PAO1 and Staphylococcus aureus 1061A monitored for 24 h in CNF dispersions sterilized by γ-irradiation. Two CNF formulations were prepared (20 g m-2) with CNF as air-dried films or freeze-dried aerogels, with or without incorporation of an antimicrobial alginate oligosaccharide (OligoG CF-5/20) as a surface coating or bionanocomposite, respectively. The materials were structurally characterized by scanning electron microscopy (SEM) and laser profilometry (LP). The antimicrobial properties of the formulations were assessed using single- and mixed-species biofilms grown on the materials and analyzed using LIVE/DEAD staining with confocal laser scanning microscopy (CLSM) and COMSTAT software. OligoG-CNF suspensions significantly decreased the growth of both bacterial strains at OligoG concentrations >2.58% (P < 0.05). SEM showed that aerogel-OligoG bionanocomposite formulations had a more open three-dimensional structure, whereas LP showed that film formulations coated with OligoG were significantly smoother than untreated films or films incorporating PEG400 as a plasticizer (P < 0.05). CLSM of biofilms grown on films incorporating OligoG demonstrated altered biofilm architecture, with reduced biomass and decreased cell viability. The OligoG-CNF formulations as aerogels or films both inhibited pyocyanin production (P < 0.05). These novel CNF formulations or bionanocomposites were able to modify bacterial growth, biofilm development, and virulence factor production in vitro. These data support the potential of OligoG and CNF bionanocomposites for use in biomedical applications where prevention of infection or biofilm growth is required.}, } @article {pmid31251015, year = {2019}, author = {Ng, CK and Karahan, HE and Loo, SCJ and Chen, Y and Cao, B}, title = {Biofilm-Templated Heteroatom-Doped Carbon-Palladium Nanocomposite Catalyst for Hexavalent Chromium Reduction.}, journal = {ACS applied materials & interfaces}, volume = {11}, number = {27}, pages = {24018-24026}, doi = {10.1021/acsami.9b04095}, pmid = {31251015}, issn = {1944-8252}, abstract = {In this study, we report an interdisciplinary and novel strategy toward biofilm engineering for the development of a biofilm-templated heteroatom-doped catalytic system through bioreduction and biofilm matrix-facilitated immobilization of the in situ-formed catalytic nanoparticles followed by controlled pyrolysis. We showed that (i) even under room temperature and bulk aerobic conditions, Shewanella oneidensis MR-1 biofilms reduced Pd(II) to form Pd(0) nanocrystals (∼10 to 20 nm) that were immobilized in the biofilm matrix and in cellular membranes, (ii) the MR-1 biofilms with the immobilized Pd(0) nanocrystals exhibited nanocatalytic activity, (iii) exposure to Pd(II) greatly increased the rate of cell detachment from the biofilm and posed a risk of biofilm dispersal, (iv) controlled pyrolysis (carbonization) of the biofilm led to the formation of a stable heteroatom-doped carbon-palladium (C-Pd) nanocomposite catalyst, and (v) the biofilm-templated C-Pd nanocomposite catalyst exhibited a high Cr(VI) reduction activity and maintained a high reduction rate over multiple catalytic cycles. Considering that bacteria are capable of synthesizing a wide range of metal and metalloid nanoparticles, the biofilm-templated approach for the fabrication of the catalytic C-Pd nanocomposite we have demonstrated here should prove to be widely applicable for the production of different nanocomposites that are of importance to various environmental applications.}, } @article {pmid31250405, year = {2019}, author = {Pham, DTN and Khan, F and Phan, TTV and Park, SK and Manivasagan, P and Oh, J and Kim, YM}, title = {Biofilm inhibition, modulation of virulence and motility properties by FeOOH nanoparticle in Pseudomonas aeruginosa.}, journal = {Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology]}, volume = {}, number = {}, pages = {}, doi = {10.1007/s42770-019-00108-z}, pmid = {31250405}, issn = {1678-4405}, support = {20150220//Ministry of Education/ ; }, abstract = {Biofilm formation is one of the resistance mechanisms of Pseudomonas aeruginosa against antimicrobial compounds. Biofilm formation also characterizes for the infection and pathogenesis of P. aeruginosa, along with production of various virulence factors. With recent development of nanotechnology, the present study aims to employ the synthetic iron nanoparticle (FeOOH-NP) as an active agent to inhibit the formation of P. aeruginosa biofilm. The FeOOH-NP was synthesized and characterized with rod shape and average size of 40 nm. Inhibition of biofilm formation by the FeOOH-NP is in a concentration-dependent manner, with inhibition of biofilm formation increased as the FeOOH-NP concentration increased. Microscopic observations also confirmed the disruption of the biofilm architecture in the presence of the FeOOH-NP. In addition, the presence of the FeOOH-NP was also found to modulate bacterial motility as well as some other important virulence factors produced simultaneously with biofilm formation. These findings provide insights to anti-biofilm effect of a new iron NP, contributing to the search for an effective agent to combat P. aeruginosa infections resulted from biofilm formation.}, } @article {pmid31250387, year = {2019}, author = {Fallatah, H and Elhaneid, M and Ali-Boucetta, H and Overton, TW and El Kadri, H and Gkatzionis, K}, title = {Antibacterial effect of graphene oxide (GO) nano-particles against Pseudomonas putida biofilm of variable age.}, journal = {Environmental science and pollution research international}, volume = {}, number = {}, pages = {}, doi = {10.1007/s11356-019-05688-9}, pmid = {31250387}, issn = {1614-7499}, abstract = {Graphene oxide (GO) has been reported to possess antibacterial activity; therefore, its accumulation in the environment could affect microbial communities such as biofilms. The susceptibility of biofilms to antimicrobials is known to depend on the stage of biofilm maturity. The aim of this study was to investigate the effect of GO nano-particles on Pseudomonas putida KT2440 biofilm of variable age. FT-IR, UV-vis, and Raman spectroscopy confirmed the oxidation of graphene while XPS confirmed the high purity of the synthesised GO over 6 months. Biofilms varying in maturity (24, 48, and 72 h) were formed using a CDC reactor and were treated with GO (85 μg/mL or 8.5 μg/mL). The viability of P. putida was monitored by culture on media and the bacterial membrane integrity was assessed using flow cytometry. P. putida cells were observed using confocal microscopy and SEM. The results showed that GO significantly reduced the viability of 48-h biofilm and detached biofilm cells associated with membrane damage while the viability was not affected in 24- and 72-h biofilms and detached biofilm cells. The results showed that susceptibility of P. putida biofilm to GO varied according to age which may be due to changes in the physiological state of cells during maturation. Graphical abstract.}, } @article {pmid31250076, year = {2019}, author = {Jeong, SY and Lee, CH and Yi, T and Kim, TG}, title = {Effects of Quorum Quenching on Biofilm Metacommunity in a Membrane Bioreactor.}, journal = {Microbial ecology}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00248-019-01397-5}, pmid = {31250076}, issn = {1432-184X}, support = {2018R1D1A1B07048872//Ministry of Education/ ; }, abstract = {Quorum quenching (QQ) has received attention for the control of biofilms, e.g., biofilms that cause biofouling in membrane bioreactors (MBRs). Despite the efficacy of QQ on biofouling, it is elusive how QQ influences biofilm formation on membranes. A pilot-scale QQ-MBR and non-QQ-MBR were identically operated for 4 days and 8 days to destructively sample the membranes. QQ prolonged the membrane filterability by 43% with no harmful influence on MBR performance. qPCR showed no effect of QQ on microbial density during either of these time periods. Community comparisons revealed that QQ influenced the bacterial and fungal community structures, and the fungal structure corresponded with the bacterial structure. Metacommunity and spatial analyses showed that QQ induced structural variation rather than compositional variation of bacteria and fungi. Moreover, QQ considerably enhanced the bacterial dispersal across membrane during the early development. As the dispersal enhancement by QQ counteracted the ecological drift, it eliminated the distance-decay relationship, reflecting a neutral theory archetype of metacommunity. Network analyses showed that QQ substantially reduced the amount and magnitude of interactions, e.g., competition and cooperation, for bacteria and fungi, and weakened their network structures, irrespective of time. Additionally, QQ suppressed the growth of specific microbial species (e.g., Acinetobacter), abundant and widespread at the early stage. These findings suggest that QQ influenced the community dynamics at the regional and local levels, correspondingly the ecological selection and dispersal processes, during the biofilm development.}, } @article {pmid31246756, year = {2019}, author = {Jewell, ML and Fickas, B and Jewell, H and Jewell, ML}, title = {Implant Surface Options and Biofilm Mitigation Strategies.}, journal = {Plastic and reconstructive surgery}, volume = {144}, number = {1S Utilizing a Spectrum of Cohesive Implants in Aesthetic and Reconstructive Breast Surgery}, pages = {13S-20S}, doi = {10.1097/PRS.0000000000005946}, pmid = {31246756}, issn = {1529-4242}, abstract = {Two important topics in breast augmentation and reconstruction relate to device surface texture and practices to mitigate biofilm contamination of implants. Breast augmentation can be considered a manufacturing process where planning concepts of process engineering and quality can be used to produce great outcomes. This article reviews the options available for surgeons with regards to device surface texture selection and practices to mitigate biofilm contamination of implants at the time of surgery.}, } @article {pmid31246167, year = {2019}, author = {Pal, S and Verma, J and Mallick, S and Rastogi, SK and Kumar, A and Ghosh, AS}, title = {Absence of the glycosyltransferase WcaJ in Klebsiella pneumoniae ATCC13883 affects biofilm formation, increases polymyxin resistance and reduces murine macrophage activation.}, journal = {Microbiology (Reading, England)}, volume = {165}, number = {8}, pages = {891-904}, doi = {10.1099/mic.0.000827}, pmid = {31246167}, issn = {1465-2080}, abstract = {Multidrug-resistant Klebsiella pneumoniae has emerged as one of the deadliest opportunistic nosocomial pathogens that forms biofilm for the establishment of chronic K. pneumoniae infections. Herein, we made an attempt to identify the genes involved in biofilm formation in the strain K. pneumoniae ATCC13883. To achieve this, we constructed mini-Tn5 transposon insertion mutants and screened them for biofilm production. We observed that the biofilm formation was enhanced in the mutant where the wcaJ gene was disrupted. WcaJ is the initiating enzyme of colanic acid synthesis and loads the first sugar (glucose-1-P) on the lipid carrier undecaprenyl phosphate. The absence of this glycosyltransferase results in the absence of colanic acid, which renders a non-mucoid phenotype to the mutant. Further, to determine the effect of mucoidy on antibiotic susceptibility, we tested the sensitivity of the strains towards different groups of antibiotics. Unlike the mucoid strains, the resistance of the non-mucoid cells was greater for polymyxins, but less for quinolones. Capsular polysaccharides are known to have a protective effect against phagocytosis, therefore we assessed the role of colanic acid in virulence by conducting infection studies on murine macrophages. Surprisingly, the ΔwcaJ strain was less efficient in macrophage activation and was not readily phagocytosed. Thus, the presence of colanic acid appeared to increase the immunogenicity of K. pneumoniae. Overall, the results indicate that the presence of colanic acid increases the vulnerability of K. pneumoniae towards both polymyxins and macrophages, implying that the mucoid strains are less threatening as compared to their high biofilm forming non-mucoid counterparts.}, } @article {pmid31244785, year = {2019}, author = {Zeng, S and Constant, P and Yang, D and Baulard, A and Lefèvre, P and Daffé, M and Wattiez, R and Fontaine, V}, title = {Cpn60.1 (GroEL1) Contributes to Mycobacterial Crabtree Effect: Implications for Biofilm Formation.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1149}, doi = {10.3389/fmicb.2019.01149}, pmid = {31244785}, issn = {1664-302X}, abstract = {Biofilm formation is a survival strategy for microorganisms facing a hostile environment. Under biofilm, bacteria are better protected against antibacterial drugs and the immune response, increasing treatment difficulty, as persistent populations recalcitrant to chemotherapy are promoted. Deciphering mechanisms leading to biofilms could, thus, be beneficial to obtain new antibacterial drug candidates. Here, we show that mycobacterial biofilm formation is linked to excess glycerol adaptation and the concomitant establishment of the Crabtree effect. This effect is characterized by respiratory reprogramming, ATP downregulation, and secretion of various metabolites including pyruvate, acetate, succinate, and glutamate. Interestingly, the Crabtree effect was abnormal in a mycobacterial strain deficient for Cpn60.1 (GroEL1). Indeed, this mutant strain had a compromised ability to downregulate ATP and secreted more pyruvate, acetate, succinate, and glutamate in the culture medium. Importantly, the mutant strain had higher intracellular pyruvate and produced more toxic methylglyoxal, suggesting a glycolytic stress leading to growth stasis and consequently biofilm failure. This study demonstrates, for the first time, the link between mycobacterial biofilm formation and the Crabtree effect.}, } @article {pmid31241174, year = {2019}, author = {Tang, Y and Zhang, Z and Rittmann, BE and Lee, HS}, title = {Kinetics of anaerobic methane oxidation coupled to denitrification in the membrane biofilm reactor.}, journal = {Biotechnology and bioengineering}, volume = {}, number = {}, pages = {}, doi = {10.1002/bit.27098}, pmid = {31241174}, issn = {1097-0290}, support = {//Florida State University/ ; STPGP 478972//Natural Sciences and Engineering Research Council of Canada/ ; }, abstract = {Anaerobic oxidation of methane coupled to denitrification (AOM-D) in a membrane biofilm reactor (MBfR), a platform used for efficiently coupling gas delivery and biofilm development, has attracted attention in recent years due to the low cost and high availability of methane. However, experimental studies have shown that the nitrate-removal flux in the CH4 -based MBfR (<1.0 g N/m2 -day) is about one order of magnitude smaller than that in the H2 -based MBfR (1.1-6.7 g N/m2 -day). A one-dimensional multispecies biofilm model predicts that the nitrate-removal flux in the CH4 -based MBfR is limited to <1.7 g N/m2 -day, consistent with the experimental studies reported in the literature. The model also determines the two major limiting factors for the nitrate-removal flux: The methane half-maximum-rate concentration (K2) and the specific maximum methane utilization rate of the AOM-D syntrophic consortium (kmax2), with kmax2 being more important. Model simulations show that increasing kmax2 to >3 g chemical oxygen demand (COD)/g cell-day (from its current 1.8 g COD/g cell-day) and developing a new membrane with doubled methane-delivery capacity (Dm) could bring the nitrate-removal flux to ≥4.0 g N/m2 -day, which is close to the nitrate-removal flux for the H2 -based MBfR. Further increase of the maximum nitrate-removal flux can be achieved when Dm and kmax2 increase together.}, } @article {pmid31239789, year = {2019}, author = {Nuryastuti, T and Umaroh, N and Asdie, RH and Sari, IP and Musthafa, A}, title = {Pan-drug-resistant and biofilm-producing strain of Burkholderia pseudomallei: first report of melioidosis from a diabetic patient in Yogyakarta, Indonesia [Response to Letter].}, journal = {International medical case reports journal}, volume = {12}, number = {}, pages = {171-172}, doi = {10.2147/IMCRJ.S213150}, pmid = {31239789}, issn = {1179-142X}, } @article {pmid31239382, year = {2019}, author = {Kavanaugh, JS and Flack, CE and Lister, J and Ricker, EB and Ibberson, CB and Jenul, C and Moormeier, DE and Delmain, EA and Bayles, KW and Horswill, AR}, title = {Identification of Extracellular DNA-Binding Proteins in the Biofilm Matrix.}, journal = {mBio}, volume = {10}, number = {3}, pages = {}, doi = {10.1128/mBio.01137-19}, pmid = {31239382}, issn = {2150-7511}, support = {I01 BX002711/BX/BLRD VA/United States ; P01 AI083211/AI/NIAID NIH HHS/United States ; }, abstract = {We developed a new approach that couples Southwestern blotting and mass spectrometry to discover proteins that bind extracellular DNA (eDNA) in bacterial biofilms. Using Staphylococcus aureus as a model pathogen, we identified proteins with known DNA-binding activity and uncovered a series of lipoproteins with previously unrecognized DNA-binding activity. We demonstrated that expression of these lipoproteins results in an eDNA-dependent biofilm enhancement. Additionally, we found that while deletion of lipoproteins had a minimal impact on biofilm accumulation, these lipoprotein mutations increased biofilm porosity, suggesting that lipoproteins and their associated interactions contribute to biofilm structure. For one of the lipoproteins, SaeP, we showed that the biofilm phenotype requires the lipoprotein to be anchored to the outside of the cellular membrane, and we further showed that increased SaeP expression correlates with more retention of high-molecular-weight DNA on the bacterial cell surface. SaeP is a known auxiliary protein of the SaeRS system, and we also demonstrated that the levels of SaeP correlate with nuclease production, which can further impact biofilm development. It has been reported that S. aureus biofilms are stabilized by positively charged cytoplasmic proteins that are released into the extracellular environment, where they make favorable electrostatic interactions with the negatively charged cell surface and eDNA. In this work we extend this electrostatic net model to include secreted eDNA-binding proteins and membrane-attached lipoproteins that can function as anchor points between eDNA in the biofilm matrix and the bacterial cell surface.IMPORTANCE Many bacteria are capable of forming biofilms encased in a matrix of self-produced extracellular polymeric substances (EPS) that protects them from chemotherapies and the host defenses. As a result of these inherent resistance mechanisms, bacterial biofilms are extremely difficult to eradicate and are associated with chronic wounds, orthopedic and surgical wound infections, and invasive infections, such as infective endocarditis and osteomyelitis. It is therefore important to understand the nature of the interactions between the bacterial cell surface and EPS that stabilize biofilms. Extracellular DNA (eDNA) has been recognized as an EPS constituent for many bacterial species and has been shown to be important in promoting biofilm formation. Using Staphylococcus aureus biofilms, we show that membrane-attached lipoproteins can interact with the eDNA in the biofilm matrix and promote biofilm formation, which suggests that lipoproteins are potential targets for novel therapies aimed at disrupting bacterial biofilms.}, } @article {pmid31236717, year = {2019}, author = {Cavero-Olguin, VH and Hatti-Kaul, R and Cardenas-Alegria, OV and Gutierrez-Valverde, M and Alfaro-Flores, A and Romero-Calle, DX and Alvarez-Aliaga, MT}, title = {Stress induced biofilm formation in Propionibacterium acidipropionici and use in propionic acid production.}, journal = {World journal of microbiology & biotechnology}, volume = {35}, number = {7}, pages = {101}, doi = {10.1007/s11274-019-2679-9}, pmid = {31236717}, issn = {1573-0972}, support = {2008-00849//VINNOVA/ ; }, mesh = {*Biofilms ; Bioreactors/microbiology ; Cells, Immobilized ; Fermentation ; Gene Expression Regulation ; Genes, Bacterial ; Glycerol/metabolism ; In Situ Hybridization, Fluorescence ; Microscopy, Atomic Force ; Propionates/*metabolism ; Propionibacterium/genetics/*metabolism ; RNA, Ribosomal, 16S/genetics/isolation & purification ; Reverse Transcriptase Polymerase Chain Reaction ; *Stress, Physiological ; Trehalose/metabolism ; }, abstract = {Propionibacterium acidipropionici produces propionic acid from different sugars and glycerol; the production can be improved by high cell density fermentations using immobilized cells that help to overcome the limitations of the non-productive lag phase and product inhibition. In this study, the use of stress factors to induce P. acidipropionici to form biofilm and its use as an immobilization procedure in fermentations in bioreactors for producing propionic acid was investigated. Citric acid and sodium chloride increased exopolysaccharide production, biofilm forming capacity index and trehalose production. Analysis of the expression of trehalose synthesis-related genes otsA and treY by RT-qPCR showed significantly increased expression of only treY during log phase with citric acid, while FISH analysis showed expression of treY and luxS under the influence of both stress factors. The stress factors were then used for development of microbial biofilms as immobilization procedure on Poraver® and AnoxKaldnes® carriers in recycle batch reactors for propionic acid production from 20 g/L glycerol. Highest productivities of 0.7 and 0.78 g/L/h were obtained in Poraver® reactors, and 0.39 and 0.43 g/L/h in AnoxKaldnes® reactors with citric acid and NaCl, respectively.}, } @article {pmid31235750, year = {2019}, author = {Costa, ACBP and Omran, RP and Correia-Mesquita, TO and Dumeaux, V and Whiteway, M}, title = {Screening of Candida albicans GRACE library revealed a unique pattern of biofilm formation under repression of the essential gene ILS1.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {9187}, doi = {10.1038/s41598-019-45624-y}, pmid = {31235750}, issn = {2045-2322}, support = {209671//Fonds de Recherche du Qu&#x00E9;bec - Nature et Technologies (Quebec Fund for Research in Nature and Technology)/ ; RGPIN/4799//Canadian Network for Research and Innovation in Machining Technology, Natural Sciences and Engineering Research Council of Canada (NSERC Canadian Network for Research and Innovation in Machining Technology)/ ; 950-228957//Canada Research Chairs (Chaires de recherche du Canada)/ ; }, abstract = {Candida albicans biofilm formation is governed by a regulatory circuit comprising nine transcription factors which control a network of target genes. However, there are still unknown genes contributing to biofilm features. Thus, the GRACE library was screened to identify genes involved in mature biofilm development. Twenty-nine conditional mutants were selected for a second screening revealing three groups of genes: twenty- two conditional mutants were defective for normal growth and unable to form biofilms; six strains, conditionally defective in genes ARC40, ARC35, ORF19.2438, SKP1, ERG6, and ADE5,7 that are likely essential or involved in general cell processes, grew normally as free-floating cells but produced less biofilm; finally, the conditional strain for a putative essential isoleucyl- tRNA synthetase gene, ILS1, was unable to grow as yeast-phase cells but was capable of producing a tridimensional biofilm structure in spite of reduced metabolic activity. This unique biofilm still relied on the classical biofilm genes, while it differentially induced groups of genes involved in adhesion, protein synthesis, cell wall organization, and protein folding. Although the conditional mutant repressed genes annotated for morphology and homeostasis processes affecting morphology and metabolism, the dynamic cell growth enabled the formation of a complex biofilm community independent of ILS1.}, } @article {pmid31235348, year = {2019}, author = {Takeuchi, N and Ohkusu, M and Wada, N and Kurosawa, S and Miyabe, A and Yamaguchi, M and Nahm, MH and Ishiwada, N}, title = {Molecular typing, antibiotic susceptibility, and biofilm production in nonencapsulated Streptococcus pneumoniae isolated from children in Japan.}, journal = {Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.jiac.2019.02.007}, pmid = {31235348}, issn = {1437-7780}, abstract = {The prevalence of nonencapsulated Streptococcus pneumoniae (NESp) has increased with the introduction of pneumococcal conjugate vaccines in children; however, the bacteriological characteristics of NESp have not been sufficiently clarified. In this study, NESp strains isolated from the nasopharyngeal carriage of children from four nursery schools in Japan were analyzed for molecular type, antibiotic susceptibility, and biofilm productivity. A total of 152 putative S. pneumoniae strains were identified by optochin-susceptibility analysis, of which 21 were not serotypeable by slide agglutination, quellung reaction, or multiplex PCR. Among these 21 strains, three were lytA-negative and, therefore, not S. pneumoniae. The remaining 18 strains were positive for lytA, ply, pspK, and bile solubility and were confirmed as NESp. Therefore, the isolation rate of NESp in the S. pneumoniae strains in this study was 12.0% (18/149). Molecular-typing analyses classified five strains as two existing sequence types (STs; ST7502 and ST7786), and 13 strains formed four novel STs. Horizontal spread was suspected, because strains with the same ST were often isolated from the same nursery school. The NESp isolates were generally susceptible to most antimicrobials, with the exception of macrolides; however, all isolates possessed more than one abnormal penicillin-binding protein gene. Furthermore, NESp strains were more effective than encapsulated counterparts at forming biofilms, which showed obvious differences in morphology. These data indicated that NESp strains should be continuously monitored as emerging respiratory pathogens.}, } @article {pmid31234908, year = {2019}, author = {Hagos, DG and Mezgebo, TA and Berhane, S and Medhanyie, AA}, title = {Biofilm and hemagglutinin formation: a Hallmark for drug resistant uropathogenic Escherichia coli.}, journal = {BMC research notes}, volume = {12}, number = {1}, pages = {358}, doi = {10.1186/s13104-019-4382-1}, pmid = {31234908}, issn = {1756-0500}, support = {40//Mekelle University/ ; 000.00 Eth.Birr//Mekelle University/ ; }, abstract = {OBJECTIVE: Urinary tract infection (UTI) is one of the most frequent disease encounters in pregnant mothers, and the most drug resistant, biofilm and hemagglutinin producer Uropathogenic Escherichia coli (UPEC) is the major etiologic agent. Therefore, the aim of this study was to assess the association between the antimicrobial resistance, and biofilm and hemagglutinin production of Uropathogenic Escherichia coli.

RESULTS: UTI among the study participants was 27.3%; and UPEC was found the major etiologic agent followed by coagulase negative staphylococcus. Risk factors, previous history of catheterization and previous history of UTI were found significantly associated with UTI, recurrent UTI, drug resistance and biofilm formation. Of the tested antibiotics, nitrofurantoin was the most effective drug for UPEC. Nearly 100% of the biofilm producers were resistant to norfloxacin, cotrimoxazole, and gentamicin.}, } @article {pmid31234765, year = {2019}, author = {Grishin, AV and Karyagina, AS}, title = {Polysaccharide Galactan Inhibits Pseudomonas aeruginosa Biofilm Formation but Protects Pre-formed Biofilms from Antibiotics.}, journal = {Biochemistry. Biokhimiia}, volume = {84}, number = {5}, pages = {509-519}, doi = {10.1134/S0006297919050055}, pmid = {31234765}, issn = {1608-3040}, mesh = {Anti-Bacterial Agents/*pharmacology ; Bacterial Adhesion/drug effects ; Biofilms/*drug effects ; Galactans/*pharmacology ; Microbial Sensitivity Tests ; Microscopy, Fluorescence ; Pseudomonas aeruginosa/growth & development/*physiology ; Solanum tuberosum/metabolism ; }, abstract = {Microorganisms residing within a biofilm become more tolerant to antibiotics and other types of adverse impact, and biofilm formation by pathogenic bacteria is an important problem of current medicine. Polysaccharides that prevent biofilm formation are among the promising candidates to help tackle this problem. Earlier we demonstrated the ability of a potato polysaccharide galactan to inhibit biofilm formation by a Pseudomonas aeruginosa clinical isolate. Here we investigate the effect of potato galactan on P. aeruginosa biofilms in more detail. Microscopic analysis indicated that the galactan did not interfere with the adhesion of bacterial cells to the substrate but prevented the build-up of bacterial biomass. Moreover, the galactan not only inhibited biofilm formation, but partially destroyed pre-formed biofilms. Presumably, this activity of the galactan was due to the excessive aggregation of bacterial cells, which prohibited the formation and maintenance of proper biofilm architecture, or due to some other mechanisms of biofilm structure remodeling. This led to an unexpected effect, i.e., P. aeruginosa biofilms treated with an antibiotic and the galactan retained more viable bacterial cells compared to biofilms treated with the antibiotic alone. Galactan is the first polysaccharide demonstrated to exert such effect on bacterial biofilms.}, } @article {pmid31233774, year = {2019}, author = {Nakamura, H and Shimizu, T and Takatani, A and Suematsu, T and Nakamura, T and Kawakami, A}, title = {Initial human T-cell leukemia virus type 1 infection of the salivary gland epithelial cells requires a biofilm-like structure.}, journal = {Virus research}, volume = {269}, number = {}, pages = {197643}, doi = {10.1016/j.virusres.2019.197643}, pmid = {31233774}, issn = {1872-7492}, abstract = {The initial phase of the human T cell leukemia virus-1 (HTLV-1) infection of salivary gland epithelial cells (SGECs) was examined. SGECs of patients with Sjögren's syndrome (SS) and non-SS subjects were co-cultured with the HTLV-1-infected cell line HCT-5 or MOLT-4, then immunofluorescence (IF), scanning and transmission electron microscopy (SEM/TEM) were employed. The extracellular matrix and linker proteins galectin-3, agrin, and tetherin were expressed on the surfaces of both HCT-5 and MOLT-4 cells. HTLV-1 Gag-positive spots were observed on adjacent SGECs after 1 h of co-culture with HCT-5. Both in subjects with and those without SS, agrin and tetherin were co-expressed with HTLV-1 Gag on SGECs after co-culture with HCT-5, although no polarization of HTLV-1 Gag and relevant molecules was observed. SEM showed HTLV-1 virions that were found on HCT-5 were observed in the interfaces between HCT-5 cells and SGECs. TEM imaging showed that HTLV-1 virions were transmitted to SGECs at the interface with thin film-like structure, while HTLV-1 virions were released from the surface of HCT-5 cells. No endogenous retroviruses were observed. These results showed that the initial phase of HTLV-1 infection toward SGECs of SS was mediated not by viral synapses, but by biofilm-like components.}, } @article {pmid31233560, year = {2019}, author = {Mendis, HC and Ozcan, A and Santra, S and De La Fuente, L}, title = {A novel Zn chelate (TSOL) that moves systemically in citrus plants inhibits growth and biofilm formation of bacterial pathogens.}, journal = {PloS one}, volume = {14}, number = {6}, pages = {e0218900}, doi = {10.1371/journal.pone.0218900}, pmid = {31233560}, issn = {1932-6203}, abstract = {Ternary solution (TSOL) is a novel Zn chelate-based systemic antimicrobial formulation designed for treating citrus bacterial pathogens 'Candidatus Liberibacter asiaticus' and Xanthomonas citri subsp. citri. TSOL is a component of MS3T, a novel multifunctional surface/sub-surface/systemic therapeutic formulation. Antimicrobial activity of TSOL was compared with the antimicrobial compound ZnO against X. citri subsp. citri and 'Ca. L. asiaticus' surrogate Liberibacter crescens in batch cultures. X. citri subsp. citri and L. crescens were also introduced into microfluidic chambers, and the inhibitory action of TSOL against biofilm formation was evaluated. The minimum inhibitory concentration of TSOL for both X. citri subsp. citri and L. crescens was 40ppm. TSOL was bactericidal to X. citri subsp. citri and L. crescens above 150 ppm and 200 ppm, respectively. On the contrary, ZnO was more effective as a bactericidal agent against L. crescens than X. citri subsp. citri. TSOL was more effective in controlling growth and biofilm formation of X. citri subsp. citri in batch cultures compared to ZnO. Time-lapse video imaging microscopy showed that biofilm formation of X. citri subsp. citri was inhibited in microfluidic chambers treated with 60 ppm TSOL. TSOL also inhibited further growth of already formed X. citri subsp. citri and L. crescens biofilms in microfluidic chambers. Leaf spraying of TSOL showed higher plant uptake and systemic movement in citrus (Citrus reshni) plants compared to that of ZnO, suggesting that TSOL is a promising antimicrobial compound to control vascular plant pathogens such as 'Ca. L. asiaticus'.}, } @article {pmid31233528, year = {2019}, author = {Soler-Arango, J and Figoli, C and Muraca, G and Bosch, A and Brelles-Mariño, G}, title = {The Pseudomonas aeruginosa biofilm matrix and cells are drastically impacted by gas discharge plasma treatment: A comprehensive model explaining plasma-mediated biofilm eradication.}, journal = {PloS one}, volume = {14}, number = {6}, pages = {e0216817}, doi = {10.1371/journal.pone.0216817}, pmid = {31233528}, issn = {1932-6203}, abstract = {Biofilms are microbial communities encased in a protective matrix composed of exopolymeric substances including exopolysaccharides, proteins, lipids, and extracellular DNA. Biofilms cause undesirable effects such as biofouling, equipment damage, prostheses colonization, and disease. Biofilms are also more resilient than free-living cells to regular decontamination methods and therefore, alternative methods are needed to eradicate them. The use of non-thermal atmospheric pressure plasmas is a good alternative as plasmas contain reactive species, free radicals, and UV photons well-known for their decontamination potential against free microorganisms. Pseudomonas aeruginosa biofilms colonize catheters, indwelling devices, and prostheses. Plasma effects on cell viability have been previously documented for P. aeruginosa biofilms. Nonetheless, the effect of plasma on the biofilm matrix has received less attention and there is little evidence regarding the changes the matrix undergoes. The aim of this work was to study the effect plasma exerts mostly on the P. aeruginosa biofilm matrix and to expand the existing knowledge about its effect on sessile cells in order to achieve a better understanding of the mechanism/s underlying plasma-mediated biofilm inactivation. We report a reduction in the amount of the biofilm matrix, the loss of its tridimensional structure, and morphological changes in sessile cells at long exposure times. We show chemical and structural changes on the biofilm matrix (mostly on carbohydrates and eDNA) and cells (mostly on proteins and lipids) that are more profound with longer plasma exposure times. We also demonstrate the presence of lipid oxidation products confirming cell membrane lipid peroxidation as plasma exposure time increases. To our knowledge this is the first report providing detailed evidence of the variety of chemical and structural changes that occur mostly on the biofilm matrix and sessile cells as a consequence of the plasma treatment. Based on our results, we propose a comprehensive model explaining plasma-mediated biofilm inactivation.}, } @article {pmid31233504, year = {2019}, author = {MacKenzie, KD and Wang, Y and Musicha, P and Hansen, EG and Palmer, MB and Herman, DJ and Feasey, NA and White, AP}, title = {Parallel evolution leading to impaired biofilm formation in invasive Salmonella strains.}, journal = {PLoS genetics}, volume = {15}, number = {6}, pages = {e1008233}, doi = {10.1371/journal.pgen.1008233}, pmid = {31233504}, issn = {1553-7404}, abstract = {Pathogenic Salmonella strains that cause gastroenteritis are able to colonize and replicate within the intestines of multiple host species. In general, these strains have retained an ability to form the rdar morphotype, a resistant biofilm physiology hypothesized to be important for Salmonella transmission. In contrast, Salmonella strains that are host-adapted or even host-restricted like Salmonella enterica serovar Typhi, tend to cause systemic infections and have lost the ability to form the rdar morphotype. Here, we investigated the rdar morphotype and CsgD-regulated biofilm formation in two non-typhoidal Salmonella (NTS) strains that caused invasive disease in Malawian children, S. Typhimurium D23580 and S. Enteritidis D7795, and compared them to a panel of NTS strains associated with gastroenteritis, as well as S. Typhi strains. Sequence comparisons combined with luciferase reporter technology identified key SNPs in the promoter region of csgD that either shut off biofilm formation completely (D7795) or reduced transcription of this key biofilm regulator (D23580). Phylogenetic analysis showed that these SNPs are conserved throughout the African clades of invasive isolates, dating as far back as 80 years ago. S. Typhi isolates were negative for the rdar morphotype due to truncation of eight amino acids from the C-terminus of CsgD. We present new evidence in support of parallel evolution between lineages of nontyphoidal Salmonella associated with invasive disease in Africa and the archetypal host-restricted invasive serovar; S. Typhi. We hypothesize that the African invasive isolates are becoming human-adapted and 'niche specialized' with less reliance on environmental survival, as compared to gastroenteritis-causing isolates.}, } @article {pmid31232165, year = {2019}, author = {Wang, Y and Wang, Y and Liu, B and Wang, S and Li, J and Gong, S and Sun, L and Yi, L}, title = {pdh modulate virulence through reducing stress tolerance and biofilm formation of Streptococcus suis serotype 2.}, journal = {Virulence}, volume = {10}, number = {1}, pages = {588-599}, doi = {10.1080/21505594.2019.1631661}, pmid = {31232165}, issn = {2150-5608}, abstract = {Streptococcus suis serotype 2 (S. suis 2) is a zoonotic pathogen. It causes meningitis, arthritis, pneumonia and sepsis in pigs, leading to extremely high mortality, which seriously affects public health and the development of the pig industry. Pyruvate dehydrogenase (PDH) is an important sugar metabolism enzyme that is widely present in microorganisms, mammals and higher plants. It catalyzes the irreversible oxidative decarboxylation of pyruvate to acetyl-CoA and reduces NAD+ to NADH. In this study, we found that the virulence of the S. suis ZY05719 sequence type 7 pdh deletion strain (Δpdh) was significantly lower than the wild-type strain (WT) in the mouse infection model. The distribution of viable bacteria in the blood and organs of mice infected with the Δpdh was significantly lower than those infected with WT. Bacterial survival rates were reduced in response to temperature stress, salt stress and oxidative stress. Additionally, compared to WT, the ability to adhere to and invade PK15 cells, biofilm formation and stress resistance of Δpdh were significantly reduced. Moreover, real-time PCR results showed that pdh deletion reduced the expression of multiple adhesion-related genes. However, there was no significant difference in the correlation biological analysis between the complemented strain (CΔpdh) and WT. Moreover, the survival rate of Δpdh in RAW264.7 macrophages was significantly lower than that of the WT strain. This study shows that PDH is involved in the pathogenesis of S. suis 2 and reduction in virulence of Δpdh may be related to the decreased ability to resist stress of the strain.}, } @article {pmid31232051, year = {2019}, author = {Perkowski, K and Baltaza, W and Conn, DB and Marczyńska-Stolarek, M and Chomicz, L}, title = {Examination of oral biofilm microbiota in patients using fixed orthodontic appliances in order to prevent risk factors for health complications.}, journal = {Annals of agricultural and environmental medicine : AAEM}, volume = {26}, number = {2}, pages = {231-235}, doi = {10.26444/aaem/105797}, pmid = {31232051}, issn = {1898-2263}, abstract = {INTRODUCTION AND OBJECTIVE: In recent decades the use of orthodontic appliances in Poland has increased; however, data on their influence on changes of components of the microbiome connected with oral biofilm are scarce. The objective of this study was to evaluate oral microbiota in terms of their role as risk factors for health complications.

MATERIAL AND METHODS: The study included 100 patients treated with removable or fixed appliances. Oral hygiene and gingival health were determined, and periodontal swabs taken from each patient for parasitological, bacteriological and mycological microscopic and in vitro examinations.

RESULTS: Oral protists and various pathogenic and opportunistic bacterial and fungal strains were identified in the superficial layer of biofilm. A higher prevalence of bacteria, Enterococcus faecalis, E. faecium, Staphylococcus aureus and Escherichia coli, and various strains of yeast-like fungi from the Candida albicans group, occurred in patients treated with the fixed appliance than in those using a removable appliance or not treated orthodontically. In some periodontal samples from patients treated with fixed appliances, cysts of the Acanthamoeba spp. were found.

CONCLUSIONS: The use of orthodontic appliances alters the status of the oral cavity; it has impact on the colonization of oral biofilm by opportunistic/pathogenic strains, and increases the risk of their dissemination to various human tissues and organs. Pretreatment examination of oral microbiome, its monitoring particularly during treatment with fixed appliances, and preventive elimination of the potentially pathogenic strains to avoid health complications, are highly recommended, especially in patients with impaired immunity.}, } @article {pmid31231348, year = {2019}, author = {Singh, VK and Mishra, A and Jha, B}, title = {3-Benzyl-Hexahydro-Pyrrolo[1,2-a]Pyrazine-1,4-Dione Extracted From Exiguobacterium indicum Showed Anti-biofilm Activity Against Pseudomonas aeruginosa by Attenuating Quorum Sensing.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1269}, doi = {10.3389/fmicb.2019.01269}, pmid = {31231348}, issn = {1664-302X}, abstract = {Bacterial cell-to-cell communication promotes biofilm formation and can potentially lead to multidrug resistance development. Quorum sensing inhibition (QSI) is an effective and widely employed strategy against biofilm formation. The extract from Exiguobacterium indicum SJ16, a gram-positive bacterium, isolated from the rhizosphere of Cyperus laevigatus showed significant anti-quorum sensing activity (about 99%) against the reference Chromobacterium violaceum CV026 strain without exerting any antibacterial effect. The potentially active QSI compound identified in the SJ16 extract was 3-Benzyl-hexahydro-pyrrolo[1, 2-a]pyrazine-1,4-dione. The SJ16 extract containing this active compound showed significant anti-quorum sensing activity against a model quorum sensing bacterium strain Pseudomonas aeruginosa PAO1 and a clinical isolate P. aeruginosa PAH by preventing biofilm formation without attenuating the cell growth within the biofilm. More specifically, the SJ16 extract changed the topography and architecture of the biofilm, thus preventing bacterial adherence and further development of the biofilm. Furthermore, it decreased virulence factors (rhamnolipid and pyocyanin), the bacterial motility, as well as the elastase, and protease activities in P. aeruginosa. Microarray analysis revealed the differential expression of quorum sensing regulatory genes. Based on these results, we herein propose a hypothetical model, characterizing the role of this QSI agent in the transcriptional regulation of quorum sensing in P. aeruginosa PAO1, demonstrating that this compound has significant drug-development potential. Further research is required to delineate its possible applications in therapeutics in the context of biofilm forming bacterial infections.}, } @article {pmid31231324, year = {2019}, author = {Pathirana, RU and McCall, AD and Norris, HL and Edgerton, M}, title = {Filamentous Non-albicans Candida Species Adhere to Candida albicans and Benefit From Dual Biofilm Growth.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1188}, doi = {10.3389/fmicb.2019.01188}, pmid = {31231324}, issn = {1664-302X}, abstract = {Non-albicans Candida species (NACS) are often isolated along with Candida albicans in cases of oropharyngeal candidiasis. C. albicans readily forms biofilms in conjunction with other oral microbiota including both bacteria and yeast. Adhesion between species is important to the establishment of these mixed biofilms, but interactions between C. albicans and many NACS are not well-characterized. We adapted a real-time flow biofilm model to study adhesion interactions and biofilm establishment in C. albicans and NACS in mono- and co-culture. Out of five NACS studied, only the filamenting species C. tropicalis and C. dubliniensis were capable of adhesion with C. albicans, while C. parapsilosis, C. lusitaniae, and C. krusei were not. Over the early phase (0-4 h) of biofilm development, both mono- and co-culture followed similar kinetics of attachment and detachment events, indicating that initial biofilm formation is not influenced by inter-species interactions. However, the NACS showed a preference for inter-species cell-cell interactions with C. albicans, and at later time points (5-11 h) we found that dual-species interactions impacted biofilm surface coverage. Dual-species biofilms of C. tropicalis and C. albicans grew more slowly than C. albicans alone, but achieved higher surface coverage than C. tropicalis alone. Biofilms of C. dubliniensis with C. albicans increased surface coverage more rapidly than either species alone. We conclude that dual culture biofilm of C. albicans with C. tropicalis or C. dubliniensis offers a growth advantage for both NACS. Furthermore, the growth and maintenance, but not initial establishment, of dual-species biofilms is likely facilitated by interspecies cell-cell adherence.}, } @article {pmid31230907, year = {2019}, author = {Wang, J and Liu, Q and Ma, S and Hu, H and Wu, B and Zhang, XX and Ren, H}, title = {Distribution characteristics of N-acyl homoserine lactones during the moving bed biofilm reactor biofilm development process: Effect of carbon/nitrogen ratio and exogenous quorum sensing signals.}, journal = {Bioresource technology}, volume = {289}, number = {}, pages = {121591}, doi = {10.1016/j.biortech.2019.121591}, pmid = {31230907}, issn = {1873-2976}, abstract = {Carbon/nitrogen (C/N) ratios play an important role in biological wastewater treatment processes, with quorum sensing (QS) coordinating biological group behaviors. However, the relationship between them remains unclear. This study investigated the effects of varying C/N ratios and exogenous QS signals on the distribution characteristics of AHLs in Moving Bed Biofilm Reactors during the biofilm development process. Results show that C10-HSL and C12-HSL were the dominant AHLs, with the highest concentrations observed in the reactor with a C/N ratio of 10, followed by C/N ratios of 20 and 4. With varying C/N ratios, the biofilm microbial community structure changed significantly, which may contribute to significant differences in the distribution of AHLs. Furthermore, with the addition of a QS strain Sphingomonas rubra sp. nov., the pollutant removal efficiency of the reactor was not significantly improved and a reversible change in community composition was temporarily observed.}, } @article {pmid31229548, year = {2019}, author = {Bellich, B and Distefano, M and Syrgiannis, Z and Bosi, S and Guida, F and Rizzo, R and Brady, JW and Cescutti, P}, title = {The polysaccharide extracted from the biofilm of Burkholderia multivorans strain C1576 binds hydrophobic species and exhibits a compact 3D-structure.}, journal = {International journal of biological macromolecules}, volume = {136}, number = {}, pages = {944-950}, doi = {10.1016/j.ijbiomac.2019.06.140}, pmid = {31229548}, issn = {1879-0003}, support = {R01 GM123283/GM/NIGMS NIH HHS/United States ; }, abstract = {Microorganisms often grow in communities called biofilms where cells are imbedded in a complex self-produced biopolymeric matrix composed mainly of polysaccharides, proteins, and DNA. This matrix, together with cell proximity, confers many advantages to these microbial communities, but also constitutes a serious concern when biofilms develop in human tissues or on implanted prostheses. Although polysaccharides are considered the main constituents of the matrices, their specific role needs to be clarified. We have investigated the chemical and morphological properties of the polysaccharide extracted from biofilms produced by the C1576 reference strain of the opportunistic pathogen Burkholderia multivorans, which causes lung infections in cystic fibrosis patients. The aim of the present study is the definition of possible interactions of the polysaccharide and the three-dimensional conformation of its chain within the biofilm matrix. Surface plasmon resonance experiments confirmed the ability of the polysaccharide to bind hydrophobic molecules, due to the presence of rhamnose dimers in its primary structure. In addition, atomic force microscopy studies evidenced an extremely compact three-dimensional structure of the polysaccharide which may form aggregates, suggesting a novel view of its structural role into the biofilm matrix.}, } @article {pmid31229099, year = {2019}, author = {Cruzado-Bravo, MLM and Silva, NCC and Rodrigues, MX and Silva, GOE and Porto, E and Sturion, GL}, title = {Phenotypic and genotypic characterization of Staphylococcus spp. isolated from mastitis milk and cheese processing: Study of adherence and biofilm formation.}, journal = {Food research international (Ottawa, Ont.)}, volume = {122}, number = {}, pages = {450-460}, doi = {10.1016/j.foodres.2019.04.017}, pmid = {31229099}, issn = {1873-7145}, abstract = {The aim of this study was to identify the phenotypic and genotypic profiles of Staphylococcus spp. isolated from mastitis milk and cheese processing plant.To evaluate the biofilm production of wild-type strains on contact surfaces by testing different factors through adhered cells and biofilm quantifications, finally, these biofilms were observed by Scanning Electron Microscopy (SEM). Congo red agar (CRA) plate method was used to identify slime production by strains. Screening of genes encoding adhesion factors and biofilm formation was carried out using PCR. After strains selection, adhesion and biofilm assays were designed testing different times (12, 48, 96 h), strains (n = 13), contact surfaces (stainless steel and polypropylene), and temperatures (5 °C and 25 °C); and then, bacterial count and crystal violet staining were conducted. Relative frequencies of positive on CRA and genes presence were determined, and Friedman test was applied for bacterial counts and OD values. Additionally, significant factors (P ≤ .05) were subjected to multiple comparisons using the Nemenyi test. The slime production in CRA was observed by visual inspection in 38.7% of strains. A large distribution of genes was described among strains, implying a high variability of genotypic profiles. Moreover, relative frequencies of CRA positive and gene presence were described. The developed assay showed that the strain, temperature, contact surface, were significant for both variables. The SEM corroborated the findings, showing greater biofilm formation on stainless steel at 25 °C. Thus, it is essential to highlight the importance of temperature control and material with low superficial energy to avoid biofilm formation by staphylococci.}, } @article {pmid31228833, year = {2019}, author = {Wang, J and Liu, Q and Hu, H and Wu, B and Zhang, XX and Ren, H}, title = {Insight into mature biofilm quorum sensing in full-scale wastewater treatment plants.}, journal = {Chemosphere}, volume = {234}, number = {}, pages = {310-317}, doi = {10.1016/j.chemosphere.2019.06.007}, pmid = {31228833}, issn = {1879-1298}, abstract = {Quorum sensing (QS) has been thoroughly investigated during initial biofilm formation stages, while the role of QS in mature biofilms has received little research attention. This study assessed QS in 22 biofilm samples from full-scale wastewater treatment plants in China. Results showed that the concentration of acyl-homoserine lactones (AHLs) in various biofilm bound forms, ranged from 15.63 to 609.76 ng/g. The highest concentration of AHLs was found in the tightly bound biofilm fraction, while the lowest concentrations were observed in the surface biofilm fraction. Environmental variables, C/N ratio and temperature, were found to be significant factors influencing biofilm AHL distribution (p < 0.01). Higher C/N ratios (ranging from 3 to 12) and low temperatures contributed to the higher concentration of AHLs in biofilms. Dominant AHLs (C10-HSL and C12-HSL) were significantly associated with biofilm activity (R2 = 0.98/0.97, p < 0.05), with the tightly bound biofilm fraction (TB-biofilm) presenting the highest activity (ATP concentration). Biofilm aging and re-formation processes were more active in the surface biofilm layer (S-biofilm), while the stable structure of the TB-biofilm layer which is attached to the surface of bio-carriers ensures high biofilm activity. This study furthers our understanding of the roles of AHLs in the regulation of mature biofilm activities.}, } @article {pmid31228790, year = {2019}, author = {Luo, JH and Wu, M and Liu, J and Qian, G and Yuan, Z and Guo, J}, title = {Microbial chromate reduction coupled with anaerobic oxidation of methane in a membrane biofilm reactor.}, journal = {Environment international}, volume = {130}, number = {}, pages = {104926}, doi = {10.1016/j.envint.2019.104926}, pmid = {31228790}, issn = {1873-6750}, abstract = {It has been reported that microbial reduction of sulfate, nitrite/nitrate and iron/manganese could be coupled with anaerobic oxidation of methane (AOM), which plays a significant role in controlling methane emission from anoxic niches. However, little is known about microbial chromate (Cr(VI)) reduction coupling with AOM. In this study, a microbial consortium was enriched via switching nitrate dosing to chromate feeding as the sole electron acceptor under anaerobic condition in a membrane biofilm reactor (MBfR), in which methane was continuously provided as the electron donor through bubble-less hollow fiber membranes. According to long-term reactor operation and chromium speciation analysis, soluble chromate could be reduced into Cr(III) compounds by using methane as electron donor. Fluorescence in situ hybridization and high-throughput 16S rRNA gene amplicon profiling further indicated that after feeding chromate Candidatus 'Methanoperedens' (a known nitrate-dependent anaerobic methane oxidation archaeon) became sole anaerobic methanotroph in the biofilm, potentially responsible for the chromate bio-reduction driven by methane. Two potential pathways of the microbial AOM-coupled chromate reduction were proposed: (i) Candidatus 'Methanoperedens' independently utilizes chromate as electron acceptor to form Cr(III) compounds, or (ii) Candidatus 'Methanoperedens' oxidizes methane to generate intermediates or electrons, which will be utilized to reduce chromate to Cr(III) compounds by unknown chromate reducers synergistically. Our findings suggest a possible link between the biogeochemical chromium and methane cycles.}, } @article {pmid31228542, year = {2019}, author = {Cardoso, MH and Santos, VPM and Costa, BO and Buccini, DF and Rezende, SB and Porto, WF and Santos, MJ and Silva, ON and Ribeiro, SM and Franco, OL}, title = {A short peptide with selective anti-biofilm activity against Pseudomonas aeruginosa and Klebsiella pneumoniae carbapenemase-producing bacteria.}, journal = {Microbial pathogenesis}, volume = {135}, number = {}, pages = {103605}, doi = {10.1016/j.micpath.2019.103605}, pmid = {31228542}, issn = {1096-1208}, abstract = {Biofilm-related infections represent an enormous clinical challenge nowadays. In this context, diverse studies are underway to develop effective antimicrobial agents targeting bacterial biofilms. Here, we describe the antibacterial and anti-biofilm activities of a short, cationic peptide named R5F5, obtained from sliding-window analysis based on a peptide (PcDBS1R5) derived from Plasmodium chabaudi. Ten fragments were generated (R5F1 to F10) and submitted to initial antibacterial assays against Pseudomonas aeruginosa. As a result, R5F5 showed the highest antimicrobial activity. We therefore carried out further antibacterial and anti-biofilm assays against P. aeruginosa and Klebsiella pneumoniae carbapenemase-producing bacterial strains. R5F5 revealed selective anti-biofilm activity, as the peptide inhibited >60% biofilm formation in all cases from 8 to 64 μg·mL-1. Moreover, R5F5 was not hemolytic against mice erythrocytes at 640 μg mL-1. Cytotoxic effects on human lung fibroblast cells were not detected at 160 μg·mL-1. Structural studies revealed that R5F5 presents random coil conformations in water and 50% 2,2,2-trifluoroethanol (TFE)/water (v/v), whereas amphipathic, extended conformations were observed in contact with sodium dodecyl sulfate (SDS) micelles. Thus, here we report a novel peptide with selective anti-biofilm activity against susceptible and resistant bacterial strains, with no toxicity toward mammalian cells and that adopts a stable structure in anionic environment.}, } @article {pmid31226983, year = {2019}, author = {Sánchez, MC and Ribeiro-Vidal, H and Esteban-Fernández, A and Bartolomé, B and Figuero, E and Moreno-Arribas, MV and Sanz, M and Herrera, D}, title = {Antimicrobial activity of red wine and oenological extracts against periodontal pathogens in a validated oral biofilm model.}, journal = {BMC complementary and alternative medicine}, volume = {19}, number = {1}, pages = {145}, doi = {10.1186/s12906-019-2533-5}, pmid = {31226983}, issn = {1472-6882}, support = {ALIBIRD-CM S2013/ABI-2728//Comunidad de Madrid/ ; AGL2015-64522-C2-R project//Spanish MINECO/ ; }, abstract = {BACKGROUND: Previous research findings support an antimicrobial effect of polyphenols against a variety of pathogens, but there is no evidence of this effect against periodontal pathogens in complex biofilms. The purpose of this study was to evaluate the antimicrobial activity of red wine and oenological extracts, rich in polyphenols, against the periodontal pathogens Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum and total bacteria growing in an in vitro oral biofilm static model.

METHODS: A previously validated biofilm model, including Streptococcus oralis, Actinomyces naeslundii, Veillonella parvula, F. nucleatum, P. gingivalis and A. actinomycetemcomitans was developed on sterile hydroxyapatite discs. Red wine (and dealcoholized wine), and two polyphenols-rich extracts (from wine and grape seeds) were applied to 72 h biofilms by dipping the discs during 1 and 5 min in the wine solutions and during 30 s and 1 min in the oenological extracts. Resulting biofilms were analyzed by confocal laser scanning microscopy and viable bacteria (colony forming units/mL) were measured by quantitative polymerase chain reaction combined with propidium monoazide. A generalized linear model was constructed to determine the effect of the tested products on the viable bacterial counts of A. actinomycetemcomitans, P. gingivalis and F. nucleatum, as well on the total number of viable bacteria.

RESULTS: The results showed that red wine and dealcoholized red wine caused reduction in viability of total bacteria within the biofilm, with statistically significant reductions in the number of viable P. gingivalis after 1 min (p = 0.008) and in A. actinomycetemcomitans after 5 min of exposure (p = 0.011) with red wine. No evidence of relevant antibacterial effect was observed with the oenological extracts, with statistically significant reductions of F. nucleatum after 30 s of exposure to both oenological extracts (p = 0.001).

CONCLUSIONS: Although moderate, the antimicrobial impact observed in the total bacterial counts and counts of A. actinomycetemcomitans, P. gingivalis and F. nucleatum, encourage further investigations on the potential use of these natural products in the prevention and treatment of periodontal diseases.}, } @article {pmid31226270, year = {2019}, author = {Short, B and Brown, J and Delaney, C and Sherry, L and Williams, C and Ramage, G and Kean, R}, title = {Candida auris exhibits resilient biofilm characteristics in vitro: implications for environmental persistence.}, journal = {The Journal of hospital infection}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.jhin.2019.06.006}, pmid = {31226270}, issn = {1532-2939}, abstract = {Surfaces within healthcare play a key role in the transmission of drug-resistant pathogens. Candida auris is an emerging multidrug-resistant yeast which can survive for prolonged periods on environmental surfaces. Here we show that the ability to form cellular aggregates increases survival after 14 days, which coincides with the upregulation of biofilm-associated genes. Additionally, the aggregating strain demonstrated tolerance to clinical concentrations of sodium hypochlorite and remained viable 14 days post treatment. The ability of C. auris to adhere to and persist on environmental surfaces emphasizes our need to better understand the biology of this fungal pathogen.}, } @article {pmid31222089, year = {2019}, author = {Ramos-Vivas, J and Chapartegui-González, I and Fernández-Martínez, M and González-Rico, C and Fortún, J and Escudero, R and Marco, F and Linares, L and Montejo, M and Aranzamendi, M and Muñoz, P and Valerio, M and Aguado, JM and Resino, E and Ahufinger, IG and Vega, AP and Martínez, L and Fariñas, MC and , }, title = {Biofilm formation by multidrug resistant Enterobacteriaceae strains isolated from solid organ transplant recipients.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {8928}, doi = {10.1038/s41598-019-45060-y}, pmid = {31222089}, issn = {2045-2322}, abstract = {Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant bacteria (MDR). In this study, the biofilm-forming capability of 209 MDR strains (Escherichia coli n = 106, Klebsiella pneumoniae n = 78, and Enterobacter spp. n = 25) isolated from rectal swabs in the first 48 hours before or after kidney (93 patients), liver (60 patients) or kidney/pancreas transplants (5 patients) were evaluated by using a microplate assay. Thirty-nine strains were isolated before transplant and 170 strains were isolated post-transplant. Overall, 16% of E. coli strains, 73% of K. pneumoniae strains and 4% Enterobacter strains showed moderate or strong biofilm production. Nine strains isolated from infection sites after transplantation were responsible of infections in the first month. Of these, 4 K. pneumoniae, 1 E. coli and 1 Enterobacter spp. strains isolated pre-transplant or post-transplant as colonizers caused infections in the post-transplant period. Our results suggest that in vitro biofilm formation could be an important factor for adhesion to intestine and colonization in MDR K. pneumoniae strains in SOT recipients, but this factor appears to be less important for MDR E. coli and Enterobacter spp.}, } @article {pmid31222015, year = {2019}, author = {Tassinari, E and Duffy, G and Bawn, M and Burgess, CM and McCabe, EM and Lawlor, PG and Gardiner, G and Kingsley, RA}, title = {Microevolution of antimicrobial resistance and biofilm formation of Salmonella Typhimurium during persistence on pig farms.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {8832}, doi = {10.1038/s41598-019-45216-w}, pmid = {31222015}, issn = {2045-2322}, support = {BB/R012504/1//RCUK | Biotechnology and Biological Sciences Research Council (BBSRC)/ ; BB/N007964/1//RCUK | Biotechnology and Biological Sciences Research Council (BBSRC)/ ; BB/M025489/1//RCUK | Biotechnology and Biological Sciences Research Council (BBSRC)/ ; 2015028//Teagasc/ ; }, abstract = {Salmonella Typhimurium and its monophasic variant S. 4,[5],12:i:- are the dominant serotypes associated with pigs in many countries. We investigated their population structure on nine farms using whole genome sequencing, and their genotypic and phenotypic variation. The population structure revealed the presence of phylogenetically distinct clades consisting of closely related clones of S. Typhimurium or S. 4,[5],12:i:- on each pig farm, that persisted between production cycles. All the S. 4,[5],12:i:- strains carried the Salmonella genomic island-4 (SGI-4), which confers resistance to heavy metals, and half of the strains contained the mTmV prophage, harbouring the sopE virulence gene. Most clonal groups were highly drug resistant due to the presence of multiple antimicrobial resistance (AMR) genes, and two clades exhibited evidence of recent on-farm plasmid-mediated acquisition of additional AMR genes, including an IncHI2 plasmid. Biofilm formation was highly variable but had a strong phylogenetic signature. Strains capable of forming biofilm with the greatest biomass were from the S. 4,[5],12:i:- and S. Typhimurium DT104 clades, the two dominant pandemic clones found over the last 25 years. On-farm microevolution resulted in enhanced biofilm formation in subsequent production cycle.}, } @article {pmid31220767, year = {2019}, author = {Zhong, H and Wang, H and Tian, Y and Liu, X and Yang, Y and Zhu, L and Yan, S and Liu, G}, title = {Treatment of polluted surface water with nylon silk carrier-aerated biofilm reactor (CABR).}, journal = {Bioresource technology}, volume = {289}, number = {}, pages = {121617}, doi = {10.1016/j.biortech.2019.121617}, pmid = {31220767}, issn = {1873-2976}, abstract = {Carrier aerated biofilm reactor (CABR) with nylon silk as the biofilm growth carrier was constructed to treatment of polluted surface water, which could improve the practical application in comparison with MABR process. The results show that CABR process can effectively improve the self-purification capacity of the polluted surface water, efficient removal of COD and NH3-N, making water quality achieve the level V of Environmental Quality Standards for Surface Water (GB 3838-2002, China). Modified nylon silk can alter the community structures and increase bacteria during CABR process operation. Large pore size of nylon silk leads to the formation of special biofilm structure in CABR. Extracellular polymer (EPS) and membrane fouling resistance distribution indicated that the nylon silk fouling control ability of CABR reactor is much higher than that of membrane-aerated biofilm reactors (MABR). The results show that the CABR process can effectively purify surface water and improve the practical application.}, } @article {pmid31220446, year = {2019}, author = {Lee, TH and Jung, MK and Kim, TK and Pack, CG and Park, YK and Kim, SO and Park, DH}, title = {Safety and efficacy of a metal stent covered with a silicone membrane containing integrated silver particles in preventing biofilm and sludge formation in endoscopic drainage of malignant biliary obstruction: Phase II pilot study.}, journal = {Gastrointestinal endoscopy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.gie.2019.06.007}, pmid = {31220446}, issn = {1097-6779}, abstract = {BACKGROUND AND AIMS: Membrane-covered self-expandable metal stents (SEMSs) have been developed to prolong patency of stents by reducing tissue hyperplasia or tumor ingrowth. However, their effectiveness is attenuated by stent clogging due to biofilm formation on the inner covering surface of membrane. This pilot study planned to evaluate the efficacy and safety of SEMSs covered with a silicone membrane containing integrated silver particles (Ag-P) in malignant distal biliary obstruction.

METHODS: Twenty-four patients who underwent SEMS placement due to malignant distal biliary obstruction were enrolled in this single-center pilot study. The main outcomes were technical success, clinical success, adverse events, stent patency, and survival.

RESULTS: The technical and clinical success rates were 100% and 91.7% (22/24), respectively. The rates of early and late adverse events were 22.7% and 36.4%, respectively. The primary reintervention rate was 27.3% (6/22). Only one case involving stent malfunction was associated with sludge impaction. Median stent patency was 179 days. During follow-up, there were no serious adverse events or mortality related to the stents or Ag-P. Serum and urine silver concentrations before and after stent placement and at 32 weeks after placement did not differ. All serum and urine silver concentrations were <3 μg/L (3 ppb) and 5 μg/L (5 ppb), respectively.

CONCLUSIONS: SEMS covered with a silicone membrane containing integrated Ag-Ps may be effective and safe in malignant distal biliary obstruction. Sludge-impaction-related stent dysfunction may be less frequent using this new stent (cris.nih.go.kr, Identifier: KCT 0002310).}, } @article {pmid31219091, year = {2019}, author = {George, J and Halami, PM}, title = {Presence of extracellular DNA & protein in biofilm formation by gentamicin-resistant Lactobacillus plantarum.}, journal = {The Indian journal of medical research}, volume = {149}, number = {2}, pages = {257-262}, doi = {10.4103/ijmr.IJMR_2022_17}, pmid = {31219091}, issn = {0971-5916}, abstract = {Background & objectives: Bacterial biofilms a multi-layered defence, comprise extracellular DNA (eDNA) and proteins, protect bacteria from harmful environment and nutrient limitation and utilize the mutual benefits within a community. Bacterial biofilms also defend bacteria from harsh environments such as antibiotic treatment. This leads to poor antibiotic penetration, slow growth, adaptive stress responses, and formation of persister cells. This study was done to determine the relation of antibiotic resistance deciphered by the biofilms in Lactobacillus plantarum, a lactic acid bacteria (LAB) with probiotic significance.

Methods: The gentamicin-resistant L. plantarum isolates were allowed to form biofilms and subjected to DNase I and proteinase K treatment. The optical density (OD) values were recorded for the biofilm assay and the cell count for the number of viable cells was taken for the control and the test samples. Percentage reduction was calculated based on the difference between the initial and final OD for both the parameters.

Results: The biofilm assay revealed that the native L. plantarum isolates which were phenotypically susceptible, possessed the ability to form biofilms. The OD values were significantly decreased in comparison to the biofilm-forming control culture when these were treated with DNase I and proteinase K.

The study revealed that the biofilms formed by L. plantarum comprised of eDNA and proteins which was evidenced by the reduction in OD values and percentage in comparison to the control upon DNase I and proteinase K treatment. This indicates that the eDNA and biofilm matrix proteins are vital constituents of biofilms and may carry significant risk when coupled with antibiotic resistance.}, } @article {pmid31218543, year = {2019}, author = {Pepoyan, AZ and Manvelyan, AM and Balayan, MH and Galstyan, S and Tsaturyan, VV and Grigoryan, B and Chikindas, ML}, title = {Low-Dose Electron-Beam Irradiation for the Improvement of Biofilm Formation by Probiotic Lactobacilli.}, journal = {Probiotics and antimicrobial proteins}, volume = {}, number = {}, pages = {}, doi = {10.1007/s12602-019-09566-1}, pmid = {31218543}, issn = {1867-1314}, support = {A-2134//The International Science and Technology Center/ ; 17A-1F010//CANDLE Synchrotron Research Institute foundation/ ; }, abstract = {The effects of 50-150 gray electron-beam irradiation on the biofilm-formation ability and cell surface hydrophobicity of the commercial strain, Lactobacillus acidophilus DDS®-1, from Lacto-G (a marketed synbiotic formulation) and the putative probiotic, L. rhamnosus Vahe, were evaluated. No significant changes in cell surface hydrophobicity were found after irradiation, while increases in biofilm-formation abilities were documented for both investigated microorganisms 0.22 ± 0.03 vs. 0.149 ± 0.02 (L. rhamnosus Vahe, 150 Gy) and 0.218 ± 0.021 vs. 0.17 ± 0.012 (L. acidophilus DDS®-1, 150 Gy). Given this, the use of electron-beam irradiation (50-100 Gy) for the treatment of L. rhamnosus Vahe and L. acidophilus DDS®-1 cells may be considered in product sterilization, quality improvement, and packaging practices.}, } @article {pmid31218489, year = {2019}, author = {De-la-Pinta, I and Cobos, M and Ibarretxe, J and Montoya, E and Eraso, E and Guraya, T and Quindós, G}, title = {Effect of biomaterials hydrophobicity and roughness on biofilm development.}, journal = {Journal of materials science. Materials in medicine}, volume = {30}, number = {7}, pages = {77}, doi = {10.1007/s10856-019-6281-3}, pmid = {31218489}, issn = {1573-4838}, abstract = {Most hospitalized patients are carriers of biomedical devices. Infections associated with these devices cause great morbidity and mortality, especially in patients in intensive care units. Numerous strategies have been designed to prevent biofilm development on biodevices. However, biofilm formation is a complex process not fully clarified. In the current study, roughness and hydrophobicity of different biomaterials was analyzed to assess their influences on the biofilm formation of four leading etiological causes of healthcare-associated infections, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis and Candida albicans, using a CDC biofilm reactor. Hydrophobic materials allowed the formation of more abundant and profuse biofilms. Roughness had effect on biofilm formation, but its influence was not significant when material hydrophobicity was considered.}, } @article {pmid31218468, year = {2019}, author = {Stacchi, C and Del Lupo, V and Berton, F and Lombardi, T and Bressan, R and Di Lenarda, R and Lagatolla, C}, title = {Aspergillus fumigatus biofilm formation on different bone substitutes used in maxillary sinus augmentation: an in vitro analysis.}, journal = {International journal of implant dentistry}, volume = {5}, number = {1}, pages = {22}, doi = {10.1186/s40729-019-0175-5}, pmid = {31218468}, issn = {2198-4034}, abstract = {BACKGROUND: Fungus ball (FB) typically affects healthy adults, and Aspergillus fumigatus is the most frequent etiologic agent: iatrogenic factors represent an important issue in FB pathogenesis. Moreover, a recent study suggested a significant association between the use of anorganic bovine bone as sinus grafting material and subsequent development of FB. The aim of the present investigation is to evaluate in vitro eventual differences in the ability of Aspergillus fumigatus to colonize different bone grafting materials and grow on them as biofilm.

FINDINGS: Five different bone substitutes (demineralized bone matrix, anorganic bovine bone, ß-tricalcium phosphate, synthetic nano-hydroxyapatite, and synthetic hydroxyapatite), commonly used in sinus floor augmentation procedures, were inoculated with conidia suspensions of A. fumigatus and incubated at 37 °C for 4 and 8 h, in standardized conditions. Biofilm bound to the different materials underwent quantitative and qualitative analysis by confocal and scanning electron microscopy. A. fumigatus proved to be able to adhere and form biofilm on all the tested bone substitutes. The surface plot representation of the samples displayed some differences in the density of the superficial layer, due to the physical characteristics of the biomaterials. Nevertheless, Kruskal-Wallis test showed no significant differences in biomass amount among the five bone substitutes (p = 0.236 and p = 0.55 after 4 and 8 h adhesion, respectively).

CONCLUSIONS: All the bone substitutes normally used in sinus floor augmentation represent a favorable substrate for fungal growth, due to their physical and chemical characteristics. During sinus floor elevation procedures, Schneiderian membrane integrity should be maintained in order to avoid the exposure of the grafting material at the respiratory environment, with potential risks of fungal colonization.}, } @article {pmid31217919, year = {2019}, author = {Khalifehzadeh, S and Haghanifar, S and Jenabian, N and Kazemi, S and Hajiahmadi, M}, title = {Clinical and radiographic evaluation of applying 1% metformin biofilm with plasma rich in growth factor (PRGF) for treatment of two-wall intrabony periodontal defects: A randomized clinical trial.}, journal = {Journal of dental research, dental clinics, dental prospects}, volume = {13}, number = {1}, pages = {51-56}, doi = {10.15171/joddd.2019.008}, pmid = {31217919}, issn = {2008-210X}, abstract = {Background . The ultimate aim of periodontal treatment is to regenerate periodontium and regenerative treatment after that. The aim of this study was to evaluate the effect of PRGF with 1% metformin biofilm in the treatment of two-wall intrabony periodontal defects. Methods . In this clinical trial, 8 patients with moderate chronic periodontitis and two-wall intrabony defect were selected. The defects were assigned to 4 groups: debridement, 1% metformin, PRGF, PRGF and metformin. The parameters of vertical probing depth, vertical clinical attachment level and gingival index were measured at baseline, immediately before surgery, and 3 and 6 months after surgery. In addition, the radiographic changes were evaluated with digital subtraction radiography before and 6 months after surgery. Analysis of the results was performed with repeated measurements, Friedman test and chisquared test. Results . All the groups exhibited improvements in all the clinical parameters after 6 months. Inter-group comparison of GI, CAL and PPD parameters revealed no statistically significant differences. Radiographic changes in the group of 1% metformin with PRGF revealed statistically significant differences compared with other groups; however, there were no statistically significant differences in other groups. Conclusion . Application of PRGF with 1% metformin in intrabony two-wall periodontal defects was effective in improving the clinical parameters but this effect revealed no difference compared with other groups; however, in terms of radiographic changes significant improvements were noted.}, } @article {pmid31217374, year = {2019}, author = {Zhou, G and Peng, H and Wang, YS and Huang, XM and Xie, XB and Shi, QS}, title = {Enhanced synergistic effects of xylitol and isothiazolones for inhibition of initial biofilm formation by Pseudomonas aeruginosa ATCC 9027 and Staphylococcus aureus ATCC 6538.}, journal = {Journal of oral science}, volume = {61}, number = {2}, pages = {255-263}, doi = {10.2334/josnusd.18-0102}, pmid = {31217374}, issn = {1880-4926}, abstract = {Bacterial biofilms, formed on biotic or abiotic surfaces, can lead to serious environmental or medical problems. Therefore, it is necessary to find novel antimicrobial agents to combat biofilms, or more effective combinations of existing biocides. In this study, initial biofilms of Pseudomonas aeruginosa ATCC 9027 and Staphylococcus aureus ATCC 6538 in the presence of xylitol or xylitol and isothiazolones were determined using crystal violet staining in 96-well microplates and confocal laser scanning microscopy. Xylitol and isothiazolones exhibited enhanced synergistic inhibition of initial biofilm formation, and also the structure and production of extracellular polymeric substances by P. aeruginosa ATCC 9027 and S. aureus ATCC 6538 in a dose-dependent manner. In addition, xylitol and isothiazolones inhibited and restored the swimming motility of P. aeruginosa ATCC 9027, respectively. These findings show that a combination of xylitol and isothiazolones exerts pronounced antimicrobial activity against P. aeruginosa and S. aureus biofilms and may be applicable for preventing or reducing bacterial biofilms in vitro.}, } @article {pmid31217292, year = {2019}, author = {Arnaouteli, S and Matoz-Fernandez, DA and Porter, M and Kalamara, M and Abbott, J and MacPhee, CE and Davidson, FA and Stanley-Wall, NR}, title = {Pulcherrimin formation controls growth arrest of the Bacillus subtilis biofilm.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {116}, number = {27}, pages = {13553-13562}, doi = {10.1073/pnas.1903982116}, pmid = {31217292}, issn = {1091-6490}, support = {//Wellcome Trust/United Kingdom ; }, abstract = {Biofilm formation by Bacillus subtilis is a communal process that culminates in the formation of architecturally complex multicellular communities. Here we reveal that the transition of the biofilm into a nonexpanding phase constitutes a distinct step in the process of biofilm development. Using genetic analysis we show that B. subtilis strains lacking the ability to synthesize pulcherriminic acid form biofilms that sustain the expansion phase, thereby linking pulcherriminic acid to growth arrest. However, production of pulcherriminic acid is not sufficient to block expansion of the biofilm. It needs to be secreted into the extracellular environment where it chelates Fe3+ from the growth medium in a nonenzymatic reaction. Utilizing mathematical modeling and a series of experimental methodologies we show that when the level of freely available iron in the environment drops below a critical threshold, expansion of the biofilm stops. Bioinformatics analysis allows us to identify the genes required for pulcherriminic acid synthesis in other Firmicutes but the patchwork presence both within and across closely related species suggests loss of these genes through multiple independent recombination events. The seemingly counterintuitive self-restriction of growth led us to explore if there were any benefits associated with pulcherriminic acid production. We identified that pulcherriminic acid producers can prevent invasion by neighboring communities through the generation of an "iron-free" zone, thereby addressing the paradox of pulcherriminic acid production by B. subtilis.}, } @article {pmid31216375, year = {2019}, author = {Palmioli, A and Sperandeo, P and Polissi, A and Airoldi, C}, title = {Targeting bacterial biofilm: a new LecA multivalent ligand with inhibitory activity.}, journal = {Chembiochem : a European journal of chemical biology}, volume = {}, number = {}, pages = {}, doi = {10.1002/cbic.201900383}, pmid = {31216375}, issn = {1439-7633}, abstract = {Biofilm formation by bacterial pathogens is a hallmark of chronic infections and is associated to increased antibiotic tolerance that makes pathogens difficult to eradicate with conventional antibiotic therapies. Infections caused by Pseudomonas aeruginosa are of great concern, especially for immunocompromised and cystic fibrosis patients. P. aeruginosa lectins LecA and LecB are virulence factors and play a key role in establishing biofilm; therefore, inhibition of the function of these proteins has potential in dismantling the bacterium from the protective biofilm environment and in restoring the activity of antibiotics. Here we report the NMR characterization of the binding of a galactose-based dendrimer (Gal18) to LecA. Moreover, we demonstrate the activity of Gal18 molecule in inhibiting P. aeruginosa biofilm formation in vitro.}, } @article {pmid31216354, year = {2019}, author = {Pickering, AC and Vitry, P and Prystopiuk, V and Garcia, B and Höök, M and Schoenebeck, J and Geoghegan, JA and Dufrêne, YF and Fitzgerald, JR}, title = {Host-specialized fibrinogen-binding by a bacterial surface protein promotes biofilm formation and innate immune evasion.}, journal = {PLoS pathogens}, volume = {15}, number = {6}, pages = {e1007816}, doi = {10.1371/journal.ppat.1007816}, pmid = {31216354}, issn = {1553-7374}, abstract = {Fibrinogen is an essential part of the blood coagulation cascade and a major component of the extracellular matrix in mammals. The interface between fibrinogen and bacterial pathogens is an important determinant of the outcome of infection. Here, we demonstrate that a canine host-restricted skin pathogen, Staphylococcus pseudintermedius, produces a cell wall-associated protein (SpsL) that has evolved the capacity for high strength binding to canine fibrinogen, with reduced binding to fibrinogen of other mammalian species including humans. Binding occurs via the surface-expressed N2N3 subdomains, of the SpsL A-domain, to multiple sites in the fibrinogen α-chain C-domain by a mechanism analogous to the classical dock, lock, and latch binding model. Host-specific binding is dependent on a tandem repeat region of the fibrinogen α-chain, a region highly divergent between mammals. Of note, we discovered that the tandem repeat region is also polymorphic in different canine breeds suggesting a potential influence on canine host susceptibility to S. pseudintermedius infection. Importantly, the strong host-specific fibrinogen-binding interaction of SpsL to canine fibrinogen is essential for bacterial aggregation and biofilm formation, and promotes resistance to neutrophil phagocytosis, suggesting a key role for the interaction during pathogenesis. Taken together, we have dissected a bacterial surface protein-ligand interaction resulting from the co-evolution of host and pathogen that promotes host-specific innate immune evasion and may contribute to its host-restricted ecology.}, } @article {pmid31214138, year = {2019}, author = {Flament-Simon, SC and Duprilot, M and Mayer, N and García, V and Alonso, MP and Blanco, J and Nicolas-Chanoine, MH}, title = {Association Between Kinetics of Early Biofilm Formation and Clonal Lineage in Escherichia coli.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {1183}, doi = {10.3389/fmicb.2019.01183}, pmid = {31214138}, issn = {1664-302X}, abstract = {Background: Escherichia coli biofilm formation has mostly been assessed in specific pathogenic E. coli groups. Here, we assessed the early biofilm formation (EBF), i.e., adhesion stage, using the BioFilm Ring Test® on 394 E. coli clinical isolates (EC) [196 consecutively isolated (CEC) in 2016 and 198 ESBL-producing E. coli (ESBLEC) isolated in 2015]. Then, biofilm-forming ability was contrasted with phylogroups, clonotypes (fumC-fimH), and sequence types (STs), all being used to define clones, virulence factors (VF), and FimB.

Result: According to both biofilm production levels at 2, 3, and 5 h, and EBF kinetics over 5 h, CEC and ESBLEC isolates segregated into three EBF groups: strong (G1), moderate (G2), and weak (G3) producers. At 2 h, strong producers were more frequent among CEC (n = 28; 14.3%) than among ESBLEC (n = 8; 4%) (P = 0.0004). As CEC and ESBLEC isolates showed similar individual EBF kinetics in each group, a comparison of isolate features between each group was applied to gathered CEC and ESBLEC isolates after 2 h of incubation, 2 h being the most representative time point of the CEC and ESBLEC isolate segregation into the three groups. Phylogroup B2 displayed by 51.3% of the 394 isolates was more frequent in G1 (77.8%) than in G3 (47.6%) (P = 0.0006). The 394 isolates displayed 153 clones, of which 31 included at least three isolates. B2-CH14-2-ST127, B2-CH40-22-ST131, B2-CH52-5/14-ST141, and E-CH100-96-ST362 clones were associated with G1 (P < 0.03) and accounted for 41.7% of G1 isolates. B2-CH40-30-ST131 clone was associated with G3 (P < 0.0001) and accounted for 25.5% of G3 isolates. VF mean was higher among G1 than among G3 isolates (P < 0.001). FimB-P2 variant was associated with G1 (P = 0.0011) and FimB-P1 variant was associated with G3 (P = 0.0023). Clone, some VF, and FimB were associated with EBF, with clonal lineage being able to explain 72% of the variability of EBF.

Conclusion: Among our 394 isolates, <10% are able to quickly and persistently produce high biofilm levels over 5 h. These isolates belong to a few clones previously described in various studies as dominant gut colonizers in mammalians and birds and comprised the B2-CH40-22-ST131 clone, i.e., the ancestor of the globally disseminated B2-CH40-30-ST131 clone that is the dominant clone among the weak biofilm producers.}, } @article {pmid31213555, year = {2019}, author = {Keogh, D and Lam, LN and Doyle, LE and Matysik, A and Pavagadhi, S and Umashankar, S and Low, PM and Dale, JL and Song, Y and Ng, SP and Boothroyd, CB and Dunny, GM and Swarup, S and Williams, RBH and Marsili, E and Kline, KA}, title = {Correction for Keogh et al., "Extracellular Electron Transfer Powers Enterococcus faecalis Biofilm Metabolism".}, journal = {mBio}, volume = {10}, number = {3}, pages = {}, doi = {10.1128/mBio.01080-19}, pmid = {31213555}, issn = {2150-7511}, } @article {pmid31212792, year = {2019}, author = {Cepas, V and López, Y and Gabasa, Y and Martins, CB and Ferreira, JD and Correia, MJ and Santos, LMA and Oliveira, F and Ramos, V and Reis, M and Castelo-Branco, R and Morais, J and Vasconcelos, V and Probert, I and Guilloud, E and Mehiri, M and Soto, SM}, title = {Inhibition of Bacterial and Fungal Biofilm Formation by 675 Extracts from Microalgae and Cyanobacteria.}, journal = {Antibiotics (Basel, Switzerland)}, volume = {8}, number = {2}, pages = {}, doi = {10.3390/antibiotics8020077}, pmid = {31212792}, issn = {2079-6382}, support = {634588//Horizon 2020 Framework Programme/ ; }, abstract = {Bacterial biofilms are complex biological systems that are difficult to eradicate at a medical, industrial, or environmental level. Biofilms confer bacteria protection against external factors and antimicrobial treatments. Taking into account that about 80% of human infections are caused by bacterial biofilms, the eradication of these structures is a great priority. Biofilms are resistant to old-generation antibiotics, which has led to the search for new antimicrobials from different sources, including deep oceans/seas. In this study, 675 extracts obtained from 225 cyanobacteria and microalgae species (11 phyla and 6 samples belonging to unknown group) were obtained from different culture collections: The Blue Biotechnology and Ecotoxicology Culture Collection (LEGE-CC), the Coimbra Collection of Algae (ACOI) from Portugal, and the Roscoff Culture Collection (RCC) from France. The largest number of samples was made up of the microalgae phylum Chlorophyta (270) followed by Cyanobacteria (261). To obtain a large range of new bioactive compounds, a method involving three consecutive extractions (hexane, ethyl acetate, and methanol) was used. The antibiofilm activity of extracts was determined against seven different bacterial species and two Candida strains in terms of minimal biofilm inhibitory concentration (MBIC). The highest biofilm inhibition rates (%) were achieved against Candida albicans and Enterobacter cloacae. Charophyta, Chlorophyta, and Cyanobacteria were the most effective against all microorganisms. In particular, extracts of Cercozoa phylum presented the lowest MBIC50 and MBIC90 values for all the strains except C. albicans.}, } @article {pmid31211205, year = {2019}, author = {Heuschkel, I and Hoschek, A and Schmid, A and Bühler, B and Karande, R and Bühler, K}, title = {Data on mixed trophies biofilm for continuous cyclohexane oxidation to cyclohexanol using Synechocystis sp. PCC 6803.}, journal = {Data in brief}, volume = {25}, number = {}, pages = {104059}, doi = {10.1016/j.dib.2019.104059}, pmid = {31211205}, issn = {2352-3409}, abstract = {Photosynthetic microorganisms offer promising perspectives for the sustainable production of value-added compounds. Nevertheless, the cultivation of phototrophic organisms to high cell densities (HCDs) is hampered by limited reactor concepts. Co-cultivation of the photoautotrophic Synechocystis sp. PCC 6803 and the chemoheterotrophic P. taiwanensis VLB 120 enabled HCDs up to 51.8 gCDW L-1. Respective biofilms have been grown as a biofilm in capillary flow-reactors, and oxygen evolution, total biomass, as well as the ratio of the two strains, have been followed under various cultivation conditions. Furthermore, biofilm formation on a microscopic level was analyzed via confocal laser scanning microscopy using a custom made flow-cell setup. The concept of mixed trophies co-cultivation was coupled to biotransformation, namely the oxyfunctionalization of cyclohexane to cyclohexanol. For benchmarking, the performance of the phototrophic reaction was compared to the chemical process, and to a biotechnological approach using a heterotrophic organism only. The data presented refer to our research paper "Mixed-species biofilms for high-cell-density application of Synechocystis sp. PCC 6803 in capillary reactors for continuous cyclohexane oxidation to cyclohexanol" Hoschek et al., 2019.}, } @article {pmid31209011, year = {2019}, author = {Rodríguez López, AL and Lee, MR and Wang, NB and Dunn, KK and Sanchez, H and Raman, N and Andes, DR and Lynn, DM and Palecek, SP}, title = {Small-molecule morphogenesis modulators enhance the ability of 14-helical β-peptides to prevent Candida albicans biofilm formation.}, journal = {Antimicrobial agents and chemotherapy}, volume = {}, number = {}, pages = {}, doi = {10.1128/AAC.02653-18}, pmid = {31209011}, issn = {1098-6596}, abstract = {Candida albicans is an opportunistic fungal pathogen responsible for mucosal candidiasis and systemic candidemia in humans. Often these infections are associated with the formation of drug-resistant biofilms on the surfaces of tissues or medical devices. Increased incidence of C. albicans resistance to current antifungals has heightened the need for new strategies to prevent or eliminate biofilm-related fungal infections. In prior studies we designed 14-helical β-peptides to mimic the structural properties of natural antimicrobial α-peptides (AMPs) in an effort to develop active and selective antifungal compounds. These amphiphilic, cationic, helical β-peptides exhibited antifungal activity against planktonic C. albicans cells and inhibited biofilm formation in vitro and in vivo Recent studies have suggested the use of anti-virulence agents in combination with antifungals. In this study we investigated the use of compounds that target C. albicans polymorphism, such as 1-dodecanol, isoamyl alcohol and farnesol, to attempt to improve β-peptide efficacy for preventing C. albicans biofilms. Isoamyl alcohol, which prevents hyphal formation, reduced the minimum biofilm prevention concentrations (MBPCs) of β-peptides by up to 128-fold. Combinations of isoamyl alcohol and antifungal β-peptides resulted in less than 10% hemolysis at the antifungal MBPCs. Overall, our results suggest potential benefits of combination therapies comprised of morphogenesis modulators and antifungal AMP peptidomimetics for preventing C. albicans biofilm formation.}, } @article {pmid31207891, year = {2019}, author = {Fu, TK and Ng, SK and Chen, YE and Lee, YC and Demeter, F and Herczeg, M and Borbás, A and Chiu, CH and Lan, CY and Chen, CL and Chang, MD}, title = {Rhamnose Binding Protein as an Anti-Bacterial Agent-Targeting Biofilm of Pseudomonas aeruginosa.}, journal = {Marine drugs}, volume = {17}, number = {6}, pages = {}, doi = {10.3390/md17060355}, pmid = {31207891}, issn = {1660-3397}, support = {MOST 103-2627-M-007-006//Ministry of Science and Technology/ ; MOST 107-0210-01-19-04//Ministry of Science and Technology/ ; GINOP-2.3.2-15-2016-00008//European Regional Development Fund/ ; ÚNKP-18-3 New National Excellence Program//Ministry of Human Capacities of Hungary/ ; }, abstract = {More than 80% of infectious bacteria form biofilm, which is a bacterial cell community surrounded by secreted polysaccharides, proteins and glycolipids. Such bacterial superstructure increases resistance to antimicrobials and host defenses. Thus, to control these biofilm-forming pathogenic bacteria requires antimicrobial agents with novel mechanisms or properties. Pseudomonas aeruginosa, a Gram-negative opportunistic nosocomial pathogen, is a model strain to study biofilm development and correlation between biofilm formation and infection. In this study, a recombinant hemolymph plasma lectin (rHPLOE) cloned from Taiwanese Tachypleus tridentatus was expressed in an Escherichia coli system. This rHPLOE was shown to have the following properties: (1) Binding to P. aeruginosa PA14 biofilm through a unique molecular interaction with rhamnose-containing moieties on bacteria, leading to reduction of extracellular di-rhamnolipid (a biofilm regulator); (2) decreasing downstream quorum sensing factors, and inhibiting biofilm formation; (3) dispersing the mature biofilm of P. aeruginosa PA14 to improve the efficacies of antibiotics; (4) reducing P. aeruginosa PA14 cytotoxicity to human lung epithelial cells in vitro and (5) inhibiting P. aeruginosa PA14 infection of zebrafish embryos in vivo. Taken together, rHPLOE serves as an anti-biofilm agent with a novel mechanism of recognizing rhamnose moieties in lipopolysaccharides, di-rhamnolipid and structural polysaccharides (Psl) in biofilms. Thus rHPLOE links glycan-recognition to novel anti-biofilm strategies against pathogenic bacteria.}, } @article {pmid31207076, year = {2019}, author = {Liang, D and Li, H and Xu, X and Liang, J and Dai, X and Zhao, W}, title = {Rational design of peptides with enhanced antimicrobial and anti-biofilm activities against cariogenic bacterium Streptococcus mutans.}, journal = {Chemical biology & drug design}, volume = {}, number = {}, pages = {}, doi = {10.1111/cbdd.13579}, pmid = {31207076}, issn = {1747-0285}, support = {2018B030311047//the Science and Technology Department of Guangdong Province, China/ ; JCYJ20160428142231354//the Science and Technology Program of Shenzhen, China/ ; 201804010419//the Science and Technology Program of Guangzhou, China/ ; }, abstract = {Streptococcus mutans (S. mutans) is known to be a leading cariogenic pathogen in the oral cavity. Antimicrobial peptides possess excellent properties to combat such pathogens. In this study, we compared the antimicrobial activity of novel linear reutericin 6- and/or gassericin A-inspired peptides and identified LR-10 as the leading peptide. Antibacterial assays demonstrate that LR-10 is more active against S. mutans (3.3 μM) than many peptide-based agents without resistance selection, capable of killing many oral pathogens, and tolerant of physiological conditions. LR-10 also presented a faster killing rate than chlorhexidine and erythromycin, and appeared to display selective activity against S. mutans within 10 s. S. mutans is usually encased in plaque biofilms. Biofilm inhibitory assays indicated that LR-10 had excellent inhibitory effect on the biofilm formation of S. mutans and biofilm-encased cells in vitro at low concentrations (6.5 μM). Consistent with most peptides, LR-10 kills S. mutans mainly by disrupting the cell membranes. Notably, both hemolytic activity assays and cytotoxicity tests indicated that LR-10 could keep biocompatible at the effective concentrations. Hence, LR-10 could be a good candidate for clinical treatment of dental caries.}, } @article {pmid31206966, year = {2019}, author = {Melian, C and Segli, F and Gonzalez, R and Vignolo, G and Castellano, P}, title = {Lactocin AL705 as quorum sensing inhibitor to control Listeria monocytogenes biofilm formation.}, journal = {Journal of applied microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1111/jam.14348}, pmid = {31206966}, issn = {1365-2672}, support = {PICT2016, PICT2014//Agencia Nacional de Promoción Científica y Tecnológica/ ; 0585//Agencia Nacional de Promoción Científica y Tecnológica/ ; 441//Consejo Nacional de Investigaciones Científicas y Técnicas/ ; }, abstract = {AIMS: The control of Listeria monocytogenes biofilm formation using lactocin AL705 bacteriocin at sub-minimum inhibitory concentrations (MICs) through an antiquorum sensing strategy, was preliminarily investigated.

METHODS AND RESULTS: The screening for biofilm formation of different Listeria species at 10°C allowed selecting L. monocytogenes FBUNT for its use as biofilm producer. MIC and minimum bactericidal concentration of lactocin AL705 purified extract against the pathogen was determined. Bacteriocin sub-MICs were used to evaluate biofilm reduction. Concentrations between 2·5-20 AU ml-1 of lactocin AL705 produced significant decreases in biofilm formation without affecting the growth of the pathogen after 3 days of incubation. When bacteriocin concentrations (5-20 arbitrary units per millilitre (AU ml-1)) were investigated as quorum sensing (QS) inhibitors using Vibrio harveyi as reporter strain, a significant reduction in luminescence by lactocin AL705 (20 AU ml-1) was observed. Even when L. monocytogenes produced AI-2 like molecules as recognized by the reporter strain, bacteriocins did not interfere with this compound.

CONCLUSION: Antilisterial lactocin AL705 used to disrupt QS through a signal molecule inactivation was able to control L. monocytogenes FBUNT biofilm formation. Other molecule(s) different from the AI-2 involved during biofilm formation could be acting as target of the bacteriocin.

The use of bacteriocins derived from food-grade micro-organisms as a QS inhibition represents an effective strategy to control pathogens as well as an environmentally friendly sanitation method to mitigate postprocessing food contamination.}, } @article {pmid31202712, year = {2019}, author = {Zhao, Y and Liu, D and Huang, W and Yang, Y and Ji, M and Nghiem, LD and Trinh, QT and Tran, NH}, title = {Insights into biofilm carriers for biological wastewater treatment processes: Current state-of-the-art, challenges, and opportunities.}, journal = {Bioresource technology}, volume = {288}, number = {}, pages = {121619}, doi = {10.1016/j.biortech.2019.121619}, pmid = {31202712}, issn = {1873-2976}, abstract = {Biofilm carriers play an important role in attached growth systems for wastewater treatment processes. This study systematically summarizes the traditional and novel biofilm carriers utilized in biofilm-based wastewater treatment technology. The advantages and disadvantages of traditional biofilm carriers are evaluated and discussed in light of basic property, biocompatibility and applicability. The characteristics, applications performance, and mechanism of novel carriers (including slow-release carriers, hydrophilic/electrophilic modified carriers, magnetic carriers and redox mediator carriers) in wastewater biological treatment were deeply analyzed. Slow release biofilm carriers are used to provide a solid substrate and electron donor for the growth of microorganisms and denitrification for anoxic and/or anaerobic bioreactors. Carriers with hydrophilic/electrophilic modified surface are applied for promoting biofilm formation. Magnetic materials-based carriers are employed to shorten the start-up time of bioreactor. Biofilm carriers acting as redox mediators are used to accelerate biotransformation of recalcitrant pollutants in industrial wastewater.}, } @article {pmid31202424, year = {2019}, author = {Moraes, JO and Cruz, EA and Pinheiro, Í and Oliveira, TCM and Alvarenga, V and Sant'Ana, AS and Magnani, M}, title = {An ordinal logistic regression approach to predict the variability on biofilm formation stages by five Salmonella enterica strains on polypropylene and glass surfaces as affected by pH, temperature and NaCl.}, journal = {Food microbiology}, volume = {83}, number = {}, pages = {95-103}, doi = {10.1016/j.fm.2019.04.012}, pmid = {31202424}, issn = {1095-9998}, abstract = {This study assessed the adhesion and formation of biofilm by five Salmonella enterica strains (S. Enteritidis 132, S. Infantis 176, S. Typhimurium 177, S. Heidelberg 281 and S. Corvallis 297) on polypropylene (PP) and glass (G) surfaces as affected by pH (4-7), NaCl concentration (0-10% w/v) and temperature (8-35 °C). Sessile counts <3 log CFU/cm2 were considered lack of adhesion (category 1), while counts ≥ 3 and < 5 log CFU/cm2 corresponded to adhesion (category 2) and counts ≥ 5 log CFU/cm2 corresponded biofilm formation (category 3). The obtained results categorized in these three responses were used to develop ordinal regression models to predict the probability of biofilm stages on PP- and G-surfaces. The experimental outcomes for lack of adhesion were >90% on PP- and G-surfaces. Generally, adhesion outcomes corresponded to approximately 36% of the total, whereas biofilm outcomes were close to 65% in both PP- and G-surfaces. The biofilm stages varied among the strains studied and with the material surface under the same experimental conditions. According to the generated ordinal models, the probability of adhesion and biofilm formation on PP-surface by the five S. enterica strains tested decreased at pH 4 or 5 in NaCl concentrations >4% and at a temperature <20 °C. On G-surface, the probability of adhesion increased pH 6 or 7, in the absence of NaCl and temperatures <20 °C, while, the probability of biofilm formation increased in the same pH, NaCl concentration up to 4% and temperatures ≥20 °C. This is the first study assessing the biofilm formation through categorical, ordinal responses and it shows that ordinal regression models can be useful to predict biofilm stages of S. enterica as a function of pH, NaCl, and temperature or their interactions.}, } @article {pmid31202413, year = {2019}, author = {García-Sánchez, L and Melero, B and Jaime, I and Rossi, M and Ortega, I and Rovira, J}, title = {Biofilm formation, virulence and antimicrobial resistance of different Campylobacter jejuni isolates from a poultry slaughterhouse.}, journal = {Food microbiology}, volume = {83}, number = {}, pages = {193-199}, doi = {10.1016/j.fm.2019.05.016}, pmid = {31202413}, issn = {1095-9998}, abstract = {The fastidious requirement of the zoonotic pathogen Campylobacter jejuni contrasts with its ability to overcome harsh conditions. Different strategies might be involved in the survival and persistence of C. jejuni through the poultry food chain. Therefore, the aims of this study were to get insights in the survival strategies in the poultry slaughterhouse environment by (i) characterizing factors such as biofilm formation, virulence and antimicrobial resistance in environmental isolates and (ii) understanding the possible link between the phenotypic and genetic characterization using whole genome sequencing (WGS). Results have shown that three STs: ST 443 (PFGE A), ST 904 (PFGE C) and ST 3769 (PFGE G), out of the six studied, formed biofilms with variable intensity according to different conditions (temperatures -37 °C, 30 °C, 25°C- and materials -stainless steel and plastic-). High levels of antimicrobial resistance were found in isolates to ciprofloxacin, nalidixic acid and tetracycline as well as to two common detergents used in the slaughterhouse. A combination of several changes in the genome of ST 904 (PFGE C) including mutations, insertions in antimicrobial resistance genes, the presence of T6SS and a set of genes related to virulence factors might explain its ability to form biofilm and persist longer in the environment. However, the complexity of the survival strategies adopted by the different strains of C. jejuni suggests that multiple mechanisms may exist that allow these organisms to persist and ultimately cause disease in humans.}, } @article {pmid31200347, year = {2019}, author = {Dawas, A and Abu-Salih, S and Sabbah, I and Nejidat, A and Dosoretz, CG}, title = {Controlling nitritation in a continuous split-feed/aeration biofilm nitrifying bioreactor.}, journal = {Bioresource technology}, volume = {288}, number = {}, pages = {121599}, doi = {10.1016/j.biortech.2019.121599}, pmid = {31200347}, issn = {1873-2976}, abstract = {This study explored the stability of partial ammonium oxidation at low feed concentration (50 g N/m3), suitable for anammox process, in continuous fixed bed up-flow biofilm reactors with external recirculation-aeration. The reactors, filled with crushed basalt, were fed with synthetic medium at 20-25 °C at constant flow-rate with limiting dissolved oxygen concentration controlled by the recirculation ratio (R). Successful nitritation was achieved at R ≅ 4-6 with approx. 50% of NH4+ oxidized to NO2- with <5% NO3-accumulation. q-PCR analysis along the reactor showed ammonia oxidizing bacteria being the prevalent nitrifiers over the three-fourths of the bed in the flow direction, negligible denitrifiers and absent ammonium oxidizing archaea. A numerical model for predicting the concentration of the nitrogen species and DO was formulated. The model successfully predicted the experimental results and displayed good sensitivity to intrinsic oxygen uptake parameters. The proposed numerical model can serve both as an operational and design tool.}, } @article {pmid31198058, year = {2019}, author = {Manilal, A and Shewangizaw, M and Mama, M and Gezmu, T and Merdekios, B}, title = {Methicillin-resistant Staphylococcus aureus colonization in HIV patients of Arba Minch province, Ethiopia: Carriage rates, antibiotic resistance, and biofilm formation.}, journal = {Acta microbiologica et immunologica Hungarica}, volume = {}, number = {}, pages = {1-15}, doi = {10.1556/030.66.2019.014}, pmid = {31198058}, issn = {1588-2640}, abstract = {Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a significant opportunistic pathogen among human immunodeficiency virus (HIV) patients of Ethiopia. This study aimed at delineating the prevalence, antimicrobial resistance, and biofilm-forming potentials of nasally colonized MRSA among HIV patients in the Arba Minch province of Ethiopia. A cross-sectional study was performed in HIV patients who visit anti-retroviral therapy clinic of the Arba Minch Hospital between February and April 2017. Nasal samples were collected and inspected for Staphylococcus following standard procedures. MRSA was identified using cefoxitin disk and antibiotics sensitivity test was performed as per Kirby-Baur disk diffusion method. The formation of biofilm was inspected using both qualitative and quantitative methods. A total of 307 HIV patients were examined. The overall prevalence of S. aureus was found to be 39.7%. The prevalence of MRSA was 20.8%. The rate of nasal colonization of MRSA was relatively higher among females. In bivariate analysis, MRSA colonization was statistically significant in patients with CD4 count ≤350 (p value = 0.002) and co-trimoxazole prophylaxis (p value = 0.003). Concomitant resistance to erythromycin, tetracycline, and co-trimoxazole were 48.4%, 45.3%, and 39.0%, respectively. Invariably, all MRSA isolates were 100% sensitive to vancomycin. Of the 64 MRSA isolates, 18.7% were considered as multidrug-resistant. The rate of biofilm formation was 34.3%. The results revealed a high prevalence rate in the nasal colonization of MRSA in HIV patients.}, } @article {pmid31198057, year = {2019}, author = {Shivaee, A and Mohammadzadeh, R and Shahbazi, S and Pardakhtchi, E and Ohadi, E and Kalani, BS}, title = {Time-variable expression levels of mazF, atlE, sdrH, and bap genes during biofilm formation in Staphylococcus epidermidis.}, journal = {Acta microbiologica et immunologica Hungarica}, volume = {}, number = {}, pages = {1-10}, doi = {10.1556/030.66.2019.019}, pmid = {31198057}, issn = {1588-2640}, abstract = {Staphylococcus epidermidis is an opportunistic pathogen causing infections related to the usage of implants and medical devices. Pathogenicity of this microorganism is mainly linked to its capability to form biofilm structures. Biofilm formation vastly depends on several factors including different proteins. We studied the expression levels of three proteins including SdrH, Bap, AtlE, and MazF at different time intervals during the course of biofilm formation. In this study, a catheter-derived S. epidermidis isolate with strong ability of biofilm formation was selected. PCR assay was used to detect sdrH, bap, atlE, and mazF genes in this isolate. Real-time PCR was used to determine the expression levels of these genes after 4, 8, and 20 h during the course of biofilm formation. The studied genes showed different expression levels at different time intervals during biofilm formation by real-time PCR method. Expression levels of atlE and sdrH genes were the highest at 4 h, whereas bap gene showed the highest expression level at 8 h during the course of biofilm formation. In addition, the expression level of mazF gene peaked at 4 h and then progressively decreased at 8 and 20 h. Our results suggest the importance of AtlE, SdrH, and MazF proteins in the establishment and development of the biofilm structure. In addition, our results showed the important role of protein Bap in the accumulation of biofilm structure. Future studies are required to understand the exact role of MazF in the process of biofilm formation.}, } @article {pmid31197408, year = {2019}, author = {Ariafar, MN and Iğci, N and Akçelik, M and Akçelik, N}, title = {Investigation of the effect of different environmental conditions on biofilm structure of Salmonella enterica serotype Virchow via FTIR spectroscopy.}, journal = {Archives of microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00203-019-01681-5}, pmid = {31197408}, issn = {1432-072X}, abstract = {This study aims to describe the content of polymeric matrix components under different incubation temperatures and pH levels. Optimal biofilm production of 15 S. Virchow isolates occurred following the incubation in LB-NaCl for 72 h, at pH 6.6 and 20 °C. The expression of csgA, csgD, adrA and bcsA genes at 20 °C, 25 °C and 30 °C in S. Virchow DMC18 was analyzed, and it was discovered that the maximum production of cellulose and curli fimbriae occurred at 20 °C. The physical characteristics of pellicle structure of S. Virchow DMC18 was determined as rigid at 20 °C, while becoming fragile at higher temperatures. FTIR analyses confirmed the obtained molecular findings. The intensities of the 16 different peaks originating from carbohydrate, protein, and nucleic acid in the spectra of biofilm samples significantly diminished (p < 0.05) with the increasing temperature. The highest intensities of lipids and carbohydrates were observed at 20 °C indicating the changes in cell surface properties.}, } @article {pmid31195653, year = {2019}, author = {Zhou, Y and Gao, X}, title = {Characterization of Biofilm Formed by Phenanthrene-Degrading Bacteria on Rice Root Surfaces for Reduction of PAH Contamination in Rice.}, journal = {International journal of environmental research and public health}, volume = {16}, number = {11}, pages = {}, doi = {10.3390/ijerph16112002}, pmid = {31195653}, issn = {1660-4601}, support = {No. 31200084//Funding from the Natural Sciences Foundation of China./ ; }, abstract = {One effective method in to reduce the uptake of organic contaminants by plants is the development of a root barrier. In this study, the characterization of biofilm structure and function by phenanthrene-degrading Pseudomonas sp. JM2-gfp on rice root surfaces were carried out. Our results showed that root surfaces from three rice species, namely Liaojing401, Koshihikari, and Zhenzhuhong all present hydrophobicity and a high initial adhesion of strain JM2-gfp. Matured robust biofilm formation occurred at 48 h on the root surfaces. The biofilm exhibited cell dense aggregates and biomass embedded in the extracellular polymeric substance (EPS) matrix. EPS composition results showed that the proteins, carbohydrates, lipids and nucleic acids are produced in the biofilm, while the content varied with rice species. Under the initial concentration of phenanthrene 50 mg·L-1, the residual phenanthrene in plant roots from 'Zhengzhuhong', 'Koshihikari' and 'Liaojing401' with biofilm mediated were significantly decreased by 71.9%, 69.3% and 58.7%, respectively, compared to those without biofilm groups after 10 days of exposure. Thus, the biofilm colonized on roots plays an important role of degradation in order to reduce the level of phenanthrene uptake of plants. Thereby, the present work provides significant new insights into lowering the environmental risks of polycyclic aromatic hydrocarbons (PAHs) in crop products from contaminated agriculture soils.}, } @article {pmid31195361, year = {2019}, author = {Zheng, M and Zhu, H and Han, Y and Xu, C and Zhang, Z and Han, H}, title = {Comparative investigation on carbon-based moving bed biofilm reactor (MBBR) for synchronous removal of phenols and ammonia in treating coal pyrolysis wastewater at pilot-scale.}, journal = {Bioresource technology}, volume = {288}, number = {}, pages = {121590}, doi = {10.1016/j.biortech.2019.121590}, pmid = {31195361}, issn = {1873-2976}, abstract = {By regulating the extraction solvent and alkali in pretreatment, two carbon-based MBBRs were compared in pilot-scale to synchronously remove phenols and ammonia of coal pyrolysis wastewater (CPW) under fluctuant phenols-ammonia loadings. It revealed that lignite activated coke (LAC)-based MBBR performed more stable with phenols increasing (250-550 mg/L), and reached higher tolerance limit to ammonia (>320 mg/L) than activated carbon (AC)-based MBBR under fluctuant ammonia loadings. During the phenols-ammonia synchronous removal process, the LAC provided the firm basis for shock resistance due to superior resilient adsorption capacity, enhanced sludge property and microbial cooperation. Furthermore, microbial analysis revealed that the strengthened collaboration between archaea and facultative bacteria played the primary role in phenols-ammonia synchronous degradation. Specifically, the heterotrophic bacteria consumed phenols-ammonia by partial nitrification process and ammonia assimilation, following by denitrifying process to further eliminate phenols. The multifunctional Comamonas was the critical genus participating in all procedures.}, } @article {pmid31194941, year = {2019}, author = {Zeng, R and Xu, H and Liu, Y and Du, L and Duan, Z and Tong, J and He, Y and Chen, Q and Chen, X and Li, M}, title = {miR-146a inhibits biofilm-derived Cutibacterium acnes induced inflammatory reactions in human keratinocytes.}, journal = {The Journal of investigative dermatology}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.jid.2019.03.1161}, pmid = {31194941}, issn = {1523-1747}, abstract = {Acne is a chronic inflammatory skin disorder that often involves the formation of C. acnes biofilms. Several microRNAs (miRNAs) are known to be involved in inflammatory responses. However, it is unknown whether miRNAs play a role in the inflammatory reaction triggered by C. acnes biofilm. Here we investigated the role of miR-146a in biofilm-derived C. acnes induced inflammatory responses. Increased expressions of miR-146a and toll-like receptor (TLR) 2 were detected in acne lesions. In presence of biofilm-derived C. acnes, TLR2 and its downstream NF-kB and mitogen-activated protein kinase (MAPK) pathways were activated in keratinocytes. Subsequently, miR-146a was up-regulated in these cells along with induction of IL-6, IL-8, and TNF-α. Further, our data indicated that miR-146a could directly bind the 3'-untranslated region (3'-UTR) of IL-1 receptor associated kinase 1 (IRAK1) and TNF receptor-associated factor 6 (TRAF6), and suppress their expression, leading to inhibition of biofilm-derived C. acnes induced activation of NF-kB, p38, and Erk1/2 pathways. Overall, our results indicate that biofilm-derived C. acnes induces miR-146a, which can down-regulate the production of IL-6, -8, and TNF-α in acne inflammation by inhibiting TLR2/IRAK1/TRAF6/NF-κB and MAPK pathways.}, } @article {pmid31194008, year = {2018}, author = {Sanawar, H and Pinel, I and Farhat, NM and Bucs, SS and Zlopasa, J and Kruithof, JC and Witkamp, GJ and van Loosdrecht, MCM and Vrouwenvelder, JS}, title = {Enhanced biofilm solubilization by urea in reverse osmosis membrane systems.}, journal = {Water research X}, volume = {1}, number = {}, pages = {100004}, doi = {10.1016/j.wroa.2018.10.001}, pmid = {31194008}, issn = {2589-9147}, abstract = {Chemical cleaning is routinely performed in reverse osmosis (RO) plants for the regeneration of RO membranes that suffer from biofouling problems. The potential of urea as a chaotropic agent to enhance the solubilization of biofilm proteins has been reported briefly in the literature. In this paper the efficiency of urea cleaning for RO membrane systems has been compared to conventionally applied acid/alkali treatment. Preliminary assessment confirmed that urea did not damage the RO polyamide membranes and that the membrane cleaning efficiency increased with increasing concentrations of urea and temperature. Accelerated biofilm formation was carried out in membrane fouling simulators which were subsequently cleaned with (i) 0.01M sodium hydroxide (NaOH) and 0.1M hydrochloric acid (HCl) (typically applied in industry), (ii) urea (CO(NH2)2) and hydrochloric acid, or (iii) urea only (1340 g/Lwater). The pressure drop over the flow channel was used to evaluate the efficiency of the applied chemical cleanings. Biomass removal was evaluated by measuring chemical oxygen demand (COD), adenosine triphosphate (ATP), protein, and carbohydrate content from the membrane and spacer surfaces after cleaning. In addition to protein and carbohydrate quantification of the extracellular polymeric substances (EPS), fluorescence excitation-emission matrix (FEEM) spectroscopy was used to distinguish the difference in organic matter of the remaining biomass to assess biofilm solubilization efficacy of the different cleaning agents. Results indicated that two-stage CO(NH2)2/HCl cleaning was as effective as cleaning with NaOH/HCl in terms of restoring the feed channel pressure drop (>70% pressure drop decrease). One-stage cleaning with urea only was not as effective indicating the importance of the second-stage low pH acid cleaning in weakening the biofilm matrix. All three chemical cleaning protocols were equally effective in reducing the concentration of predominant EPS components protein and carbohydrate (>50% reduction in concentrations). However, urea-based cleaning strategies were more effective in solubilizing protein-like matter and tyrosine-containing proteins. Furthermore, ATP measurements showed that biomass inactivation was up to two-fold greater after treatment with urea-based chemical cleanings compared to the conventional acid/alkali treatment. The applicability of urea as an alternative, economical, eco-friendly and effective chemical cleaning agent for the control of biological fouling was successfully demonstrated.}, } @article {pmid31193536, year = {2019}, author = {Gomes, F and Martins, N and Ferreira, ICFR and Henriques, M}, title = {Anti-biofilm activity of hydromethanolic plant extracts against Staphylococcus aureus isolates from bovine mastitis.}, journal = {Heliyon}, volume = {5}, number = {5}, pages = {e01728}, doi = {10.1016/j.heliyon.2019.e01728}, pmid = {31193536}, issn = {2405-8440}, abstract = {Bovine mastitis (BM) presents a high incidence, being Staphylococcus aureus one of the major causative agents. Antibiotics comprise the most common therapeutic approach, but due to their indiscriminate use, high rates of increasingly resistant bacterial species have been markedly pointed out. Particularly, S. aureus possesses a pronounced ability to form biofilms, and therefore, are of pivotal interest due to its alarming pathogenicity. The present study investigates the antibacterial properties of Eucalyptus globulus methanol: water extracts, alone and in combination with Juglans regia, against S. aureus isolates from BM. All isolates and reference strain proved to be good biofilm producers after 24 h of bacterial growth. Individually, the studied plant extracts (PE) lead to a considerable biofilm cells reduction, but their combination revealed to be the most effective strategy. When tested in combination, both extracts led to a 3 and 5 log reduction for S. aureus ATCC 25923 and S. aureus 1, respectively. Based on these findings, both PE seem to be promissory antimicrobial agents for upcoming use on dairy industry contaminations, BM and even S. aureus-triggered food poisoning. Further studies are needed to understand which of the compounds present in the extracts are responsible for the observed effects, including their corresponding modes of action.}, } @article {pmid31193467, year = {2019}, author = {Singhal, N and Maurya, AK and Singh, NS and Kumar, M and Virdi, JS}, title = {Antimicrobial resistance and its relationship with biofilm production and virulence-related factors in Yersinia enterocolitica biotype 1A.}, journal = {Heliyon}, volume = {5}, number = {5}, pages = {e01777}, doi = {10.1016/j.heliyon.2019.e01777}, pmid = {31193467}, issn = {2405-8440}, abstract = {The aim of the present study was to determine antimicrobial susceptibilities, biofilm production and, to discern a relationship between antimicrobial resistance, biofilm potential and virulence-related genes in strains of Yersinia entercocolitica biotype 1A. Thirty strains of Y. enterocolitica biotype 1A including clinical and non-clinical strains were investigated. Antimicrobial susceptibility for 15 antibiotics (representing different classes) was determined by disk-diffusion assay. Biofilm potential was determined on two different culture media using crystal violet assay. Also, a co-relation was studied between antimicrobial susceptibilities, biofilm production and virulence-related genes. All strains of biotype 1A produced biofilms and exhibited varied level of susceptibilities for different antibiotics. More than 60% of the strains were strong to moderate biofilm producers and, were exclusively associated with REP/ERIC clonal group B. Moderate and strong biofilm producers exhibited both sensitive and resistant phenotypes towards different antibiotics. Interestingly, weak biofilm producers were resistant to amoxicillin, amoxicillin-clavulanate and cefazolin. Analysis of antimicrobial susceptibilities, biofilm potential and virulence-related genes did not reveal any unequivocal relationships. The differential biofilm potential of Indian strains of Y. enterocolitica biotype 1A, suggests that biotype 1A strains are heterogeneous in nature.}, } @article {pmid31191696, year = {2019}, author = {Zaatout, N and Ayachi, A and Kecha, M}, title = {Interaction of primary mammary bovine epithelial cells with biofilm-forming staphylococci associated with subclinical bovine mastitis.}, journal = {Iranian journal of veterinary research}, volume = {20}, number = {1}, pages = {27-32}, pmid = {31191696}, issn = {1728-1997}, abstract = {Background: Staphylococci are recognized worldwide as one of the most important etiological agents of bovine mastitis due to their virulence factors such as their ability to penetrate inside mammary epithelial cells and their ability to form biofilm.

Aims: The objectives of this study were to establish a model of primary mammary epithelial cells originating from the secretory tissue of the bovine udder in order to evaluate the invasion ability of 42 staphylococci isolated from subclinical bovine mastitis cases.

Methods: Two techniques were used to establish a model of primary mammary epithelial cells, the explant technique and the enzymatic method. Biofilm formation was detected using a quantitative spectrophotometric assay. When compared with the enzymatic digestion method, the epithelial cells obtained by the explant technique grew faster and reached quickly to confluence.

Results: The results showed that 60% of Staphylococcus aureus isolates (n=12) were able to invade the epithelial cells and 72.7% of coagulase negative staphylococci (CNS) isolates were invasive (n=16). Staphylococcus xylosus isolates showed higher invasion values compared to S. aureus isolates and non-biofilm forming staphylococci were able to invade primary epithelial cells, but no significant difference was found between the internalization capabilities of biofilm positive and negative isolates.

Conclusion: The results show that the explant technique is a valuable method for developing primary epithelial cells without damaging the cells, and provides new insights regarding the ability of staphylococci to penetrate inside primary mammary epithelial cells.}, } @article {pmid31190904, year = {2019}, author = {Navidifar, T and Amin, M and Rashno, M}, title = {Effects of sub-inhibitory concentrations of meropenem and tigecycline on the expression of genes regulating pili, efflux pumps and virulence factors involved in biofilm formation by Acinetobacter baumannii.}, journal = {Infection and drug resistance}, volume = {12}, number = {}, pages = {1099-1111}, doi = {10.2147/IDR.S199993}, pmid = {31190904}, issn = {1178-6973}, abstract = {Background: Sub-minimal inhibitory concentrations of antibiotics have been indicated to affect the biofilm formation in pathogens of nosocomial infections. This study aimed to investigate the effects of meropenem and tigecycline at their sub-minimum inhibitory concentrations (MICs) on the biofilm formation capacity of Acinetobacter baumannii (A. baumannii), as well as the expression levels of genes involved in biofilm formation, quorum sensing, pili assembly and efflux pumps. Materials and methods: In this study, four non-clonal strains (AB10, AB13, AB32 and AB55), which were different from the aspects of antibiotic susceptibility and biofilm formation from each other were selected for the evaluation of antimicrobial susceptibility, biofilm inducibility at sub-MICs of meropenem and tigecycline and the gene expression levels (the abaI, abaR, bap, pgaA, csuE, bfmS, bfmR, ompA, adeB, adeJ and adeG genes). Result: A significant increase in the MICs of all antibiotics was demonstrated in the biofilm cells in each four strains. The biofilm formation was significantly decreased in all the representative strains exposed to tigecycline. However, the biofilm inducibility at sub-MICs of meropenem was dependent on strain genotype. In concordance with these results, Pearson correlation analysis indicated a positive significant correlation between the biofilm formation capacity and the mRNA levels of genes encoding efflux pumps except adeJ, the genes involved in biofilm formation, pili assembly and quorum sensing following exposure to meropenem and tigecycline at their sub-MICs. Conclusion: These results revealed valuable data into the correlation between the gene transcription levels and biofilm formation, as well as quorum sensing and their regulation at sub-MICs of meropenem and tigecycline.}, } @article {pmid31188854, year = {2019}, author = {Meza-Villezcas, A and Gallego-Hernández, AL and Yildiz, FH and Jaime-Acuña, OE and Raymond-Herrera, O and Huerta-Saquero, A}, title = {Effect of antimicrobial nanocomposites on Vibrio cholerae lifestyles: Pellicle biofilm, planktonic and surface-attached biofilm.}, journal = {PloS one}, volume = {14}, number = {6}, pages = {e0217869}, doi = {10.1371/journal.pone.0217869}, pmid = {31188854}, issn = {1932-6203}, abstract = {Vibrio cholerae is an important human pathogen causing intestinal disease with a high incidence in developing countries. V. cholerae can switch between planktonic and biofilm lifestyles. Biofilm formation is determinant for transmission, virulence and antibiotic resistance. Due to the enhanced antibiotic resistance observed by bacterial pathogens, antimicrobial nanomaterials have been used to combat infections by stopping bacterial growth and preventing biofilm formation. In this study, the effect of the nanocomposites zeolite-embedded silver (Ag), copper (Cu), or zinc (Zn) nanoparticles (NPs) was evaluated in V. cholerae planktonic cells, and in two biofilm states: pellicle biofilm (PB), formed between air-liquid interphase, and surface-attached biofilm (SB), formed at solid-liquid interfaces. Each nanocomposite type had a distinctive antimicrobial effect altering each V. cholerae lifestyles differently. The ZEO-AgNPs nanocomposite inhibited PB formation at 4 μg/ml, and prevented SB formation and eliminated planktonic cells at 8 μg/ml. In contrast, the nanocomposites ZEO-CuNPs and ZEO-ZnNPs affect V. cholerae viability but did not completely avoid bacterial growth. At transcriptional level, depending on the nanoparticles and biofilm type, nanocomposites modified the relative expression of the vpsL, rbmA and bap1, genes involved in biofilm formation. Furthermore, the relative abundance of the outer membrane proteins OmpT, OmpU, OmpA and OmpW also differs among treatments in PB and SB. This work provides a basis for further study of the nanomaterials effect at structural, genetic and proteomic levels to understand the response mechanisms of V. cholerae against metallic nanoparticles.}, } @article {pmid31187657, year = {2019}, author = {Salman, M and Rizwana, R and Khan, H and Munir, I and Hamayun, M and Iqbal, A and Rehman, A and Amin, K and Ahmed, G and Khan, M and Khan, A and Amin, FU}, title = {Synergistic effect of silver nanoparticles and polymyxin B against biofilm produced by Pseudomonas aeruginosa isolates of pus samples in vitro.}, journal = {Artificial cells, nanomedicine, and biotechnology}, volume = {47}, number = {1}, pages = {2465-2472}, doi = {10.1080/21691401.2019.1626864}, pmid = {31187657}, issn = {2169-141X}, abstract = {Pseudomonas aeruginosa (P. aeruginosa) is an aerobic gram-negative, non-spore forming, rod-shaped bacterium. It accelerates the decline in lung function and ultimately leads to increased mortality and morbidity rate. Survival and virulence of P. aeruginosa is due to its biofilm formation ability. The main aim of this study was to test the synergistic effect of silver nanoparticles (AgNPs) in combination with Polymyxin B against biofilms of P. aeruginosa. A total of 500 pus aspirations were collected and bacterial pathogens were identified. Biofilm formation was attained using a glass tube method and microtiter plate assay. The minimum inhibitory concentration of Polymyxin B was determined using agar well diffusion method. Silver nanoparticles were synthesized by chemical reduction method followed by determination of their anti-pseudomonal ability separately and in combination with Polymyxin B using microtiter plate assay. Our results showed that 120 out of 500 samples were Pseudomonas positive. The ratio of multidrug-resistant (MDR) in our collected Pseudomonas samples was 83% (25/30). Generally, the minimum inhibitory concentration (MIC) of Polymyxin B was 16 µg/mL and that of AgNPs was null. However, AgNPs showed great synergistic effect in combination with Polymyxin B. Synergistically, the efficacy of Polymyxin B was enhanced four times as compared to unaided Polymyxin B.}, } @article {pmid31187647, year = {2019}, author = {Alavi, M and Karimi, N}, title = {Ultrasound assisted-phytofabricated Fe3O4 NPs with antioxidant properties and antibacterial effects on growth, biofilm formation, and spreading ability of multidrug resistant bacteria.}, journal = {Artificial cells, nanomedicine, and biotechnology}, volume = {47}, number = {1}, pages = {2405-2423}, doi = {10.1080/21691401.2019.1624560}, pmid = {31187647}, issn = {2169-141X}, abstract = {Complicated issue in infectious illnesses therapy is increasing of multidrug resistant (MDR) bacteria and biofilms in bacterial infections. In this way, emerging of nanotechnology as a new weapon specifically in the cases of metal nanoparticle (MNPs) synthesis and MNPs surface modification has obtained more attention. In this study, ultrasound-assisted green synthesis method was utilized for the preparation of Fe3O4 NPs with novel shape (dendrimer) through leaf aqueous extract of Artemisia haussknechtii Boiss. Ultraviolet-visible spectroscopy, energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), atomic force microscopic (AFM), X-ray diffraction (XRD) techniques were applied for MNPs physicochemical characterization. Also, disc diffusion assay, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), planktonic and biofilm morphology of three pathogenic bacteria involving Serratia marcescens ATCC 13880, Escherichia coli ATCC 25922, and methicillin-resistant Staphylococcus aureus (MRSA) were evaluated upon treatment of Fe3O4 NPs as antiplanktonic and antibiofilm analysis. Results showed efficient antiplanktonic and antibiofilm activities of biosynthesized Fe3O4 NPs with average diameter size of 83.4 nm. Reduction in biofilm formation of S. aureus ATCC under Fe3O4 NPs stress was significant (66%) in higher MNPs concentration (100 μg/mL). In addition, as first report, spreading ability of S. aureus as important factor in colony expansion on culture medium was reduced by increasing of Fe3O4 NPs. Present study demonstrates striking antiplanktonic, antibiofilm, antispreading mobility and antioxidant aspects of one-pot biosynthesized Fe3O4 NPs with novel shape.}, } @article {pmid31187383, year = {2019}, author = {García-Rodríguez, JP and Amezquita-Garcia, HJ and Escamilla-Alvarado, C and Rangel-Mendez, JR and Gutiérrez-García, K}, title = {Biofilm microbial composition changes due to different surface chemical modifications of activated carbon cloths in the biotransformation of 4-nitrophenol.}, journal = {Biodegradation}, volume = {}, number = {}, pages = {}, doi = {10.1007/s10532-019-09880-z}, pmid = {31187383}, issn = {1572-9729}, support = {CVU: 781364//Consejo Nacional de Ciencia y Tecnología, CONACYT/ ; IT606-18//PAICYT 2018/ ; UANL-CA-385//PRODEP/ ; }, abstract = {Activated carbon cloths (ACCs) were used as biofilms supports in the anaerobic biotransformation of 4-nitrophenol (4NP). As received ACC material (AW) was oxidized with HNO3 (OX) and then functionalized with anthraquinone-2,6-disulfonate (AQ). The three ACCs were packed in hybrid UASB reactors and seeded with anaerobic granular sludge for biotransformation experiments. The results indicated that ACC-packed bioreactors improved the biotransformation of 4NP by twofold as compared to the control reactor without support materials. However, the biotransformation effciency of AW, OX and AQ was very similar (59%), indicating the role of ACC as biofilm support and not as redox mediator. After 4NP biotransformation several physicochemical and biological changes were observed like (1) the point of zero charge (pHPZC) shift from acidic values (AW = 5.0, OX = 3.4, AQ = 3.1) to neutral values (pHPZC = 7.6 on average), (2) increase in the concentration of acidic and basic surface functional groups over ACC materials and the amount of supported biomass on ACCs due to biofilm formation, and (3) enrichment of exoelectrogenic microorganisms belonging to the genera Geobacter over carbonyl-rich ACC surface as revealed by 16S rRNA amplicon sequencing. Overall, the results suggest that chemical modifications of ACCs changed the microbial composition of the biofilm, but the higher concentration of carbonyl groups on ACC did not affect the biotransformation of 4NP.}, } @article {pmid31187378, year = {2019}, author = {Zou, H and Wang, Y}, title = {Functional collaboration of biofilm-cathode electrode and microbial fuel cell for biodegradation of methyl orange and simultaneous bioelectricity generation.}, journal = {Environmental science and pollution research international}, volume = {26}, number = {22}, pages = {23061-23069}, doi = {10.1007/s11356-019-05617-w}, pmid = {31187378}, issn = {1614-7499}, support = {1604f0704047//Research Items from the Department of Science and Technology of Anhui Province, China/ ; gxyqZD2016212//Special Foundation for Young Scientists of Anhui province, China/ ; }, abstract = {A distinctive process (BCE-MFC) was developed to explore the methyl orange (MO) degradation and simultaneous bioelectricity generation based on the functional collaboration of biofilm, electrolysis, constructed wetland, and microbial fuel cell. The biofilm-cathode electrode-microbial fuel cell (BCE-MFC) was capable of sustaining an excellent MO removal (100%) and bioelectricity production (0.63 V). BCE significantly enhanced MO biodegradability, thus resulting in a 56.3% improvement of COD removal in subsequent MFC. Bacillus was dominant in biofilm on cathode in BCE. In MFC, Proteobacteria phylum (64.84%) and Exiguobacterium genus (13.30%) were predominated in the anode region, probably basically responsible for electricity generation. Interestingly, relatively high content of Heliothrix sp. (9.94%) was found in the MFC designed here, which was likely to participate in electricity production as well. The proposed functional collaboration may be an effective strategy in refractory wastewater treatment and power production.}, } @article {pmid31187338, year = {2019}, author = {Devadas, SM and Nayak, UY and Narayan, R and Hande, MH and Ballal, M}, title = {2,5-Dimethyl-4-hydroxy-3(2H)-furanone as an Anti-biofilm Agent Against Non-Candida albicans Candida Species.}, journal = {Mycopathologia}, volume = {184}, number = {3}, pages = {403-411}, doi = {10.1007/s11046-019-00341-y}, pmid = {31187338}, issn = {1573-0832}, abstract = {BACKGROUND: The predominance of non-Candida albicans Candida (NCAC) species causing healthcare-associated infections has increased over the last decade pertaining to their ability to form biofilms on medical devices. These biofilm-associated infections are challenging to treat as they are resistant to antifungal agents and evade host-immune response resulting in a high risk of device failure or biomaterial removal. Thus, to minimize the risk of biofilm-associated infections, preventing biofilm formation is the best approach which is mediated by the quorum quenching process.

METHODS: The present study investigated the modulatory effect of 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) on NCAC biofilm formation and also assessed the effect of the DMHF-coated catheters on biofilm formation of NCAC. The NCAC isolates studied were Candida tropicalis, Candida glabrata and Candida krusei isolated from catheter tip, urine and blood, respectively.

RESULTS: DMHF at a concentration of 30 µg/mL showed an inhibitory effect against NCAC biofilms at various stages and was statistically significant (p ≤ 0.05) against the various concentrations (50-5 µg/mL) tested and also among the three phases of experiment. The furanone content on coated catheters ranged from 170 to 750 µg and release of furanone from the coated catheter was about 15 µg for 30 days. The effect of DMHF-coated catheters on NCAC biofilm formation was observed by the scanning electron microscopy which revealed the absence of NCAC adherence on DMHF-coated catheters.

DISCUSSION: This study provides a design to develop furanone-coated biomaterials which could be implemented in healthcare settings to reduce medical device-associated infections. The excellent biological performance, combined with their antimicrobial properties, suggests that 2,5-dimethyl-4-hydroxy-3(2H)-furanone could be an effective anti-infective coating for implantable devices.}, } @article {pmid31185817, year = {2019}, author = {Dzianach, PA and Dykes, GA and Strachan, NJC and Forbes, KJ and Pérez-Reche, FJ}, title = {Challenges of biofilm control and utilization: lessons from mathematical modelling.}, journal = {Journal of the Royal Society, Interface}, volume = {16}, number = {155}, pages = {20190042}, doi = {10.1098/rsif.2019.0042}, pmid = {31185817}, issn = {1742-5662}, abstract = {This article reviews modern applications of mathematical descriptions of biofilm formation. The focus is on theoretically obtained results which have implications for areas including the medical sector, food industry and wastewater treatment. Examples are given as to how models have contributed to the overall knowledge on biofilms and how they are used to predict biofilm behaviour. We conclude that the use of mathematical models of biofilms has demonstrated over the years the ability to significantly contribute to the vast field of biofilm research. Among other things, they have been used to test various hypotheses on the nature of interspecies interactions, viability of biofilm treatment methods or forces behind observed biofilm pattern formations. Mathematical models can also play a key role in future biofilm research. Many models nowadays are analysed through computer simulations and continue to improve along with computational capabilities. We predict that models will keep on providing answers to important challenges involving biofilm formation. However, further strengthening of the ties between various disciplines is necessary to fully use the tools of collective knowledge in tackling the biofilm phenomenon.}, } @article {pmid31185326, year = {2019}, author = {Pourhajibagher, M and Ghorbanzadeh, R and Bahador, A}, title = {Antimicrobial properties of acrylic resins doped with Undaria pinnatifida exposed to light-emitting diode: In silico and in vitro assessments on multispecies biofilm-producing microbiota.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.05.039}, pmid = {31185326}, issn = {1873-1597}, abstract = {BACKGROUND: This study sought to evaluates the efficiency of anti-microbial activity of acrylic resins doped with different concentrations of Undaria pinnatifida after activation with light-emitting diode (LED) at producing photodynamic damage to multispecies biofilm-producing microbiome MATERIAL AND METHODS: In this study, bioinformatics tools and computer simulation molecular modeling were used to evaluate the capacity of ferredoxin (FDX), an electron acceptor in metabolic pathways of U. pinnatifida, which can discharge electrons produced from photo-excited chlorophyll-a (Chl-a) by LED irradiation. Acrylic resin discs containing different concentration of U. pinnatifida (0, 0.5, 1, and 2%) were fabricated and were subjected to LED irradiation immediately before each experiment. After continuously rinsed (up to 30 days), the antimicrobial activity of acrylic resins doped with U. pinnatifida following photo-activation was determined by disc agar diffusion, biofilm formation inhibition, and eluted component assays versus bacterial species linked to caries that constitute a mixed biofilm including Streptococcus mutans, S. sanguinis, and Lactobacillus acidophilus, as well as Candida albicans as main etiology of candidal stomatitis.

RESULTS: Modeling and a virtual screening analysis of FDX indicated that it is a stable protein with an iron-sulfur center that can discharge electrons produced from photo-excited Chl-a and transfers them to FDX-NADP+ reductase for NADP+ reduction in photosystem I, which is essential in the Calvin cycle for carbon assimilation. FDX acts as an electron transfer agent in the redox reactions. The results showed that growth inhibition zones were not seen around acrylic resin discs in any group. In biofilm test, the colony counts of all test microorganisms significantly decreased (36% to 87%) by an increase in the percentage of U. pinnatifida in acrylic resins after photo-activation (P < 0.05). Acrylic resins doped with 2% wt. U. pinnatifida following photo-activation using LED was inhibited biofilm formation by the test microorganisms, up to 30 days of rinsing CONCLUSION: Based on the results that presented here, an acrylic resin containing U. pinnatifida, even at the lowest concentration, following photo-activation using LED have antimicrobial properties against planktonic and biofilm forms of the cariogenic microorganisms as well as C. albicans.}, } @article {pmid31182496, year = {2019}, author = {Nicastro, LK and Tursi, SA and Le, LS and Miller, AL and Efimov, A and Buttaro, B and Tam, V and Tükel, Ç}, title = {Cytotoxic curli intermediates form during Salmonella biofilm development.}, journal = {Journal of bacteriology}, volume = {}, number = {}, pages = {}, doi = {10.1128/JB.00095-19}, pmid = {31182496}, issn = {1098-5530}, abstract = {Enterobacteriaceae produce amyloid proteins called curli that are the major proteinaceous component of biofilms. Amyloids are also produced by humans and are associated with diseases such as Alzheimer's. During the multi-step process of amyloid formation, monomeric subunits form oligomers, protofibrils, and finally mature fibrils. Amyloid β oligomers are more cytotoxic to cells than the mature amyloid fibrils. Oligomeric intermediates of curli have not been previously detected. We determined that turbulence inhibited biofilm formation, and that, intriguingly, curli aggregates purified from cultures grown under high-turbulence conditions were structurally smaller and contained less DNA than did curli preparations from cultures grown with less turbulence. Using flow cytometry analysis, we demonstrated that CsgA was expressed in cultures exposed to higher turbulence but that these cultures had lower levels of cell death than less turbulent cultures. Our data suggests that the DNA released during cell death drives the formation of larger fibrillar structures. Consistent with this idea, addition of exogenous genomic DNA increased the size of the curli intermediates and led to binding to Thioflavin T at levels observed with mature aggregates. Similar to the intermediate oligomers of amyloid β, intermediate curli aggregates were more cytotoxic than the mature curli fibrils when incubated with bone marrow-derived macrophages. The discovery of cytotoxic curli intermediates will enable research into the roles of amyloid intermediates in the pathogenesis of Salmonella and other bacteria that cause enteric infections.IMPORTANCE Amyloid proteins are the major proteinaceous components of biofilms, which are associated with up to 65% of human bacterial infections. Amyloids produced by human cells are also associated with diseases such as Alzheimer's. The amyloid monomeric subunits self-associate to form oligomers, protofibrils, and finally mature fibrils. Amyloid β oligomers are more cytotoxic to cells than the mature amyloid fibrils. Here we detected oligomeric intermediates of curli for the first time. Like the oligomers of amyloid β, intermediate curli fibrils were more cytotoxic than the mature curli fibrillar aggregates when incubated with bone marrow-derived macrophages. The discovery of cytotoxic curli intermediates will enable research into the roles of amyloid intermediates in the pathogenesis of Salmonella and other bacteria that cause enteric infections.}, } @article {pmid31181853, year = {2019}, author = {Lotlikar, SR and Gallaway, E and Grant, T and Popis, S and Whited, M and Guragain, M and Rogers, R and Hamilton, S and Gerasimchuk, NG and Patrauchan, MA}, title = {Polymeric Composites with Silver (I) Cyanoximates Inhibit Biofilm Formation of Gram-Positive and Gram-Negative Bacteria.}, journal = {Polymers}, volume = {11}, number = {6}, pages = {}, doi = {10.3390/polym11061018}, pmid = {31181853}, issn = {2073-4360}, support = {1R15AI088594-01A1//National Institutes of Health/ ; CC 6598//Cottrell College Research Corporation/ ; }, abstract = {Biofilms are surface-associated microbial communities known for their increased resistance to antimicrobials and host factors. This resistance introduces a critical clinical challenge, particularly in cases associated with implants increasing the predisposition for bacterial infections. Preventing such infections requires the development of novel antimicrobials or compounds that enhance bactericidal effect of currently available antibiotics. We have synthesized and characterized twelve novel silver(I) cyanoximates designated as Ag(ACO), Ag(BCO), Ag(CCO), Ag(ECO), Ag(PiCO), Ag(PICO) (yellow and red polymorphs), Ag(BIHCO), Ag(BIMCO), Ag(BOCO), Ag(BTCO), Ag(MCO) and Ag(PiPCO). The compounds exhibit a remarkable resistance to high intensity visible light, UV radiation and heat and have poor solubility in water. All these compounds can be well incorporated into the light-curable acrylate polymeric composites that are currently used as dental fillers or adhesives of indwelling medical devices. A range of dry weight % from 0.5 to 5.0 of the compounds was tested in this study. To study the potential of these compounds in preventing planktonic and biofilm growth of bacteria, we selected two human pathogens (Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus) and Gram-positive environmental isolate Bacillus aryabhattai. Both planktonic and biofilm growth was abolished completely in the presence of 0.5% to 5% of the compounds. The most efficient inhibition was shown by Ag(PiCO), Ag(BIHCO) and Ag(BTCO). The inhibition of biofilm growth by Ag(PiCO)-yellow was confirmed by scanning electron microscopy (SEM). Application of Ag(BTCO) and Ag(PiCO)-red in combination with tobramycin, the antibiotic commonly used to treat P. aeruginosa infections, showed a significant synergistic effect. Finally, the inhibitory effect lasted for at least 120 h in P. aeruginosa and 36 h in S. aureus and B. aryabhattai. Overall, several silver(I) cyanoximates complexes efficiently prevent biofilm development of both Gram-negative and Gram-positive bacteria and present a particularly significant potential for applications against P. aeruginosa infections.}, } @article {pmid31181494, year = {2019}, author = {Yang, S and Guo, B and Shao, Y and Mohammed, A and Vincent, S and Ashbolt, NJ and Liu, Y}, title = {The value of floc and biofilm bacteria for anammox stability when treating ammonia-rich digester sludge thickening lagoon supernatant.}, journal = {Chemosphere}, volume = {233}, number = {}, pages = {472-481}, doi = {10.1016/j.chemosphere.2019.05.287}, pmid = {31181494}, issn = {1879-1298}, abstract = {Ammonia-rich lagoon supernatant was treated using anammox process in an integrated fixed-film activated sludge (IFAS) laboratory reactor. Effective anammox activities were demonstrated over 259 days of operation. The ammonium removal efficiency reached 94% in Phase I with influent concentrations of NH4+, NO2- and chemical oxygen demand (COD) at 250 mg-N/L, 325 mg-N/L, and 145 mg-COD/L, and reached 88% in Phase II at 420 mg-N/L, 525 mg-N/L, and 305 mg-COD/L. When supplemented with nitritation effluent for nitrite sources in Phase III, the influent COD concentration increased to 583 mg-COD/L without loss of ammonia removal efficiency (87%). The specific anammox activity was higher in biofilm than in the suspended flocs (P < 0.05), increased from Phase I to II (P < 0.05), and decreased in Phase III. Ammonia removal related genes were quantified using qPCR. Results showed higher anammox gene (AMX nirS) prevalence in biofilm, while denitrification genes (nosZ and narG) were higher in flocs (P < 0.05). Microbial community analysis showed that the seeded anammox bacteria Candidatus Brocadia was maintained at 19% in the biofilm and only 0.3% in the flocs. The major taxa in the flocs were related to denitrifiers. The floc community was affected largely under high COD conditions, but the biofilm community was not. These results suggest that the anammox activity in biofilm is resilient to high COD loadings, due to the existence of flocs with denitrification activity. The segregation of bacterial communities between biofilm and flocs in the anammox IFAS system resulted in high ammonia removal efficiency and resistance to high organic loadings.}, } @article {pmid31180246, year = {2019}, author = {Liu, J and Jiang, J and Zong, J and Li, B and Pan, T and Diao, Y and Zhang, Z and Zhang, X and Lu, M and Wang, S}, title = {Antibacterial and anti-biofilm effects of fatty acids extract of dried Lucilia sericata larvae against Staphylococcus aureus and Streptococcus pneumoniae in vitro.}, journal = {Natural product research}, volume = {}, number = {}, pages = {1-4}, doi = {10.1080/14786419.2019.1627353}, pmid = {31180246}, issn = {1478-6427}, abstract = {Development of new effective antimicrobial drugs is still a big challenge to date due to microbial infection remains an inevitable problem against human health. In this study, fatty acids extract of Lucilia sericata larvae (LFAs) was obtained and evaluated by gas chromatograph-mass spectrometry (GC-MS), and its antibacterial activity against Staphylococcus aureus (S. aureus) and Streptococcus pneumoniae (S. pneumoniae) was investigated. We found that LFAs exhibited effective antibacterial activity against S. aureus and S. pneumoniae with minimal inhibitory concentrations (MICs) of 125 μg/mL and 100 μg/mL, respectively. The bacterial wall and membrane were the main targets, which was confirmed by fluorescence microscopy, scanning electron microscopy and transmission electron microscopy. Furthermore, a notable anti-biofilm activity against S. aureus and S. pneumoniae was also observed, which was able to both prevent biofilm formation and eradicate mature biofilms of these bacteria. As a promising antibacterial agent, LFAs showed good application prospects in clinical practice.}, } @article {pmid31180065, year = {2019}, author = {Lahiri, D and Dash, S and Dutta, R and Nag, M}, title = {Elucidating the effect of anti-biofilm activity of bioactive compounds extracted from plants.}, journal = {Journal of biosciences}, volume = {44}, number = {2}, pages = {}, pmid = {31180065}, issn = {0973-7138}, } @article {pmid31179649, year = {2019}, author = {Liu, L and Ye, C and Soteyome, T and Zhao, X and Xia, J and Xu, W and Mao, Y and Peng, R and Chen, J and Xu, Z and Shirtliff, ME and Harro, JM}, title = {Inhibitory effects of two types of food additives on biofilm formation by foodborne pathogens.}, journal = {MicrobiologyOpen}, volume = {}, number = {}, pages = {e853}, doi = {10.1002/mbo3.853}, pmid = {31179649}, issn = {2045-8827}, support = {B17018//111 Project/ ; 31501582//National Natural Science Foundation of China/ ; 2018CFB514//Hubei Provincial Natural Science Foundation of China/ ; }, abstract = {The inhibition of microbial biofilms is a significant concern in food safety. In the present study, the inhibitory effect of sodium citrate and cinnamic aldehyde on biofilm formation at minimum inhibitory concentrations (MICs) and sub-MICs was investigated for Escherichia coli O157:H7 and Staphylococcus aureus. The biofilm inhibition rate was measured to evaluate the effect of sodium citrate on S. aureus biofilms at 24, 48, 72, and 96 hr. According to the results, an antibiofilm effect was shown by both food additives, with 10 mg/ml of sodium citrate exhibiting the greatest inhibition of S. aureus biofilms at 24 hr (inhibition rate as high as 77.51%). These findings strongly suggest that sodium citrate exhibits a pronounced inhibitory effect on biofilm formation with great potential in the extension of food preservation and storage.}, } @article {pmid31177828, year = {2019}, author = {Yunda, E and Quilès, F}, title = {In situ spectroscopic analysis of Lactobacillus rhamnosus GG flow on an abiotic surface reveals a role for nutrients in biofilm development.}, journal = {Biofouling}, volume = {}, number = {}, pages = {1-14}, doi = {10.1080/08927014.2019.1617279}, pmid = {31177828}, issn = {1029-2454}, abstract = {In this work, infrared spectroscopy was used to monitor the changes in the biochemical composition of biofilms of the probiotic bacterium Lactobacillus rhamnosus GG (LGG) in three nutritive media (10-fold diluted MRS, AOAC, and mTSB), in situ and under flow conditions. Epifluorescence microscopy was used to observe the shape of LGG cells and their distribution on the surface. Spectroscopic fingerprints recorded as a function of time revealed a medium-dependent content of nucleic acids, phospholipids and polysaccharides in the biofilms. In addition, time-dependent synthesis of lactic acid was observed in MRS/10 and AOAC/10. Polysaccharides were produced to the highest extent in mTSB/10, and the biofilms obtained were the densest in this medium. The rod shape of the cells was preserved in MRS/10, whereas acidic stress induced in AOAC/10 and the nutritional quality of mTSB/10 led to strong morphological changes. These alterations due to the nutritive environment are important to consider in research and use of LGG biofilms.}, } @article {pmid31177008, year = {2019}, author = {Pousti, M and Lefèvre, T and Amirdehi, MA and Greener, J}, title = {A surface spectroscopy study of a Pseudomonas fluorescens biofilm in the presence of an immobilized air bubble.}, journal = {Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy}, volume = {222}, number = {}, pages = {117163}, doi = {10.1016/j.saa.2019.117163}, pmid = {31177008}, issn = {1873-3557}, abstract = {A linear spectral mapping technique was applied to monitor the growth of biomolecular absorption bands at the bio-interface of a nascent Pseudomonas fluorescens biofilm during and after interaction with a surface-adhered air bubble. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectra were obtained in different locations in a microchannel with adequate spatial and temporal resolution to study the effect of a static bubble on the evolution of protein and lipid signals at the ATR crystal surface. The results reveal that the presence of a bubble during the lag phase modified levels of extracellular lipids and affected a surface restructuring process, many hours after the bubble's disappearance.}, } @article {pmid31176763, year = {2019}, author = {Niavarzi, S and Pourhajibagher, M and Khedmat, S and Ghabraei, S and Chiniforush, N and Bahador, A}, title = {Effect of ultrasonic activation on the efficacy of antimicrobial photodynamic therapy: Evaluation of penetration depth of photosensitizer and elimination of Enterococcus faecalis biofilm.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.06.001}, pmid = {31176763}, issn = {1873-1597}, abstract = {BACKGROUND: This study aimed to assess the effect of ultrasonic activation of photosensitizer on the efficacy of Antimicrobial Photodynamic Therapy (aPDT) against Enterococcus faecalis and penetration depth of photosensitizer.

MATERIALS AND METHODS: In this ex vivo study, mature microbial biofilm of E. faecalis was formed in the root canals of 58 single-rooted single-canal mandibular incisors following their decoronation. The roots were longitudinally sectioned by a diamond disc and split into halves by a chisel. The E. faecalis biofilm was quantified and the penetration depth of photosensitizer was determined by the microbial viability assay and stereomicroscopic analysis in the following three study groups: (1) Ultrasonically activated 5.25% sodium hypochlorite (NaOCl) for 20 seconds, (2) aPDT using methylene blue (MB) plus 660 nm diode laser with 150 mW power for 1 minute, and (3) ultrasonically activated MB for 20 seconds followed by laser irradiation as in group 2. Independent sample t-test and one-way ANOVA were used to compare the dye penetration depth and microbial load, respectively in the apical and coronal regions among the groups.

RESULTS: The penetration depth of photosensitizer in group 3 was significantly greater than that in group 2 (P < 0.05). The E. faecalis count in all three experimental groups was significantly lower than that in the control group (P < 0.05). Groups 1 and 3 were significantly superior to group 2 in terms of reduction in microbial count but the difference between groups 1 and 3 was not significant (P > 0.05).

CONCLUSION: Ultrasonic activation of photosensitizer in aPDT increases the penetration depth of photosensitizer into the dentinal tubules and enhances its antibacterial activity.

HIGHLIGHT: Ultrasonic activation of photosensitizer in aPDT enhances its penetration depth into dentinal tubules. Ultrasonic increase antibacterial efficacy of aPDT. There was no significant difference between antibacterial effects of aPDT + ultrasonic and ultrasonic activated NaOCl.}, } @article {pmid31174686, year = {2019}, author = {Shah, MS and Qureshi, S and Kashoo, Z and Farooq, S and Wani, SA and Hussain, MI and Banday, MS and Khan, AA and Gull, B and Habib, A and Khan, SM and Dar, BA}, title = {Methicillin resistance genes and in vitro biofilm formation among Staphylococcus aureus isolates from bovine mastitis in India.}, journal = {Comparative immunology, microbiology and infectious diseases}, volume = {64}, number = {}, pages = {117-124}, doi = {10.1016/j.cimid.2019.02.009}, pmid = {31174686}, issn = {1878-1667}, abstract = {INTRODUCTION: Biofilms, an assemblage of microbial cells irreversibly associated with a surface and enclosed in a matrix of polysaccharide material pose serious health challenges, resulting in high economic losses. The emergence of methicillin-resistant S. aureus (MRSA) infections and ability to form biofilms in dairy animals is of emerging concern for livestock and public health owing to their association with serious infections. The present study was undertaken to examine the presence of methicillin resistance genes among the biofilm forming Staphylococcus aureus strains isolated from cases of acute and subacute bovine mastitis. A total of 150 mastitic milk samples referred to Veterinary Clinical Complex, Shuhama (Aulesteng) SKUAST-K were screened in present study. The methicillin resistant Staphylococcus aureus isolates were also screened for in vitro biofilm forming ability.

RESULTS: A total of 80 (53.33%) S. aureus isolates were recovered from cases of bovine mastitis of which 20 (25%) were methicillin (mecA) gene positive. Of the 20 mecA positive isolates, 20% were positive for SCCmec I, 35% for SCCmec IV and 45% for SCCmec V subtypes. In vitro antibiotic sensitivity testing of MRSA revealed complete resistance towards methicillin and other pencillin group of antibiotics.

CONCLUSION: A significant correlation was observed between in vitro biofilm formation and presence of methicillin resistance gene in S aureus isolates recovered from acute and subacute mastitis. The Staphylococcus aureus isolates positive for methicillin resistance gene (mecA) were either strong or moderate biofilm formers.}, } @article {pmid31173863, year = {2019}, author = {Rajasekharan, SK and Lee, JH and Lee, J}, title = {Aripiprazole repurposed as an inhibitor of biofilm formation, and sterol biosynthesis in multi-drug resistant Candida albicans.}, journal = {International journal of antimicrobial agents}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.ijantimicag.2019.05.016}, pmid = {31173863}, issn = {1872-7913}, abstract = {Drug repurposing is an anticipative chemotherapeutic strategy that serves to accentuate the inadequacy of antifungal drugs. The study identifies an antipsychotic drug, aripiprazole, as a biofilm and hyphal inhibitor of Candida albicans. Microtitre plate biofilm inhibition, metabolic activity, and hyphal inhibitory assays were used initially to assess the potency of aripiprazole, while assays like filipin staining, reactive oxygen species staining, cAMP rescue, propidium iodide staining, computational studies, and qRT-PCR assays were used to elucidate its mode of action. The study revealed aripiprazole functioned in a manner similar to standard azoles, especially the imidazole ketoconazole, by inhibiting pseudohyphal formations during the early stages of hyphal development. The action of aripiprazole on C. albicans was dose-dependent and it exhibited varied action mechanisms at low and high dosages. At low dosage, aripiprazole outperformed ketoconazole in terms of inhibiting biofilm formation, hyphal filamentations, and yeast flocculation whereas at higher dosage it mimicked ketoconazole. In conclusion, the study illustrates the anti-candidal potential and mechanistic activities of aripiprazole, and suggests the future use of this drug as an anti-biofilm agent.}, } @article {pmid31173560, year = {2019}, author = {Kreth, J and Ferracane, JL and Pfeifer, CS and Khajotia, S and Merritt, J}, title = {At the Interface of Materials and Microbiology: A Call for the Development of Standardized Approaches to Assay Biomaterial-Biofilm Interactions.}, journal = {Journal of dental research}, volume = {98}, number = {8}, pages = {850-852}, doi = {10.1177/0022034519854685}, pmid = {31173560}, issn = {1544-0591}, support = {K02 DE025280/DE/NIDCR NIH HHS/United States ; R01 DE026113/DE/NIDCR NIH HHS/United States ; U01 DE023756/DE/NIDCR NIH HHS/United States ; R56 DE021726/DE/NIDCR NIH HHS/United States ; R35 DE028252/DE/NIDCR NIH HHS/United States ; R15 DE019940/DE/NIDCR NIH HHS/United States ; }, } @article {pmid31172798, year = {2019}, author = {Dell'Olmo, E and Gaglione, R and Pane, K and Sorbo, S and Basile, A and Esposito, S and Arciello, A}, title = {Fighting multidrug resistance with a fruit extract: anti-cancer and anti-biofilm activities of Acca sellowiana.}, journal = {Natural product research}, volume = {}, number = {}, pages = {1-4}, doi = {10.1080/14786419.2019.1624961}, pmid = {31172798}, issn = {1478-6427}, abstract = {In this study, the efficacy of Acca sellowiana fruit acetonic extract on human MDR cancer cells was tested for the first time, and it was demonstrated that the fruit extract is effective on both sensitive and resistant tumor cells. The effects of A. sellowiana extract on bacterial biofilm were also examined for the first time. By crystal violet assays and confocal microscopy analyses, it was demonstrated that the plant extract is able to strongly inhibit biofilm formation of both sensitive and resistant bacterial strains. Furthermore, antimicrobial activity assays and TEM analyses clearly demonstrated the effectiveness of plant extract on planktonic bacterial cells in both sensitive and resistant strains. Altogether, these findings intriguingly expand the panel of activities of A. sellowiana fruit extract with respect to previous reports, and open interesting perspectives to its therapeutic applications.}, } @article {pmid31171741, year = {2019}, author = {Shakibaie, M and Hajighasemi, E and Adeli-Sardou, M and Doostmohammadi, M and Forootanfar, H}, title = {Antimicrobial and anti-biofilm activities of Bi subnitrate and BiNPs produced by Delftia sp. SFG against clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa, and Proteus mirabilis.}, journal = {IET nanobiotechnology}, volume = {13}, number = {4}, pages = {377-381}, doi = {10.1049/iet-nbt.2018.5102}, pmid = {31171741}, issn = {1751-875X}, abstract = {In the present study Delftia sp. Shakibaie, Forootanfar, and Ghazanfari (SFG), was applied for preparation of biogenic Bi nanoparticles (BiNPs) and antibacterial and anti-biofilm activities of the purified BiNPs were investigated by microdilution and disc diffusion methods. Transmission electron micrographs showed that the produced nanostructures were spherical with a size range of 40-120 nm. The measured minimum inhibitory concentration of both the Bi subnitrate and BiNPs against three biofilms producing bacterial pathogens of Staphylococcus aureus, Pseudomonas aeruginosa, and Proteus mirabilis were found to be above 1280 µg/ml. Addition of BiNPs (1000 µg/disc) to antibiotic discs containing tobramycin, nalidixic acid, ceftriaxone, bacitracin, cefalexin, amoxicillin, and cefixime significantly increased the antibacterial effects against methicillin-resistant S. aureus (MRSA) in comparison with Bi subnitrate (p < 0.05). Furthermore, the biogenic BiNPs decreased the biofilm formation of S. aureus, P. aeruginosa, and P. mirabilis to 55, 85, and 15%, respectively. In comparison to Bi subnitrate, BiNPs indicated significant anti-biofilm activity against P. aeruginosa (p < 0.05) while the anti-biofilm activity of BiNPs against S. aureus and P. mirabilis was similar to that of Bi subnitrate. To sum up, the attained results showed that combination of biogenic BiNPs with commonly used antibiotics relatively enhanced their antibacterial effects against MRSA.}, } @article {pmid31170510, year = {2019}, author = {Kłodzińska, SN and Pletzer, D and Rahanjam, N and Rades, T and Hancock, REW and Nielsen, HM}, title = {Hyaluronic acid-based nanogels improve in vivo compatibility of the anti-biofilm peptide DJK-5.}, journal = {Nanomedicine : nanotechnology, biology, and medicine}, volume = {20}, number = {}, pages = {102022}, doi = {10.1016/j.nano.2019.102022}, pmid = {31170510}, issn = {1549-9642}, abstract = {Anti-biofilm peptides are a subset of antimicrobial peptides and represent promising broad-spectrum agents for the treatment of bacterial biofilms, though some display host toxicity in vivo. Here we evaluated nanogels composed of modified hyaluronic acid for the encapsulation of the anti-biofilm peptide DJK-5 in vivo. Nanogels of 174 to 194 nm encapsulating 33-60% of peptide were created. Efficacy and toxicity of the nanogels were tested in vivo employing a murine abscess model of a Pseudomonas aeruginosa LESB58 high bacterial density infection. The dose of DJK-5 that could be administered intravenously to mice without inducing toxicity was more than doubled after encapsulation in nanogels. Upon subcutaneous administration, the toxicity of the DJK-5 in nanogels was decreased four-fold compared to non-formulated peptide, without compromising the anti-abscess effect of DJK-5. These findings support the use of nanogels to increase the safety of antimicrobial and anti-biofilm peptides after intravenous and subcutaneous administration.}, } @article {pmid31169511, year = {2019}, author = {Mendoza, MV and Sáez, RT}, title = {Modelling biofilm anaerobic reactor with effluent from hydrolytic/acidogenic reactor as substrate.}, journal = {Water science and technology : a journal of the International Association on Water Pollution Research}, volume = {79}, number = {8}, pages = {1534-1540}, doi = {10.2166/wst.2019.152}, pmid = {31169511}, issn = {0273-1223}, mesh = {Anaerobiosis ; Bacteria ; *Biofilms ; Bioreactors/*statistics & numerical data ; Hydrolysis ; Methane ; *Models, Statistical ; Waste Disposal, Fluid/*statistics & numerical data ; }, abstract = {This work presents modelling of an anaerobic biofilm reactor using ceramic bricks as support. The results were compared with the experimental data. It was observed that the substrate concentration curves showed the same tendency. The methane formation curves showed significant differences. The substrate removal efficiency was 83%. In the steady state, the experimental data were higher than the model, from the result the substrate degrading bacteria grew enough to reach biofilm and that the effect of the shear stress was more significant as the biofilm increased in thickness. To the methane production, the model in steady state reached a maximum value of 0.56 m3 CH4/m3 *d and the experimental data reached 0.42 (m3 CH4/m3 * d). The biofilm thickness calculated by the model was 14 μm.}, } @article {pmid31169162, year = {2019}, author = {Kriswandini, IL and Rahardjo, MB and Budi, HS and Amalia, R}, title = {The difference in biofilm molecular weight in Streptococcus mutans and Aggregatibacter actinomycetemcomitans induced by sucrose and soy protein (glycine soja).}, journal = {Indian journal of dental research : official publication of Indian Society for Dental Research}, volume = {30}, number = {2}, pages = {273-276}, doi = {10.4103/ijdr.IJDR_183_17}, pmid = {31169162}, issn = {1998-3603}, abstract = {Context: Biofilms consist of microbial cells and extracellular polymeric substance (EPS). Streptococcus mutans and Aggregatibacter actinomycetemcomtans are bacteria that can form biofilms and generate EPS. Biofilm formation can be induced by specific substances such as sucrose and protein.

Aims: To identify the molecular weight that determines biofilm protein profile expression of S. mutans and A. actinomycetemcomitans induced by sucrose (carbohydrate) and soy protein (glycine soja).

Settings and Design: Experimental laboratory study.

Materials and Methods: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to determine the molecular weight.

Statistical Analysis Used: Nil.

Results: The results of analysis of protein SDS-PAGE showed the presence of 28 protein bands on A. actinomycetemcomitans biofilm in the media trypticase soy broth (TSB), 20 protein bands on biofilms of S. mutans in the media TSB, 29 protein bands on biofilm A. actinomycetemcomitans in the media brain heart infusion (BHI) + sucrose 2%, and 13 protein bands on biofilms of S. mutans in the media BHI + sucrose 2%.

Conclusion: There are differences in biofilm protein profile expression that determine the molecular weight of S. mutans biofilm and A. actinomycetemcomitans induced by sucrose (carbohydrate) and soy protein (glycine soja).}, } @article {pmid31167793, year = {2019}, author = {Le Mauff, F and Bamford, NC and Alnabelseya, N and Zhang, Y and Baker, P and Robinson, H and Codée, JDC and Howell, PL and Sheppard, DC}, title = {Molecular mechanism of Aspergillus fumigatus biofilm disruption by fungal and bacterial glycoside hydrolases.}, journal = {The Journal of biological chemistry}, volume = {294}, number = {28}, pages = {10760-10772}, doi = {10.1074/jbc.RA119.008511}, pmid = {31167793}, issn = {1083-351X}, support = {P41 GM103473/GM/NIGMS NIH HHS/United States ; P41 RR012408/RR/NCRR NIH HHS/United States ; }, abstract = {During infection, the fungal pathogen Aspergillus fumigatus forms biofilms that enhance its resistance to antimicrobials and host defenses. An integral component of the biofilm matrix is galactosaminogalactan (GAG), a cationic polymer of α-1,4-linked galactose and partially deacetylated N-acetylgalactosamine (GalNAc). Recent studies have shown that recombinant hydrolase domains from Sph3, an A. fumigatus glycoside hydrolase involved in GAG synthesis, and PelA, a multifunctional protein from Pseudomonas aeruginosa involved in Pel polysaccharide biosynthesis, can degrade GAG, disrupt A. fumigatus biofilms, and attenuate fungal virulence in a mouse model of invasive aspergillosis. The molecular mechanisms by which these enzymes disrupt biofilms have not been defined. We hypothesized that the hydrolase domains of Sph3 and PelA (Sph3h and PelAh, respectively) share structural and functional similarities given their ability to degrade GAG and disrupt A. fumigatus biofilms. MALDI-TOF enzymatic fingerprinting and NMR experiments revealed that both proteins are retaining endo-α-1,4-N-acetylgalactosaminidases with a minimal substrate size of seven residues. The crystal structure of PelAh was solved to 1.54 Å and structure alignment to Sph3h revealed that the enzymes share similar catalytic site residues. However, differences in the substrate-binding clefts result in distinct enzyme-substrate interactions. PelAh hydrolyzed partially deacetylated substrates better than Sph3h, a finding that agrees well with PelAh's highly electronegative binding cleft versus the neutral surface present in Sph3h Our insight into PelAh's structure and function necessitate the creation of a new glycoside hydrolase family, GH166, whose structural and mechanistic features, along with those of GH135 (Sph3), are reported here.}, } @article {pmid31166981, year = {2019}, author = {Pinto, M and Langer, TM and Hüffer, T and Hofmann, T and Herndl, GJ}, title = {The composition of bacterial communities associated with plastic biofilms differs between different polymers and stages of biofilm succession.}, journal = {PloS one}, volume = {14}, number = {6}, pages = {e0217165}, doi = {10.1371/journal.pone.0217165}, pmid = {31166981}, issn = {1932-6203}, abstract = {Once in the ocean, plastics are rapidly colonized by complex microbial communities. Factors affecting the development and composition of these communities are still poorly understood. Additionally, whether there are plastic-type specific communities developing on different plastics remains enigmatic. We determined the development and succession of bacterial communities on different plastics under ambient and dim light conditions in the coastal Northern Adriatic over the course of two months using scanning electron microscopy and 16S rRNA gene analyses. Plastics used were low- and high-density polyethylene (LDPE and HDPE, respectively), polypropylene (PP) and polyvinyl chloride with two typical additives (PVC DEHP and PVC DINP). The bacterial communities developing on the plastics clustered in two groups; one group was found on PVC and the other group on all the other plastics and on glass, which was used as an inert control. Specific bacterial taxa were found on specific surfaces in essentially all stages of biofilm development and in both ambient and dim light conditions. Differences in bacterial community composition between the different plastics and light exposures were stronger after an incubation period of one week than at the later stages of the incubation. Under both ambient and dim light conditions, one part of the bacterial community was common on all plastic types, especially in later stages of the biofilm development, with families such as Flavobacteriaceae, Rhodobacteraceae, Planctomycetaceae and Phyllobacteriaceae presenting relatively high relative abundances on all surfaces. Another part of the bacterial community was plastic-type specific. The plastic-type specific fraction was variable among the different plastic types and was more abundant after one week of incubation than at later stages of the succession.}, } @article {pmid31166551, year = {2019}, author = {Pires, JG and Braga, AS and Andrade, FB and Saldanha, LL and Dokkedal, AL and Oliveira, RC and Magalhães, AC}, title = {Effect of hydroalcoholic extract of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves on the viability and activity of microcosm biofilm and on enamel demineralization.}, journal = {Journal of applied oral science : revista FOB}, volume = {27}, number = {}, pages = {e20180514}, doi = {10.1590/1678-7757-2018-0514}, pmid = {31166551}, issn = {1678-7765}, mesh = {Anacardiaceae/*chemistry ; Animals ; Anti-Infective Agents/*pharmacology ; Biofilms/*drug effects ; Cariostatic Agents/pharmacology ; Cattle ; Colony Count, Microbial ; Dental Enamel/drug effects/microbiology ; Lactic Acid/metabolism ; Lactobacillus/drug effects ; Male ; Microbial Sensitivity Tests ; Microbial Viability/drug effects ; Microradiography/methods ; Myrtales/*chemistry ; Plant Extracts/*pharmacology ; Plant Leaves/chemistry ; Polysaccharides, Bacterial/metabolism ; Reproducibility of Results ; Saliva/chemistry ; Streptococcus mutans/drug effects ; Tooth Demineralization/*prevention & control ; }, abstract = {OBJECTIVES: The aim of this study was to assess the effect of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves hydroalcoholic extracts on viability and metabolism of a microcosm biofilm and on enamel demineralization prevention.

METHODOLOGY: Microcosm biofilm was produced on bovine enamel using inoculum from pooled human saliva mixed with McBain saliva, under 0.2% sucrose exposure, for 14 days. The biofilm was daily-treated with the extracts for 1 min. At the end, it was analyzed with respect to viability by fluorescence, CFU counting and extracellular polysaccharides (phenol-sulphuric acid colorimetric assay) and lactic acid (enzymatic assay) production. The demineralization was measured by TMR. The data were compared using ANOVA or Kruskal-Wallis (p<0.05).

RESULTS: M. urundeuva All. at 100, 10 and 0.1 μg/mL and Q. grandiflora Mart. at 100 and 0.1 μg/mL reduced biofilm viability similarly to positive control (chlorhexidine) and significantly more than the negative-vehicle control (35% ethanol). M. urundeuva at 1000, 100 and 0.1 μg/mL were able to reduce both lactobacilli and mutans streptococci CFU counting, while Q. grandiflora (1000 and 1.0 μg/mL) significantly reduced mutans streptococci CFU counting. On the other hand, the natural extracts were unable to significantly reduce extracellular polysaccharides and lactic acid productions neither the development of enamel carious lesions.

CONCLUSIONS: The extracts showed antimicrobial properties on microcosm biofilm, however, they had no effect on biofilm metabolism and caries protection.}, } @article {pmid31166390, year = {2019}, author = {Távora, FFF and Chocano, APC and Oliveira, DG and Pereira, JR and Almeida, RS and Neppelenbroek, KH and Porto, VC}, title = {Beneficial Effects of Ethyl-Cyanoacrylate Coating Against Candida Albicans Biofilm Formation.}, journal = {Brazilian dental journal}, volume = {30}, number = {3}, pages = {266-271}, doi = {10.1590/0103-6440201901953}, pmid = {31166390}, issn = {1806-4760}, abstract = {The aim of this study was to verify whether modifications made in a hard chairside reline resin by an ethyl-cyanoacrylate adhesive, ECA (Super Bonder®, Loctite, Itapevi, SP, Brazil) would be able to inhibit or reduce Candida albicans biofilm formation on its surface, comparing to a commercial surface sealant (BisCover®, Bisco, Schaumburg, USA). Reline resin specimens were fabricated and randomly divided into 6 groups (n=8): CG (control group), no surface treatment; ECA1, ECA coating on the surface before sterilization; ECA2, ECA coating after sterilization; ECA3, ECA incorporated in the resin bulk; DPE1, BisCover® coating before sterilization; DPE2, BisCover® coating after sterilization. Specimens were inoculated with C. albicans SC5314 (1x107 cells/mL) and incubated for 24 h. Then, the biofilm were stained with LIVE/DEAD® BaclightTM L7007 Kit and analyzed by Confocal Laser Scanning Microscopy. The images were evaluated by bioImageL® v.2.0 software and total biovolume (µm3), viable cells (%), and covered area (%) were calculated. Data were statistically analyzed by Kruskal-Wallis and Dunn tests (p<0.05). Results showed that ECA-coated groups presented better results, reducing C. albicans biofilm formation. Acquired images revealed that these groups (ECA1 and ECA2) presented a reduced number of cells, mostly in yeast form (less pathogenic), while the other groups presented higher number of cells, mostly in hyphae form (more pathogenic). Based on these findings, a beneficial effect of Super Bonder® coating reline resins surface could be demonstrated, suggesting a promising way to prevent fungal biofilm formation on dentures.}, } @article {pmid31166149, year = {2019}, author = {Iribarnegaray, V and Navarro, N and Robino, L and Zunino, P and Morales, J and Scavone, P}, title = {Magnesium-doped zinc oxide nanoparticles alter biofilm formation of Proteus mirabilis.}, journal = {Nanomedicine (London, England)}, volume = {14}, number = {12}, pages = {1551-1564}, doi = {10.2217/nnm-2018-0420}, pmid = {31166149}, issn = {1748-6963}, abstract = {Aim:Proteus mirabilis biofilms colonize medical devices, and their role in microbial pathogenesis is well established. Magnesium-doped zinc oxide nanoparticles (ZnO:MgO NPs) have potential antimicrobial properties; thus, we aimed at evaluating the antibiofilm activity of ZnO:MgO NPs against P. mirabilis biofilm. Materials & methods: After synthesis and characterization of ZnO:MgO NPs and their addition to a polymer film, we evaluated the stages of P. mirabilis biofilm development over glass coverslip covered by different concentrations of ZnO:MgO NPs. Results: Low concentrations of ZnO:MgO NPs affect the development of P. mirabilis biofilm. Descriptors showed reduced values in bacterial number, bacterial volume and extracellular material. Conclusion: Our results highlight this new application of ZnO:MgO NPs as a potential antibiofilm strategy in medical devices.}, } @article {pmid31165874, year = {2019}, author = {Turner, SD}, title = {Commentary on: Deposition of Host Matrix Proteins on Breast Implant Surfaces Facilitates Staphylococcus Epidermidis Biofilm Formation: In Vitro Analysis.}, journal = {Aesthetic surgery journal}, volume = {}, number = {}, pages = {}, doi = {10.1093/asj/sjz144}, pmid = {31165874}, issn = {1527-330X}, } @article {pmid31164053, year = {2019}, author = {Siebert, C and Lindgren, H and Ferré, S and Villers, C and Boisset, S and Perard, J and Sjöstedt, A and Maurin, M and Brochier-Armanet, C and Couté, Y and Renesto, P}, title = {Francisella tularensis: FupA mutation contributes to fluoroquinolone resistance by increasing vesicle secretion and biofilm formation.}, journal = {Emerging microbes & infections}, volume = {8}, number = {1}, pages = {808-822}, doi = {10.1080/22221751.2019.1615848}, pmid = {31164053}, issn = {2222-1751}, abstract = {Francisella tularensis is the causative agent in tularemia for which the high prevalence of treatment failure and relapse is a major concern. Directed-evolution experiments revealed that acquisition of fluoroquinolone (FQ) resistance was linked to factors in addition to mutations in DNA gyrase. Here, using F. tularensis live vaccine strain (LVS) as a model, we demonstrated that FupA/B (Fer-Utilization Protein) expression is linked to FQ susceptibility, and that the virulent strain F. tularensis subsp. tularensis SCHU S4 deleted for the homologous FupA protein exhibited even higher FQ resistance. In addition to an increased FQ minimal inhibitory concentration, LVSΔfupA/B displayed tolerance toward bactericidal compounds including ciprofloxacin and gentamicin. Interestingly, the FupA/B deletion was found to promote increased secretion of outer membrane vesicles (OMVs). Mass spectrometry-based quantitative proteomic characterization of vesicles from LVS and LVS∆fupA/B identified 801 proteins, including a subset of 23 proteins exhibiting differential abundance between both strains which may therefore contribute to the reduced antibiotic susceptibility of the FupA/B-deleted strain. We also demonstrated that OMVs are key structural elements of LVSΔfupA/B biofilms providing protection against FQ. These results provide a new basis for understanding and tackling antibiotic resistance and/or persistence of Francisella and other pathogenic members of the Thiotrichales class.}, } @article {pmid31163253, year = {2019}, author = {Teh, AHT and Lee, SM and Dykes, GA}, title = {Growth in the presence of specific antibiotics induces biofilm formation by a Campylobacter jejuni strain sensitive to them but not in resistant strains.}, journal = {Journal of global antimicrobial resistance}, volume = {18}, number = {}, pages = {55-58}, doi = {10.1016/j.jgar.2019.05.020}, pmid = {31163253}, issn = {2213-7173}, abstract = {OBJECTIVE: Campylobacter jejuni (C. jejuni) are among the most frequently identified bacteria associated with human gastroenteritis worldwide. Exposure to antibiotics may induce or inhibit biofilm formation in some bacterial species. Little work has been reported on the influence of antibiotics on biofilm formation by C. jejuni.

METHODS: This study investigated the effect of six different classes of antibiotics with different modes of action (ampicillin, ciprofloxacin, erythromycin, nalidixic acid, rifampicin and tetracycline) on biofilm formation in vitro by seven C. jejuni from poultry with different antibiotic resistance profiles.

RESULTS: The results indicated that in the presence of most of the tested antibiotics, biofilm formation by C. jejuni strains, which are resistant to them, was reduced but biofilm formation in sensitive strains was increased.

CONCLUSION: The ability of certain antibiotics to induce biofilm formation by a tested C. jejuni strain is of concern, with respect to the effective control of disease caused by this pathogen; however, further work is required to confirm how widespread this feature is.}, } @article {pmid31163049, year = {2019}, author = {Maczynska, B and Secewicz, A and Smutnicka, D and Szymczyk, P and Dudek-Wicher, R and Junka, A and Bartoszewicz, M}, title = {In vitro efficacy of gentamicin released from collagen sponge in eradication of bacterial biofilm preformed on hydroxyapatite surface.}, journal = {PloS one}, volume = {14}, number = {6}, pages = {e0217769}, doi = {10.1371/journal.pone.0217769}, pmid = {31163049}, issn = {1932-6203}, abstract = {Biofilm-related infections of bones pose a significant therapeutic issue. In this article we present in vitro results of the efficacy of gentamicin released from a collagen sponge carrier against Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae biofilms preformed on hydroxyapatite surface. The results indicate that high local concentrations of gentamicin released from a sponge eradicate the biofilm formed not only by gentamicin-sensitive strains but, to some extent, also by those that display a resistance pattern in routine diagnostics. The data presented in this paper is of high clinical translational value and may find application in the treatment of bone infections.}, } @article {pmid31160079, year = {2019}, author = {Bukhari, S and Karabucak, B}, title = {The Antimicrobial Effect of Bioceramic Sealer on an 8-week Matured Enterococcus faecalis Biofilm Attached to Root Canal Dentinal Surface.}, journal = {Journal of endodontics}, volume = {45}, number = {8}, pages = {1047-1052}, doi = {10.1016/j.joen.2019.04.004}, pmid = {31160079}, issn = {1878-3554}, abstract = {INTRODUCTION: The aim of this study was to test the antibacterial activity of bioceramic sealer in comparison with AH Plus (Dentsply International Inc, York, PA) on 8-week-old Enterococcus faecalis biofilms attached to root canal surfaces using a dentin infection model.

METHODS: The canal surfaces of single-rooted intact extracted teeth were infected by growing E. faecalis biofilms for 8 weeks. AH Plus sealer and EndoSequence BC Sealer (Brasseler USA, Savannah, GA) were placed on the root canal wall of the dentin specimens for 24 hours and 2 weeks in humid conditions at 37°C. Infected samples incubated with no sealers for similar periods were used as the negative controls. Specimens were labeled with fluorescent viability staining, and confocal laser scanning microscopy was used as an assessment tool of the proportions of dead and live bacteria on canal walls after exposure to root canal sealers for the determined times.

RESULTS: EndoSequence BC Sealer killed significantly more E. faecalis in biofilm attached to the canal surfaces when compared with AH plus sealer and control at both time points (P < .05-.0005).

CONCLUSIONS: EndoSequence BC Sealer exhibited significant antimicrobial capacity in the presence of dentin for up to 2 weeks on an 8-week-old E. faecalis biofilm in comparison with AH Plus sealer.}, } @article {pmid31158672, year = {2019}, author = {Pu, Y and Ngan, WY and Yao, Y and Habimana, O}, title = {Could benthic biofilm analyses be used as a reliable proxy for freshwater environmental health?.}, journal = {Environmental pollution (Barking, Essex : 1987)}, volume = {252}, number = {Pt A}, pages = {440-449}, doi = {10.1016/j.envpol.2019.05.111}, pmid = {31158672}, issn = {1873-6424}, abstract = {The quality of freshwater undoubtedly reflects the health of our surrounding environment, society, and economy, as these are supported by various freshwater ecosystems. Monitoring efforts have therefore been considered a vital means of ensuring the ecological health of freshwater environments. Nevertheless, most aquatic environmental monitoring strategies largely focus on bulk water sampling for analysis of physicochemical and key biological indicators, which for the most part do not consider pollution events that occur at any time between sampling events. Because benthic biofilms are ubiquitous in aquatic environments, pollution released during sporadic events may be absorbed by these biofilms, which can act as repositories of pollutants. The aim of this study was to assess whether benthic biofilm monitoring could provide an efficient way of properly characterizing the extent of pollution in aquatic environments. Here, bulk water and benthic biofilms were sampled from three Hong Kong streams having various pollution profiles, and subsequently compared via high-resolution microscopy, metagenomic analysis, and analytical chemistry. The results indicated that biofilms were, indeed, reservoirs of environmental pollutants, having different profiles compared with that of the corresponding bulk water samples. Moreover, the results also suggested that biofilms sampled in polluted areas were characterized by a higher species richness. While the analytical testing of benthic biofilms still needs further development, the integration of chemical-pollutant profiles and biofilm sequencing data in future studies may provide unique perspectives for understanding and identifying pollution-related biofilm biomarkers.}, } @article {pmid31158320, year = {2019}, author = {Shin, DS and Eom, YB}, title = {Zerumbone inhibits Candida albicans biofilm formation and hyphal growth.}, journal = {Canadian journal of microbiology}, volume = {}, number = {}, pages = {1-9}, doi = {10.1139/cjm-2019-0155}, pmid = {31158320}, issn = {1480-3275}, abstract = {Candida albicans biofilm formation is considered an important matter because it can lead to strong resistance to conventional antifungal agents. Hyphae formed by C. albicans can also act as an important virulence factor related to its biofilm. The objective of this study was to determine the effect of zerumbone, a monocyclic sesquiterpene extracted from Zingiber zerumbet (L.) Smith, against C. albicans biofilm formation. Our results suggest that zerumbone possesses antifungal and antibiofilm activity that inhibits biofilm formation and eradicates preformed biofilm. Notably, zerumbone considerably reduced carbohydrate and DNA contents of biofilm matrix. In addition, zerumbone showed antivirulence effects by decreasing the growth of hyphae and inhibiting morphologic changes of C. albicans. Furthermore, zerumbone significantly downregulated expression levels of biofilm-related and hyphae-specific genes, including HWP1 and ALS3. Since zerumbone suppresses biofilm formation and hyphae growth, these results indicate that zerumbone could be used as a potential candidate to treat and prevent C. albicans biofilm-related infections.}, } @article {pmid31158231, year = {2019}, author = {Panmanee, W and Su, S and Schurr, MJ and Lau, GW and Zhu, X and Ren, Z and McDaniel, CT and Lu, LJ and Ohman, DE and Muruve, DA and Panos, RJ and Yu, HD and Thompson, TB and Tseng, BS and Hassett, DJ}, title = {The anti-sigma factor MucA of Pseudomonas aeruginosa: Dramatic differences of a mucA22 vs. a ΔmucA mutant in anaerobic acidified nitrite sensitivity of planktonic and biofilm bacteria in vitro and during chronic murine lung infection.}, journal = {PloS one}, volume = {14}, number = {6}, pages = {e0216401}, doi = {10.1371/journal.pone.0216401}, pmid = {31158231}, issn = {1932-6203}, abstract = {Mucoid mucA22 Pseudomonas aeruginosa (PA) is an opportunistic lung pathogen of cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) patients that is highly sensitive to acidified nitrite (A-NO2-). In this study, we first screened PA mutant strains for sensitivity or resistance to 20 mM A-NO2- under anaerobic conditions that represent the chronic stages of the aforementioned diseases. Mutants found to be sensitive to A-NO2- included PA0964 (pmpR, PQS biosynthesis), PA4455 (probable ABC transporter permease), katA (major catalase, KatA) and rhlR (quorum sensing regulator). In contrast, mutants lacking PA0450 (a putative phosphate transporter) and PA1505 (moaA2) were A-NO2- resistant. However, we were puzzled when we discovered that mucA22 mutant bacteria, a frequently isolated mucA allele in CF and to a lesser extent COPD, were more sensitive to A-NO2- than a truncated ΔmucA deletion (Δ157-194) mutant in planktonic and biofilm culture, as well as during a chronic murine lung infection. Subsequent transcriptional profiling of anaerobic, A-NO2--treated bacteria revealed restoration of near wild-type transcript levels of protective NO2- and nitric oxide (NO) reductase (nirS and norCB, respectively) in the ΔmucA mutant in contrast to extremely low levels in the A-NO2--sensitive mucA22 mutant. Proteins that were S-nitrosylated by NO derived from A-NO2- reduction in the sensitive mucA22 strain were those involved in anaerobic respiration (NirQ, NirS), pyruvate fermentation (UspK), global gene regulation (Vfr), the TCA cycle (succinate dehydrogenase, SdhB) and several double mutants were even more sensitive to A-NO2-. Bioinformatic-based data point to future studies designed to elucidate potential cellular binding partners for MucA and MucA22. Given that A-NO2- is a potentially viable treatment strategy to combat PA and other infections, this study offers novel developments as to how clinicians might better treat problematic PA infections in COPD and CF airway diseases.}, } @article {pmid31157279, year = {2019}, author = {Lavery, LA and Bhavan, K and Wukich, DK}, title = {Biofilm and diabetic foot ulcer healing: all hat and no cattle.}, journal = {Annals of translational medicine}, volume = {7}, number = {7}, pages = {159}, doi = {10.21037/atm.2019.03.33}, pmid = {31157279}, issn = {2305-5839}, } @article {pmid31155952, year = {2019}, author = {Brilhante, RSN and Aguiar, L and Sales, JA and Araújo, GDS and Pereira, VS and Pereira-Neto, WA and Pinheiro, AQ and Paixão, GC and Cordeiro, RA and Sidrim, JJC and Bersano, PRO and Rocha, MFG and Castelo-Branco, DSCM}, title = {Ex vivo biofilm-forming ability of dermatophytes using dog and cat hair: an ethically viable approach for an infection model.}, journal = {Biofouling}, volume = {35}, number = {4}, pages = {392-400}, doi = {10.1080/08927014.2019.1599361}, pmid = {31155952}, issn = {1029-2454}, abstract = {The aim of this study was to establish an ex vivo model for dermatophyte biofilm growth, using hair from dogs and cats. Strains of Microsporum canis, M. gypseum, Trichophyton mentagrophytes and T. tonsurans were assessed for in vitro and ex vivo biofilm production. All T. mentagrophytes and T. tonsurans isolates and 8/12 M. canis and 1/7 M. gypseum isolates formed biofilms in vitro, while all tested isolates presented biofilm growth on ex vivo models. T. mentagrophytes and M. canis formed more homogeneous and better-structured biofilms with greater biomass production on cat hair but T. tonsurans formed more biofilm on dog hair. Confocal and scanning electron microscopy demonstrated fungal hyphae colonizing and perforating the hair shaft, abundant fungal conidia, biofilm extracellular matrix and biofilm water channels. The present study demonstrated an ex vivo model for the performance of studies on biofilm formation by dermatophytes, using dog and cat hair.}, } @article {pmid31155569, year = {2019}, author = {Ikezaki, S and Cho, T and Nagao, JI and Tasaki, S and Yamaguchi, M and Arita-Morioka, KI and Yasumatsu, K and Chibana, H and Ikebe, T and Tanaka, Y}, title = {Mild Heat Stress Affects on the Cell Wall Structure in Candida albicans Biofilm.}, journal = {Medical mycology journal}, volume = {60}, number = {2}, pages = {29-37}, doi = {10.3314/mmj.19-00001}, pmid = {31155569}, issn = {1882-0476}, abstract = {We previously reported that Candida albicans responded to mild heat stress in a range of temperature elevations simulating fever, and concluded that mild heat stress increases susceptibility to antifungal drugs. In this study, we show that mild heat stress causes a morphological change in hyphae during the process of biofilm formation. We found that mild heat stress extended the period of hyphal stage maintenance in C. albicans biofilm. Although the rate of hyphal change from yeast form to hyphal form reached the maximum within 3 hr, later, almost every cell quickly reverted to the yeast growth phase within 6 hr at 37°C but not at 39°C, or under mild heat stress. Electron microscopy using a smart specimen preparation technique revealed that mild heat stress significantly increased the thickness of the inner cell wall accompanied by a decrease in density of the outer cell wall in the hyphae of C. albicans biofilm. To identify the gene responsible for the morphological changes associated with mild heat stress, we performed microarray gene expression analysis. Eleven genes were upregulated and 17 genes were downregulated under mild heat stress in biofilm cells. The increased PHR1 gene expression in response to mild heat stress was confirmed in quantitative RT-PCR analysis. The mutant upregulated PHR1 expression showed the same sensitivity against antifungal drug micafungin as dependent on mild heat stress. Our findings point to possible therapeutic effects of hyperthermia as well as to the effect of fever during infections.}, } @article {pmid31152793, year = {2019}, author = {Albayaty, YN and Thomas, N and Jambhrunkar, M and Al-Hawwas, M and Kral, A and Thorn, CR and Prestidge, CA}, title = {Enzyme responsive copolymer micelles enhance the anti-biofilm efficacy of the antiseptic chlorhexidine.}, journal = {International journal of pharmaceutics}, volume = {566}, number = {}, pages = {329-341}, doi = {10.1016/j.ijpharm.2019.05.069}, pmid = {31152793}, issn = {1873-3476}, abstract = {Staphylococcal biofilms cause many infectious diseases and are highly tolerant to the effects of antimicrobials; this is partly due to the biofilm matrix, which acts as a physical barrier retarding the penetration and reducing susceptibility to antimicrobials, thereby decreasing successful treatment outcomes. In this study, both single and mixed micellar systems based on poly vinyl caprolactam (PCL)-polyethylene glycol (PEG) copolymers were optimised for delivery of chlorhexidine (CHX) to S. aureus, MRSA and S. epidermidis biofilms and evaluated for their toxicity using Caenorhabditis elegans. The respective polyethylene glycol (PEG) and poly vinyl caprolactam (PCL) structural components promoted stealth properties and enzymatic responsive release of CHX inside biofilms, leading to significantly enhanced penetration (56%) compared with free CHX and improving the efficacy against Staphylococcus aureus biofilms grown on an artificial dermis (2.4 log reduction of CFU). Mixing Soluplus-based micelles with Solutol further enhanced the CHX penetration (71%) and promoted maximum reduction in biofilm biomass (>60%). Nematodes-based toxicity assay showed micelles with no lethal effects as indicated by their high survival rate (100%) after 72 h exposure. This study thus demonstrated that bio-responsive carriers can be designed to deliver a poorly water-soluble antimicrobial agent and advance the control of biofilm associated infections.}, } @article {pmid31152205, year = {2019}, author = {Mahdinia, E and Demirci, A and Berenjian, A}, title = {Biofilm reactors as a promising method for vitamin K (menaquinone-7) production.}, journal = {Applied microbiology and biotechnology}, volume = {103}, number = {14}, pages = {5583-5592}, doi = {10.1007/s00253-019-09913-w}, pmid = {31152205}, issn = {1432-0614}, support = {Project PEN04561 and Accession number 1002249//USDA National Institute of Food and Agriculture Federal Appropriations/ ; }, abstract = {Menaquinone-7 (MK-7) is the most potent subtype of vitamin K with extraordinarily high half-life in the circulatory system. Therefore, MK-7 plays a critical role in promoting human wellbeing today. Studies on MK-7 every year show more and more magnificent benefits of it in preventing cardiovascular diseases and osteoporosis to battling cancer cells, Alzheimer's and Parkinson's diseases. Thus, it needs to be supplemented to daily diet for accumulative and long-term benefits. Chemical synthesis of MK-7 produces a significant cis-isomer form of it, which has no biological activity. Fortunately, due to its key role in electron transfer in bacteria, trans-MK-7 is biosynthesized by especially Gram-positive strains mainly Bacillus genus. Concordantly, MK-7 could be produced via solid or liquid state fermentation strategies. In either regime, when static fermentation is applied in the absence of agitation and aeration, operational issues arise such as heat and mass transfer inefficiencies. Thus, scaling up the process becomes a challenge. On the other hand, studies have indicated that biofilm and pellicle formation that occur in static fermentations are key characteristics for extracellular MK-7 secretion. Therefore, this review covers the most recent discoveries of the therapeutic properties of MK-7 and optimization attempts at increasing its biosynthesis in different media compositions and effective growth parameters as well as the cutting-edge use of biofilm reactors where B. subtilis cells have the infrastructures to form mature biofilm formations on plastic composite supports. Biofilm reactors therefore can provide robust extracellular MK-7 secretion while simultaneously enduring high agitation and aeration rates, which then address the scale-up and operational issues associated with static fermentation strategies.}, } @article {pmid31151296, year = {2019}, author = {Picco, DCR and Marangoni-Lopes, L and Parisotto, TM and Mattos-Graner, R and Nobre-Dos-Santos, M}, title = {Activity of Carbonic Anhydrase VI is Higher in Dental Biofilm of Children with Caries.}, journal = {International journal of molecular sciences}, volume = {20}, number = {11}, pages = {}, doi = {10.3390/ijms20112673}, pmid = {31151296}, issn = {1422-0067}, support = {2012/02886-3 and 2012/15834-1//Fundação de Amparo à Pesquisa do Estado de São Paulo/ ; 1289/2006//Fundo de Apoio ao Ensino, à Pesquisa e Extensão, Universidade Estadual de Campinas/ ; }, abstract = {This study investigated pH, activity and concentration of carbonic anhydrase VI (CA VI) in dental biofilm of caries and caries-free children of 7-9 years old. Seventy-four children were selected and divided into two groups. The caries diagnosis was performed according to the WHO criteria, including the early caries lesion. After biofilm collection and pH determination, CA VI concentration and activity were determined by ELISA and Zimography respectively. The data were submitted to a Mann-Whitney test and to Pearson and Spearman correlation analyses. Means and standard deviations of dental caries for the caries group were of 3.162 ± 1.385. The biofilm pH was significantly higher in the caries-free group. The CA VI activity was significantly higher in biofilm of children with caries. The CA VI concentration was significantly higher in biofilm of caries-free children. In caries-free children, there was a moderate negative correlation between CA VI activity and concentration in dental biofilm as well as between pH and CA VI activity. A negative correlation between biofilm pH and CA VI concentration was found in the caries group. In conclusion, CA VI was shown to be more active in the biofilm of school children with caries in order to contribute to neutralization of biofilm acid.}, } @article {pmid31151290, year = {2019}, author = {Simonetti, G and Palocci, C and Valletta, A and Kolesova, O and Chronopoulou, L and Donati, L and Di Nitto, A and Brasili, E and Tomai, P and Gentili, A and Pasqua, G}, title = {Anti-Candida Biofilm Activity of Pterostilbene or Crude Extract from Non-Fermented Grape Pomace Entrapped in Biopolymeric Nanoparticles.}, journal = {Molecules (Basel, Switzerland)}, volume = {24}, number = {11}, pages = {}, doi = {10.3390/molecules24112070}, pmid = {31151290}, issn = {1420-3049}, support = {C26A14RP98//University Sapienza of Rome/ ; }, abstract = {Polymeric nanoparticle-based carriers are promising agents to deliver drugs to cells. Vitisvinifera phenolic compounds are known for their antifungal activity against Candida albicans. The aim of the present study was to investigate the antifungal activity of pterostilbene or crude extracts from non-fermented grape pomace, entrapped in poly(lactic-co-glycolic) acid nanoparticles (NPs), with diameters of 50 and 150 nm, on Candida biofilm. The fluorescent probe coumarin 6 was used to study the uptake of poly(lactic-co-glycolic)acid (PLGA) NPs in planktonic cells and biofilm. The green fluorescent signal of coumarin 6 was observed in Candida biofilm after 24 and 48 hours. Both pterostilbene and crude pomace extract entrapped in NPs exerted a significantly higher anti-biofilm activity compared to their free forms. The entrapment efficiency of both pterostilbene and crude pomace extract in PLGA NPs was ~90%. At 16 µg/mL, pterostilbene loaded in PLGA NPs reduced biofilm formation of 63% and reduced mature biofilm of 50%. Moreover, at 50 µg/mL, the pomace extract loaded in NPs reduced mature biofilm of 37%. These results strongly suggest that PLGA NPs are promising nanodevices for the delivery of antifungal drugs as the crude grape pomace extract, a by-product of white wine making.}, } @article {pmid31151195, year = {2019}, author = {Heersema, LA and Smyth, HDC}, title = {A Multispecies Biofilm In Vitro Screening Model of Dental Caries for High-Throughput Susceptibility Testing.}, journal = {High-throughput}, volume = {8}, number = {2}, pages = {}, doi = {10.3390/ht8020014}, pmid = {31151195}, issn = {2571-5135}, support = {DGE-1610403//National Science Foundation/ ; }, abstract = {There is a current need to develop and optimize new therapeutics for the treatment of dental caries, but these efforts are limited by the relatively low throughput of relevant in vitro models. The aim of this work was to bridge the 96-well microtiter plate system with a relevant multispecies dental caries model that could be reproducibly grown to allow for the high-throughput screening of anti-biofilm therapies. Various media and inoculum concentrations were assessed using metabolic activity, biomass, viability, and acidity assays to determine the optimal laboratory-controlled conditions for a multispecies biofilm composed of Streptococcus gordonii, Streptococcus mutans, and Candida albicans. The selected model encompasses several of the known fundamental characteristics of dental caries-associated biofilms. The 1:1 RPMI:TSBYE 0.6% media supported the viability and biomass production of mono- and multispecies biofilms best. Kinetic studies over 48 h in 1:1 RPMI:TSBYE 0.6% demonstrated a stable biofilm phase between 10 and 48 h for all mono- and multispecies biofilms. The 1:1:0.1 S. gordonii: S. mutans: C. albicans multispecies biofilm in 1:1 RPMI:TSBYE 0.6% is an excellent choice for a high-throughput multispecies model of dental caries. This high-throughput multispecies model can be used for screening novel therapies and for better understanding the treatment effects on biofilm interactions and stability.}, } @article {pmid31151056, year = {2019}, author = {Rajivgandhi, G and Maruthupandy, M and Muneeswaran, T and Anand, M and Quero, F and Manoharan, N and Li, WJ}, title = {Biosynthesized silver nanoparticles for inhibition of antibacterial resistance and biofilm formation of methicillin-resistant coagulase negative Staphylococci.}, journal = {Bioorganic chemistry}, volume = {89}, number = {}, pages = {103008}, doi = {10.1016/j.bioorg.2019.103008}, pmid = {31151056}, issn = {1090-2120}, abstract = {The ability of a natural stabilizing and reducing agent on the synthesis of silver nanoparticles (Ag NPs) was explored using a rapid and single-pot biological reduction method using Nocardiopsis sp. GRG1 (KT235640) biomass. The UV-visible spectral analysis of Ag NPs was found to show a maximum absorption peak located at a wavelength position of ∼422 nm for initial conformation. The major peaks in the XRD pattern were found to be in excellent agreement with the standard values of metallic Ag NPs. No other peaks of impurity phases were observed. The morphology of Ag NPs was confirmed through TEM observation, demonstrating that the particle size distribution of Ag NPs entrenched in spherical particles is in a range between 20 and 50 nm. AFM analysis further supported the nanosized morphology of the synthesized Ag NPs and allowed quantifying the Ag NPs surface roughness. The synthesized Ag NPs showed significant antibacterial and antibiofilm activity against biofilm positive methicillin-resistant coagulase negative Staphylococci (MR-CoNS), which were isolated from urinary tract infection as determined by spectroscopic methods in the concentration range of 5-60 µg/ml. The inhibition of biofilm formation with coloring stain was morphologically imaged by confocal laser scanning microscopy (CLSM). Morphological alteration of treated bacteria was observed by SEM analysis. The results clearly indicate that these biologically synthesized Ag NPs could provide a safer alternative to conventional antibiofilm agents against uropathogen of MR-CoNS.}, } @article {pmid31149345, year = {2019}, author = {Tahrioui, A and Duchesne, R and Bouffartigues, E and Rodrigues, S and Maillot, O and Tortuel, D and Hardouin, J and Taupin, L and Groleau, MC and Dufour, A and Déziel, E and Brenner-Weiss, G and Feuilloley, M and Orange, N and Lesouhaitier, O and Cornelis, P and Chevalier, S}, title = {Extracellular DNA release, quorum sensing, and PrrF1/F2 small RNAs are key players in Pseudomonas aeruginosa tobramycin-enhanced biofilm formation.}, journal = {NPJ biofilms and microbiomes}, volume = {5}, number = {}, pages = {15}, doi = {10.1038/s41522-019-0088-3}, pmid = {31149345}, issn = {2055-5008}, abstract = {Biofilms are structured microbial communities that are the leading cause of numerous chronic infections which are difficult to eradicate. Within the lungs of individuals with cystic fibrosis (CF), Pseudomonas aeruginosa causes persistent biofilm infection that is commonly treated with aminoglycoside antibiotics such as tobramycin. However, sublethal concentrations of this aminoglycoside were previously shown to increase biofilm formation by P. aeruginosa, but the underlying adaptive mechanisms still remain elusive. Herein, we combined confocal laser scanning microscope analyses, proteomics profiling, gene expression assays and phenotypic studies to unravel P. aeruginosa potential adaptive mechanisms in response to tobramycin exposure during biofilm growth. Under this condition, we show that the modified biofilm architecture is related at least in part to increased extracellular DNA (eDNA) release, most likely as a result of biofilm cell death. Furthermore, the activity of quorum sensing (QS) systems was increased, leading to higher production of QS signaling molecules. We also demonstrate upon tobramycin exposure an increase in expression of the PrrF small regulatory RNAs, as well as expression of iron uptake systems. Remarkably, biofilm biovolumes and eDNA relative abundances in pqs and prrF mutant strains decrease in the presence of tobramycin. Overall, our findings offer experimental evidences for a potential adaptive mechanism linking PrrF sRNAs, QS signaling, biofilm cell death, eDNA release, and tobramycin-enhanced biofilm formation in P. aeruginosa. These specific adaptive mechanisms should be considered to improve treatment strategies against P. aeruginosa biofilm establishment in CF patients' lungs.}, } @article {pmid31148964, year = {2019}, author = {Abbas, HA and Elsherbini, AM and Shaldam, MA}, title = {Glyceryl trinitrate blocks staphyloxanthin and biofilm formation in Staphylococcus aureus.}, journal = {African health sciences}, volume = {19}, number = {1}, pages = {1376-1384}, doi = {10.4314/ahs.v19i1.10}, pmid = {31148964}, issn = {1729-0503}, abstract = {Background: Staphylococcus aureus is an important nosocomial bacterium that is responsible for a number of infections that may be fatal. The treatment of such infections is limited by emergence of antibiotic resistance. Targeting virulence of Staphylococcus aureus may provide an alternative option to antibiotic that may bypass the emergence of resistant strains due to lack of stress on viability.

Objectives: Investigation of the ability of glyceryl trinitrate (GTN) to inhibit staphyloxanthin, biofilm and tolerance to oxidative stress.

Methods: The disk sensitivity method was used to detect the methicillin resistance of Staphylococcus aureus. The effect of sub-inhibitory concentration of GTN on biofilm formation, staphyloxanthin production and tolerance to oxidative stress was evaluated. Molecular docking study was used to investigate the ability of GTN to bind to dehydrosqualene synthase enzyme.

Results: GTN showed a significant inhibition of biofilm, staphyloxanthin and tolerance to oxidative stress. In the molecular docking study, it was found that GTN could bind to dehydrosqualene synthase enzyme by hydrogen bonding, electrostatic interaction and pi-cation interaction.

Conclusion: The present study revealed the ability of GTN to serve as a potential anti-virulence candidate for attenuation of S. aureus pathogenicity.}, } @article {pmid31147809, year = {2019}, author = {Song, H and Zhang, J and Qu, J and Liu, J and Yin, P and Zhang, G and Shang, D}, title = {Lactobacillus rhamnosus GG microcapsules inhibit Escherichia coli biofilm formation in coculture.}, journal = {Biotechnology letters}, volume = {41}, number = {8-9}, pages = {1007-1014}, doi = {10.1007/s10529-019-02694-2}, pmid = {31147809}, issn = {1573-6776}, support = {81601734//National Natural Science Foundation of China/ ; }, abstract = {OBJECTIVES: Microbial biofilms have become one of the most significant causes of nosocomial infections. The aim of this study was to examine the potential quorum sensing inhibitor activities of Lactobacillus rhamnosus GG microcapsules.

RESULTS: Lactobacillus rhamnosus GG microcapsules effectively inhibited initial biofilm formation at a concentration of 2.5 × 108 CFU/mL. Furthermore, the inhibition rate was increased to 79% in the Lactobacillus rhamnosus GG microcapsules group, resulting in a reduction in the biofilm maturation stage. In addition, real-time PCR analysis revealed that the LGG microcapsules can act as effective inhibitors of transcriptional activators of the quorum sensing circuit in E.coli, luxS, lsrK, and lsrR.

CONCLUSIONS: Lactobacillus rhamnosus GG microcapsules can effectively inhibit biofilm formation and disturb mature biofilms.}, } @article {pmid31147580, year = {2019}, author = {Tanaka, N and Kogo, T and Hirai, N and Ogawa, A and Kanematsu, H and Takahara, J and Awazu, A and Fujita, N and Haruzono, Y and Ichida, S and Tanaka, Y}, title = {In-situ detection based on the biofilm hydrophilicity for environmental biofilm formation.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {8070}, doi = {10.1038/s41598-019-44167-6}, pmid = {31147580}, issn = {2045-2322}, support = {AS2715165U//MEXT | Japan Science and Technology Agency (JST)/ ; VP29117939804//MEXT | Japan Science and Technology Agency (JST)/ ; 18K18374//MEXT | Japan Society for the Promotion of Science (JSPS)/ ; 18KK0416//MEXT | Japan Society for the Promotion of Science (JSPS)/ ; }, abstract = {A biofilm has a unique structure composed of microorganisms, extracellular polymeric substances (EPSs), etc., and it is layered on a substrate in water. In material science, it is important to detect the biofilm formed on a surface to prevent biofouling. EPSs, the major component of the biofilm, mainly consist of polysaccharides, proteins, nucleic acids, and lipids. Because these biomolecules have a variety of hydrophilicities or hydrophobicities, the substrate covered with the biofilm shows different wettability from the initial state. To detect the biofilm formation, this study employed a liquid-squeezing-based wettability assessment method with a simple wettability index: the liquid-squeezed diameter of a smaller value indicates higher wettability. The method is based on the liquid-squeezing behaviour of a liquid that covers sample surfaces when an air-jet is applied. To form the biofilm, polystyrene surfaces were immersed and incubated in a water-circulated bioreactor that had collected microorganisms in ambient air. After the 14-d incubation, good formation of the biofilm on the surfaces was confirmed by staining with crystal violet. Although the contact angles of captive bubbles on the surfaces with the biofilm were unmeasurable, the liquid-squeezing method could distinguish between hydrophilic and hydrophobic initial surfaces with and without biofilm formation using the diameter of the liquid-squeezed area. The surface wettability is expected to be a promising property for in-situ detection of biofilm formation on a macroscopic scale.}, } @article {pmid31146243, year = {2019}, author = {Gong, M and Yang, G and Zhuang, L and Zeng, EY}, title = {Microbial biofilm formation and community structure on low-density polyethylene microparticles in lake water microcosms.}, journal = {Environmental pollution (Barking, Essex : 1987)}, volume = {252}, number = {Pt A}, pages = {94-102}, doi = {10.1016/j.envpol.2019.05.090}, pmid = {31146243}, issn = {1873-6424}, abstract = {The occurrence of microplastics (MPs) in the environment has been gaining widespread attention globally. MP-colonizing microorganisms are important links for MPs contamination in various ecosystems, but have not been well understood. To partially address this issue, the present study investigated biofilm formation by microorganisms originating from lake water on low-density polyethylene (LDPE) MPs using a cultivation approach and the surface-related effects on the MP-associated microbial communities using 16S rRNA high-throughput sequencing. With the addition of nonionic surfactants and UV-irradiation pretreatment that changed the surface properties of LDPE MPs, more microorganisms were colonized on LDPE surface. Microbial community analysis indicated that LDPE MPs were primarily colonized by the phyla Proteobacteria, Bacteroidetes and Firmicutes, and the surface roughness and hydrophobicity of MP were important factors shaping the LDPE MP-associated microbial community structure. Half of the top 20 most abundant genera colonizing on LDPE were found to be potential pathogens, e.g., plant pathogens Agrobacterium, nosocomial pathogens Chryseobacterium and fish pathogens Flavobacterium. This study demonstrated rapid bacterial colonization of LDPE MPs in lake water microcosms, the role of MPs as transfer vectors for harmful microorganisms in lake water, and provided a first glimpse into the effect of surface properties on LDPE MP-associated biofilm communities.}, } @article {pmid31146189, year = {2019}, author = {Li, J and Peng, Y and Zhang, L and Liu, J and Wang, X and Gao, R and Pang, L and Zhou, Y}, title = {Quantify the contribution of anammox for enhanced nitrogen removal through metagenomic analysis and mass balance in an anoxic moving bed biofilm reactor.}, journal = {Water research}, volume = {160}, number = {}, pages = {178-187}, doi = {10.1016/j.watres.2019.05.070}, pmid = {31146189}, issn = {1879-2448}, abstract = {In this study, enhanced nitrogen removal through in situ enrichment of anammox bacteria was successfully obtained in a full-scale municipal wastewater treatment plant (WWTP). The WWTP was an anaerobic-anoxic-oxic (AAO) process and upgraded by adding moving carriers into the anoxic zone. Enhanced nitrogen removal was obtained during almost two years of operation. The significant nitrogen removal might be associated with the in situ enrichment of anammox bacteria on the adding carriers, as revealed by the comprehensive results of molecular analysis and 15N-stable isotope tracing tests. Quantitative PCR results indicated that anammox bacteria in the anoxic-carrier biofilms presented a higher abundance than flocculent sludge (16S rRNA: P < 0.005; HzsB: P < 0.042). The 16S rRNA amplicon sequencing showed significant differences in the phylum Planctomycetes (P < 0.001) between anoxic-carrier biofilms and flocculent sludge. And metagenomic sequencing analysis further revealed the anammox relative abundance in the anoxic-carrier biofilms was significantly higher than the reported level in the flocculent sludge of conventional WWTPs. In addition, 15N-stable isotope tracing tests showed that anammox could be combined with nitrate reduction by the anoxic-carrier biofilms. Thus, enriched anammox bacteria might contribute to nitrogen loss and lead to improvements in the nitrogen removal, which was also supported by the mass balance analysis of organic carbon, nitrogen, and phosphorus of the WWTP. Overall, this study suggests that anoxic-carrier biofilms might be a candidate to enhance nitrogen removal through partial anammox in municipal WWTPs.}, } @article {pmid31146064, year = {2019}, author = {Richard, H and Carpenter, EJ and Komada, T and Palmer, PT and Rochman, CM}, title = {Biofilm facilitates metal accumulation onto microplastics in estuarine waters.}, journal = {The Science of the total environment}, volume = {683}, number = {}, pages = {600-608}, doi = {10.1016/j.scitotenv.2019.04.331}, pmid = {31146064}, issn = {1879-1026}, mesh = {*Biofilms ; *Environmental Monitoring ; *Estuaries ; Metals/*chemistry ; Plastics/*chemistry ; Polyethylene ; Waste Products ; Water Pollutants, Chemical/analysis/*chemistry ; }, abstract = {In aquatic environments, plastic debris accumulates chemical pollutants from the surrounding water, potentially altering the fate of xenobiotics in these ecosystems. The effects of biofouling on the potential for plastic to sorb environmental pollutants remain poorly understood. In this study, we test the hypothesis that concentrations of metals are directly related to biofilm accumulation on microplastics submerged in natural estuarine waters. Two types of pre-production plastic pellets (polylactic acid (PLA) and low-density polyethylene (LDPE)) and glass pellets, were suspended for up to 28 days in an urbanized estuary (San Francisco Bay, California) to investigate how biofilm affects the accumulation of metals on these materials. During the initial weeks of the experiment, biofilm growth differed between locations, but after 28 days, PLA and LDPE had similar amounts of biofilm at the two field sites. Biofilm was the only significant predictor variable for Ba, Cs, Fe, Ga, Ni and Rb, and simple regressions of these metals after one month of submersion predicted much of the variability in the data (respective adjusted R2 values: 0.46, 0.90, 0.86, 0.81, 0.87, 0.90; p < 0.001). For other metals influenced by location or substrate material, multivariate analysis showed that increases in metal concentrations were predicted by increases in biofilm for Cu, Pb, Al, K, U, Co, Mg (p < 0.001) and Mn (p < 0.01). This work highlights the role of biofilm in facilitating metal accumulation on plastic debris and contributes to current understanding of the underlying processes that influence the behavior of microplastics as aquatic contaminants.}, } @article {pmid31145677, year = {2019}, author = {Abriat, C and Virgilio, N and Heuzey, MC and Daigle, F}, title = {Microbiological and real-time mechanical analysis of Bacillus licheniformis and Pseudomonas fluorescens dual-species biofilm.}, journal = {Microbiology (Reading, England)}, volume = {165}, number = {7}, pages = {747-756}, doi = {10.1099/mic.0.000819}, pmid = {31145677}, issn = {1465-2080}, abstract = {In natural habitats, bacterial species often coexist in biofilms. They interact in synergetic or antagonistic ways and their interactions can influence the biofilm development and properties. Still, very little is known about how the coexistence of multiple organisms impact the multispecies biofilm properties. In this study, we examined the behaviour of a dual-species biofilm at the air-liquid interface composed by two environmental bacteria: Bacillus licheniformis and a phenazine mutant of Pseudomonas fluorescens. Study of the planktonic and biofilm growths for each species revealed that P. fluorescens grew faster than B. licheniformis and no bactericidal effect from P. fluorescens was detected, suggesting that the growth kinetics could be the main factor in the dual-species biofilm composition. To validate this hypothesis, the single- and dual-species biofilm were characterized by biomass quantification, microscopy and rheology. Bacterial counts and microscale architecture analysis showed that both bacterial populations coexist in the mature pellicle, with a dominance of P. fluorescens. Real-time measurement of the dual-species biofilms' viscoelastic (i.e. mechanical) properties using interfacial rheology confirmed that P. fluorescens was the main contributor of the biofilm properties. Evaluation of the dual-species pellicle viscoelasticity at longer time revealed that the biofilm, after reaching a first equilibrium, created a stronger and more cohesive network. Interfacial rheology proves to be a unique quantitative technique, which combined with microscale imaging, contributes to the understanding of the time-dependent properties within a polymicrobial community at various stages of biofilm development. This work demonstrates the importance of growth kinetics in the bacteria competition for the interface in a model dual-species biofilm.}, } @article {pmid31145519, year = {2019}, author = {Mori, Y and Nakagami, G and Kitamura, A and Minematsu, T and Kinoshita, M and Suga, H and Kurita, M and Hayashi, C and Kawasaki, A and Sanada, H}, title = {Effectiveness of biofilm-based wound care system on wound healing in chronic wounds.}, journal = {Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society}, volume = {}, number = {}, pages = {}, doi = {10.1111/wrr.12738}, pmid = {31145519}, issn = {1524-475X}, support = {17H04455//Japan Society for the Promotion of Science/ ; //Japanese Society of Pressure Ulcers/ ; }, abstract = {A biofilm plays a crucial role in delaying wound healing. Sharp debridement, a possible effective method for eliminating biofilms, can only be applied to the wound with visible necrotic tissue; thus, no option has been available for eliminating biofilms that are not accompanied by necrotic tissue. Wound blotting was recently developed to visualize biofilm noninvasively and quickly, and ultrasonic debridement is available for biofilm removal. Therefore, the purpose of this study was to investigate the efficacy of "biofilm-based wound care system (BWCS)," a combination of wound blotting as a point-of-care testing and ultrasonic debridement, for promoting wound healing. Firstly, the cross-sectional study was conducted to examine the proportion of biofilm removal by ultrasonic debridement in pressure ulcers [Study 1]. Subsequently, the retrospective cohort study was conducted to examine the effectiveness of BWCS for healing of chronic wounds [Study 2]. The proportions of wound healing between wounds treated with BWCS and those with standard care in the home-visiting clinic were compared by Kaplan-Meier curve, and the Cox proportional hazard modeling was used to assess the effect of BWCS on wound healing. In Study 1, the median of biofilm removal proportion was 38.9% (interquartile range, 12.9-68.0%) for pressure ulcers treated with standard care and 65.2% (41.1-78.8%) for those treated with ultrasonic debridement (p = 0.009). In Study 2, the proportion of wound healing within 90 days was significantly higher in wounds treated with BWCS than in those treated with standard care (p = 0.001). The adjusted hazard ratio of BWCS for wound healing was 4.5 (95% confidence interval, 1.3-15.0; p = 0.015). In conclusion, we demonstrated that our novel approach, BWCS, can be a promising therapeutic strategy for visualizing biofilms that are not accompanied by necrotic tissue and promoting healing in chronic wounds.}, } @article {pmid31145040, year = {2019}, author = {Rizk, N and Ait-Mouheb, N and Molle, B and Roche, N}, title = {Treated wastewater reuse in micro-irrigation: effect of shear stress on biofilm development kinetics and chemical precipitation.}, journal = {Environmental technology}, volume = {}, number = {}, pages = {1-11}, doi = {10.1080/09593330.2019.1625956}, pmid = {31145040}, issn = {1479-487X}, abstract = {Treated wastewater in micro-irrigation is a promising approach that could be used to decrease the pressure on good quality water resources. However, the clogging of such systems due to biofilm development and chemical precipitation constitute a constraint with the use of treated wastewater (TWW) and lead to lower irrigation system performance. The objective of this work is to study the development of biofilm and composition of fouling due to TWW under shear stresses of 0.7, 2.2 and 4.4 Pa detected along micro-irrigation systems. For this purpose, a Taylor-Couette reactor (TCR) was specifically calibrated for the cultivation of biofilm. The analysis of fouling composition samples (organic and inorganic) shows that biofilm tends to develop under the highest shear stress value (4.4 Pa). Precipitation of calcium carbonate in the form of calcite was observed in conjunction with biofilm growth using X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). These results can be used to ascertain the origins of chemical and biological clogging of drippers and fouling of pipes related to reclaimed water- irrigation.}, } @article {pmid31144524, year = {2019}, author = {Rasmussen, RM and Epperson, RT and Taylor, NB and Williams, DL}, title = {Plume height and surface coverage analysis of methicillin-resistant Staphylococcus aureus isolates grown in a CDC biofilm reactor.}, journal = {Biofouling}, volume = {35}, number = {4}, pages = {463-471}, doi = {10.1080/08927014.2019.1612381}, pmid = {31144524}, issn = {1029-2454}, abstract = {Biofilm formation is a dynamic process that leads to mature communities over time. Despite a general knowledge of biofilm community formation and the resultant limitations of antibiotic therapy, there is a paucity of data describing specific plume heights, surface coverage and rates of maturation. Furthermore, little is published on the effect that the broth medium might have on the degree of biofilm maturation. In this study, three strains of methicillin-resistant Staphylococcus aureus (MRSA) (USA300, USA400 and a clinical isolate) were grown in brain heart infusion broth (BHI) or tryptic soy broth (TSB). Following growth, SEM images were captured for 3-D analysis to assess plume height. TSB produced significantly higher plume heights of USA300 and USA400 compared to BHI. Broth type was less influential on the clinical isolate. The data indicate that broth type and time may be important factors to consider when assessing maturation and plume height formation of MRSA biofilms.}, } @article {pmid31144441, year = {2019}, author = {Casciaro, B and Lin, Q and Afonin, S and Loffredo, MR and de Turris, V and Middel, V and Ulrich, AS and Di, YP and Mangoni, ML}, title = {Inhibition of Pseudomonas aeruginosa biofilm formation and expression of virulence genes by selective epimerization in the peptide Esculentin-1a(1-21)NH2.}, journal = {The FEBS journal}, volume = {}, number = {}, pages = {}, doi = {10.1111/febs.14940}, pmid = {31144441}, issn = {1742-4658}, support = {INST 12384/58-1 FUGG//Deutsche Forschungsgemeinschaft/ ; AI-133351//National Institutes of Health awards/ ; //Italian Cystic Fibrosis Foundation (project FFC#11/2014 adopted by FFC Delegations from Siena, Sondrio Valchiavenna, Cerea Il Sorriso di Jenny, and Pavia and project FFC 15/2017 Adopted by Delegations of Palermo, Vittoria, Ragusa, Siracusa, Catania Mascalucia, Messina, Gruppo di Sostegno di Tremestieri)/ ; RM11816436113D8A//Sapienza University of Rome/ ; R01 HL-125128//National Institutes of Health awards/ ; RM116154C8434109//Sapienza University of Rome/ ; R01 HL125128/HL/NHLBI NIH HHS/United States ; }, abstract = {Pseudomonas aeruginosa is a pathogenic bacterium known to cause serious human infections, especially in immune-compromised patients. This is due to its unique ability to transform from a drug-tolerant planktonic to a more dangerous and treatment-resistant sessile life form, called biofilm. Recently, two derivatives of the frog skin antimicrobial peptide esculentin-1a, i.e. Esc(1-21) and its D-amino acids containing diastereomer Esc(1-21)-1c, were characterized for their powerful anti-Pseudomonal activity against both forms. Prevention of biofilm formation already in its early stages could be even more advantageous for counteracting infections induced by this bacterium. In this work, we studied how the diastereomer Esc(1-21)-1c can inhibit Pseudomonas biofilm formation in comparison to the parent peptide and two clinically-used conventional antibiotics, i.e. colistin and aztreonam, when applied at dosages below the minimal growth inhibitory concentration. Biofilm prevention was correlated to the peptides' ability to inhibit Pseudomonas motility and to reduce the production of virulent metabolites, for example, pyoverdine and rhamnolipids. Furthermore, the molecular mechanism underlying these activities was evaluated by studying the peptides' effect on the expression of key genes involved in the virulence and motility of bacteria, as well as by monitoring the peptides' binding to the bacterial signaling nucleotide ppGpp. Our results demonstrate that the presence of only two D-amino acids in Esc(1-21)-1c is sufficient to downregulate ppGpp-mediated expression of biofilm-associated genes, presumably as a result of higher peptide stability and therefore prolonged interaction with the nucleotide. Overall, these studies should assist efficient design and optimization of new anti-infective agents with multiple pharmacologically beneficial properties.}, } @article {pmid31143408, year = {2019}, author = {Conrads, G and Wendt, LK and Hetrodt, F and Deng, ZL and Pieper, D and Abdelbary, MMH and Barg, A and Wagner-Döbler, I and Apel, C}, title = {Deep sequencing of biofilm microbiomes on dental composite materials.}, journal = {Journal of oral microbiology}, volume = {11}, number = {1}, pages = {1617013}, doi = {10.1080/20002297.2019.1617013}, pmid = {31143408}, issn = {2000-2297}, abstract = {Background: The microbiome on dental composites has not been studied in detail before. It has not been conclusively clarified whether restorative materials influence the oral microbiome. Methods: We used Illumina Miseq next-generation sequencing of the 16S V1-V2 region to compare the colonisation patterns of bovine enamel (BE) and the composite materials Grandio Flow (GF) and Grandio Blocs (GB) after 48 h in vivo in 14 volunteers. Applying a new method to maintain the oral microbiome ex vivo for 48 h also, we compared the microbiome on GF alone and with the new antimicrobial substance carolacton (GF+C). Results: All in vitro biofilm communities showed a higher diversity and richness than those grown in vivo but the very different atmospheric conditions must be considered. Contrary to expectations, there were only a few significant differences between BE and the composite materials GB and GF either in vivo or in vitro: Oribacterium, Peptostreptococcaceae [XI][G-1] and Streptococcus mutans were more prevalent and Megasphaera, Prevotella oulorum, Veillonella atypica, V. parvula, Gemella morbillorum, and Fusobacterium periodonticum were less prevalent on BE than on composites. In vivo, such preferences were only significant for Granulicatella adiacens (more prevalent on BE) and Fusobacterium nucleatum subsp. animalis (more prevalent on composites). On DNA sequence level, there were no significant differences between the biofilm communities on GF and GF+C. Conclusion: We found that the oral microbiome showed an increased richness when grown on various composites compared to BE in vitro, but otherwise changed only slightly independent of the in vivo or in vitro condition. Our new ex vivo biofilm model might be useful for pre-clinical testing of preventive strategies.}, } @article {pmid31142622, year = {2019}, author = {Sweeney, EG and Nishida, A and Weston, A and Bañuelos, MS and Potter, K and Conery, J and Guillemin, K}, title = {Agent-Based Modeling Demonstrates How Local Chemotactic Behavior Can Shape Biofilm Architecture.}, journal = {mSphere}, volume = {4}, number = {3}, pages = {}, doi = {10.1128/mSphere.00285-19}, pmid = {31142622}, issn = {2379-5042}, abstract = {Bacteria are often found living in aggregated multicellular communities known as biofilms. Biofilms are three-dimensional structures that confer distinct physical and biological properties to the collective of cells living within them. We used agent-based modeling to explore whether local cellular interactions were sufficient to give rise to global structural features of biofilms. Specifically, we asked whether chemorepulsion from a self-produced quorum-sensing molecule, autoinducer-2 (AI-2), was sufficient to recapitulate biofilm growth and cellular organization observed for biofilms of Helicobacter pylori, a common bacterial resident of human stomachs. To carry out this modeling, we modified an existing platform, Individual-based Dynamics of Microbial Communities Simulator (iDynoMiCS), to incorporate three-dimensional chemotaxis, planktonic cells that could join or leave the biofilm structure, and cellular production of AI-2. We simulated biofilm growth of previously characterized H. pylori strains with various AI-2 production and sensing capacities. Using biologically plausible parameters, we were able to recapitulate both the variation in biofilm mass and cellular distributions observed with these strains. Specifically, the strains that were competent to chemotax away from AI-2 produced smaller and more heterogeneously spaced biofilms, whereas the AI-2 chemotaxis-defective strains produced larger and more homogeneously spaced biofilms. The model also provided new insights into the cellular demographics contributing to the biofilm patterning of each strain. Our analysis supports the idea that cellular interactions at small spatial and temporal scales are sufficient to give rise to larger-scale emergent properties of biofilms.IMPORTANCE Most bacteria exist in aggregated, three-dimensional structures called biofilms. Although biofilms play important ecological roles in natural and engineered settings, they can also pose societal problems, for example, when they grow in plumbing systems or on medical implants. Understanding the processes that promote the growth and disassembly of biofilms could lead to better strategies to manage these structures. We had previously shown that Helicobacter pylori bacteria are repulsed by high concentrations of a self-produced molecule, AI-2, and that H. pylori mutants deficient in AI-2 sensing form larger and more homogeneously spaced biofilms. Here, we used computer simulations of biofilm formation to show that local H. pylori behavior of repulsion from high AI-2 could explain the overall architecture of H. pylori biofilms. Our findings demonstrate that it is possible to change global biofilm organization by manipulating local cell behaviors, which suggests that simple strategies targeting cells at local scales could be useful for controlling biofilms in industrial and medical settings.}, } @article {pmid31142260, year = {2019}, author = {Lima, MR and Ferreira, GF and Nunes Neto, WR and Monteiro, JM and Santos, ÁRC and Tavares, PB and Denadai, ÂML and Bomfim, MRQ and Dos Santos, VL and Marques, SG and de Souza Monteiro, A}, title = {Evaluation of the interaction between polymyxin B and Pseudomonas aeruginosa biofilm and planktonic cells: reactive oxygen species induction and zeta potential.}, journal = {BMC microbiology}, volume = {19}, number = {1}, pages = {115}, doi = {10.1186/s12866-019-1485-8}, pmid = {31142260}, issn = {1471-2180}, support = {CNPq, MCT/CNPq-NANO: 550321/2012-8//Conselho Nacional de Desenvolvimento Científico e Tecnológico/ ; APQ-00645-12//Fundação de Amparo à Pesquisa do Estado de Minas Gerais/ ; APQ-00435-14//Fundação de Amparo à Pesquisa do Estado de Minas Gerais/ ; FINEP: 0633/13//Financiadora de Estudos e Pesquisas/ ; }, abstract = {BACKGROUND: Although the most widely accepted mechanism of action for polymyxins is related to bacterial lysis via disruption, we hypothesized that this antimicrobial drug class could have other effects on Pseudomonas aeruginosa planktonic and sessile cells. Little is known regarding oxidative burst and zeta potential (ZP) data associated with the interaction between polymyxin B and P. aeruginosa cells. The present study evaluated endogenous reactive oxygen species (ROS) production and changes in the net charges of biofilm and planktonic cells in response to polymyxin B.

RESULTS: Polymyxin B induced concentration-dependent killing at all concentrations tested in planktonic and sessile cells from P. aeruginosa strains. Sublethal concentrations of polymyxin B induced oxidative burst. ROS production was higher in resistant planktonic cells than in biofilm cells but this was not observed for susceptible cells. Moreover, no net surface charge alterations were observed in planktonic cells from a susceptible strain treated with polymyxin B, but a significant increase of ZP was noted in planktonic cells from a resistant strain.

CONCLUSION: Oxidative burst generated by planktonic and sessile cells from P. aeruginosa strains against polymyxin B indicates that ROS may have an important role in the mechanism of action of this drug. ZP data revealed that electrostatic interactions of the cationic peptide with the anionic surface of the cells are strain-dependent. Therefore, we suggested that the intracellular effects of polymyxin B should be further investigated to understand polymyxin B-induced stress in P. aeruginosa.}, } @article {pmid31142151, year = {2019}, author = {Song, P and Zhou, B and Feng, G and Brooks, JP and Zhou, H and Zhao, Z and Liu, Y and Li, Y}, title = {The influence of chlorination timing and concentration on microbial communities in labyrinth channels: implications for biofilm removal.}, journal = {Biofouling}, volume = {35}, number = {4}, pages = {401-415}, doi = {10.1080/08927014.2019.1600191}, pmid = {31142151}, issn = {1029-2454}, abstract = {Chlorination is an effective method to control biofilm formation in enclosed pipelines. To date, very little is known about how to control biofilms at the mesoscale in complex pipelines through chlorination. In this study, the dynamic of microbial communities was examined under different residual chlorine concentrations on the biofilms attached to labyrinth channels for drip irrigation using reclaimed water. The results indicated that the microbial phospholipid fatty acids, extracellular polymeric substances, microbial dynamics, and the ace and Shannon microbial diversity indices showed a gradual decrease after chlorination. However, chlorination increased microbial activity by 0.5-19.2%. The increase in the relative abundances of chloride-resistant bacteria (Acinetobacter and Thermomonas) could lead to a potential risk of chlorine resistance. Thus, keeping a low chlorine concentration (0.83 mg l-1 for 3 h) is effective for controlling biofilm formation in the labyrinth channels.}, } @article {pmid31141557, year = {2019}, author = {McGinniss, JE and Imai, I and Simon-Soro, A and Brown, MC and Knecht, VR and Frye, L and Ravindran, PM and Dothard, MI and Wadell, DA and Sohn, MB and Li, H and Christie, JD and Diamond, JM and Haas, AR and Lanfranco, AR and DiBardino, DM and Bushman, FD and Collman, RG}, title = {Molecular analysis of the endobronchial stent microbial biofilm reveals bacterial communities that associate with stent material and frequent fungal constituents.}, journal = {PloS one}, volume = {14}, number = {5}, pages = {e0217306}, doi = {10.1371/journal.pone.0217306}, pmid = {31141557}, issn = {1932-6203}, abstract = {Endobronchial stents are increasingly used to treat airway complications in multiple conditions including lung transplantation but little is known about the biofilms that form on these devices. We applied deep sequencing to profile luminal biofilms of 46 endobronchial stents removed from 20 subjects primarily with lung transplantation-associated airway compromise. Microbial communities were analyzed by bacterial 16S rRNA and fungal ITS marker gene sequencing. Corynebacterium was the most common bacterial taxa across biofilm communities. Clustering analysis revealed three bacterial biofilm types: one low diversity and dominated by Corynebacterium; another was polymicrobial and characterized by Staphylococcus; and the third was polymicrobial and associated with Pseudomonas, Streptococcus, and Prevotella. Biofilm type was significantly correlated with stent material: covered metal with the Staphylococcus-type biofilm, silicone with the Corynebacterium-dominated biofilm, and uncovered metal with the polymicrobial biofilm. Subjects with sequential stents had frequent transitions between community types. Fungal analysis found Candida was most prevalent, Aspergillus was common and highly enriched in two of three stents associated with airway anastomotic dehiscence, and fungal taxa not typically considered pathogens were highly enriched in some stents. Thus, molecular analysis revealed a complex and dynamic endobronchial stent biofilm with three bacterial types that associate with stent material, a central role for Corynebacterium, and that both expected and unexpected fungi inhabit this unique niche. The current work provides a foundation for studies to investigate the relationship between stent biofilm composition and clinical outcomes, mechanisms of biofilm establishment, and strategies for improved stent technology and use in airway compromise.}, } @article {pmid31141184, year = {2019}, author = {Wang, C and Zhang, Q and Wang, Y and Tang, X and An, Y and Li, S and Xu, H and Li, Y and Luan, W and Wang, X and Liu, M and Yu, L}, title = {Comparative proteomics analysis between biofilm and planktonic cells of Mycobacterium tuberculosis.}, journal = {Electrophoresis}, volume = {}, number = {}, pages = {}, doi = {10.1002/elps.201900030}, pmid = {31141184}, issn = {1522-2683}, support = {2017YFD0502200//Key Project of Research and Development Plan/ ; 2016YFD0501302//Key Project of Research and Development Plan/ ; 31172364//National Nature Science Foundation of China/ ; 81801972//National Nature Science Foundation of China/ ; 20150101108JC//Fund for Science & Technology Development of Jilin Province/ ; 2012ZX10003002//Important National Science and Technology Specific Projects/ ; NCET-09-0434//Program for New Century Excellent Talents in University/ ; 2016444//Project of the Education Department of Jilin Province/ ; JCYJ2016031100720906//Technology and Innovation Commission of Shenzhen Municipality/ ; JSGG20160301100442775//Technology and Innovation Commission of Shenzhen Municipality/ ; }, abstract = {Tuberculosis is highly persistent and displays phenotypic resistance to high concentrations of antimicrobials. Recent reports exhibited that Mycobacterium tuberculosis biofilm was implicated to its pathogenicity and drug resistance. In this study, there were 47 kinds of differential proteins in the biofilm of M. tuberculosis H37Rv cells compared with the planktonic bacteria, and 37 proteins were nonredundant and identified by proteomics approach, such as 2DE and LC-MS/MS. Moreover, six kinds of proteins were identified as HspX, which were conservative and highly expressed in biofilm. Note that 47 differential proteins were divided into seven categories, such as cell wall and cell processes, conserved hypotheticals, intermediary metabolism and respiration, and so on by TUBERCULIST. The Gene Ontology classification results showed that the largest protein group involved in metabolism, binding proteins, and catalytic function accounts for 30% and 57% of all identified proteins, respectively. Moreover, the protein interaction network analyzed by STRING showed that the minority proteins such as RpoA, SucC, Cbs, Tuf, DnaK, and GroeL in the interaction network have high network connectivity. These results implied that the proteins involved in metabolic process and catalytic function and the minority proteins mentioned above may play an important role in M. tuberculosis biofilm formation. To our knowledge, this is the first report about differential proteins between biofilm and planktonic M. tuberculosis, which provided the potential antigens for vaccines and target proteins for anti-mycobacterial drugs.}, } @article {pmid31139155, year = {2019}, author = {Manna, S and Ghosh, AK and Mandal, SM}, title = {Curd-Peptide Based Novel Hydrogel Inhibits Biofilm Formation, Quorum Sensing, Swimming Mortility of Multi-Antibiotic Resistant Clinical Isolates and Accelerates Wound Healing Activity.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {951}, doi = {10.3389/fmicb.2019.00951}, pmid = {31139155}, issn = {1664-302X}, abstract = {The search for a bioactive natural antibacterial agent with wound healing properties is a common practice for the development of new-generation molecules. Antimicrobial peptides are a good alternative to antibiotics and easy-to-form hydrogels under self-assembled conditions without pH adjustment. With this in mind, the peptide pool was extracted from a formulated curd composed of a blend of probiotic bacteria such as Streptococcus thermophilus, Lactobacillus casei, and Bifidobacterium bifidum at an optimized ratio of 7:1:2. The water content of curd was collected by the drainage column, centrifuged, filtered through a 0.45-μM filter, and used for hydrogel preparation. Matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) analysis confirmed the presence of peptide pool in the extracted water. The prepared hydrogel was freeze dried, and its effect on biofilm formation, swarming mortality, antimicrobials, wound healing, and biocompatibility was subsequently verified. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images revealed the fibrous network of peptides after self-assembly with non-polar n-hexane solvent and a porous structure after drying, respectively. The observed biocompatibility, antimicrobial activity, and strong wound healing activity of the developed curd-based hydrogel have opened a new platform for antibacterial ointment formulation.}, } @article {pmid31138626, year = {2019}, author = {Greenwich, J and Reverdy, A and Gozzi, K and Di Cecco, G and Tashjian, T and Godoy-Carter, V and Chai, Y}, title = {A Decrease in Serine Levels during Growth Transition Triggers Biofilm Formation in Bacillus subtilis.}, journal = {Journal of bacteriology}, volume = {201}, number = {15}, pages = {}, doi = {10.1128/JB.00155-19}, pmid = {31138626}, issn = {1098-5530}, abstract = {Biofilm development in Bacillus subtilis is regulated at multiple levels. While a number of known signals that trigger biofilm formation do so through the activation of one or more sensory histidine kinases, it was discovered that biofilm activation is also coordinated by sensing intracellular metabolic signals, including serine starvation. Serine starvation causes ribosomes to pause on specific serine codons, leading to a decrease in the translation rate of sinR, which encodes a master repressor for biofilm matrix genes and ultimately triggers biofilm induction. How serine levels change in different growth stages, how B. subtilis regulates intracellular serine levels, and how serine starvation triggers ribosomes to pause on selective serine codons remain unknown. Here, we show that serine levels decrease as cells enter stationary phase and that unlike most other amino acid biosynthesis genes, expression of serine biosynthesis genes decreases upon the transition into stationary phase. The deletion of the gene for a serine deaminase responsible for converting serine to pyruvate led to a delay in biofilm formation, further supporting the idea that serine levels are a critical intracellular signal for biofilm activation. Finally, we show that levels of all five serine tRNA isoacceptors are decreased in stationary phase compared with exponential phase. However, the three isoacceptors recognizing UCN serine codons are reduced to a much greater extent than the two that recognize AGC and AGU serine codons. Our findings provide evidence for a link between serine homeostasis and biofilm development in B. subtilisIMPORTANCE In Bacillus subtilis, biofilm formation is triggered in response to environmental and cellular signals. It was proposed that serine limitation acts as a proxy for nutrient status and triggers biofilm formation at the onset of biofilm entry through a novel signaling mechanism caused by global ribosome pausing on selective serine codons. In this study, we reveal that serine levels decrease at the biofilm entry due to catabolite control and a serine shunt mechanism. We also show that levels of five serine tRNA isoacceptors are differentially decreased in stationary phase compared with exponential phase; three isoacceptors recognizing UCN serine codons are reduced much more than the two recognizing AGC and AGU codons. This finding indicates a possible mechanism for selective ribosome pausing.}, } @article {pmid31138130, year = {2019}, author = {Dakheel, KH and Rahim, RA and Neela, VK and Al-Obaidi, JR and Hun, TG and Isa, MNM and Yusoff, K}, title = {Genomic analyses of two novel biofilm-degrading methicillin-resistant Staphylococcus aureus phages.}, journal = {BMC microbiology}, volume = {19}, number = {1}, pages = {114}, doi = {10.1186/s12866-019-1484-9}, pmid = {31138130}, issn = {1471-2180}, support = {FRGS/1/2015/SGOS/UPM/01/2//the Ministry of Higher Education/ Malaysia/ ; }, abstract = {BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) biofilm producers represent an important etiological agent of many chronic human infections. Antibiotics and host immune responses are largely ineffective against bacteria within biofilms. Alternative actions and novel antimicrobials should be considered. In this context, the use of phages to destroy MRSA biofilms presents an innovative alternative mechanism.

RESULTS: Twenty-five MRSA biofilm producers were used as substrates to isolate MRSA-specific phages. Despite the difficulties in obtaining an isolate of this phage, two phages (UPMK_1 and UPMK_2) were isolated. Both phages varied in their ability to produce halos around their plaques, host infectivity, one-step growth curves, and electron microscopy features. Furthermore, both phages demonstrated antagonistic infectivity on planktonic cultures. This was validated in an in vitro static biofilm assay (in microtiter-plates), followed by the visualization of the biofilm architecture in situ via confocal laser scanning microscopy before and after phage infection, and further supported by phages genome analysis. The UPMK_1 genome comprised 152,788 bp coding for 155 putative open reading frames (ORFs), and its genome characteristics were between the Myoviridae and Siphoviridae family, though the morphological features confined it more to the Siphoviridae family. The UPMK_2 has 40,955 bp with 62 putative ORFs; morphologically, it presented the features of the Podoviridae though its genome did not show similarity with any of the S. aureus in the Podoviridae family. Both phages possess lytic enzymes that were associated with a high ability to degrade biofilms as shown in the microtiter plate and CLSM analyses.

CONCLUSIONS: The present work addressed the possibility of using phages as potential biocontrol agents for biofilm-producing MRSA.}, } @article {pmid31136790, year = {2019}, author = {Alkhudhairy, MK and Alshadeedi, SMJ and Mahmood, SS and Al-Bustan, SA and Ghasemian, A}, title = {Comparison of adhesin genes expression among Klebsiella oxytoca ESBL-non-producers in planktonic and biofilm mode of growth, and imipenem sublethal exposure.}, journal = {Microbial pathogenesis}, volume = {134}, number = {}, pages = {103558}, doi = {10.1016/j.micpath.2019.103558}, pmid = {31136790}, issn = {1096-1208}, abstract = {BACKGROUND: Bacterial adhesins play an important role in the bacterial attachment and colonization. The aim of this study was comparison of adhesin genes expression in the planktonic and biofilm mode of growth among ESBL-non-producers isolates of K. oxytoca and effect of imipenem.

MATERIALS AND METHODS: A total of eight extended-spectrum beta-lactamase (ESBL) non-producer K. oxytoca isolates were included from patients with hemorrhagic colitis. The adhesin genes including fimA (type 1 fimbria), mrkA (type 3 fimbria), pilQ and the capsular matB genes were adopted. Phenotypic biofilm production was assessed by microtiter tissue plate assay. Expression of adhesin genes in the planktonic and biofilm growth conditions was calculated using quantitative Real-time PCR (RT-qPCR) technique and sub-MIC (0.25 μg/ml) levels of imipenem were also added to broth culture of isolates to evaluate the gene expression.

RESULTS: The isolates produced biofilm in moderate level. The expression of pilQ, mrkA and matB but not fimA genes was significantly higher in biofilm conditions compared to the planktonic mode of growth (p = 0.002, p = 0.011 and p = 001, respectively). In addition, imipenem sub-MIC treatment led to a significant overexpression of matB (p = 0.002) and mrkA (p = 0.003) genes compared to the control group.

CONCLUSION: Although none of isolates produced strong biofilm, biofilm conditions led to the increase in the expression of adhesin encoding genes in non-ESBL-producing K. oxytoca. Furthermore, β-lactams; and especially carbapenems possibly increase the colonization of K. oxytoca and increase the biofilm formation. Hence, accurate consumption of antibiotics must be considered.}, } @article {pmid31136296, year = {2019}, author = {Ghasemian, A and Mohabati Mobarez, A and Najar Peerayeh, S and Talebi Bezmin Abadi, A and Khodaparast, S and Mahmood, SS}, title = {Expression of adhesin genes and biofilm formation among Klebsiella oxytoca clinical isolates from patients with antibiotic-associated haemorrhagic colitis.}, journal = {Journal of medical microbiology}, volume = {68}, number = {7}, pages = {978-985}, doi = {10.1099/jmm.0.000965}, pmid = {31136296}, issn = {1473-5644}, mesh = {Adhesins, Bacterial/genetics/*metabolism ; Adolescent ; Adult ; Aged ; Aged, 80 and over ; Anti-Bacterial Agents/adverse effects ; Biofilms/*growth & development ; Child ; Child, Preschool ; Colitis/*microbiology/pathology ; Feces/microbiology ; Female ; Gastrointestinal Hemorrhage/*microbiology/pathology ; Gene Expression Regulation, Bacterial/*physiology ; Humans ; Infant ; Klebsiella Infections/microbiology ; Klebsiella oxytoca/drug effects/genetics/*metabolism/physiology ; Male ; Middle Aged ; Real-Time Polymerase Chain Reaction ; Young Adult ; }, abstract = {PURPOSE: Biofilm formation and resistance to last-line antibiotics have restricted chemotherapy options toward infection eradication.

METHODOLOGY: Fifty K. oxytoca isolates were collected from patients with antibiotic-associated haemorrhagic colitis (AAHC). Antibiotic susceptibility tests were conducted and phenotypic biofilm formation was assessed using microtitre tissue plate (MTP) assay. PCR was employed to amplify the adhesins, extended-spectrum β-lactamases (ESBLs), carbapenemase and colistin resistance genes. The expression of adhesin genes was evaluated using quantitative real-time PCR (RT-qPCR).Results/Key findings. The previous antibiotic consumption and hospitalization (P<0.05) and older ages (P=0.0033) were significantly associated with AAHC. None of the isolates produced biofilm strongly, but 70% of them produced moderate-level biofilm. The blaCTX-M (12/14), the blaIMP (8/14 MICIMI =4 µg ml-1) and blaOXA-48-like (5/14) and mcr-1 (4/14) genes were predominant, three of which harbouring all the genes. The expression of matB (0.023) and mrkA (0.011) was significantly different between multidrug-resistant and susceptible isolates. Furthermore, moderately biofilm producer isolates significantly exhibited higher expression of fimA (P=.0117), pilQ (P=0.002) and mrkA (P=0.020) genes compared to biofilm non-producers. No significant difference regarding gene expression was observed among ESBL alleles.

CONCLUSION: Bacterial attachment by adhesins and biofilm formation among extensive drug-resistant K. oxytoca isolates hinder the efficient infection eradication. Hence, control and surveillance studies should be performed and other therapeutic auspicious approaches must be taken into account against AAHC, biofilm formation and drug resistance spread. Furthermore, previous antibiotic consumption and long-term hospitalization should be controlled.}, } @article {pmid31135555, year = {2019}, author = {Tsikopoulos, K and Bidossi, A and Drago, L and Petrenyov, DR and Givissis, P and Mavridis, D and Papaioannidou, P}, title = {Is Implant Coating With Tyrosol- and Antibiotic-loaded Hydrogel Effective in Reducing Cutibacterium (Propionibacterium) acnes Biofilm Formation? A Preliminary In Vitro Study.}, journal = {Clinical orthopaedics and related research}, volume = {477}, number = {7}, pages = {1736-1746}, doi = {10.1097/CORR.0000000000000663}, pmid = {31135555}, issn = {1528-1132}, abstract = {BACKGROUND: Studies have suggested that Cutibacterium acnes (formerly known as Propionibacterium) is the most frequently isolated pathogen after shoulder arthroplasty. To address the burden of periprosthetic joint infections associated with this pathogen, new prevention methods are needed. Tyrosol has a promising record of effectiveness in the field of biofilm-associated infections; however, to our knowledge, it has not been tested against C. acnes thus far.

QUESTIONS/PURPOSES: In this in vitro study, we asked: (1) Is tyrosol effective in inhibiting and eradicating C. acnes planktonic growth? (2) Is there synergy between tyrosol and rifampicin? (3) Is supplementation of hydrogel with tyrosol at the minimum inhibitory and subinhibitory concentrations efficacious in reducing free-floating C. acnes growth? (4) Is implant hydrogel coating (either alone or combined with tyrosol, rifampicin, or vancomycin) beneficial in reducing C. acnes biofilm formation? (5) Is the administration of soluble tyrosol an effective measure against C. acnes biofilm formation?

METHODS: We assessed C. acnes planktonic growth and eradication by inspecting visually the results of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. We also evaluated macroscopically the presence of synergy among tyrosol and rifampicin by means of the MIC checkerboard testing. Thereafter, we addressed colorimetrically the efficacy of tyrosol-loaded Defensive Antibacterial Coating (DAC®) hydrogel against the C. acnes free-floating form by means of the XTT cell proliferation reduction assay. Then, we explored photometrically the effect of hydrogel and soluble tyrosol at reducing C. acnes biofilm formation on titanium alloy disks that simulated orthopaedic implants by using the minimum biofilm inhibition concentration assay. In particular, 16 disks were sequentially allocated to each of the following testing conditions: (1) hydrogel alone; (2) tyrosol-loaded hydrogel; (3) rifampicin-supplemented hydrogel; (4) vancomycin-loaded hydrogel; and (5) soluble tyrosol. Subsequently, implants were sonicated and cell viability was evaluated in terms of the XTT assay.

RESULTS: Tyrosol was effective in inhibiting C. acnes planktonic (free-floating) growth demonstrating MIC values of 63 mM (9 mg/mL) and MBC values of 250 mM (35 mg/mL). Concerning synergy assessment, the checkerboard testing revealed additivity among tyrosol and rifampicin with a fractional inhibitory concentration index of 0.56. In addition, a hydrogel coating with tyrosol at the MIC showed no difference in the inhibition of free-floating C. Acnes form over control (median absorbance [MA] for tyrosol-supplemented hydrogel versus control groups were 0.21 [interquartile range {IQR}, 0.19-0.24] versus 0.26 [IQR, 0.23-0.31], p = 0.066). Furthermore, loaded hydrogel with tyrosol at 597 mg/mL (1 M) was no more effective than control in reducing C. acnes biofilm formation (MAs for tyrosol versus control were 0.12 [IQR, 0.11-0.13] versus 0.14 [IQR, 0.12-0.16], respectively; p = 0.076). This was also the case when we considered hydrogel in conjunction with vancomycin and rifampicin (MAs for vancomycin at 2% and 5% and rifampicin at 1% versus biofilm control were 0.139 [IQR, 0.133-0.143] and 0.141 [IQR, 0.133-0.143] and 0.135 [IQR, 0.128-0.146] versus 0.142 [IQR, 0.136-0.144], correspondingly). In contrast, soluble tyrosol at 597 mg/mL (1 M) inhibited biofilm formation compared to control (MAs for tyrosol and control groups were 0.11 [IQR, 0.09-0.13] versus 0.13 [IQR, 0.12-0.14], p = 0.007).

CONCLUSIONS: Although the implant coating with hydrogel (either pure or supplemented with antimicrobial agents) did not diminish C. acnes biofilm development in vitro, soluble tyrosol at 597 mg/mL (1 M) exceeded the meaningful biofilm inhibition threshold of 80%.

CLINICAL RELEVANCE: The results of the current preclinical investigation did not support the use of a fast, bioresorbable hydrogel as a coating method against C. acnes biofilms. Instead, direct local administration of soluble tyrosol at high concentrations should be further tested in future animal studies.}, } @article {pmid31134579, year = {2019}, author = {Córdova-Alcántara, IM and Venegas-Cortés, DL and Martínez-Rivera, MÁ and Pérez, NO and Rodriguez-Tovar, AV}, title = {Biofilm characterization of Fusarium solani keratitis isolate: increased resistance to antifungals and UV light.}, journal = {Journal of microbiology (Seoul, Korea)}, volume = {57}, number = {6}, pages = {485-497}, doi = {10.1007/s12275-019-8637-2}, pmid = {31134579}, issn = {1976-3794}, mesh = {Antifungal Agents/*pharmacology ; Biofilms/*drug effects/*growth & development/*radiation effects ; Drug Resistance, Fungal/drug effects/radiation effects ; Eye Infections, Fungal/*microbiology ; Fungi/drug effects/radiation effects ; Fusarium/*drug effects/pathogenicity/*radiation effects ; Humans ; Hyphae/drug effects/radiation effects ; Keratitis/*microbiology ; Mexico ; Microbial Sensitivity Tests ; Microbial Viability/drug effects/radiation effects ; Microscopy, Electron, Scanning ; }, abstract = {Fusarium solani has drawn phytopathogenic, biotechnological, and medical interest. In humans, it is associated with localized infections, such as onychomycosis and keratomycosis, as well as invasive infections in immunocompromised patients. One pathogenicity factor of filamentous fungi is biofilm formation. There is still only scarce information about the in vitro mechanism of the formation and composition of F. solani biofilm. In this work, we describe the biofilm formed by a clinical keratomycosis isolate in terms of its development, composition and susceptibility to different antifungals and ultraviolet light (UV) at different biofilm formation stages. We found five biofilm formation stages using scanning electron microscopy: adherence, germination, hyphal development, maturation, and cell detachment. Using epifluorescence microscopy with specific fluorochromes, it was elucidated that the extracellular matrix consists of carbohydrates, proteins, and extracellular DNA. Specific inhibitors for these molecules showed significant biofilm reductions. The antifungal susceptibility against natamycin, voriconazole, caspofungin, and amphotericin B was evaluated by metabolic activity and crystal violet assay, with the F. solani biofilm preformation to 24 h increased in resistance to natamycin, voriconazole, and caspofungin, while the biofilm preformation to 48 h increased in resistance to amphotericin B. The preformed biofilm at 24 h protected and reduced UV light mortality. F. solani isolate could produce a highly structured extra biofilm; its cellular matrix consists of carbohydrate polymers, proteins, and eDNA. Biofilm confers antifungal resistance and decreases its susceptibility to UV light. The fungal biofilm functions as a survival strategy against antifungals and environmental factors.}, } @article {pmid31134255, year = {2019}, author = {Gupta, A and Holoidovsky, L and Thamaraiselvan, C and Thakur, AK and Singh, SP and Meijler, MM and Arnusch, CJ}, title = {Silver-doped laser-induced graphene for potent surface antibacterial activity and anti-biofilm action.}, journal = {Chemical communications (Cambridge, England)}, volume = {55}, number = {48}, pages = {6890-6893}, doi = {10.1039/c9cc02415h}, pmid = {31134255}, issn = {1364-548X}, mesh = {Anti-Bacterial Agents/*chemistry/pharmacology ; Biofilms/*drug effects ; Coated Materials, Biocompatible/*chemistry ; Graphite/*chemistry ; Lasers ; Metal Nanoparticles/*chemistry ; Polymers/chemistry ; Pseudomonas aeruginosa/drug effects ; Silver/*chemistry ; Sulfones/chemistry ; Surface Properties ; }, abstract = {Previously, laser-induced graphene (LIG) coated surfaces were shown to resist biofilm growth, although the material was not strongly antibacterial. Here, we show LIG surfaces doped with silver nanoparticles (Ag0 or AgNPs) as highly antibacterial surfaces. Starting from AgNO3 polyethersulfone (PES) polymer substrates, silver nanoparticles between 5-10 nm were generated in situ during the lasing process and stably embedded in the fibrous and porous structure of LIG in a single step. These silver doped LIG (Ag@LIG) surfaces were highly toxic to bacteria via a mechanism of both Ag+ ion release and possible surface toxicity of the AgNPs. The added antibacterial function of Ag-nanoparticles expands the functionality of LIG coated surfaces and might lead to highly effective point of use/entry devices in rural areas or in disaster situations with contaminated water sources.}, } @article {pmid31134027, year = {2019}, author = {Maudsdotter, L and Ushijima, Y and Morikawa, K}, title = {Fitness of Spontaneous Rifampicin-Resistant Staphylococcus aureus Isolates in a Biofilm Environment.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {988}, doi = {10.3389/fmicb.2019.00988}, pmid = {31134027}, issn = {1664-302X}, abstract = {Biofilms of S. aureus accumulate cells resistant to the antibiotic rifampicin. We show here that the accumulation of rifampicin resistant mutants (RifR) in biofilms is not equable but rather is a local event, suggesting that the growth of a few locally emerged mutants is responsible for this. Competition assays demonstrated that, compared to wild-type bacteria, the isolated RifR mutants have a growth advantage in biofilms, but not in planktonic culture. To gain insight into the mechanism of the growth advantage, we tested the involvement of the two-component systems (TCS) that sense and respond to environmental changes. We found that a deletion of SrrAB or NreBC has a drastic effect on the growth advantage of RifR mutants, suggesting the importance of oxygen/respiration responses. All six of the RifR isolates tested showed increased resistance to at least one of the common stresses found in the biofilm environment (i.e., oxidative, nitric acid, and organic acid stress). The RifR mutants also had a growth advantage in a biofilm flow model, which highlights the physiological relevance of our findings.}, } @article {pmid31133998, year = {2019}, author = {Zhang, R and Neu, TR and Li, Q and Blanchard, V and Zhang, Y and Schippers, A and Sand, W}, title = {Insight Into Interactions of Thermoacidophilic Archaea With Elemental Sulfur: Biofilm Dynamics and EPS Analysis.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {896}, doi = {10.3389/fmicb.2019.00896}, pmid = {31133998}, issn = {1664-302X}, abstract = {Biooxidation of reduced inorganic sulfur compounds (RISCs) by thermoacidophiles is of particular interest for the biomining industry and for environmental issues, e.g., formation of acid mine drainage (AMD). Up to now, interfacial interactions of acidophiles with elemental sulfur as well as the mechanisms of sulfur oxidation by acidophiles, especially thermoacidophiles, are not yet fully clear. This work focused on how a crenarchaeal isolate Acidianus sp. DSM 29099 interacts with elemental sulfur. Analysis by Confocal laser scanning microscopy (CLSM) and Atomic force microscopy (AFM) in combination with Epifluorescence microscopy (EFM) shows that biofilms on elemental sulfur are characterized by single colonies and a monolayer in first stage and later on 3-D structures with a diameter of up to 100 μm. The analysis of extracellular polymeric substances (EPS) by a non-destructive lectin approach (fluorescence lectin-barcoding analysis) using several fluorochromes shows that intial attachment was featured by footprints rich in biofilm cells that were embedded in an EPS matrix consisting of various glycoconjugates. Wet chemistry data indicate that carbohydrates, proteins, lipids and uronic acids are the main components. Attenuated reflectance (ATR)-Fourier transformation infrared spectroscopy (FTIR) and high-performance anion exchange chromatography with pulsed amperometric detection (HPAE-PAD) indicate glucose and mannose as the main monosaccharides in EPS polysaccharides. EPS composition as well as sugar types in EPS vary according to substrate (sulfur or tetrathionate) and lifestyle (biofilms and planktonic cells). This study provides information on the building blocks/make up as well as dynamics of biofilms of thermoacidophilic archaea in extremely acidic environments.}, } @article {pmid31133642, year = {2019}, author = {An, SQ and Murtagh, J and Twomey, KB and Gupta, MK and O'Sullivan, TP and Ingram, R and Valvano, MA and Tang, JL}, title = {Modulation of antibiotic sensitivity and biofilm formation in Pseudomonas aeruginosa by interspecies signal analogues.}, journal = {Nature communications}, volume = {10}, number = {1}, pages = {2334}, doi = {10.1038/s41467-019-10271-4}, pmid = {31133642}, issn = {2041-1723}, support = {//Wellcome Trust/United Kingdom ; 100304/A/12/Z//Wellcome Trust (Wellcome)/International ; }, mesh = {Animals ; Anti-Bacterial Agents/*pharmacology/therapeutic use ; Bacterial Proteins/genetics/*metabolism ; Biofilms/drug effects ; Disease Models, Animal ; Drug Resistance, Bacterial ; Fatty Acids, Unsaturated/*metabolism ; Female ; Gene Expression Regulation, Bacterial/drug effects/immunology ; Histidine Kinase/genetics/*metabolism ; Humans ; Liposomes/metabolism ; Mice ; Mice, Inbred C57BL ; Microbial Sensitivity Tests ; Mutagenesis ; Phosphorylation ; Polymyxins/pharmacology/therapeutic use ; Pseudomonas Infections/*drug therapy/immunology/microbiology ; Pseudomonas aeruginosa/*physiology ; Virulence Factors/genetics/metabolism ; }, abstract = {Pseudomonas aeruginosa, a significant opportunistic pathogen, can participate in inter-species communication through signaling by cis-2-unsaturated fatty acids of the diffusible signal factor (DSF) family. Sensing these signals leads to altered biofilm formation and increased tolerance to various antibiotics, and requires the histidine kinase PA1396. Here, we show that the membrane-associated sensory input domain of PA1396 has five transmembrane helices, two of which are required for DSF sensing. DSF binding is associated with enhanced auto-phosphorylation of PA1396 incorporated into liposomes. Further, we examined the ability of synthetic DSF analogues to modulate or inhibit PA1396 activity. Several of these analogues block the ability of DSF to trigger auto-phosphorylation and gene expression, whereas others act as inverse agonists reducing biofilm formation and antibiotic tolerance, both in vitro and in murine infection models. These analogues may thus represent lead compounds to develop novel adjuvants improving the efficacy of existing antibiotics.}, } @article {pmid31132246, year = {2019}, author = {Cutrona, N and Gillard, K and Ulrich, R and Seemann, M and Miller, HB and Blackledge, MS}, title = {From Antihistamine to Anti-infective: Loratadine Inhibition of Regulatory PASTA Kinases in Staphylococci Reduces Biofilm Formation and Potentiates β-Lactam Antibiotics and Vancomycin in Resistant Strains of Staphylococcus aureus.}, journal = {ACS infectious diseases}, volume = {}, number = {}, pages = {}, doi = {10.1021/acsinfecdis.9b00096}, pmid = {31132246}, issn = {2373-8227}, abstract = {Staphylococcus epidermidis and Staphylococcus aureus are important human pathogens responsible for two-thirds of all postsurgical infections of indwelling medical devices. Staphylococci form robust biofilms that provide a reservoir for chronic infection, and antibiotic-resistant isolates are increasingly common in both healthcare and community settings. Novel treatments that can simultaneously inhibit biofilm formation and antibiotic-resistance pathways are urgently needed to combat the increasing rates of antibiotic-resistant infections. Herein we report that loratadine, an FDA-approved antihistamine, significantly inhibits biofilm formation in both S. aureus and S. epidermidis. Furthermore, loratadine potentiates β-lactam antibiotics in methicillin-resistant strains of S. aureus and potentiates both β-lactam antibiotics and vancomycin in vancomycin-resistant strains of S. aureus. Additionally, we elucidate loratadine's mechanism of action as a novel inhibitor of the regulatory PASTA kinases Stk and Stk1 in S. epidermidis and S. aureus, respectively. Finally, we describe how Stk1 inhibition affects the expression of genes involved in both biofilm formation and antibiotic resistance in S. epidermidis and S. aureus.}, } @article {pmid31132181, year = {2019}, author = {Singh, R and Kaur, M and Chakrabarti, A and Shankarnarayan, SA and Rudramurthy, SM}, title = {Biofilm formation by Candida auris isolated from colonising sites and candidemia cases.}, journal = {Mycoses}, volume = {62}, number = {8}, pages = {706-709}, doi = {10.1111/myc.12947}, pmid = {31132181}, issn = {1439-0507}, abstract = {BACKGROUND: Candida auris, an emerging nosocomial pathogen, exhibits phenotypic variation. Non-aggregating C. auris isolates display greater biofilm-forming capacity and virulence than aggregate-forming isolates. Most of the studies till date have focused on clinical isolates. The biofilm-forming capacity of colonising isolates remains uninvestigated.

OBJECTIVES: The present study aimed to elucidate the biofilm-forming capacity of the colonising isolates of C. auris, correlate it with their aggregation behaviour and antifungal susceptibility, and compare it with that of the isolates from blood-stream infection.

METHODS: Colonising and clinical (candidemia) isolates of C. auris were screened for aggregation behaviour, biofilm-forming capacity and antifungal susceptibility testing. Aggregation behaviour was assessed microscopically. Biofilm-forming capacity was determined on 96-well flat-bottomed microtitre plates. Antifungal susceptibility testing was performed by broth microdilution assay.

RESULTS: Aggregative and non-aggregative phenotypes were found to be predominantly associated with colonising and clinical isolates, respectively, with the former ones being stronger biofilm producers in the colonising group. Non-aggregative isolates in the colonising group showed lower susceptibility to amphotericin B and fluconazole than aggregative isolates. In contrast, no association was noted between biofilm formation, aggregation behaviour and antifungal susceptibility amongst the clinical isolates.

CONCLUSION: Biofilm formation is a strain-dependent trait in C. auris, strongly associated with the type and phenotypic behaviour of the isolates. Colonising isolates of this fungus were found to be predominantly aggregative in nature, with a higher biofilm-forming capacity than non-aggregative ones.}, } @article {pmid31131107, year = {2019}, author = {Sharma, D and Misba, L and Khan, AU}, title = {Antibiotics versus biofilm: an emerging battleground in microbial communities.}, journal = {Antimicrobial resistance and infection control}, volume = {8}, number = {}, pages = {76}, doi = {10.1186/s13756-019-0533-3}, pmid = {31131107}, issn = {2047-2994}, abstract = {Biofilm is a complex structure of microbiome having different bacterial colonies or single type of cells in a group; adhere to the surface. These cells are embedded in extracellular polymeric substances, a matrix which is generally composed of eDNA, proteins and polysaccharides, showed high resistance to antibiotics. It is one of the major causes of infection persistence especially in nosocomial settings through indwelling devices. Quorum sensing plays an important role in regulating the biofilm formation. There are many approaches being used to control infections by suppressing its formation but CRISPR-CAS (gene editing technique) and photo dynamic therapy (PDT) are proposed to be used as therapeutic approaches to subside bacterial biofim infections, especially caused by deadly drug resistant bad bugs.}, } @article {pmid31129521, year = {2019}, author = {Yang, S and Peng, Y and Zhang, L and Zhang, Q and Li, J and Wang, X}, title = {Autotrophic nitrogen removal in an integrated fixed-biofilm activated sludge (IFAS) reactor: Anammox bacteria enriched in the flocs have been overlooked.}, journal = {Bioresource technology}, volume = {288}, number = {}, pages = {121512}, doi = {10.1016/j.biortech.2019.121512}, pmid = {31129521}, issn = {1873-2976}, abstract = {In this study, an autotrophic nitrogen removal process was established using an integrated fixed-biofilm activated sludge (IFAS) reactor treated with high ammonium wastewater. A nitrogen removal rate (NRR) of 2.78 kg N/(m3·d) was obtained during the 206-day operation. Moreover, during the stable period, the large flocs (D > 0.2 mm) had a significantly higher abundance of anammox bacteria than the small flocs (D < 0.2 mm) and biofilm, resulting in 51% of the anammox bacteria being located in the flocs. The result indicates that anammox bacteria can be enriched in the flocs and in the biofilm, which has been rarely reported for IFAS reactors. In addition, the large flocs are likely formed through biofilm detachment since the microbial community was similar for the two kinds of biomass. Overall, the role of flocs in IFAS reactors are complicated and their contribution to the anammox reaction have been overlooked thus far.}, } @article {pmid31129476, year = {2019}, author = {Iñiguez-Moreno, M and Gutiérrez-Lomelí, M and Avila-Novoa, MG}, title = {Kinetics of biofilm formation by pathogenic and spoilage microorganisms under conditions that mimic the poultry, meat, and egg processing industries.}, journal = {International journal of food microbiology}, volume = {303}, number = {}, pages = {32-41}, doi = {10.1016/j.ijfoodmicro.2019.04.012}, pmid = {31129476}, issn = {1879-3460}, mesh = {Animals ; Bacterial Adhesion ; Biofilms/*growth & development ; Colony Count, Microbial ; Eggs/*microbiology ; *Food Microbiology ; *Food-Processing Industry ; Kinetics ; Meat/*microbiology ; Poultry ; Stainless Steel ; }, abstract = {Pathogens and spoilage microorganisms can develop multispecies biofilms on food contact surfaces; however, few studies have been focused on evaluated mixed biofilms of these microorganisms. Therefore this study investigated the biofilm development by pathogenic (Bacillus cereus, Escherichia coli, Listeria monocytogenes, and Salmonella enterica Enteritidis and Typhimurium serotypes) and spoilage (Bacillus cereus and Pseudomonas aeruginosa) microorganisms onto stainless-steel (SS) and polypropylene B (PP) coupons; under conditions that mimic the dairy, meat, and egg processing industry. Biofilms were developed in TSB with 10% chicken egg yolk (TSB + EY), TSB with 10% meat extract (TSB + ME) and whole milk (WM) onto SS and PP. Each tube was inoculated with 25 μL of each bacteria and then incubated at 9 or 25 °C, with enumeration at 1, 48, 120, 180 and 240 h. Biofilms were visualized by epifluorescence and scanning electron microscopy (SEM). Biofilm development occurred at different phases, depending on the incubation conditions. In the reversible adhesion, the cell density of each bacteria was between 1.43 and 6.08 Log10 CFU/cm2 (p < 0.05). Moreover, significant reductions in bacteria appeared at 9 °C between 1 and 48 h of incubation. Additionally, the constant multiplication of bacteria in the biofilm occurred at 25 °C between 48 and 180 h of incubation, with increments of 2.08 Log10 CFU/cm2 to S. Typhimurium. Population establishment was observed between 48 and 180 h and 180-240 h incubation, depending on the environmental conditions (25 and 9 °C, respectively). For example, in TSB + ME at 25 °C, S. Typhimurium, P aeruginosa, and L. monocytogenes showed no statistical differences in the amounts between 48 and 180 h incubation. The dispersion phase was identified for L. monocytogenes and B. cereus at 25 °C. Epifluorescence microscopy and SEM allowed visualizing the bacteria and extracellular polymeric substances at the different biofilm stages. In conclusion, pathogens and spoilage microorganisms developed monospecies with higher cellular densities than multiespecies biofilms. In multispecies biofilms, the time to reach each biofilm phase varied is depending on environmental factors. Cell count decrements of 1.12-2.44 Log10 CFU/cm2 occurred at 48 and 240 h and were most notable in the biofilms developed at 9 °C. Additionally, cell density reached by each microorganism was different, P. aeruginosa and Salmonella were the dominant microorganisms in the biofilms while B. cereus showed the lower densities until undetectable levels.}, } @article {pmid31129376, year = {2019}, author = {Meng, Y and Zhou, Z and Meng, F}, title = {Impacts of diel temperature variations on nitrogen removal and metacommunity of anammox biofilm reactors.}, journal = {Water research}, volume = {160}, number = {}, pages = {1-9}, doi = {10.1016/j.watres.2019.05.021}, pmid = {31129376}, issn = {1879-2448}, abstract = {The influence of diel temperature variations (DTVs) on nitrogen removal and bacterial communities was investigated in two parallel anammox reactors (i.e., control and DTV reactors). The control reactor was operated at a constant temperature of 30 °C, whereas the DTV reactor was operated in a temperature fluctuation mode with a cycle of 12/12 h of high/low temperatures. Nine water temperature variations for the day/night periods were set from 30/30 °C (i.e., Δ0 °C) to 38/22 °C (i.e., Δ16 °C). An increase in DTVs from Δ8 °C (34/26 °C) to Δ16 °C (38/22 °C) caused a significant decline in reactor performance and a shift in bacterial diversity. Compared to the control reactor, for instance, nitrogen removal efficiency decreased (P < 0.05) when temperature fluctuations exceeded Δ8 °C in the DTV reactor with a decreasing ΔNO3-/ΔNH4+ ratio (from 0.21 ± 0.15 to 0.16 ± 0.04). The results of 16S rRNA gene sequencing showed that the initial disturbance of temperature variations led to increased levels of bacterial diversity (i.e., alpha diversity) and decreased community levels of anammox consortia whereas they slightly recovered at the end of each DTV phase. Notably, Candidatus Jettenia was more sensitive to strong water temperature fluctuations, with the lower relative abundance at Δ14 °C (17.11 ± 5.01%) and Δ16 °C (17.83 ± 7.22%) than at Δ4 °C (39.82 ± 0.01%). In contrast, Ca. Brocadia and Ca. Kuenenia had higher relative abundance at Δ14 °C (i.e., 0.24 ± 0.07% and 0.09 ± 0.02%, respectively) and Δ16 °C (i.e., 0.28 ± 0.05% and 0.12 ± 0.03%, respectively) compared to that at Δ4 °C (i.e., 0.15 ± 0.04% and 0.04 ± 0.01%, respectively). Nitrifiers (i.e., unidentified_Nitrospiraceae and Nitrosomonas) and denitrifiers (i.e., Denitratisoma) were also capable of tolerating high temperature perturbations. Overall this study furthers our knowledge of responses of the microbial ecology of anammox bacteria to DTVs in anammox processes, which could aid us in optimizing anammox-related wastewater treatment systems and in understanding the nitrogen cycles of natural ecosystems.}, } @article {pmid31129309, year = {2019}, author = {Lin, H and Liu, X and Shen, Z and Cheng, W and Zeng, Z and Chen, Y and Tang, C and Jiang, T}, title = {The effect of isoflavaspidic acid PB extracted from Dryopteris fragrans (L.) Schott on planktonic and biofilm growth of dermatophytes and the possible mechanism of antibiofilm.}, journal = {Journal of ethnopharmacology}, volume = {241}, number = {}, pages = {111956}, doi = {10.1016/j.jep.2019.111956}, pmid = {31129309}, issn = {1872-7573}, abstract = {Dryopteris fragrans (L.) Schott (D. fragrans), a deciduous perennial herb, has been traditionally used for treatment of various skin diseases in Heilongjiang province of China for many years. Phloroglucinol derivatives extracted from D. fragrans were the most effective fraction against dermatophytes. Isoflavaspidic acid PB is a typically phloroglucinol derivative which extracted from D. fragrans and has been reported to exert anti-fungal activities against several dermatophytes.

AIM OF THE STUDY: This study aimed to evaluate anti-fungal and anti-biofilm activity of isoflavaspidic acid PB on planktonic and biofilm growth of dermatophytes and explore possible mechanisms of anti-biofilm.

MATERIALS AND METHODS: Minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) of isoflavaspidic acid PB against 25 isolates of dermatophytes were determined by the Clinical and Laboratory Standards Institute (CLSI) M38-A2 method. The effects of isoflavaspidic acid PB on dermatophytes biofilm formation and pre-formed biofilm were assessed by 2.3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[carbonyl (phenylamino)]-2H-tetrazolium hydroxide (XTT) assay. Morphology of mature biofilm were observed by Scanning Electron Microscope (SEM). Biomass, exopolysaccharide and ergosterol content of mature biofilm were analyzed by gravimetric analysis, anthranone sulfuric acid method and Ultra Performance Liquid Chromatography (UPLC) assay respectively.

RESULT: The MIC and MFC ranges of isoflavaspidic acid PB against 25 isolates of dermatophytes were 20-80 μg/mL and 40-80 μg/mL respectively. Isoflavaspidic acid PB (2 MIC) inhibited not only Trichophyton biofilm formation (54.8% ∼ 81.2%) but also the metabolic activity of mature biofilm (20.7% ∼ 44.2%). The result of SEM showed that isoflavaspidic acid PB (8 MIC) could destroy the morphology of hyphae seriously. Comparing with control group, biomass, exopolysaccharide and ergosterol content of the mature biofilm under isoflavaspidic acid PB (8 MIC) were significantly decreased (P < 0.01).

CONCLUSION: Isoflavaspidic acid PB had anti-fungal and fungicidal activities against dermatophytes. Isoflavaspidic acid PB could inhibit the biofilm of Trichophyton. The mechanism might be related to the decline of the biofilm biomass, exopolysaccharide and ergosterol content. These results showed that isoflavaspidic acid PB could be explored for promising anti-biofilm drugs.}, } @article {pmid31128369, year = {2019}, author = {Taşkan, B and Casey, E and Hasar, H}, title = {Simultaneous oxidation of ammonium and tetracycline in a membrane aerated biofilm reactor.}, journal = {The Science of the total environment}, volume = {682}, number = {}, pages = {553-560}, doi = {10.1016/j.scitotenv.2019.05.111}, pmid = {31128369}, issn = {1879-1026}, abstract = {The membrane aerated biofilms reactor (MABR) is an emerging technology in wastewater treatment with particular advantages including high rate nitrification, and very high oxygen transfer efficiencies. In this study a synthetic feed water incorporating tetracycline (TC) was investigated in a MABR. Simultaneous removal of ammonium and tetracycline (TC) in the reactor, formation of TC transformation products (TPs), and microbial community analysis in the biofilm growing on the membrane were performed. A range of TC and ammonium loading rates and the effect of different intra-membrane oxygen pressures were on treatment performance were systematically investigated. Successful nitrification and TC degradation were achieved with the highest TC removal (63%) obtained at a HRT of 18 h HRT and 0.41 bar gas pressure. It has shown that different operating conditions (HRT and gas pressure) do not cause a significant change in ammonium removal. The concentration of TPs such as ETC, EATC, and ATC was determined to be at the ppb level. Molecular results showed that MABR reactor was mainly dominated by β-proteobacteria. The relative abundance of this group decreased in parallel with the increasing ammonium and TC loading.}, } @article {pmid31125769, year = {2019}, author = {Peeridogaheh, H and Pourhajibagher, M and Barikani, HR and Bahador, A}, title = {The impact of Aggregatibacter actinomycetemcomitans biofilm-derived effectors following antimicrobial photodynamic therapy on cytokines production in human gingival fibroblasts.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.05.025}, pmid = {31125769}, issn = {1873-1597}, abstract = {BACKGROUND: Antimicrobial photodynamic therapy (aPDT) is an effective adjunctive therapeutic modality for the treatment of local infections, including periodontitis and peri-implantitis. After receiving aPDT, microbial cells in the biofilm structure may produce and/ or release soluble biofilm-derived effectors (BDEs), which may affect the biology of the host cells in the community context of their surrounding microenvironment. Given the fact that no study has investigated the role of BDEs following aPDT in the pathogenesis of infectious diseases, the aim of the current study was to determine the effect of BDEs of Aggregatibacter actinomycetemcomitans following exposure to sub-lethal doses of indocyanine green (ICG)-aPDT on human gingival fibroblasts (HGFs) in terms of cytokines produced.

MATERIALS AND METHODS: In this study, we evaluated the effect of biofilm-conditioned medium (BCM) resulting from the treatment of A. actinomycetemcomitans biofilm with a sub-lethal dose of aPDT on cytokines production, including IL-6, IL-8, CXCL10, TGF-β, and bFGF of HGFs using enzyme-linked immunoassays (ELISA). The sensitivity of cytokines to BDEs was determined by micro-titer plates.

RESULTS: The maximal sub-lethal dose of ICG-PDT was 20.15 μM/mL ICG at a fluence of 31.2 J/cm2. The BCM of ICG-PDT-treated viable A. actinomycetemcomitans significantly reduced IL-6, IL-8, and CXCL10 levels compared to the BCM of untreated viable A. actinomycetemcomitans (78-, 93-, and 61.6-fold reduction, respectively; all P < 0.01). TGF-β and bFGF were strongly induced by BCM of ICG-PDT treated viable A. actinomycetemcomitans (by 57.7 and 36.1 folds, respectively; both P < 0.05). The BCM of untreated viable A. actinomycetemcomitans degraded most of the CxCL10, TGF-β and bFGF (58.8, 61.5, and 71.6%, respectively) in 24 h, while it degraded 9.3% of IL-6 and 15.1% of IL-8 after 24 h.

CONCLUSION: The results of the current study revealed that a sub-lethal dose of ICG-aPDT through the effect of BCM on HGFs could not only significantly reduce the production of pro-inflammatory cytokines but also promoted their role in the periodontal regeneration due increasing the bFGF level. Altogether, ICG-aPDT, along with antimicrobial effects by reducing inflammation and induction of tissue regeneration resulting from BCM, can be considered an efficient adjunctive therapeutic method for the treatment of local infections.}, } @article {pmid31124069, year = {2019}, author = {Singhal, N and Singh, NS and Maurya, AK and Virdi, JS}, title = {Virulence-associated traits and in vitro biofilm-forming ability of Escherichia coli isolated from a major river traversing Northern India.}, journal = {Environmental science and pollution research international}, volume = {26}, number = {21}, pages = {21304-21311}, doi = {10.1007/s11356-019-05389-3}, pmid = {31124069}, issn = {1614-7499}, abstract = {Several strains of Escherichia coli harbor virulence traits, resulting in E. coli-related intestinal and extra-intestinal infections. Various studies have reported that extra-intestinal pathogenic E. coli (ExPEC) strains were prevalent in nonhuman reservoirs, including environmental waterways. It is therefore important to identify the pathogenic potential and/or ExPEC status of E. coli strains inhabiting the aquatic environments associated with anthropogenic activities. Besides virulence-associated genes, biofilm production also helps in the survival of E. coli in environmental waterbodies. Thus, the aim of the current study was to assess the virulence potential, ExPEC status, and biofilm-producing capability of E. coli isolated from the River Yamuna, a major river traversing the National Capital Region of Delhi, India. We also tried to discern a co-relation, if any, between virulence, biofilm formation, and antimicrobial resistance in these strains. Our results indicated that virulence-associated genes were scarce and none of the strain qualified the molecular criteria essential for ExPEC. This suggested that E. coli strains which can presumably cause human extra-intestinal infections were not prominent in the River Yamuna. However, the fact that more than 80% of the aquatic E. coli isolates were moderate and strong biofilm producers suggests that E. coli in these environments might serve as opportunistic pathogens. Also, no unequivocal association was observed between biofilm production, virulence, and β-lactamase genes in E. coli strains. As per the best of our knowledge, this is the first study where the relationship between virulence, biofilms, and antimicrobials has been examined in E. coli, isolated from an Indian urban aquatic waterbody.}, } @article {pmid31120391, year = {2019}, author = {Zhou, X and Li, M and Xu, L and Shi, C and Shi, X}, title = {Characterization of Antibiotic Resistance Genes, Plasmids, Biofilm Formation, and In Vitro Invasion Capacity of Salmonella Enteritidis Isolates from Children with Gastroenteritis.}, journal = {Microbial drug resistance (Larchmont, N.Y.)}, volume = {}, number = {}, pages = {}, doi = {10.1089/mdr.2018.0421}, pmid = {31120391}, issn = {1931-8448}, abstract = {Objectives: The primary aim of this study was to investigate the presence of antibiotic resistance genes (ARGs) and plasmid replicon types for 75 multidrug-resistant (MDR) Salmonella Enteritidis isolates from children with gastroenteritis. We also evaluated the association among biofilm formation, in vitro invasion capacity, and antibiotic resistance phenotypes. Materials and Methods: Twenty-two ARGs and 18 different plasmid incompatibility types were investigated using polymerase chain reaction (PCR) and DNA sequencing. In vitro invasion capacity of S. Enteritidis isolates possessing different antibiotic resistance patterns was assessed using the Caco2 human intestinal epithelial cell line and biofilm formation was performed in a 96-well polystyrene well format using crystal violet detection. Results: The presence of plasmid-mediated quinolone resistance genes and β-lactamase genes was established using PCR amplification. All the tested S. Enteritidis isolates that were fluoroquinolone resistant possessed gyrA mutations and 50% also possessed mutations in parC. MDR S. Enteritidis isolates containing three (29/75) or four (21/75) plasmid replicon types were predominant and 71/75 carried both FIIs and FIC replicon-type plasmids. MDR isolates were strong or moderate biofilm producers and a significant positive association (p < 0.05) between antibiotic resistance and biomass of biofilms was observed in the strains assayed. A ceftiofur-resistant strain was significantly more invasive (p < 0.01) than the other isolates. Conclusions: We observed a high incidence of ARGs and diversity of plasmids in S. Enteritidis isolates from children. Biofilm formation and invasion capacity highlight a significant hazard to public health.}, } @article {pmid31120377, year = {2019}, author = {Cowle, MW and Webster, G and Babatunde, AO and Bockelmann-Evans, BN and Weightman, AJ}, title = {Impact of flow hydrodynamics and pipe material properties on biofilm development within drinking water systems.}, journal = {Environmental technology}, volume = {}, number = {}, pages = {1-13}, doi = {10.1080/09593330.2019.1619844}, pmid = {31120377}, issn = {1479-487X}, abstract = {The aim of this study was to investigate the combined impact of flow hydrodynamics and pipe material on biofilm development in drinking water distribution systems (DWDS). Biofilms were formed on four commonly used pipe materials (namely polyvinyl chloride, polypropylene, structured wall high-density polyethylene and solid wall high-density polyethylene) within a series of purpose built flow cell reactors at two different flow regimes. Results indicate that varying amounts of microbial material with different morphologies were present depending on the pipe material and conditioning. The amount of microbial biomass was typically greater for the biofilms conditioned at lower flows. Whereas, biofilm development was inhibited at higher flows indicating shear forces imposed by flow conditions were above the critical levels for biofilm attachment. Alphaproteobacteria was the predominant bacterial group within the biofilms incubated at low flow and represented 48% of evaluated phylotypes; whilst at higher flows, Betaproteobacteria (45%) and Gammaproteobacteria (33%) were the dominant groups. The opportunistic pathogens, Sphingomonas and Pseudomonas were found to be particularly abundant in biofilms incubated at lower flows, and only found within biofilms incubated at higher flows on the rougher materials assessed. This suggests that these bacteria have limited ability to propagate within biofilms under high shear conditions without sufficient protection (roughness). These findings expand on knowledge relating to the impact of surface roughness and flow hydrodynamics on biofilm development within DWDS.}, } @article {pmid31119950, year = {2019}, author = {Irankhah, S and Abdi Ali, A and Mallavarapu, M and Soudi, MR and Subashchandrabose, S and Gharavi, S and Ayati, B}, title = {Ecological role of Acinetobacter calcoaceticus GSN3 in natural biofilm formation and its advantages in bioremediation.}, journal = {Biofouling}, volume = {35}, number = {4}, pages = {377-391}, doi = {10.1080/08927014.2019.1597061}, pmid = {31119950}, issn = {1029-2454}, abstract = {This study assessed the role of a new Acinetobacter calcoaceticus strain, GSN3, with biofilm-forming and phenol-degrading abilities. Three biofilm reactors were spiked with activated sludge (R1), green fluorescent plasmid (GFP) tagged GSN3 (R2), and their combination (R3). More than 99% phenol removal was achieved during four weeks in R3 while this efficiency was reached after two and four further operational weeks in R2 and R1, respectively. Confocal scanning electron microscopy revealed that GSN3-gfp strains appeared mostly in the deeper layers of the biofilm in R3. After four weeks, almost 7.07 × 107 more attached sludge cells were counted per carrier in R3 in comparison to R1. Additionally, the higher numbers of GSN3-gfp in R2 were unable to increase the efficiency as much as measured in R3. The presence of GSN3-gfp in R3 conveyed advantages, including enhancement of cell immobilization, population diversity, metabolic cooperation and ultimately treatment efficiency.}, } @article {pmid31118922, year = {2019}, author = {Zhang, M and Zhang, X and Tong, L and Ou, D and Wang, Y and Zhang, J and Wu, Q and Ye, Y}, title = {Random Mutagenesis Applied to Reveal Factors Involved in Oxidative Tolerance and Biofilm Formation in Foodborne Cronobacter malonaticus.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {877}, doi = {10.3389/fmicb.2019.00877}, pmid = {31118922}, issn = {1664-302X}, abstract = {Cronobacter species are linked with life-treating diseases in neonates and show strong tolerances to environmental stress. However, the information about factors involved in oxidative tolerance in Cronobacter remains elusive. Here, factors involved in oxidative tolerance in C. malonaticus were identified using a transposon mutagenesis. Eight mutants were successfully screened based on a comparison of the growth of strains from mutant library (n = 215) and wild type (WT) strain under 1.0 mM H2O2. Mutating sites including thioredoxin 2, glutaredoxin 3, pantothenate kinase, serine/threonine protein kinase, pyruvate kinase, phospholipase A, ferrous iron transport protein A, and alanine racemase 2 were successfully identified by arbitrary PCR and sequencing alignment. Furthermore, the comparison about quantity and structure of biofilms formation among eight mutants and WT was determined using crystal violet staining (CVS), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). Results showed that the biofilms of eight mutants significantly decreased within 48 h compared to that of WT, suggesting that mutating genes play important roles in biofilm formation under oxidative stress. The findings provide valuable information for deeply understanding molecular mechanism about oxidative tolerance of C. malonaticus.}, } @article {pmid31118702, year = {2019}, author = {Shrestha, LB and Baral, R and Khanal, B}, title = {Comparative study of antimicrobial resistance and biofilm formation among Gram-positive uropathogens isolated from community-acquired urinary tract infections and catheter-associated urinary tract infections.}, journal = {Infection and drug resistance}, volume = {12}, number = {}, pages = {957-963}, doi = {10.2147/IDR.S200988}, pmid = {31118702}, issn = {1178-6973}, abstract = {Background: Gram-positive cocci have emerged to be an important cause of urinary tract infection (UTI) both in community-acquired UTI (Com-UTI) and catheter-associated urinary tract infection (CA-UTI). The objective of this study was to investigate the frequency of Gram-positive cocci urinary tract infections, their susceptibility patterns to commonly used antimicrobial agents and the biofilm forming property with respect to catheter-associated UTI and community-acquired UTI. Methods: A total of 1,360 urine samples from indwelling catheter and 10,423 from mid-stream urine were obtained during a 6-month period and processed following standard microbiological guidelines. Biofilm formation was detected using congo red agar (CRA), tube method (TM) and tissue culture plate (TCP) method. Chi-square test and independent sample t-test were employed to calculate the significance. Statistical significance was set at P-value ≤0.05. Results: The infection rate was significantly higher in CA-UTI as compared to Com-UTI (25% vs 18%, p=0.0001). Among 2,216 organisms isolated, 471 were Gram-positive cocci; 401 were obtained from Com-UTI while 70 were from CA-UTI. Enterococcus faecalis was the most common organism isolated from Com-UTI, while Staphylococcus aureus was commonest among CA-UTI. Multi-drug resistance, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci were also significantly higher in CA-UTI as compared to Com-UTI. Biofilm-forming property was significantly higher in CA-UTI than Com-UTI. The sensitivity of congo red agar method and tube method was 79% and 81.9% respectively and specificity was 98.5% each. Antimicrobial resistance was significantly higher in biofilm-formers as compared to non-formers. Conclusion: Gram-positive bacteria are a significant cause of both CA-UTI and Com-UTI with Enterococcus faecalis and Staphylococcus aureus as common pathogen. Biofilm formation and multi-drug resistance is significantly higher in CA-UTI than Com-UTI. Routine surveillance of antimicrobial resistance and biofilm formation is necessary in all cases of UTI to ensure the proper management of patients.}, } @article {pmid31118466, year = {2019}, author = {Dettweiler, M and Lyles, JT and Nelson, K and Dale, B and Reddinger, RM and Zurawski, DV and Quave, CL}, title = {American Civil War plant medicines inhibit growth, biofilm formation, and quorum sensing by multidrug-resistant bacteria.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {7692}, doi = {10.1038/s41598-019-44242-y}, pmid = {31118466}, issn = {2045-2322}, support = {R01 AT007052/AT/NCCIH NIH HHS/United States ; R21 AI136563/AI/NIAID NIH HHS/United States ; 52006923//Howard Hughes Medical Institute (HHMI)/ ; R21 AI136563//U.S. Department of Health & Human Services | NIH | Office of Extramural Research, National Institutes of Health (OER)/ ; }, abstract = {A shortage of conventional medicine during the American Civil War (1861-1865) spurred Confederate physicians to use preparations of native plants as medicines. In 1863, botanist Francis Porcher compiled a book of medicinal plants native to the southern United States, including plants used in Native American traditional medicine. In this study, we consulted Porcher's book and collected samples from three species that were indicated for the formulation of antiseptics: Liriodendron tulipifera, Aralia spinosa, and Quercus alba. Extracts of these species were tested for the ability to inhibit growth in three species of multidrug-resistant pathogenic bacteria associated with wound infections: Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter baumannii. Extracts were also tested for biofilm and quorum sensing inhibition against S. aureus. Q. alba extracts inhibited growth in all three species of bacteria (IC50 64, 32, and 32 µg/mL, respectively), and inhibited biofilm formation (IC50 1 µg/mL) in S. aureus. L. tulipifera extracts inhibited biofilm formation (IC50 32 µg/mL) in S. aureus. A. spinosa extracts inhibited biofilm formation (IC50 2 µg/mL) and quorum sensing (IC50 8 µg/mL) in S. aureus. These results support that this selection of plants exhibited some antiseptic properties in the prevention and management of wound infections during the conflict.}, } @article {pmid31117281, year = {2019}, author = {Rajkowska, K and Nowicka-Krawczyk, P and Kunicka-Styczyńska, A}, title = {Effect of Clove and Thyme Essential Oils on Candida Biofilm Formation and the Oil Distribution in Yeast Cells.}, journal = {Molecules (Basel, Switzerland)}, volume = {24}, number = {10}, pages = {}, doi = {10.3390/molecules24101954}, pmid = {31117281}, issn = {1420-3049}, abstract = {Candida biofilm structure is particularly difficult to eradicate, since biofilm is much more resistant to antifungal agents than planktonic cells. In this context, a more effective strategy seems to be the prevention of biofilm formation than its eradication. The aim of the study was to examine whether the process of initial colonization of materials (glass, polyethylene terephthalate, polypropylene) by food-borne Candida sp. can be impeded by clove and thyme essential oils, used at their minimal inhibitory concentrations. In the presence of clove oil, 68.4-84.2% of the yeast tested showed a statistically significant reduction in biofilm formation, depending on the material. After treatment with thyme oil, statistically significant decrease in biofilm cell numbers was observed for 63.2-73.7% of yeasts. Confocal laser scanning microscopy showed diverse compounds of clove and thyme oils that were disparately located in C. albicans cell, on a cell wall and a cell membrane, in cytoplasm, and in vacuoles, depicting the multidirectional action of essential oils. However, essential oils that were used in sub-inhibitory concentration were sequestrated in the yeast vacuoles, which indicate the activation of Candida defense mechanisms by cell detoxification. Clove and thyme essential oils due to their anti-biofilm activity can be efficiently used in the prevention of the tested abiotic surfaces colonization by Candida sp.}, } @article {pmid31117001, year = {2019}, author = {Huang, TC and Chen, CJ and Chen, CC and Ding, SJ}, title = {Enhancing osteoblast functions on biofilm-contaminated titanium alloy by concentration-dependent use of methylene blue-mediated antimicrobial photodynamic therapy.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.pdpdt.2019.05.021}, pmid = {31117001}, issn = {1873-1597}, abstract = {The concentration of methylene blue (MB) photosensitizer could affect the eradication efficacy of antimicrobial photodynamic therapy (aPDT) in the treatment of contaminated implants, which is linked to the osseointegration of the implant. This was the first report of evaluating osteoblast functions on the contaminated SLA (sandblasting, large-grit and acid-etching) Ti alloy surfaces after the concentration-dependent use of MB-aPDT. Totally 1,164 SLA discs were randomly distributed for the analyses of antibacterial efficacy and osteoblast functions. Gram-negative (Aggregatibacter actinomycetemcomitans; A. actinomycetemcomitans) or Gram-positive (Streptococcus mutans; S. mutans) adhered on disc samples was subjected to aPDT with different MB concentrations (200, 250, 300, 350, and 400 μg/mL) using 660 nm diode laser with maximum output 80 mW for 1 min irradiation (4.8 J/cm2). Bactericidal effect was examined by viability, morphology, and lipopolysaccharide (LPS) assays. The disinfected disc surfaces by MB-aPDT to support osteoblast-like MG63 attachment, proliferation, differentiation, and mineralization were assessed for the predetermined culture time intervals. The statistical differences between the means were performed using a one-way analysis of variance (ANOVA) with a post hoc Scheffe test. The results of the morphology observation and bacterial survival examination consistently indicated a remarkably lower quantity of bacterial colonies on biofilm-contaminated surfaces after the aPDT treatment with higher MB concentration. Similarly, the higher MB concentration in aPDT resulted in the lower LPS amounts remaining on the A. actinomycetemcomitans-contaminated surfaces. Intriguingly, the expression of osteoblast cultured on disinfected surfaces using aPDT with higher MB concentration was comparable to the control without contamination. Within the limits of this in vitro model, this formulation of 400 μg/mL MB used in aPDT may be not only the lethal concentration against the 2 bacteria-contaminated implants, but it could also enhance the osteoblast functions on the contaminated implants. Nevertheless, the efficacy in the clinical practice for peri-implantitis therapy remains to be studied.}, } @article {pmid31116790, year = {2019}, author = {Feng, R and Zhao, G and Yang, Y and Xu, M and Huang, S and Sun, G and Guo, J and Li, J}, title = {Enhanced biological removal of intermittent VOCs and deciphering the roles of sodium alginate and polyvinyl alcohol in biofilm formation.}, journal = {PloS one}, volume = {14}, number = {5}, pages = {e0217401}, doi = {10.1371/journal.pone.0217401}, pmid = {31116790}, issn = {1932-6203}, abstract = {Developing a robust biofilm is a prerequisite for a biotrickling filter to obtain the good performance in removing volatile organic compounds (VOCs). But the biofilm formation can be seriously disturbed under intermittent loading condition due to carbon starvation stress in idle time. In this study, a biotrickling filter, with its packing materials being modified by 3% sodium alginate and 5% polyvinyl alcohol (v/v = 1:3), was employed to treat intermittent VOCs. Results showed that the removal efficiencies of toluene, ethylbenzene, p-xylene, m-xylene, and o-xylene was significantly enhanced in the BTF compared to the control one. Under relatively lower inlet loading, nearly complete removal of the five pollutants was achieved. A quantitative analysis showed that the concentration of total organic compound (TOC) in the leachate maintained at a high level, and had a strongly positive correlation with the divergence of microbial communities. The capacity of biofilm formation in the BTF was approximately four-fold higher than the control BTF, while the quantity of EPS secreted was more than ten-fold. EPS comprised largely of protein, and to less extent, polysaccharide. The biofilm formed on the modified packing materials maintained higher levels of microbial diversity and stability, even when modifiers were complete depleted or the VOCs inlet loading was increased. This study highlights the importance of packing materials for reducing the gap in performance between laboratory and industrial applications of BTFs.}, } @article {pmid31116789, year = {2019}, author = {Huang, MY and Woolford, CA and May, G and McManus, CJ and Mitchell, AP}, title = {Circuit diversification in a biofilm regulatory network.}, journal = {PLoS pathogens}, volume = {15}, number = {5}, pages = {e1007787}, doi = {10.1371/journal.ppat.1007787}, pmid = {31116789}, issn = {1553-7374}, abstract = {Genotype-phenotype relationships can vary extensively among members of a species. One cause of this variation is circuit diversification, the alteration of gene regulatory relationships among members of a species. Circuit diversification is thought to be a starting point for the circuit divergence or rewiring that occurs during speciation. How widespread is circuit diversification? Here we address this question with the fungal pathogen Candida albicans, which forms biofilms rich in distinctive hyphal cells as a prelude to infection. Our understanding of the biofilm/hyphal regulatory network comes primarily from studies of one clinical isolate, strain SC5314, and its marked derivatives. We used CRISPR-based methods to create mutations of four key biofilm transcription factor genes-BCR1, UME6, BRG1, and EFG1 -in SC5314 and four additional clinical isolates. Phenotypic analysis revealed that mutations in BCR1 or UME6 have variable impact across strains, while mutations in BRG1 or EFG1 had uniformly severe impact. Gene expression, sampled with Nanostring probes and examined comprehensively for EFG1 via RNA-Seq, indicates that regulatory relationships are highly variable among isolates. Our results suggest that genotype-phenotype relationships vary in this strain panel in part because of differences in control of BRG1 by BCR1, a hypothesis that is supported through engineered constitutive expression of BRG1. Overall, the data show that circuit diversification is the rule, not the exception, in this biofilm/hyphal regulatory network.}, } @article {pmid31116437, year = {2019}, author = {Abbondante, S and Pearlman, E}, title = {Breaching bacterial biofilm with neutrophil α-mannosidase.}, journal = {Journal of leukocyte biology}, volume = {105}, number = {6}, pages = {1085}, doi = {10.1002/JLB.4CE0419-139R}, pmid = {31116437}, issn = {1938-3673}, } @article {pmid31116394, year = {2019}, author = {Laulund, ASB and Trøstrup, H and Lerche, CJ and Thomsen, K and Christophersen, L and Calum, H and Høiby, N and Moser, C}, title = {Synergistic effect of immunomodulatory S100A8/A9 and ciprofloxacin against Pseudomonas aeruginosa biofilm in a murine chronic wound model.}, journal = {Pathogens and disease}, volume = {}, number = {}, pages = {}, doi = {10.1093/femspd/ftz027}, pmid = {31116394}, issn = {2049-632X}, abstract = {The majority of chronic wounds are associated with bacterial biofilms recalcitrant to antibiotics and host responses.Immunomodulatory S100A8/A9 is suppressed in P. aeruginosa biofilms infected wounds. We aimed at investigating a possible additive effect between S100A8/A9 and ciprofloxacin against biofilms.

MATERIALS/METHODS: Thirty-two mice were injected with alginate embedded P.aeruginosa following a third-degree burn. Mice were randomized into four groups receiving combination ciprofloxacin and S100A8/A9 or monotherapy ciprofloxacin, S100A8/A9 or placebo. Evaluated by host responses and quantitative bacteriology in wounds.In addition, in vitro checkerboard analysis was performed, with P. aeruginosa and ascending S100A8/A9 and ciprofloxacin concentrations.

RESULTS: S100A8/A9 augmented the effect of ciprofloxacin in vivo, by lowering bacterial quantity compared to the placebo arm and the two mono-intervention groups (P < 0.0001).S100A8 and 100A9 were increased in the double-treated group as compared to the mono-intervention groups (P = 0.032, P = 0.0023). TIMP-1 and KC/CXCL-1 were increased in the double-intervention group compared to the S100A8/A9 group (P = 0.050, P = 0.050).No in vitro synergism was detected.

CONCLUSION: The observed ciprofloxacin augmenting effect of S100A8/A9 in vivo was not confirmed by checkerboard analysis indicating dependence of host cells for the S100A8/A9 effect. S100A8/A9 and ciprofloxacin is a promising therapy for optimizing chronic wound treatment.}, } @article {pmid31115692, year = {2019}, author = {Daood, U and Burrow, MF and Yiu, CKY}, title = {Effect of a novel quaternary ammonium silane cavity disinfectant on cariogenic biofilm formation.}, journal = {Clinical oral investigations}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00784-019-02928-7}, pmid = {31115692}, issn = {1436-3771}, abstract = {OBJECTIVE: Evaluate effect of quaternary ammonium silane (QAS) cavity disinfectant on cariogenic biofilm.

MATERIALS AND METHODS: Single- (Streptococcus mutans or Lactobacillus acidophilus), dual- (Streptococcus mutans/Lactobacillus Acidophilus), and multi-species (Streptococcus mutans, Actinomyces naeslundii, and Streptococcus sanguis) biofilms were grown on acid-etched dentine discs. Biofilms were incubated (120 min/37 °C) and allowed to grow for 3 days anaerobically. Discs (no treatment) served as control (group 1). Groups II, III, IV, and V were then treated with 2% chlorhexidine, and 2%, 5%, and 10% QAS (20 s). Discs were returned to well plates with 300 μL of bacterial suspension and placed in anaerobic incubator at 37 °C and biofilms redeveloped for 4 days. Confocal microscopy, Raman, CFU, and MTT assay were performed.

RESULTS: Raman peaks show shifts at 1450 cm-1, 1453 cm-1, 1457 cm-1, 1460 cm-1, and 1462 cm-1 for control, 2% CHX, 2%, 5%, and 10% QAS groups in multi-species biofilms. There was reduction of 484 cm-1 band in 10% QAS group. CLSM revealed densely clustered green colonies in control group and red confluent QAS-treated biofilms with significantly lower log CFU for single/dual species. Metabolic activities of Streptococcus mutans and Lactobacillus acidophilus decreased with increasing QAS exposure time.

CONCLUSION: Quaternary ammonium silanes possess antimicrobial activities and inhibit growth of cariogenic biofilms.

CLINICAL SIGNIFICANCE: Available data demonstrated use of QAS as potential antibacterial cavity disinfectant in adhesive dentistry. Experimental QAS can effectively eliminate caries-forming bacteria, when used inside a prepared cavity, and can definitely overcome problems associated with present available cavity disinfectants.}, } @article {pmid31114932, year = {2019}, author = {Montazeri, A and Salehzadeh, A and Zamani, H}, title = {Effect of silver nanoparticles conjugated to thiosemicarbazide on biofilm formation and expression of intercellular adhesion molecule genes, icaAD, in Staphylococcus aureus.}, journal = {Folia microbiologica}, volume = {}, number = {}, pages = {}, doi = {10.1007/s12223-019-00715-1}, pmid = {31114932}, issn = {1874-9356}, abstract = {Biofilm formation is regarded as an important factor in the establishment of infections caused by Staphylococcus aureus. In the present study, phenotypic and molecular assays were used to evaluate antibiofilm potential of thiosemicarbazide (Tsc) conjugated with silver nanoparticles (Ag NPs) and functionalized by glutamic acid (Ag@Glu/Tsc NPs) against methicillin-resistant S. aureus (MRSA). Ag NPs were synthesized using precipitation method and conjugated to Tsc using glutamic acid. The NPs were characterized using SEM and FTIR spectroscopy analyses. Then, antibiofilm potential of the prepared NPs against MRSA strains was evaluated using phenotypic method and their effects on the expression of biofilm-associated genes icaA and icaD. Finally, the genes involved with the synthesis of intercellular adhesion molecules were determined. According to the results, Ag@Glu/Tsc NPs inhibited biofilm formation of MRSA strains up to 76.7% compared with the control. In addition, expression of the biofilm-associated genes icaA and icaD reduced by 66.7% and 60.3%, respectively in the presence of sub-inhibitory concentration of Ag@Glu/Tsc NPs. In conclusion, Ag@Glu/Tsc NPs could be considered as a potent antibacterial agent to inhibit bacterial biofilms.}, } @article {pmid31114399, year = {2019}, author = {Dance, DA and Wuthiekanun, V and Sarovich, D and Price, EP and Limmathurotsakul, D and Currie, BJ and Trung, TT}, title = {Pan-drug-resistant and biofilm-producing strain of Burkholderia pseudomallei: first report of melioidosis from a diabetic patient in Yogyakarta, Indonesia [Letter].}, journal = {International medical case reports journal}, volume = {12}, number = {}, pages = {117-118}, doi = {10.2147/IMCRJ.S205245}, pmid = {31114399}, issn = {1179-142X}, } @article {pmid31113899, year = {2019}, author = {Pisithkul, T and Schroeder, JW and Trujillo, EA and Yeesin, P and Stevenson, DM and Chaiamarit, T and Coon, JJ and Wang, JD and Amador-Noguez, D}, title = {Metabolic Remodeling during Biofilm Development of Bacillus subtilis.}, journal = {mBio}, volume = {10}, number = {3}, pages = {}, doi = {10.1128/mBio.00623-19}, pmid = {31113899}, issn = {2150-7511}, support = {P41 GM066326/GM/NIGMS NIH HHS/United States ; P41 GM103399/GM/NIGMS NIH HHS/United States ; }, abstract = {Biofilms are structured communities of tightly associated cells that constitute the predominant state of bacterial growth in natural and human-made environments. Although the core genetic circuitry that controls biofilm formation in model bacteria such as Bacillus subtilis has been well characterized, little is known about the role that metabolism plays in this complex developmental process. Here, we performed a time-resolved analysis of the metabolic changes associated with pellicle biofilm formation and development in B. subtilis by combining metabolomic, transcriptomic, and proteomic analyses. We report surprisingly widespread and dynamic remodeling of metabolism affecting central carbon metabolism, primary biosynthetic pathways, fermentation pathways, and secondary metabolism. Most of these metabolic alterations were hitherto unrecognized as biofilm associated. For example, we observed increased activity of the tricarboxylic acid (TCA) cycle during early biofilm growth, a shift from fatty acid biosynthesis to fatty acid degradation, reorganization of iron metabolism and transport, and a switch from acetate to acetoin fermentation. Close agreement between metabolomic, transcriptomic, and proteomic measurements indicated that remodeling of metabolism during biofilm development was largely controlled at the transcriptional level. Our results also provide insights into the transcription factors and regulatory networks involved in this complex metabolic remodeling. Following upon these results, we demonstrated that acetoin production via acetolactate synthase is essential for robust biofilm growth and has the dual role of conserving redox balance and maintaining extracellular pH. This report represents a comprehensive systems-level investigation of the metabolic remodeling occurring during B. subtilis biofilm development that will serve as a useful road map for future studies on biofilm physiology.IMPORTANCE Bacterial biofilms are ubiquitous in natural environments and play an important role in many clinical, industrial, and ecological settings. Although much is known about the transcriptional regulatory networks that control biofilm formation in model bacteria such as Bacillus subtilis, very little is known about the role of metabolism in this complex developmental process. To address this important knowledge gap, we performed a time-resolved analysis of the metabolic changes associated with bacterial biofilm development in B. subtilis by combining metabolomic, transcriptomic, and proteomic analyses. Here, we report a widespread and dynamic remodeling of metabolism affecting central carbon metabolism, primary biosynthetic pathways, fermentation pathways, and secondary metabolism. This report serves as a unique hypothesis-generating resource for future studies on bacterial biofilm physiology. Outside the biofilm research area, this work should also prove relevant to any investigators interested in microbial physiology and metabolism.}, } @article {pmid31113370, year = {2019}, author = {Liu, X and Yan, Y and Wu, H and Zhou, C and Wang, X}, title = {Biological and transcriptomic studies reveal hfq is required for swimming, biofilm formation and stress response in Xanthomonas axonpodis pv. citri.}, journal = {BMC microbiology}, volume = {19}, number = {1}, pages = {103}, doi = {10.1186/s12866-019-1476-9}, pmid = {31113370}, issn = {1471-2180}, support = {cstc2016shms-ztzx80003//Chongqing Science and Technology Commission/ ; }, abstract = {BACKGROUND: Hfq is a widely conserved bacterial RNA-binding protein which generally mediates the global regulatory activities involv ed in physiological process and virulence. The goal of this study was to characterize the biological function of hfq gene in Xanthomonas axonpodis pv. citri (Xac), the causal agent of citrus canker disease.

RESULTS: An hfq mutant in Xac was generated by plasmid integration. The loss of hfq resulted in attenuation of bacterial growth, motility and biofilm formation. In addition, the hfq mutation impaired Xac resistance to H2O2 and both high and low pH environments, but did not affect the virulence to citrus. RNA-Seq analyses indicated that Hfq played roles in regulating the expression of 746 genes. In hfq mutant, gene expression related to chemotaxis, secretion system, two-component system, quorum sensing and flagellar assembly were repressed, whereas expression of ribosomal genes were significantly up-regulated. The down-regulated expression of three bacterial chemotaxis related genes and seven flagella genes, which involved in cell growth and biofilm formation, were further validated by RT-qPCR.

CONCLUSIONS: The study demonstrated that hfq was involved in multiple biological processes in Xac. The results could serve as initiate points for identifying regulatory sRNAs and genes controlled by Hfq-sRNA interactions in Xac.}, } @article {pmid31112769, year = {2019}, author = {Jannadi, H and Correa, W and Zhang, Z and Brandenburg, K and Oueslati, R and Rouabhia, M}, title = {Antimicrobial peptides Pep19-2.5 and Pep19-4LF inhibit Streptococcus mutans growth and biofilm formation.}, journal = {Microbial pathogenesis}, volume = {133}, number = {}, pages = {103546}, doi = {10.1016/j.micpath.2019.103546}, pmid = {31112769}, issn = {1096-1208}, abstract = {With this study, we investigated the effect of synthetic antimicrobial peptides Pep19-2.5 and Pep194LF alone or in combination with antibiotics on S. mutans growth and biofilm formation/disruption. We also examined the cytotoxic effect of each peptide on monocytes. S. mutans was cultured in the presence of different concentrations of each peptide. We showed that Pep19-2.5 and Pep19-4LF were able to significantly (p ≤ 0.01) inhibit the growth of S. mutans. The synthetic peptides also decreased biofilm formation by S. mutans. Furthermore, both peptides reduced the viability of S. mutans in already formed biofilms. The combination of each peptide with antibiotics (penicillin/streptomycin, P/S) produced additive interactions which inhibited S. mutans growth and biofilm formation. Pep19-2.5 and Pep19-4LF were nontoxic, as they did not decrease monocyte viability and did not increase the lactate dehydrogenase activity of the exposed cells. In conclusion, synthetic peptides Pep19-2.5 and Pep19-4LF did inhibit S. mutans growth and its capacity to form biofilm. Both peptides were found to be nontoxic to monocytes. These data provide new insight into the efficacy of synthetic peptides Pep19-2.5 and Pep19-4LF against S. mutans. These peptides may thus be useful in controlling the adverse effects of this cariogenic bacterium in human.}, } @article {pmid31110496, year = {2019}, author = {Rizzato, C and Torres, J and Kasamatsu, E and Camorlinga-Ponce, M and Bravo, MM and Canzian, F and Kato, I}, title = {Potential Role of Biofilm Formation in the Development of Digestive Tract Cancer With Special Reference to Helicobacter pylori Infection.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {846}, doi = {10.3389/fmicb.2019.00846}, pmid = {31110496}, issn = {1664-302X}, abstract = {Bacteria are highly social organisms that communicate via signaling molecules and can assume a multicellular lifestyle to build biofilm communities. Until recently, complications from biofilm-associated infection have been primarily ascribed to increased bacterial resistance to antibiotics and host immune evasion, leading to persistent infection. In this theory and hypothesis article we present a relatively new argument that biofilm formation has potential etiological role in the development of digestive tract cancer. First, we summarize recent new findings suggesting the potential link between bacterial biofilm and various types of cancer to build the foundation of our hypothesis. To date, evidence has been particularly convincing for colorectal cancer and its precursor, i.e., polyps, pointing to several key individual bacterial species, such as Bacteroides fragilis, Fusobacterium nucleatum, and Streptococcus gallolyticus subsp. Gallolyticus. Then, we further extend this hypothesis to one of the most common bacterial infection in humans, Helicobacter pylori (Hp), which is considered a major cause of gastric cancer. Thus far, there has been no direct evidence linking in vivo Hp gastric biofilm formation to gastric carcinogenesis. Yet, we synthesize the information to support an argument that biofilm associated-Hp is potentially more carcinogenic, summarizing biological characteristics of biofilm-associated bacteria. We also discuss mechanistic pathways as to how Hp or other biofilm-associated bacteria control biofilm formation and highlight recent findings on Hp genes that influence biofilm formation, which may lead to strain variability in biofilm formation. This knowledge may open a possibility of developing targeted intervention. We conclude, however, that this field is still in its infancy. To test the hypothesis rigorously and to link it ultimately to gastric pathologies (e.g., premalignant lesions and cancer), studies are needed to learn more about Hp biofilms, such as compositions and biological properties of extracellular polymeric substance (EPS), presence of non-Hp microbiome and geographical distribution of biofilms in relation to gastric gland types and structures. Identification of specific Hp strains with enhanced biofilm formation would be helpful not only for screening patients at high risk for sequelae from Hp infection, but also for development of new antibiotics to avoid resistance, regardless of its association with gastric cancer.}, } @article {pmid31109992, year = {2019}, author = {Berne, C and Brun, YV}, title = {The two chemotaxis clusters in Caulobacter crescentus play different roles in chemotaxis and biofilm regulation.}, journal = {Journal of bacteriology}, volume = {}, number = {}, pages = {}, doi = {10.1128/JB.00071-19}, pmid = {31109992}, issn = {1098-5530}, support = {R35 GM122556/GM/NIGMS NIH HHS/United States ; }, abstract = {The holdfast polysaccharide adhesin is crucial for irreversible cell adhesion and biofilm formation in Caulobacter crescentus Holdfast production is tightly controlled via developmental regulators, as well as via environmental and physical signals. Here we identify a novel mode of regulation of holdfast synthesis that involves chemotaxis proteins. We characterized the two identified chemotaxis clusters of C. crescentus and showed that only the previously characterized, major cluster is involved in chemotactic response towards different carbon sources. However, both chemotaxis clusters encoded in the C. crescentus genome play a role in biofilm formation and holdfast production, by regulating the expression of hfiA, the gene encoding the holdfast inhibitor HfiA. We show that CheA and CheB proteins act in an antagonistic manner: while the two CheA proteins negatively regulate hfiA expression, the CheB proteins are positive regulators, thus providing a modulation of holdfast synthesis and surface attachment.IMPORTANCEChemosensory systems constitute major signal transduction pathways in bacteria. These systems are involved in chemotaxis and other cell responses to environment conditions, such as production of adhesins to enable irreversible adhesion to a surface and surface colonization. The C. crescentus genome encodes two complete chemotaxis clusters. Here we characterized the second, novel chemotaxis-like cluster. While only the major chemotaxis cluster is involved in chemotaxis, both chemotaxis systems modulate C. crescentus adhesion by controlling expression of the holdfast synthesis inhibitor HfiA. Here, we identify a new level in holdfast regulation, providing new insights into the control of adhesin production that leads to the formation of biofilms in response to the environment.}, } @article {pmid31107334, year = {2019}, author = {Stoodley, P}, title = {CORR Insights®: Is Implant Coating With Tyrosol- and Antibiotic-loaded Hydrogel Effective in Reducing Cutibacterium (Propionibacterium) acnes Biofilm Formation? A Preliminary In Vitro Study.}, journal = {Clinical orthopaedics and related research}, volume = {477}, number = {7}, pages = {1747-1749}, doi = {10.1097/CORR.0000000000000721}, pmid = {31107334}, issn = {1528-1132}, } @article {pmid31107198, year = {2019}, author = {Volejníková, A and Melicherčík, P and Nešuta, O and Vaňková, E and Bednárová, L and Rybáček, J and Čeřovský, V}, title = {Antimicrobial peptides prevent bacterial biofilm formation on the surface of polymethylmethacrylate bone cement.}, journal = {Journal of medical microbiology}, volume = {68}, number = {6}, pages = {961-972}, doi = {10.1099/jmm.0.001000}, pmid = {31107198}, issn = {1473-5644}, mesh = {Anti-Bacterial Agents/pharmacology ; Anti-Infective Agents/*pharmacology ; Bacterial Adhesion/drug effects ; Biofilms/*drug effects/growth & development ; Bone Cements ; Methicillin-Resistant Staphylococcus aureus/*drug effects/growth & development ; Microbial Sensitivity Tests ; Peptides/chemical synthesis/*pharmacology ; Polymethyl Methacrylate ; Prostheses and Implants/microbiology ; Pseudomonas aeruginosa/*drug effects/growth & development ; Staphylococcus epidermidis/*drug effects/growth & development ; }, abstract = {PURPOSE: Antibiotic-loaded polymethylmethacrylate-based bone cement has been implemented in orthopaedics to cope with implant-related infections associated with the formation of bacterial biofilms. In the context of emerging bacterial resistance to current antibiotics, we examined the efficacy of short antimicrobial peptide-loaded bone cement in inhibiting bacterial adhesion and consequent biofilm formation on its surface.

METHODOLOGY: The ability of α-helical antimicrobial peptides composed of 12 amino acid residues to prevent bacterial biofilm [methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli] formation on the surface of model implants made from polymethylmethacrylate-based bone cement was evaluated by colony-forming unit (c.f.u.) counting of bacteria released by sonication from the biofilms formed on their surfaces. The biofilms on model implant surfaces were also visualized by light microscopy after staining with tetrazolium dye (MTT) and by scanning electron microscopy.

RESULTS: When incorporated in the implants, these peptides caused a mean reduction in the number of bacterial cells attached to implants' surfaces (by five orders of magnitude), and 88 % of these implants showed no bacterial adhesion after being exposed to growth media containing various bacteria.

CONCLUSION: The results showed that the antibiofilm activity of these peptides was comparable to that of the antibiotics, but the peptides exhibited broader specificity than the antibiotics. Given the rapid development of antibiotic resistance, antimicrobial peptides show promise as a substitute for antibiotics for loading into bone cements.}, } @article {pmid31106716, year = {2019}, author = {Perez, LRR}, title = {Equal, but different: Fluctuant biofilm formation and its impact on polymyxin B susceptibility among a clonal spreading of KPC-2-producing Klebsiella pneumoniae isolates.}, journal = {Infection control and hospital epidemiology}, volume = {40}, number = {8}, pages = {954-955}, doi = {10.1017/ice.2019.106}, pmid = {31106716}, issn = {1559-6834}, } @article {pmid31106237, year = {2019}, author = {Colomer-Winter, C and Lemos, JA and Flores-Mireles, AL}, title = {Biofilm Assays on Fibrinogen-coated Silicone Catheters and 96-well Polystyrene Plates.}, journal = {Bio-protocol}, volume = {9}, number = {6}, pages = {}, doi = {10.21769/BioProtoc.3196}, pmid = {31106237}, issn = {2331-8325}, support = {16PRE29860000//American Heart Association-American Stroke Association/United States ; R21 AI135158/AI/NIAID NIH HHS/United States ; }, abstract = {Biofilm formation is a well-known bacterial strategy that protects cells from hostile environments. During infection, bacteria found in a biofilm community are less sensitive to antibiotics and to the immune response, often allowing them to colonize and persist in the host niche. Not surprisingly, biofilm formation on medical devices, such as urinary catheters, is a major problem in hospital settings. To be able to eliminate such biofilms, it is important to understand the key bacterial factors that contribute to their formation. A common practice in the lab setting is to study biofilms grown in laboratory media. However, these media do not fully reflect the host environment conditions, potentially masking relevant biological determinants. This is the case during urinary catheterization, where a key element for Enterococcus faecalis and Staphylococcus aureus colonization and biofilm formation is the release of fibrinogen (Fg) into the bladder and its deposition on the urinary catheter. To recapitulate bladder conditions during catheter-associated urinary tract infection (CAUTI), we have developed a fibrinogen-coated catheter and 96-well plate biofilm assay in urine. Notably, enterococcal biofilm factors identified in these in vitro assays proved to be important for biofilm formation in vivo in a mouse model of CAUTI. Thus, the method described herein can be used to uncover biofilm-promoting factors that are uniquely relevant in the host environment, and that can be exploited to develop new antibacterial therapies.}, } @article {pmid31106062, year = {2019}, author = {Khider, M and Hansen, H and Hjerde, E and Johansen, JA and Willassen, NP}, title = {Exploring the transcriptome of luxI- and ΔainS mutants and the impact of N-3-oxo-hexanoyl-L- and N-3-hydroxy-decanoyl-L-homoserine lactones on biofilm formation in Aliivibrio salmonicida.}, journal = {PeerJ}, volume = {7}, number = {}, pages = {e6845}, doi = {10.7717/peerj.6845}, pmid = {31106062}, issn = {2167-8359}, abstract = {Background: Bacterial communication through quorum sensing (QS) systems has been reported to be important in coordinating several traits such as biofilm formation. In Aliivibrio salmonicida two QS systems the LuxI/R and AinS/R, have been shown to be responsible for the production of eight acyl-homoserine lactones (AHLs) in a cell density dependent manner. We have previously demonstrated that inactivation of LitR, the master regulator of the QS system resulted in biofilm formation, similar to the biofilm formed by the AHL deficient mutant ΔainSluxI- . In this study, we aimed to investigate the global gene expression patterns of luxI and ainS autoinducer synthases mutants using transcriptomic profiling. In addition, we examined the influence of the different AHLs on biofilm formation.

Results: The transcriptome profiling of ΔainS and luxI- mutants allowed us to identify genes and gene clusters regulated by QS in A. salmonicida. Relative to the wild type, the ΔainS and luxI- mutants revealed 29 and 500 differentially expressed genes (DEGs), respectively. The functional analysis demonstrated that the most pronounced DEGs were involved in bacterial motility and chemotaxis, exopolysaccharide production, and surface structures related to adhesion. Inactivation of luxI, but not ainS genes resulted in wrinkled colony morphology. While inactivation of both genes (ΔainSluxI-) resulted in strains able to form wrinkled colonies and mushroom structured biofilm. Moreover, when the ΔainSluxI- mutant was supplemented with N-3-oxo-hexanoyl-L-homoserine lactone (3OC6-HSL) or N-3-hydroxy-decanoyl-L-homoserine lactone (3OHC10-HSL), the biofilm did not develop. We also show that LuxI is needed for motility and for repression of EPS production, where repression of EPS is likely operated through the RpoQ-sigma factor.

Conclusion: These findings imply that the LuxI and AinS autoinducer synthases play a critical role in the regulation of biofilm formation, EPS production, and motility.}, } @article {pmid31105285, year = {2019}, author = {Samad, A and Khan, AA and Sajid, M and Zahra, R}, title = {Assessment of biofilm formation by pseudomonas aeruginosa and hydrodynamic evaluation of microtiter plate assay.}, journal = {JPMA. The Journal of the Pakistan Medical Association}, volume = {69}, number = {5}, pages = {666-671}, pmid = {31105285}, issn = {0030-9982}, abstract = {OBJECTIVE: To assess the biofilm formation in clinical and environmental isolates of Pseudomonas aeruginosa and to evaluate the hydrodynamics in microtiter plate assay and compare it with conventional assays for biofilm formation.

METHODS: The cross-sectional study was conducted at the Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan, in 2013-14, while the computational work was done at the National University of Science and Technology, Islamabad. The study comprised environmental and clinical isolates of pseudomonas aeruginosa. Pseudomonas citramide agar was used as a selective media, and further confirmation was done by biochemical tests. Biofilm formation was assessed by Congo red assay, air liquid interfaceassay and microtiter plate assay. Computational Fluid Dynamics (CFD) simulations were also used to improve the microtiter plate assay for biofilm formation assessment. Polymerase chain reaction was used for screening of pelA and pelG genes.

RESULTS: Of the 50 isolates, 25(50%) each were environmental and clinical. The number of biofilm producers observed in Congo red assay, air liquid interface assay and microtiter plate assay were 7(14%), 15(30%) and 30(60%) respectively. Biofilm former gene pelA was observed in 22(44%) isolates while 36(72%) isolates showed the presence of pelG gene.

CONCLUSIONS: Microtiter plate assay was found to be a reliable method to detect biofilm forming pseudomonas aeruginosa isolates which further provides a base for development of methods to detect biofilms readily and accurately.}, } @article {pmid31104214, year = {2019}, author = {Aiyer, KS and Vijayakumar, BS}, title = {An improvised microtiter dish biofilm assay for non-invasive biofilm detection on microbial fuel cell anodes and studying biofilm growth conditions.}, journal = {Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology]}, volume = {}, number = {}, pages = {}, doi = {10.1007/s42770-019-00091-5}, pmid = {31104214}, issn = {1678-4405}, abstract = {Microbial life is predominantly observed as biofilms, which are a sessile aggregation of microbial cells formed in response to stress conditions. The microtiter dish biofilm formation assay is one of the most important methods of studying biofilm formation. In this study, the assay has been improvised to allow easy detection of biofilm formation on different substrata. The method has then been used to study growth conditions that affect biofilm formation, viz., the effect of pH, temperature, shaking conditions, and the carbon source provided. Glass, cellulose acetate, and carbon cloth materials were used as substrata to study biofilm development under the above conditions. The method was then extended to determine biofilm formation on the anodes of a microbial fuel cell in order to study the effect of biofilm formation on power production. A high correlation was observed between biofilm formation and power density (r = 0.951). When the electrode containing a biofilm was replaced with another electrode without biofilm, the average power density dropped from 59.55 to 5.76 mW/m2. This method offers an easy way to study the suitability of different materials to support biofilm formation. Growth conditions determining biofilm formation can be studied using this method. This method also offers a non-invasive way to determine biofilm formation on anodes of microbial fuel cells and preserves the anode for further studies.}, } @article {pmid31102859, year = {2019}, author = {Liang, C and Zhang, L and Nord, NB and Carvalho, PN and Bester, K}, title = {Dose-dependent effects of acetate on the biodegradation of pharmaceuticals in moving bed biofilm reactors.}, journal = {Water research}, volume = {159}, number = {}, pages = {302-312}, doi = {10.1016/j.watres.2019.04.026}, pmid = {31102859}, issn = {1879-2448}, abstract = {Moving bed biofilm reactors (MBBR) are promising as a post-treatment for removing pharmaceuticals from wastewater. However, the effect of easily degradable carbon sources on the degradation of pharmaceuticals is unclear. This study shows the influence of acetate on the degradation of 26 pharmaceuticals in an MBBR was dose- and compound-dependent: while the degradation of venlafaxine, tramadol and ciprofloxacin was promoted (increase of reaction rate constant (k) by 133%, 212%, 55%) by acetate, its presence caused negative effects on the removal of ibuprofen, citalopram and diclofenac (decrease of k by 76%, 57%, 44%). The deconjugation of acetyl-sulfadiazine was clearly slowed down (decrease of k by 75%) by the dosed acetate, probably due to feedback inhibition by abundant acetate. 17 out of 25 tested compounds were found to be independent of the acetate dosage, which suggested dosing acetate induced minor effects on most of pharmaceuticals' removal. Enrichment of S- or first eluted enantiomer of 4 β-blockers and the metabolite metoprolol acid was observed. Both non-enantioselective (rapid at elevated compound concentration) and enantioselective enzymes (slower and predominant at lower compound concentration) played a part in the biodegradation. High doses of acetate slowed down the enantiomeric enrichment of atenolol, metoprolol, propranolol and metoprolol acid, which demonstrated that the acetate is able to up- or down-regulate enzymes involved in the enantioselective degradation of β-blockers and thus reveals a complex co-metabolism relationship between transformation pathways of pharmaceuticals and carbon source.}, } @article {pmid31102615, year = {2019}, author = {Campbell, M and Zhao, W and Fathi, R and Mihreteab, M and Gilbert, ES}, title = {Rhamnus prinoides (gesho): A source of diverse anti-biofilm activity.}, journal = {Journal of ethnopharmacology}, volume = {241}, number = {}, pages = {111955}, doi = {10.1016/j.jep.2019.111955}, pmid = {31102615}, issn = {1872-7573}, abstract = {Rhamnus prinoides (gesho) is an evergreen shrub from East Africa traditionally used for the treatment of illnesses including atopic dermatitis, ear, nose and throat infections, pneumonia, arthritis, brucellosis, flu, indigestion and fatigue.

AIM OF THE STUDY: Several of the conditions for which gesho is traditionally used are associated with communities of surface-attached microorganisms, or biofilms. We hypothesized that gesho has anti-biofilm activity. The principal aim of this study was to evaluate gesho-associated anti-biofilm activity and identify active compounds.

MATERIALS AND METHODS: Lyophilized ethanol and aqueous extracts were prepared from dried Rhamnus prinoides stems and leaves. Biofilm inhibition was measured by crystal violet staining and subsequent viability assays were conducted on growth agar. Chemical fractionation, chemical testing, Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) were used to isolate and identify active compounds.

RESULTS: Leaf and stem ethanol extracts significantly inhibited Staphylococcus aureus, Bacillus subtilis and Streptococcus mutans biofilm formation up to 99.9% and reduced planktonic cell growth up to 10 log units relative to untreated controls. The anti-biofilm activity of the ethanol stem extracts was due to a biocidal or bacteriostatic mechanism while bacteriostatic or anti-pathogenic mechanisms were attributed to the leaf ethanol extract. Gesho extracts showed activity against all three species tested but the treatment efficacy and mechanism were species dependent. Chemical fractionation and activity screens of the leaf ethanol extract identified ethyl 4-ethoxybenzoate and 4-hydroxy 4-methyl pentanone to be compounds with anti-biofilm activity. Ethyl 4-ethoxybenzoate activity was potentiated by DMSO. Notably, concentrations of both compounds were identified where biofilm formation was prevented without inhibition of cell growth; i.e. anti-pathogenic characteristics were evident.

CONCLUSION: Gesho leaf ethanol extract contains chemicals with anti-biofilm and bactericidal activities. This work lends support to the traditional use of gesho for treating topical infections and warrants further investigation into Rhamnus prinoides as a source of antibacterial and anti-biofilm agents.}, } @article {pmid31102398, year = {2019}, author = {Carvajal, J and Carvajal, M}, title = {Further Clarification About "Back to Basics: Could the Preoperative Skin Antiseptic Agent Help Prevent Biofilm-Related Capsular Contracture?".}, journal = {Aesthetic surgery journal}, volume = {39}, number = {7}, pages = {NP295-NP297}, doi = {10.1093/asj/sjz076}, pmid = {31102398}, issn = {1527-330X}, } @article {pmid31100490, year = {2019}, author = {Senpuku, H and Mohri, S and Mihara, M and Arai, T and Suzuki, Y and Saeki, Y}, title = {Effects of 7S globulin 3 derived from the adzuki bean [Vigna angularis] on the CSP- and eDNA- dependent biofilm formation of Streptococcus mutans.}, journal = {Archives of oral biology}, volume = {102}, number = {}, pages = {256-265}, doi = {10.1016/j.archoralbio.2019.04.010}, pmid = {31100490}, issn = {1879-1506}, abstract = {OBJECTIVE: Streptococcus mutans is a principal bacterium that forms pathogenic biofilm involved in the development of dental caries. S. mutans possesses a quorum sensing system (QS) stimulated by competence stimulating peptide (CSP), which is associated with bacteriocin production, genetic competency and biofilm formation. Inhibiting CSP-dependent QS is one of the aims leading to the inhibition of biofilm formation and is useful for establishing new prevention systems for dental caries.

DESIGN: In this study, we selected adzuki bean [Vigna angularis] extract as a candidate component to inhibit CSP-dependent biofilm formation among various foods. To purify an inhibitory component from the adzuki extracts, we performed the salting-out method, two rounds of ion-exchange chromatography, and SDS and native PAGE.

RESULTS: A primary protein band that inhibits CSP-dependent biofilm formation appeared at approximately 50 kDa and was identified as 7S globulin 3 (7S3), a major seed storage protein in adzuki bean. To determine the characteristics of 7S3 as an inhibitory component, aggregated proteins were extracted from the adzuki crude extracts at pH values lower than 6. The aggregated proteins inhibited CSP- and eDNA-dependent biofilm formation and showed 50 kDa band, which is identical with 7S3 in the purified sample. Moreover, 7S globulin 3 in the adzuki bean extract directly interacted with CSP at low pH conditions but not at neutral conditions, and inhibited CSP-dependent bacteriocin production.

CONCLUSION: It was suggested that 7S3 might be a safe and useful material to prevent pathogenic activities in the biofilm formation of S. mutans.}, } @article {pmid31100153, year = {2019}, author = {Lin, CJ and Hou, YH and Chen, YL}, title = {The histone acetyltransferase GcnE regulates conidiation and biofilm formation in Aspergillus fumigatus.}, journal = {Medical mycology}, volume = {}, number = {}, pages = {}, doi = {10.1093/mmy/myz043}, pmid = {31100153}, issn = {1460-2709}, abstract = {Histone modifications play a crucial role in eukaryotic gene regulation. The Spt-Ada-Gcn5-acetyltransferase (SAGA) complex controls histone acetylation, with Gcn5 (GcnE) acting as the acetyltransferase. In the Aspergillus species, GcnE has been shown to regulate asexual development and secondary metabolism. Apart from this, GcnE is required for pathogenicity in plant fungal pathogen A. flavus; however, the role of GcnE in the pathogenicity of human pathogenic fungus A. fumigatus is unknown. In this study, we uncovered the key roles of GcnE in A. fumigatus conidiation, stress responses, and biofilm formation. We observed that deletion of gcnE resulted in aberrant conidiation in which conidiophores displayed abnormal phialide formation. In addition, the ΔgcnE mutant grew slightly faster under limited nitrogen sources (1 mM of ammonium or nitrate) compared to the wild type. The ΔgcnE mutant exhibited increased susceptibility to cell wall-perturbing agents, H2O2 and menadione but enhanced tolerance to LiCl. Furthermore, we showed that GcnE is involved in biofilm formation, and overexpression of adherence-related genes such as somA or uge3 partially rescued biofilm formation defects in the ΔgcnE mutant background. Interestingly, GcnE was not required for virulence in a neutropenic murine model of invasive aspergillosis. These results suggest that GcnE is critical for conidiation and biofilm formation but not virulence in A. fumigatus.}, } @article {pmid31099708, year = {2019}, author = {Sato, A and Yamaguchi, T and Hamada, M and Ono, D and Sonoda, S and Oshiro, T and Nagashima, M and Kato, K and Okazumi, S and Katoh, R and Ishii, Y and Tateda, K}, title = {Morphological and Biological Characteristics of Staphylococcus aureus Biofilm Formed in the Presence of Plasma.}, journal = {Microbial drug resistance (Larchmont, N.Y.)}, volume = {25}, number = {5}, pages = {668-676}, doi = {10.1089/mdr.2019.0068}, pmid = {31099708}, issn = {1931-8448}, abstract = {Characteristics of Staphylococcus aureus infections include biofilm formation, leading to the spread of bacteria to the bloodstream causing sepsis and metastatic infections. In particular, in methicillin-resistant S. aureus (MRSA) infections, biofilm formation critically hampers treatment and causes poor prognosis. We explored the biofilm formation of MRSA in the presence or absence of plasma and compared morphological characteristics, accumulation of antibiotics, and resistance to bactericidal activity, using continuous optimizing confocal reflection microscopy. Addition of plasma significantly increased biofilm formation, which is characterized by an uneven surface and aggregation of bacteria (hereafter plasma biofilm). The flow-cell system, which enabled a continuous supply of plasma, accelerated biofilm formation in both the tested strains of MRSA (BAA1556 and N315). Accumulation of green fluorescence-labeled vancomycin was observed within 5 minutes in the plasma-free biofilm, but not in the plasma biofilm. Delay of accumulation was also observed for daptomycin in plasma biofilm. Plasma biofilm bacteria were more resistant to anti-MRSA antibiotics than plasma-free biofilm bacteria. These data demonstrate that the plasma biofilm of S. aureus is substantially different from the plasma-free biofilm. Plasma biofilm, especially in the flow-cell system, could be a clinically relevant model to analyze MRSA infections and treatment.}, } @article {pmid31099211, year = {2018}, author = {André, CB and Chan, DC and Giannini, M}, title = {Antibacterial-containing dental adhesives' effects on oral pathogens and on Streptococcus mutans biofilm: Current perspectives.}, journal = {American journal of dentistry}, volume = {31}, number = {Sp Is B}, pages = {37B-41B}, pmid = {31099211}, issn = {0894-8275}, mesh = {*Anti-Bacterial Agents/pharmacology ; *Biofilms ; *Dental Cements ; Dentin ; Dentin-Bonding Agents ; Humans ; Resin Cements ; *Streptococcus mutans/drug effects ; }, abstract = {PURPOSE: To describe the literature findings regarding commercially available antibacterial-containing dental adhesives and the futures perspectives of this field.

RESULTS: High-risk caries patients could yield benefits from restorative materials containing antibacterial properties in order to reduce the recurrent caries formation. Dental adhesives with antibacterial agents may reduce restoration replacement, as recurrent caries is still one of the major reasons for replacing a resin restoration. Literature results of three commercially available adhesives: Gluma 2Bond, Clearfil SE Protect and Peak Universal Bond, containing glutaraldehyde, MDPB and chlorhexidine, respectively indicates that Clearfil SE Protect seems to have better results against oral pathogens and on Streptococcus mutans biofilm. Besides the promising findings, clinical studies are still necessary in order to validate the clinical efficacy when exposed to a more complex environment and the long-term effect of either commercially available materials, experimental antibacterial monomers or antibacterial incorporations. As a suggestion of this article and according to the current scientific trends in this specific field, future directions should focus on restorative materials with therapeutic components targeting the virulence factors of cariogenic biofilm with minimal toxicity and side effects, and long-term action.

CLINICAL SIGNIFICANCE: Antibacterial-containing dental adhesives may have therapeutic effects, working as an additional source to reduce recurrent caries development in patients with high-risk of caries, and consequently the reduction in restoration replacements.}, } @article {pmid31099066, year = {2019}, author = {Ali, SE and Songe, MM and Skaar, I}, title = {Colorimetric assay for the in vitro evaluation of Saprolegnia biofilm inhibitors.}, journal = {Journal of fish diseases}, volume = {42}, number = {8}, pages = {1119-1124}, doi = {10.1111/jfd.13017}, pmid = {31099066}, issn = {1365-2761}, support = {238550//European Commission through the EU Marie Curie ITN project and CGIAR Research Program on Fish Agri-Food Systems (FISH). SAPRO/ ; }, abstract = {A quantitative and reproducible 96-well microtiter method that is easily adaptable for the screening of Saprolegnia biofilm inhibitors is described. As opposed to other methods previously developed for the screening of Saprolegnia inhibitors on spore germination or mycelial growth, this technique is of particular significance as it investigates potential inhibitors against surface-attached mycelial mats of Saprolegnia spp. (biofilm). In this study, we have investigated the effects of propionic acid (PPA) on reducing the viability of induced Saprolegnia biofilms using colorimetric MTS assay based on the reduction of tetrazolium salts. Viability of Saprolegnia hyphae in treated biofilms was reduced significantly following treatment with different PPA concentrations. The effect was enhanced after combining each of the tested PPA concentrations with 500 mg/L of boric acid (BA). However, the percentage of non-viable hyphae was still higher in 200 mg L-1 bronopol-treated biofilms (positive control) following 6- and 12-hr exposure. Similar results were observed using other recently described fluorescence-based assays for viability.}, } @article {pmid31098293, year = {2019}, author = {Dubois, T and Tremblay, YDN and Hamiot, A and Martin-Verstraete, I and Deschamps, J and Monot, M and Briandet, R and Dupuy, B}, title = {A microbiota-generated bile salt induces biofilm formation in Clostridium difficile.}, journal = {NPJ biofilms and microbiomes}, volume = {5}, number = {}, pages = {14}, doi = {10.1038/s41522-019-0087-4}, pmid = {31098293}, issn = {2055-5008}, abstract = {Clostridium difficile is a major cause of nosocomial infections. Bacterial persistence in the gut is responsible for infection relapse; sporulation and other unidentified mechanisms contribute to this process. Intestinal bile salts cholate and deoxycholate stimulate spore germination, while deoxycholate kills vegetative cells. Here, we report that sub-lethal concentrations of deoxycholate stimulate biofilm formation, which protects C. difficile from antimicrobial compounds. The biofilm matrix is composed of extracellular DNA and proteinaceous factors that promote biofilm stability. Transcriptomic analysis indicates that deoxycholate induces metabolic pathways and cell envelope reorganization, and represses toxin and spore production. In support of the transcriptomic analysis, we show that global metabolic regulators and an uncharacterized lipoprotein contribute to deoxycholate-induced biofilm formation. Finally, Clostridium scindens enhances biofilm formation of C. difficile by converting cholate into deoxycholate. Together, our results suggest that deoxycholate is an intestinal signal that induces C. difficile persistence and may increase the risk of relapse.}, } @article {pmid31097723, year = {2019}, author = {Passos da Silva, D and Matwichuk, ML and Townsend, DO and Reichhardt, C and Lamba, D and Wozniak, DJ and Parsek, MR}, title = {The Pseudomonas aeruginosa lectin LecB binds to the exopolysaccharide Psl and stabilizes the biofilm matrix.}, journal = {Nature communications}, volume = {10}, number = {1}, pages = {2183}, doi = {10.1038/s41467-019-10201-4}, pmid = {31097723}, issn = {2041-1723}, support = {5R01AI077628//U.S. Department of Health & Human Services | NIH | National Institute of Allergy and Infectious Diseases (NIAID)/International ; W911NF1810254//United States Department of Defense | United States Army | Army Medical Command | U.S. Army Research Institute of Environmental Medicine (United States Army Research Institute of Environmental Medicine)/International ; R01 AI134895//Division of Intramural Research, National Institute of Allergy and Infectious Diseases (Division of Intramural Research of the NIAID)/International ; }, mesh = {*Biofilms ; Intravital Microscopy ; Lectins/isolation & purification/*metabolism ; Microscopy, Confocal ; Molecular Docking Simulation ; Polysaccharides, Bacterial/*metabolism ; Pseudomonas aeruginosa/*physiology ; }, abstract = {Pseudomonas aeruginosa biofilms are composed of exopolysaccharides (EPS), exogenous DNA, and proteins that hold these communities together. P. aeruginosa produces lectins LecA and LecB, which possess affinities towards sugars found in matrix EPS and mediate adherence of P. aeruginosa to target host cells. Here, we demonstrate that LecB binds to Psl, a key matrix EPS, and this leads to increased retention of both cells and EPS in a growing biofilm. This interaction is predicted to occur between the lectin and the branched side chains present on Psl. Finally, we show that LecB coordinates Psl localization in the biofilm. This constitutes a unique function for LecB and identifies it as a matrix protein that contributes to biofilm structure through EPS interactions.}, } @article {pmid31096414, year = {2019}, author = {Oprei, A and Zlatanović, S and Mutz, M}, title = {Grazers superimpose humidity effect on stream biofilm resistance and resilience to dry-rewet stress.}, journal = {The Science of the total environment}, volume = {659}, number = {}, pages = {841-850}, doi = {10.1016/j.scitotenv.2018.12.316}, pmid = {31096414}, issn = {1879-1026}, mesh = {Animals ; *Biofilms ; *Climate Change ; *Droughts ; Feeding Behavior ; Germany ; Humidity ; Microbiota/*physiology ; Rivers/*microbiology ; Snails/*physiology ; Time Factors ; }, abstract = {Temperate low order streams increasingly experience intermittency and drying due to climate change. In comparison to well-studied Mediterranean streams, drying events in canopied temperate streams occur under higher ambient humidity which probably affects the metabolic response to drying. Previous work on drying sediments (in temperate streams) did not consider the interactions of trophic levels. We hypothesized that preservation of sediment moisture due to high humidity increases resistance to drying in temperate streambed biofilms and fast resilience of biofilm activity after flow resumption. We also expected the presence of macroinvertebrate grazers to modulate the biofilm response to dry-rewet stress. Following a two-level factorial design in 24 microcosms, we tested the effect of drying intensity (moderate and intense) and grazer presence and absence (P. antipodarum) on the activity of biofilm colonizing shallow hyporheic sediment. We measured the community respiration over a drying period of 27 days, a single rewetting event and a follow-up of three days. Grazer presence stimulated biofilm community respiration (CRmic) in the permanently wet control, but decreased biofilm resistance to desiccation (<0.2% of pre-disturbed activity), regardless of drying intensity. In the absence of grazers, higher atmospheric humidity in moderately drying microcosms resulted in maintaining a film of adhesive water and low CRmic (29% of pre-disturbed respiration) until the end of the drying period. After flow resumption, the CRmic increased within 8 h, achieving 79-83% of pre-disturbed respiration (no grazers) and 15-41% (with grazers), respectively. Results show that short dry periods in temperate streams, even under high humidity, impact the streambed biofilm community negatively. The complex response and strong effect of grazer presence indicates that experiments including interactions of trophic levels and settings mimicking environmental factors during dry-rewet stress are needed.}, } @article {pmid31096410, year = {2019}, author = {Ramírez-Vargas, CA and Arias, CA and Carvalho, P and Zhang, L and Esteve-Núñez, A and Brix, H}, title = {Electroactive biofilm-based constructed wetland (EABB-CW): A mesocosm-scale test of an innovative setup for wastewater treatment.}, journal = {The Science of the total environment}, volume = {659}, number = {}, pages = {796-806}, doi = {10.1016/j.scitotenv.2018.12.432}, pmid = {31096410}, issn = {1879-1026}, mesh = {Biodegradation, Environmental ; *Biofilms ; Coke/*analysis ; Electrodes ; Nitrogen/analysis ; Sulfur/analysis ; Waste Disposal, Fluid/*methods ; Waste Water/*analysis ; Water Pollutants, Chemical/*analysis ; *Wetlands ; }, abstract = {Constructed wetlands (CWs) performance enhancement can be done with intensification strategies. A recent strategy still in study is the coupling with Microbial Electrochemical Technologies (MET). An alternative system using electro-conductive biofilters instead of electrodes and circuits used in MET, resulted in the development of a Microbial Electrochemical-based CW (METland). This system relies on electroactive bacteria (EAB) metabolism to transfer electrons to an electro-conductive material, thus boosting substrate consumption, and diminishing electron availability for biomass build-up and methane generation. In previous studies this biofilters have shown an improvement in biodegradation rates in comparison with subsurface flow CW. However, this set-up is still in development, hence there are uncertainties regarding the dynamics involve in the removal of pollutants. Considering that, this work aimed at establishing the capacity and removal kinetics of organic matter and nutrients in an Electroactive Biofilm-Based CW (EABB-CW). Two electro-conductive materials were tested (PK-A and PK-LSN) in planted and non-planted mesocosms and compared with sand. The systems were operated in a continuous upflow mode for 32 weeks and fed with real wastewater. The electro-conductive systems reached removal efficiencies up to 88% for BOD5, 90% for COD, 46% for NH4-N, and 86% for PO4-P. Organic matter removal in electro-conductive systems was possible even at loading rates 10-fold higher than recommended for horizontal flow CWs. First-order area-based removal constants (k), calculated for organic matter and nutrients are higher than values typically reported for saturated CW and in certain cases comparable with vertical flow CW. The organic removal was correlated with electron current densities measures, as indicator of the presence of EAB. The tested EABB-CW profiles as a promising CW type for the removal of organic matter and PO4-P with margin for modifications to improve nitrogen removal. Future studies with pilot/real scale systems are proposed to validate the findings of this study.}, } @article {pmid31095299, year = {2019}, author = {Hogan, S and Kasotakis, E and Maher, S and Cavanagh, B and O'Gara, JP and Pandit, A and Keyes, TE and Devocelle, M and O'Neill, E}, title = {A novel medical device coating prevents Staphylococcus aureus biofilm formation on medical device surfaces.}, journal = {FEMS microbiology letters}, volume = {366}, number = {9}, pages = {}, doi = {10.1093/femsle/fnz107}, pmid = {31095299}, issn = {1574-6968}, abstract = {Prevention of device related infections due to Staphylococcus aureus biofilms on devices represents a significant challenge. Such infections have recently been shown to be dependent on the coagulation pathway via activation of pro-thrombin and fibrin production. Three direct-thrombin inhibitors, argatroban, hirudin and dabigatran, were examined to determine their effect on preventing S. aureus biofilm on plastic biochip surfaces under shear stress using an in vivo relevant model of infection. Surface functionalization of polyurethane discs via dityrosine covalent crosslinking with hirudin was performed and changes in bacterial density and microscopic appearances determined. The three direct-thrombin inhibitors prevented S. aureus biofilm formation on plasma-coated surfaces treated with these agents. Coating of polyurethane with one of these agents, hirudin, significantly inhibited biofilm formation on the modified surface. These findings reveal the exciting potential for coating biomaterial surfaces with direct thrombin inhibitors to prevent staphylococcal binding and subsequent device-related infections.}, } @article {pmid31093442, year = {2019}, author = {Reda, FM}, title = {Antibacterial and anti-adhesive efficiency of Pediococcus acidilactici against foodborne biofilm producer Bacillus cereus attached on different food processing surfaces.}, journal = {Food science and biotechnology}, volume = {28}, number = {3}, pages = {841-850}, doi = {10.1007/s10068-018-0518-7}, pmid = {31093442}, issn = {2092-6456}, abstract = {This study aimed to assess the biofilm formation by Bacillus cereus on two novel surfaces namely: aluminum and cold steel in comparison study with stainless steel and polystyrene. Also, it aimed to study the inhibitory effect of a new strain Pediococcus acidilactici against biofilm formation by B. cereus grown on these surfaces. In this study, B. cereus M50 isolated from milky machine surface was selected as the highest biofilm producer. The number of M50 cells adhered to aluminum and stainless steel surfaces were more than that adhered to polystyrene and cold steel, respectively. The antimicrobial, anti-adhesive and SEM studies revealed that the P. acidilactici P12 culture and its cell free filtrate showed a significant potential inhibition of biofilm formation of M50 on all tested surfaces under different conditions. These results demonstrated that P. acidilactici strain are considered a new biotreatment for biofilm destruction of food borne pathogens, food biopreservation and food safety.}, } @article {pmid31091746, year = {2019}, author = {Yang, CH and Su, PW and Moi, SH and Chuang, LY}, title = {Biofilm Formation in Acinetobacter Baumannii: Genotype-Phenotype Correlation.}, journal = {Molecules (Basel, Switzerland)}, volume = {24}, number = {10}, pages = {}, doi = {10.3390/molecules24101849}, pmid = {31091746}, issn = {1420-3049}, support = {106-2221-E-214-043, 107-2221-E-214-013 and 106-2221-E-151-009-MY2//Ministry of Science and Technology/ ; }, abstract = {Strains of Acinetobacter baumannii are commensal and opportunistic pathogens that have emerged as problematic hospital pathogens due to its biofilm formation ability and multiple antibiotic resistances. The biofilm-associated pathogens usually exhibit dramatically decreased susceptibility to antibiotics. This study was aimed to investigate the correlation of biofilm-forming ability, antibiotic resistance and biofilm-related genes of 154 A. baumannii isolates which were collected from a teaching hospital in Taiwan. Biofilm-forming ability of the isolates was evaluated by crystal violet staining and observed by scanning electron microscopy. Antibiotic susceptibility was determined by disc diffusion method and minimum inhibitory concentration; the biofilm-related genes were screened by polymerase chain reaction. Results showed that among the 154 tested isolates, 15.6% of the clinical isolates were weak biofilm producers, while 32.5% and 45.4% of them possessed moderate and strong biofilm formation ability, respectively. The experimental results revealed that the multiple drug resistant isolates usually provided a higher biofilm formation. The prevalence of biofilm related genes including bap, blaPER-1, csuE and ompA among the isolated strains was 79.2%, 38.3%, 91.6%, and 68.8%, respectively. The results indicated that the antibiotic resistance, the formation of biofilm and the related genes were significantly correlated. The results of this study can effectively help to understand the antibiotic resistant mechanism and provides the valuable information to the screening, identification, diagnosis, treatment and control of clinical antibiotic-resistant pathogens.}, } @article {pmid31088936, year = {2019}, author = {Tobudic, S and Kern, S and Kussmann, M and Forstner, C and Burgmann, H}, title = {Effect of Peritoneal Dialysis Fluids on Activity of Teicoplanin Against Methicillin-Resistant Staphylococcus aureus Biofilm.}, journal = {Peritoneal dialysis international : journal of the International Society for Peritoneal Dialysis}, volume = {39}, number = {3}, pages = {293-294}, doi = {10.3747/pdi.2018.00168}, pmid = {31088936}, issn = {1718-4304}, } @article {pmid31088182, year = {2019}, author = {Čabarkapa, I and Čolović, R and Đuragić, O and Popović, S and Kokić, B and Milanov, D and Pezo, L}, title = {Anti-biofilm activities of essential oils rich in carvacrol and thymol against Salmonella Enteritidis.}, journal = {Biofouling}, volume = {35}, number = {3}, pages = {361-375}, doi = {10.1080/08927014.2019.1610169}, pmid = {31088182}, issn = {1029-2454}, abstract = {The aim of the present study was to determine the bioactive compounds in four essential oils (EO's) from Origanum heracleoticum, Origanum vulgare, Thymus vulgaris and Thymus serpyllum and to assess their antimicrobial and anti-biofilm activity against Salmonella Enteritidis. Strains were previously characterized depending on the expression of the extracellular matrix components cellulose and curli fimbriae as rdar (red, dry and rough) and bdar morphotype (brown, dry and rough). This study revealed that the EO's and EOC's (carvacrol and thymol) investigated showed inhibition of biofilm formation at sub-minimum inhibitory concentration. Comparing the efficacy of EO's and EOC's in the inhibition of biofilm formation between the strains with different morphotype (rdar and bdar) did not show a statistically significant difference. Results related to the effectiveness of EO's and EOC's (the essential oil components, carvacrol and thymol) on eradication of preformed 48 h old biofilms indicated that biofilm reduction occurred in a dose-dependent manner over time.}, } @article {pmid31088179, year = {2019}, author = {Bernard, C and Lemoine, V and Hoogenkamp, MA and Girardot, M and Krom, BP and Imbert, C}, title = {Candida albicans enhances initial biofilm growth of Cutibacterium acnes under aerobic conditions.}, journal = {Biofouling}, volume = {35}, number = {3}, pages = {350-360}, doi = {10.1080/08927014.2019.1608966}, pmid = {31088179}, issn = {1029-2454}, abstract = {Candida albicans and Cutibacterium acnes are opportunistic pathogens that co-colonize the human body. They are involved in biofilm-related infections of implanted medical devices. The objective of this study was to evaluate the ability of these species to interact and form polymicrobial biofilms. SEM imaging and adhesion assays showed that C. acnes adhesion to C. albicans did not have a preference for a specific morphological state of C. albicans; bacteria adhered to both hyphal and yeast forms of C. albicans. C. albicans did not influence growth of C. acnes under anaerobic growth conditions, however under aerobic growth condition, C. albicans enhanced early C. acnes biofilm formation. This favorable impact of C. albicans was not mediated by secreted compounds accumulating in the medium, but required the presence of metabolically active C. albicans. The ability of these microorganisms to interact together could modulate the physiopathology of infections.}, } @article {pmid31087992, year = {2019}, author = {Fu, KM and Liao, MH and Zhou, HT and Fu, C and Jiang, S and Qiu, FG and Cao, XQ}, title = {[Operation Characteristics of the Biofilm CANON Reactor During the Temperature Reduction Process].}, journal = {Huan jing ke xue= Huanjing kexue}, volume = {40}, number = {3}, pages = {1412-1418}, doi = {10.13227/j.hjkx.201808184}, pmid = {31087992}, issn = {0250-3301}, abstract = {The focus of this paper, was low temperature, high ammonia nitrogen wastewater. The operation characteristics of the biofilm CANON process during the temperature reduction process were determined, by continuously adjusting different operating conditions. The aim was to explore the methods needed for the CANON process to obtain stable shortcut nitrification and a good nitrogen removal effect, when the influent NH4+-N concentration is high and the temperature low. The results showed that, ① compared with the biofilm CANON reactor temperature changing from medium to low temperature directly (30℃±1℃→19℃), it was more conducive to adapt the nitrogen-removing bacteria to the low-temperature environment, while the temperature was gradually lowered. Moreover, the extent of each reduction should be minimized. Besides, the operating conditions should be adjusted to ensure the nitrogen removal effect. ② The temperature was gradually reduced to about 19℃ after 25 d, and then decreased to about 15℃ after another 18 d. The NH4+-N and TN removal rates could be respectively stable at 90% and 70% over a long period of time. The TN removal rate and removal load could still reach 72.52% and 0.78 kg·(m3·d)-1, respectively, even when the temperature dropped to 12℃. ③ When adapting biological CANON sludge during the temperature reduction process, shortcut nitrification should be given priority. A stable shortcut nitrification effect should be obtained by maintaining a certain concentration of residual NH4+-N, and by strictly controlling the DO concentration to restrain NOB activity.}, } @article {pmid31087603, year = {2019}, author = {Zhu, L and Gong, T and Wood, TL and Yamasaki, R and Wood, TK}, title = {σ54 -Dependent regulator DVU2956 switches Desulfovibrio vulgaris from biofilm formation to planktonic growth and regulates hydrogen sulfide production.}, journal = {Environmental microbiology}, volume = {}, number = {}, pages = {}, doi = {10.1111/1462-2920.14679}, pmid = {31087603}, issn = {1462-2920}, support = {//Pennsylvania State University/ ; //Dow Chemical Company/ ; }, abstract = {Microbiologically influenced corrosion causes $100 billion in damage per year, and biofilms formed by sulfate-reducing bacteria (SRB) are the major culprit. However, little is known about the regulation of SRB biofilm formation. Using Desulfovibrio vulgaris as a model SRB organism, we compared the transcriptomes of biofilm and planktonic cells and identified that the gene for σ54 -dependent regulator DVU2956 is repressed in biofilms. Utilizing a novel promoter that is primarily transcribed in biofilms (Pdvu0304), we found production of DVU2956 inhibits biofilm formation by 70%. Corroborating this result, deleting dvu2956 increased biofilm formation, and this biofilm phenotype could be complemented. By producing proteins in biofilms from genes controlled by DVU2956 (dvu2960 and dvu2962), biofilm formation was inhibited almost completely. A second round of RNA-seq for the production of DVU2956 revealed DVU2956 influences electron transport via an Hmc complex (high-molecular-weight cytochrome c encoded by dvu0531-dvu0536) and the Fe-only hydrogenase (encoded by dvu1769, hydA and dvu1770, hydB) to control H2 S production. Corroborating these results, producing DVU2956 in biofilms decreased H2 S production by half, deleting dvu2956 increased H2 S production by 131 ± 5%, and producing DVU2956 in the dvu2956 strain reduced H2 S production. Therefore, DVU2956 maintains SRB in the planktonic state and reduces H2 S formation.}, } @article {pmid31087370, year = {2019}, author = {Banerjee, A and Bardhan, R and Chowdhury, M and Joardar, SN and Isore, DP and Batabyal, K and Dey, S and Sar, TK and Bandyopadhyay, S and Dutta, TK and Samanta, I}, title = {Characterization of beta-lactamase and biofilm producing Enterobacteriaceae isolated from organized and backyard farm ducks.}, journal = {Letters in applied microbiology}, volume = {69}, number = {2}, pages = {110-115}, doi = {10.1111/lam.13170}, pmid = {31087370}, issn = {1472-765X}, support = {BT/PR16149/NER/95/85/2015//Department of Biotechnology, Government of India/ ; 1G-25/2016//Department of Science & Technology and Biotechnology, Government of West Bengal/ ; }, abstract = {This study was undertaken to detect the occurrence of beta-lactamase and biofilm producing Enterobacteriaceae in healthy ducks. A total 202 cloacal swabs were collected from ducks kept in organized (n = 92) and backyard (n = 110) farms in West Bengal (India). The ducks had no history of antibiotic intake. Among the 87 phenotypically beta-lactamase producing Escherichia coli, 19 (17·43%), 6 (5·05%) and 15 (13·76%) isolates possessed blaTEM , blaSHV and blaCTX-M respectively. Whereas, 5 (38·46%) Salmonella isolates were found to harbour blaCTX-M . In K. pneumoniae 10 (33·33%), 3 (13·33%), 4 (13·33%) isolates possessed blaTEM , blaSHV and blaCTX-M respectively. The sequences of selected PCR products were found 98% cognate with blaCTX-M-9, blaSHV-12 and blaTEM-1 . Beta-lactamase producing E. coli isolates belonged to 14 different serogroups such as O1, O2, O3, O5, O7, O8, O35, O83, O84, O88, O119, O128, O145 and O157. Moreover, 87 E. coli (79·82%), six Samonella (46·15%) and 13 K. pneumoniae (43·33%) isolates were detected as AmpC producers possessing blaAmpC . Majority of E. coli (46·79%), Salmonella (46·15%) and K. pneumoniae (70%) isolates were detected as biofilm producers and possessed the associated genes (csgA, sdiA, rcsA, rpoS). Significantly higher occurrence of beta-lactamase and biofilm producing Enterobacteriaceae isolates was detected in backyard ducks than organized farms. SIGNIFICANCE AND IMPACT OF THE STUDY: Consumption of antibiotic through feed or during therapy is considered as potential reason for generation of antimicrobial resistant bacteria in birds. This study provides valuable evidence that exposure to contaminated environment may be an additional source for generation of antimicrobial resistant bacteria in backyard ducks. The backyard ducks are reared by marginal farmers in India who cannot offer antibiotics to them either through feed or during therapy due to high cost. The study also reveals a significant correlation between biofilm formation and possession of antimicrobial resistance genes in the bacterial isolates from the ducks.}, } @article {pmid31085909, year = {2019}, author = {Dos Santos, DMS and Pires, JG and Silva, AB and Salomão, PMA and Buzalaf, MAR and Magalhães, AC}, title = {Protective Effect of 4% Titanium Tetrafluoride Varnish on Dentin Demineralization Using a Microcosm Biofilm Model.}, journal = {Caries research}, volume = {53}, number = {5}, pages = {576-583}, doi = {10.1159/000499317}, pmid = {31085909}, issn = {1421-976X}, abstract = {This study evaluated the effect of titanium tetrafluoride (TiF4) varnish on the development of dentin carious lesions. Bovine root dentin samples were treated for 6 h with: (A) 4% TiF4 varnish (2.45% F); (B) 5.42% sodium fluoride (NaF) varnish (2.45% F); (C) 2% chlorhexidine (CHX) gel - positive control; (D) placebo varnish; or (E) untreated - negative control (n = 4 × biological triplicate, n = 12). Treated dentin samples were exposed to human saliva mixed with McBain saliva (1:50) for the first 8 h in 24-well plates. Thereafter, the medium was removed, and McBain saliva containing 0.2% sucrose was applied for 16 h. From days 2 to 5, McBain saliva with sucrose was replaced daily (37°C, 5% CO2). The demineralization was measured using transverse microradiography, while the effect on biofilm was analyzed using viability, extracellular polysaccharide (EPS), and lactic acid production assays. The data were statistically analyzed (p < 0.05). All treatments (fluorides and CHX) significantly reduced the biofilm viability compared to placebo varnish and negative control. However, none of them was able to reduce the colony-forming unit counting for total microorganism, total streptococci, and Streptococcus mutans. NaF significantly reduced the number of Lactobacillus sp. compared to negative control. No effect was seen on lactic acid production neither on EPS synthesis, except that CHX significantly reduced the amount of insoluble EPS. Both fluorides were able to reduce dentin demineralization compared to placebo varnish and negative control; TiF4 had a better effect in reducing mineral loss and lesion depth than NaF. Therefore, TiF4 varnish has the best protective effect on dentin carious lesion formation using this model.}, } @article {pmid31085695, year = {2019}, author = {Matysik, A and Kline, KA}, title = {Streptococcus pyogenes capsule promotes microcolony-independent biofilm formation.}, journal = {Journal of bacteriology}, volume = {}, number = {}, pages = {}, doi = {10.1128/JB.00052-19}, pmid = {31085695}, issn = {1098-5530}, abstract = {Biofilms play an important role in the pathogenesis of Group A Streptococcus (GAS), a gram-positive pathogen responsible for a wide range infections and significant public health impact. Although most GAS serotypes are able to form biofilms, there is large heterogeneity between individual strains in biofilm formation, as measured by standard crystal violet assays. It is generally accepted that biofilm formation includes initial adhesion of bacterial cells to a surface, followed by microcolony formation, biofilm maturation, and extensive production of extracellular matrix that links together proliferating cells and provides a scaffold for the three-dimensional biofilm structure. However, our studies show that for GAS strain JS95, microcolony formation is not an essential step in static biofilm formation, and instead, biofilm can be effectively formed from slow-growing or non-replicating late exponential or early stationary planktonic cells, via sedimentation and fixation of GAS chains into biofilms. In addition, we show that the GAS capsule specifically contributes to the alternative, sedimentation-initiated biofilms. Microcolony-independent, sedimentation biofilms are similar in morphology and 3-D structure to biofilms initiated by actively dividing planktonic bacteria. We conclude that GAS can form biofilms by an alternate, non-canonical mechanism that does not require transition from microcolony formation to biofilm maturation, and which may be obscured by biofilm phenotypes that arise via the classical biofilm maturation processes.IMPORTANCEThe static biofilm assay is a common tool for easy biomass quantification of biofilm forming bacteria. However, S. pyogenes biofilm formation as measured by the static assay is strain dependent and yields heterogeneous results for different strains of the same serotype. In this study, we show that two independent mechanisms, for which the protective capsule contributes opposing functions, may contribute to static biofilm formation. We propose that separation of these mechanisms for biofilm formation might uncover previously unappreciated biofilm phenotypes that may otherwise be masked in the classic static assay.}, } @article {pmid31085409, year = {2019}, author = {Wan, D and Li, Q and Chen, J and Niu, Z and Liu, Y and Li, H and Xiao, S}, title = {Simultaneous bio-electrochemical reduction of perchlorate and electro-disinfection in a novel Moving-Bed Biofilm Reactor (MBBR) based on proton-exchange membrane electrolysis.}, journal = {The Science of the total environment}, volume = {679}, number = {}, pages = {288-297}, doi = {10.1016/j.scitotenv.2019.04.441}, pmid = {31085409}, issn = {1879-1026}, abstract = {A novel Moving-Bed Biofilm Reactor (MBBR), based on proton-exchange membrane electrolysis, was developed and tested for perchlorate transformation. The bacteria growing on the carrier in the cathode chamber could use in situ-generated hydrogen to reduce perchlorate to chloride via electrolysis; the resulting chloride ions and chloride ions in raw water were then oxidized into chlorine by anode reaction to disinfect the final effluent and improve water quality. For a ClO4- concentration of 10.00 ± 0.08 mg/L in the influent, at hydraulic retention times (HRTs) of 4.0, 2.0, and 1.5 h, the optimal applied currents (OACs) were 130, 240, and 270 mA, with a corresponding removal efficiencies of 99.90 ± 0.21, 96.70 ± 0.36, and 78.50 ± 0.24%, respectively. Active chlorine concentration was in the range of 0.063-0.096 mg/L, contributing to simultaneous electro-disinfection. Along the water flow direction, OH- generated by the cathode could be neutralized in the anode chamber; thus, the final effluent pH was kept a balance with the influent pH. Proteobacteria, Bacteroidetes, and Firmicutes were the dominant bacteria in the MBBR. The maximum value of current efficiency (13.32 ± 0.69%) was obtained at 100 mA and an HRT of 4.0 h, which was in accordance with the abundance of Thauera.}, } @article {pmid31085405, year = {2019}, author = {Wall, G and Montelongo-Jauregui, D and Vidal Bonifacio, B and Lopez-Ribot, JL and Uppuluri, P}, title = {Candida albicans biofilm growth and dispersal: contributions to pathogenesis.}, journal = {Current opinion in microbiology}, volume = {52}, number = {}, pages = {1-6}, doi = {10.1016/j.mib.2019.04.001}, pmid = {31085405}, issn = {1879-0364}, support = {R01 AI119554/AI/NIAID NIH HHS/United States ; }, abstract = {The fungal species Candida albicans is most frequently associated with biofilm formation in immune-compromised and medically compromised patients, and it is now firmly established that biofilm formation represents a major virulence factor during candidiasis. A growing body of evidence has demonstrated that C. albicans biofilm development is a highly regulated and coordinated process, where adhesive interactions, morphogenetic conversions, and consortial behavior play significant roles. Cells within the biofilms are protected from environmental stresses including host immune defenses and antifungal treatment, which carries important clinical consequences for the treatment of biofilm-associated infections. Dispersal of cells from biofilms represents one of the hallmarks of the biofilm life-style, and in the case of C. albicans dispersed cells are responsible for candidemia and dissemination leading to the establishment of invasive disease.}, } @article {pmid31085344, year = {2019}, author = {Girish, VM and Liang, H and Aguilan, JT and Nosanchuk, JD and Friedman, JM and Nacharaju, P}, title = {Anti-biofilm activity of garlic extract loaded nanoparticles.}, journal = {Nanomedicine : nanotechnology, biology, and medicine}, volume = {20}, number = {}, pages = {102009}, doi = {10.1016/j.nano.2019.04.012}, pmid = {31085344}, issn = {1549-9642}, abstract = {The emergence and widespread distribution of multi-drug resistant bacteria are considered as a major public health concern. The inabilities to curb severe infections due to antibiotic resistance have increased healthcare costs as well as patient morbidity and mortality. Bacterial biofilms formed by drug-resistant bacteria add additional challenges to treatment. This study describes a solgel based nanoparticle system loaded with garlic extract (GE-np) that exhibits: i) slow and sustained release of garlic components; ii) stabilization of the active components; and iii) significant enhancement of antimicrobial and antibiofilm activity relative to the free garlic extract. Also, GE-np were efficient in penetrating and disrupting the well-established methicillin-resistant Staphylococcus aureus (MRSA) biofilms. Overall, the study suggests that GE-np might be a promising candidate for the treatment of chronic infections due to biofilm forming drug-resistant bacteria.}, } @article {pmid31083437, year = {2019}, author = {Nagel, C and Machulla, A and Zahn, S and Soppa, J}, title = {Several One-Domain Zinc Finger µ-Proteins of Haloferax Volcanii Are Important for Stress Adaptation, Biofilm Formation, and Swarming.}, journal = {Genes}, volume = {10}, number = {5}, pages = {}, doi = {10.3390/genes10050361}, pmid = {31083437}, issn = {2073-4425}, abstract = {Zinc finger domains are highly structured and can mediate interactions to DNA, RNA, proteins, lipids, and small molecules. Accordingly, zinc finger proteins are very versatile and involved in many biological functions. Eukaryotes contain a wealth of zinc finger proteins, but zinc finger proteins have also been found in archaea and bacteria. Large zinc finger proteins have been well studied, however, in stark contrast, single domain zinc finger µ-proteins of less than 70 amino acids have not been studied at all, with one single exception. Therefore, 16 zinc finger µ-proteins of the haloarchaeon Haloferax volcanii were chosen and in frame deletion mutants of the cognate genes were generated. The phenotypes of mutants and wild-type were compared under eight different conditions, which were chosen to represent various pathways and involve many genes. None of the mutants differed from the wild-type under optimal or near-optimal conditions. However, 12 of the 16 mutants exhibited a phenotypic difference under at least one of the four following conditions: Growth in synthetic medium with glycerol, growth in the presence of bile acids, biofilm formation, and swarming. In total, 16 loss of function and 11 gain of function phenotypes were observed. Five mutants indicated counter-regulation of a sessile versus a motile life style in H. volcanii. In conclusion, the generation and analysis of a set of deletion mutants demonstrated the high importance of zinc finger µ-proteins for various biological functions, and it will be the basis for future mechanistic insight.}, } @article {pmid31083366, year = {2019}, author = {Foster, LL and Yusa, SI and Kuroda, K}, title = {Solution-Mediated Modulation of Pseudomonas aeruginosa Biofilm Formation by a Cationic Synthetic Polymer.}, journal = {Antibiotics (Basel, Switzerland)}, volume = {8}, number = {2}, pages = {}, doi = {10.3390/antibiotics8020061}, pmid = {31083366}, issn = {2079-6382}, support = {U01DE023771//National Institutes of Health/ ; DGE-1315231//National Science Graduate Research Fellowship/ ; }, abstract = {Bacterial biofilms and their associated infections are a continuing problem in the healthcare community. Previous approaches utilizing anti-biofilm coatings suffer from short lifetimes, and their applications are limited to surfaces. In this research, we explored a new approach to biofilm prevention based on the hypothesis that changing planktonic bacteria behavior to result in sub-optimal biofilm formation. The behavior of planktonic Pseudomonas aeruginosa exposed to a cationic polymer was characterized for changes in growth behavior and aggregation behavior, and linked to resulting P. aeruginosa biofilm formation, biomass, viability, and metabolic activity. The incubation of P. aeruginosa planktonic bacteria with a cationic polymer resulted in the aggregation of planktonic bacteria, and a reduction in biofilm development. We propose that cationic polymers may sequester planktonic bacteria away from surfaces, thereby preventing their attachment and suppressing biofilm formation.}, } @article {pmid31082673, year = {2019}, author = {Guo, X and Li, B and Zhao, R and Zhang, J and Lin, L and Zhang, G and Li, RH and Liu, J and Li, P and Li, Y and Li, XY}, title = {Performance and bacterial community of moving bed biofilm reactors with various biocarriers treating primary wastewater effluent with a low organic strength and low C/N ratio.}, journal = {Bioresource technology}, volume = {287}, number = {}, pages = {121424}, doi = {10.1016/j.biortech.2019.121424}, pmid = {31082673}, issn = {1873-2976}, abstract = {A laboratory-scale sequencing batch reactor (SBR) and two moving bed biofilm reactors (MBBRs) with different types of biocarriers were operated to treat the effluent of chemically enhanced primary sedimentation (CEPS). Due to the low organic strength and low carbon/nitrogen ratio of the CEPS effluent, COD and NH4+-N were effectively removed by the MBBRs but not by the SBR. Of the two MBBRs, MBBR2 filled with LEVAPOR biocarrier cubes performed even better than MBBR1 filled with K3 polystyrene biocarriers. The continuous decline of the sludge concentration in the SBR and the high and stable biomass content in MBBR2 contributed to their performances. High-throughput sequencing analysis showed that the reactors had selective effects on the bacterial community structure. Principal coordinate analysis indicated the different dynamic successions in the three reactors. Network analysis showed different community composition and diversity that were highly suggestive of different bacterial interactions among the three bioreactors.}, } @article {pmid31081821, year = {2019}, author = {Panariello, BHD and Garcia, BA and Duarte, S}, title = {Daily Phototherapy with Red Light to Regulate Candida albicans Biofilm Growth.}, journal = {Journal of visualized experiments : JoVE}, volume = {}, number = {146}, pages = {}, doi = {10.3791/59326}, pmid = {31081821}, issn = {1940-087X}, abstract = {Here, we present a protocol to assess the outcomes of per diem red light treatment on the growth of Candida albicans biofilm. To increase the planktonic growth of C. albicans SN425, the inoculums grew on Yeast Nitrogen Base media. For biofilm formation, RPMI 1640 media, which have high concentrations of amino acids, were applied to help biofilm growth. Biofilms of 48 h were treated twice a day for a period of 1 min with a non-coherent light device (red light; wavelength = 635 nm; energy density = 87.6 J·cm-2). As a positive control (PC), 0.12% chlorhexidine (CHX) was applied, and as a negative control (NC), 0.89% NaCl was applied to the biofilms. Colony forming units (CFU), dry-weight, soluble and insoluble exopolysaccharides were quantified after treatments. Briefly, the protocol presented here is simple, reproducible and provides answers regarding viability, dry-weight and extracellular polysaccharide amounts after red light treatment.}, } @article {pmid31080568, year = {2019}, author = {Mai, HN and Hong, SH and Kim, SH and Lee, DH}, title = {Effects of different finishing/polishing protocols and systems for monolithic zirconia on surface topography, phase transformation, and biofilm formation.}, journal = {The journal of advanced prosthodontics}, volume = {11}, number = {2}, pages = {81-87}, doi = {10.4047/jap.2019.11.2.81}, pmid = {31080568}, issn = {2005-7806}, abstract = {PURPOSE: The purpose of this study was to evaluate the effects of various protocols and systems for finishing and polishing monolithic zirconia on surface topography, phase transformation, and bacterial adhesion.

MATERIALS AND METHODS: Three hundred monolithic zirconia specimens were fabricated and then treated with three finishing and polishing systems (Jota [JO], Meisinger [ME], and Edenta [ED]) using four surface treatment protocols: coarse finishing alone (C); coarse finishing and medium polishing (CM); coarse finishing and fine polishing (CF); and coarse finishing, medium polishing, and fine polishing (CMF). Surface roughness, crystal phase transformation, and bacterial adhesion were evaluated using atomic force microscopy, X-ray diffraction, and streptococcal biofilm formation assay, respectively. One-way and two-way analysis of variance with Tukey post hoc tests were used to analyze the results (α=.05).

RESULTS: In this study, the surface treatment protocols and systems had significant effects on the resulting roughness. The CMF protocol produced the lowest roughness values, followed by CM and CF. Use of the JO system produced the lowest roughness values and the smallest biofilm mass, while the ME system produced the smallest partial transformation ratio. The ED group exhibited the highest roughness values, biofilm mass, and partial transformation ratio.

CONCLUSION: Stepwise surface treatment of monolithic zirconia, combined with careful polishing system selection, is essential to obtaining optimal microstructural and biological surface results.}, } @article {pmid31079197, year = {2019}, author = {Pillot, G and Davidson, S and Auria, R and Combet-Blanc, Y and Godfroy, A and Liebgott, PP}, title = {Production of Current by Syntrophy Between Exoelectrogenic and Fermentative Hyperthermophilic Microorganisms in Heterotrophic Biofilm from a Deep-Sea Hydrothermal Chimney.}, journal = {Microbial ecology}, volume = {}, number = {}, pages = {}, doi = {10.1007/s00248-019-01381-z}, pmid = {31079197}, issn = {1432-184X}, support = {PEPS-ExoMod 2016//Institut National des Sciences de l'Univers, Centre National de la Recherche Scientifique/ ; 1166-39417//European Regional Development Fund/ ; }, abstract = {To study the role of exoelectrogens within the trophic network of deep-sea hydrothermal vents, we performed successive subcultures of a hyperthermophilic community from a hydrothermal chimney sample on a mix of electron donors in a microbial fuel cell system. Electrode (the electron acceptor) was swapped every week to enable fresh development from spent media as inoculum. The MFC at 80 °C yielded maximum current production increasing from 159 to 247 mA m-2 over the subcultures. The experiments demonstrated direct production of electric current from acetate, pyruvate, and H2 and indirect production from yeast extract and peptone through the production of H2 and acetate from fermentation. The microorganisms found in on-electrode communities were mainly affiliated to exoelectrogenic Archaeoglobales and Thermococcales species, whereas in liquid media, the communities were mainly affiliated to fermentative Bacillales and Thermococcales species. The work shows interactions between fermentative microorganisms degrading complex organic matter into fermentation products that are then used by exoelectrogenic microorganisms oxidizing these reduced compounds while respiring on a conductive support. The results confirmed that with carbon cycling, the syntrophic relations between fermentative microorganisms and exoelectrogens could enable some microbes to survive as biofilm in extremely unstable conditions. Graphical Abstract Schematic representation of cross-feeding between fermentative and exoelectrogenic microbes on the surface of the conductive support. B, Bacillus/Geobacillus spp.; Tc, Thermococcales; Gg, Geoglobus spp.; Py, pyruvate; Ac, acetate.}, } @article {pmid31079168, year = {2019}, author = {Edel, M and Horn, H and Gescher, J}, title = {Biofilm systems as tools in biotechnological production.}, journal = {Applied microbiology and biotechnology}, volume = {103}, number = {13}, pages = {5095-5103}, doi = {10.1007/s00253-019-09869-x}, pmid = {31079168}, issn = {1432-0614}, support = {DFG HO 1910/16-1//Deutsche Forschungsgemeinschaft/ ; }, abstract = {The literature provides more and more examples of research projects that develop novel production processes based on microorganisms organized in the form of biofilms. Biofilms are aggregates of microorganisms that are attached to interfaces. These viscoelastic aggregates of cells are held together and are embedded in a matrix consisting of multiple carbohydrate polymers as well as proteins. Biofilms are characterized by a very high cell density and by a natural retentostat behavior. Both factors can contribute to high productivities and a facilitated separation of the desired end-product from the catalytic biomass. Within the biofilm matrix, stable gradients of substrates and products form, which can lead to a differentiation and adaptation of the microorganisms' physiology to the specific process conditions. Moreover, growth in a biofilm state is often accompanied by a higher resistance and resilience towards toxic or growth inhibiting substances and factors. In this short review, we summarize how biofilms can be studied and what most promising niches for their application can be. Moreover, we highlight future research directions that will accelerate the advent of productive biofilms in biology-based production processes.}, } @article {pmid31078982, year = {2019}, author = {Su, JF and Zhang, YM and Liang, DH and Wang, JX and Wang, Z and Li, M}, title = {Performance and microbial community of an immobilized biofilm reactor (IBR) for Mn(II)-based autotrophic and mixotrophic denitrification.}, journal = {Bioresource technology}, volume = {286}, number = {}, pages = {121407}, doi = {10.1016/j.biortech.2019.121407}, pmid = {31078982}, issn = {1873-2976}, abstract = {An immobilized biofilm reactor (IBR) was established to treat nitrate using different electron donors. A novel material, Fe3O4@Cu/PVA, was synthesized as an adsorbent and bacterial immobilized carrier in the reactor. The optimum condition of nitrate removal were pH 7.0, hydraulic retention time (HRT) of 10 h under autotrophic and mixotrophic conditions. Strain H-117 in the mixotrophic reactor had better adaptability to changes in the initial pH. The metabolism in the mixotrophic reactor was more vigorous than that in autotrophic reactor. The microbial communities and structures were evaluated to determine the nitrate removal mechanisms in this system. Microbial analyses demonstrated that different electron donor could influence the bacterial abundance and species in the IBR system. Proteobacteria was the most dominant phylum in all IBRs and accounted for more than 50% of the total phyla. Pseudomonas and Rhizobium were the dominant contributor to the effective removal of nitrate in the IBRs.}, } @article {pmid31078886, year = {2019}, author = {Ahmed, W and Tian, X and Delatolla, R}, title = {Nitrifying moving bed biofilm reactor: Performance at low temperatures and response to cold-shock.}, journal = {Chemosphere}, volume = {229}, number = {}, pages = {295-302}, doi = {10.1016/j.chemosphere.2019.04.176}, pmid = {31078886}, issn = {1879-1298}, abstract = {In contrast with suspended growth systems, attached growth technologies such as the moving bed biofilm reactors (MBBR) have recently demonstrated significant nitrification rates at temperatures as low as 1 °C. The purpose of this study was to investigate the performance of the nitrifying MBBR system at elevated municipal concentrations with exposures to low temperatures and cold-shock conditions down to 1 °C using an enhanced temperature-controlled room. A removal rate of 98.44 ± 4.69 gN·m-3·d-1 was identified as the intrinsic rate of nitrifying MBBR systems at 1 °C and was proposed as the conservative rate for low temperature design. A temperature threshold at which attached growth nitrification displayed a significant decrease in kinetics was identified between 2 °C and 4 °C. Arrhenius correction coefficients of 1.086 and 1.09 previously applied for low temperature nitrifying MBBR systems resulted in conservative modeled removal rates on average 21% lower than the measured rates. Thus, an Arrhenius correction coefficient of 1.049 is proposed between the temperatures of 10 °C and 4 °C and another correction coefficient of 1.149 to model rates at 1 °C. For the transition from 4 °C to 1 °C, the adjustment of a previously reported Theta model is proposed in this study to account for exposure time at low temperatures; with the modified model showing strong correlation with measured rates (R2 = 0.88). Finally, a comparison of nitrification kinetics between MBBR systems acclimatized to 1 °C and systems that are cold-shocked to 1 °C demonstrated that shocked removal rates are 21% lower.}, } @article {pmid31077449, year = {2019}, author = {Bermejo, P and Sánchez, MC and Llama-Palacios, A and Figuero, E and Herrera, D and Sanz Alonso, M}, title = {Biofilm formation on dental implants with different surface micro-topography: An in vitro study.}, journal = {Clinical oral implants research}, volume = {}, number = {}, pages = {}, doi = {10.1111/clr.13455}, pmid = {31077449}, issn = {1600-0501}, abstract = {OBJECTIVES: To compare biofilm formation on whole dental titanium implants with different surface micro-topography.

METHODS: A multispecies in vitro biofilm model consisting of initial (Streptococcus oralis and Actinomyces naeslundii), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late colonizers (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans) was grown for 96 hr on sterile titanium dental implants with either minimal (Sa : 0.5-1.0 mm) or moderate-roughness titanium surfaces (Sa : 1.1-2.0 mm). The resulting biofilms were studied with Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscope. Concentrations (colony-forming units per mL [CFU/ml]) of each bacterium were measured by quantitative Polymerase Chain Reaction (qPCR) and compared by Student t tests.

RESULTS: A biofilm, located mainly at the peak and lateral areas of the implant threads, was observed on both implant surfaces, with a greater biomass and a greater live/dead ratio in moderate- compared to minimal-roughness surface implants. Statistically significant higher values of total bacteria (mean difference = 2.61 × 107 CFU/ml; 95% confidence interval - CI [1.91 × 106 ; 5.02 × 107 ]; p = 0.036), F. Nucleatum (mean difference = 4.43 × 106 CFU/ml; 95% CI [1.06 × 106 ; 7.80 × 106 ]; p = 0.013) and A. actinomycetemcomitans (mean difference = 2.55 × 107 CFU/ml; 95% CI [1.07 × 107 ; 4.04 × 107 ]; p = 0.002), were found in the moderate- compared to minimal-roughness surface dental implants.

CONCLUSIONS: Implants with moderate-roughness surfaces accumulated more bacterial biomass and significant higher number of pathogenic bacteria (F. nucleatum and A. actinomycetemcomitans), when compared to implants with minimal-roughness surfaces, within a similar biofilm structure.}, } @article {pmid31077423, year = {2019}, author = {Alves, AR and Sequeira, AM and Cunha, Â}, title = {Increase in bacterial biosurfactant production by co-cultivation with biofilm-forming bacteria.}, journal = {Letters in applied microbiology}, volume = {69}, number = {1}, pages = {79-86}, doi = {10.1111/lam.13169}, pmid = {31077423}, issn = {1472-765X}, support = {UID/AMB/50017 - POCI-01-0145-FEDER-007638//CESAM/ ; //FEDER/ ; }, mesh = {Agar/metabolism ; Bacillus licheniformis/*metabolism ; Biofilms/*growth & development ; Coculture Techniques ; Listeria/*metabolism ; Pseudomonas aeruginosa/*metabolism ; Quorum Sensing ; Surface-Active Agents/*metabolism ; }, abstract = {Considering that bacterial biosurfactants (BSFs) are released as secondary metabolites involved in biotic relations within mixed bacterial assemblages, the hypothesis that the co-cultivation of BSF producing bacteria with biofilm-forming strains would enhance BSF synthesis was tested. Environmental BSF producing strains of Bacillus licheniformis and Pseudomonas sp. were cultivated with reference biofilm-forming strains (Pseudomonas aeruginosa and Listeria innocua). BSF production and quorum-quenching effects were tested in solid media. Tensioactive and anionic BSFs were also quantified in cell-free extracts (CFEs). BSF production increased in co-cultures with inducer strains although this was not demonstrated by all screening methods. Increased concentrations of anionic BSF were detected in CFEs of co-cultures in which Pseudomonas aeruginosa was included as inducer, which is in accordance with the observation of larger halos in cetyl trimethylammonium bromide-methylene blue agar. The results demonstrate that co-cultivation positively affects the efficiency of BSF production and that higher production yields may be attained by selecting convenient inducer partners in designed consortia. SIGNIFICANCE AND IMPACT OF THE STUDY: The high production cost of biosurfactants (BSFs) still represents a major limitation to the industrial use of these otherwise advantageous alternatives to chemical surfactants. This work demonstrates that the co-cultivation of consortia of biosurfactant-producer and biofilm-forming bacteria enhances BSF production and may contribute to the cost-effectiveness of biosurfactant-based products.}, } @article {pmid31077283, year = {2019}, author = {Zeng, Z and Zhan, W and Wang, W and Wang, P and Tang, K and Wang, X}, title = {Biofilm formation in Pseudoalteromonas lipolytica is related to IS5-like insertions in the capsular polysaccharide operon.}, journal = {FEMS microbiology ecology}, volume = {95}, number = {6}, pages = {}, doi = {10.1093/femsec/fiz065}, pmid = {31077283}, issn = {1574-6941}, abstract = {Bacterial capsular polysaccharides (CPSs) participate in environmental adaptation in diverse bacteria species. However, the role and regulation of CPS production in marine bacteria have remained largely unexplored. We previously reported that both wrinkled and translucent Pseudoalteromonas lipolytica variants with altered polysaccharide production were generated in pellicle biofilm-associated cells. In this study, we observed that translucent variants were generated at a rate of ∼20% in colony biofilms of P. lipolytica cultured on HSLB agar plates for 12 days. The DNA sequencing results revealed that nearly 90% of these variants had an IS5-like element inserted within the coding or promoter regions of nine genes in the cps operon. In contrast, IS5 insertion into the cps operon was not detected in planktonic cells. Furthermore, we demonstrated that the IS5 insertion event inactivated CPS production, which leads to a translucent colony morphology. The CPS-deficient variants showed an increased ability to form attached biofilms but exhibited reduced resistance to sublethal concentrations of antibiotics. Moreover, deleting the DNA repair gene recA significantly decreased the frequency of occurrence of CPS-deficient variants during biofilm formation. Thus, IS insertion into the cps operon is an important mechanism for the production of genetic variants during biofilm formation of marine bacteria.}, } @article {pmid31076293, year = {2019}, author = {Peng, C and Gao, Y and Fan, X and Peng, P and Huang, H and Zhang, X and Ren, H}, title = {Enhanced biofilm formation and denitrification in biofilters for advanced nitrogen removal by rhamnolipid addition.}, journal = {Bioresource technology}, volume = {287}, number = {}, pages = {121387}, doi = {10.1016/j.biortech.2019.121387}, pmid = {31076293}, issn = {1873-2976}, abstract = {Denitrification biofilters (DNBFs) are widely used in advanced nitrogen removal of wastewater with low C/N and effective biofilm formation is critical to their long-term operation. Hereby the influence of rhamnolipid addition in DNBFs was investigated for the first time. Gradient concentrations (0, 20, 40, 80, 120 mg/L) of rhamnolipid were applied to investigate nitrogen removal, biofilm properties and microbial community of lab-scale DNBFs. A significant increase of nitrogen removal was observed in rhamnolipid-treated DNBFs (p < 0.05). Total solid (TS), extracellular polymeric substances (EPS) and adhesion force of biofilms in DNBF with 120 mg/L rhamnolipid reached the maximum, which were 2.17, 2.15 and 3.36 times of those in the control, respectively. Moreover, rhamnolipid exhibited an improvement in abundance of Simplicispira and Gemmatimonas which were responsible for enhanced biofilm formation and denitrification. The results suggested that rhamnolipid addition can be a novel strategy to improve the start-up and denitrification performance of DNBFs.}, } @article {pmid31075206, year = {2019}, author = {Gou, Y and Liu, W and Wang, JJ and Tan, L and Hong, B and Guo, L and Liu, H and Pan, Y and Zhao, Y}, title = {CRISPR-Cas9 knockout of qseB induced asynchrony between motility and biofilm formation in Escherichia coli.}, journal = {Canadian journal of microbiology}, volume = {}, number = {}, pages = {1-12}, doi = {10.1139/cjm-2019-0100}, pmid = {31075206}, issn = {1480-3275}, abstract = {Generally, cell motility and biofilm formation are tightly regulated. The QseBC two-component system (TCS) serves as a bridge for bacterial signal transmission, in which the protein QseB acts as a response regulator bacterial motility, biofilm formation, and virulence. The mechanisms that govern the interaction between QseBC and their functions have been studied in general, but the regulatory role of QseB on bacterial motility and biofilm formation is unknown. In this study, the CRISPR-Cas9 system was used to construct the Escherichia coli MG1655ΔqseB strain (strain ΔqseB), and the effects of the qseB gene on changes in motility and biofilm formation in the wild type (WT) were determined. The motility assay results showed that the ΔqseB strain had higher (p < 0.05) motility than the WT strain. However, there was no difference in the formation of biofilm between the ΔqseB and WT strains. Real-time quantitative PCR illustrated that deletion of qseB in the WT strain downregulated expression of the type I pili gene fimA. Therefore, we might conclude that the ΔqseB induced the downregulation of fimA, which led to asynchrony between motility and biofilm formation in E. coli, providing new insight into the functional importance of QseB in regulating cell motility and biofilm formation.}, } @article {pmid31072243, year = {2019}, author = {Spennati, F and Ricotti, A and Mori, G and Siracusa, G and Becarelli, S and Gregorio, SD and Tigini, V and Varese, GC and Munz, G}, title = {The role of cosubstrate and mixing on fungal biofilm efficiency in the removal of tannins.}, journal = {Environmental technology}, volume = {}, number = {}, pages = {1-9}, doi = {10.1080/09593330.2019.1615128}, pmid = {31072243}, issn = {1479-487X}, abstract = {Tannins are polyphenolic compounds produced by plants and they are used in industrial vegetable tanning of leather. Tannins represent one of the low biodegradability substances in tannery wastewaters with high recalcitrant soluble chemical oxygen demand, furthermore high concentration of tannins can inhibit biological treatment. In the present study, four novel rotating submerged packed bed reactors were inoculated with a selected fungal strain to reach a biological degradation of tannins in non-sterile conditions. The selected fungal strain, Aspergillus tubingensis MUT 990, was immobilised in polyurethane foam cubes carriers and inserted inside a submerged rotating cage reactors. The reactors were feed with a solution composed of four tannins: Quebracho (Schinopsis spp.), Wattle (Mimosa spp.), Chestnut (Castanea spp.) and Tara (Caesalpinia spp.). Four reactors with a volume of 4 L each were used, the co-substrate was pure malt extract, the hydraulic retention time was 24 h and the pH setpoint was 5.5. The reactors configuration was chosen to allow the study of the effect of rotation and the co-substrate addition on tannins removal. The experiment lasted two months and it was achieved 80% of chemical oxygen demand and up to 90% dissolved organic carbon removal, furthermore it was detected an important tannase activity.}, } @article {pmid31071421, year = {2019}, author = {Mehta, M and Allen-Gipson, D and Mohapatra, S and Kindy, M and Limayem, A}, title = {Study on the therapeutic index and synergistic effect of Chitosan-zinc oxide nanomicellar composites for drug-resistant bacterial biofilm inhibition.}, journal = {International journal of pharmaceutics}, volume = {565}, number = {}, pages = {472-480}, doi = {10.1016/j.ijpharm.2019.05.003}, pmid = {31071421}, issn = {1873-3476}, abstract = {The synergistic effectiveness of chitosan with zinc oxide nanomicelles (CZNPs) on broad spectrum of multidrug resistance (MDR) was previously evidenced in our labs, requiring elucidation of the therapeutic index (TI) for safe in vivo use. This in vitro assessment estimated the effective dose (ED50) of micellar CZNPs for eradication of the MDR Enterococcus faecium 1449 model and the corresponding cytotoxic dose (LD50) against rat small intestinal epithelial cells as functions of TI. In order to visually determine the mechanistic effects of micellar CZNPs on bacterial biofilm size reduction, LIVE/DEAD viability assay was used in conjunction with advanced fluorescence imaging and 3D confocal microscopy. Biofilm quantification was performed through the measure of the fluorescence intensity, using the Biotek Synergy Neo2 for calculating the ED50. To generate the LD50, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay was implemented. Quantification results revealed, at the same concentration (200 µg/mL), micellar CZNPs had average biofilm reduction of approximately 50.22% at 24 h (ED50 = 199.13 µg/mL, LD50 = 240.20 µg/mL, TI = 1.2062), compared to chitosan (15.66%) and ZnO (13.94%) alone. Conclusively, the ED50 of micellar CZNPs on MDR bacterial biofilms (199.13 µg/mL) as a function of TI reveals a promising nanotherapeutic agent in comparison to either Chitosan or ZnO alone.}, } @article {pmid31070474, year = {2019}, author = {Guo, D and Yang, Z and Zheng, X and Kang, S and Yang, Z and Xu, Y and Shi, C and Tian, H and Xia, X}, title = {Thymoquinone Inhibits Biofilm Formation and Attachment-Invasion in Host Cells of Vibrio parahaemolyticus.}, journal = {Foodborne pathogens and disease}, volume = {}, number = {}, pages = {}, doi = {10.1089/fpd.2018.2591}, pmid = {31070474}, issn = {1556-7125}, abstract = {Vibrio parahaemolyticus is a halophilic Gram-negative foodborne pathogen that is widely distributed in marine environments. It can cause acute gastroenteritis and other diseases. This study aimed to investigate the antivirulence activity of thymoquinone (TQ) on V. parahaemolyticus. TQ was shown to effectively inhibit V. parahaemolyticus. Subminimum inhibitory concentrations of TQ inhibited swimming and swarming motility, quorum sensing, biofilm formation, the ability of V. parahaemolyticus to adhere and invade the host cells, and the expression of virulence-associated genes of V. parahaemolyticus. These findings suggest that TQ can effectively inhibit the growth of V. parahaemolyticus and significantly reduce its pathogenicity. Considering its safety and various biological activities, TQ has the potential to be developed as a natural antibacterial substance to reduce the diseases associated with V. parahaemolyticus.}, } @article {pmid31067024, year = {2019}, author = {Zhou, R and Zhou, R and Wang, P and Luan, B and Zhang, X and Fang, Z and Xian, Y and Lu, X and Ostrikov, KK and Bazaka, K}, title = {Microplasma Bubbles: Reactive Vehicles for Biofilm Dispersal.}, journal = {ACS applied materials & interfaces}, volume = {11}, number = {23}, pages = {20660-20669}, doi = {10.1021/acsami.9b03961}, pmid = {31067024}, issn = {1944-8252}, abstract = {Interactions between effects generated by cold atmospheric-pressure plasmas and water have been widely investigated for water purification, chemical and nanomaterial synthesis, and, more recently, medicine and biotechnology. Reactive oxygen and nitrogen species (RONS) play critical roles in transferring the reactivity from gas plasmas to solutions to induce specific biochemical responses in living targets, e.g., pathogen inactivation and biofilm removal. While this approach works well in a single-organism system at a laboratory scale, integration of plasma-enabled biofilm removal into complex real-life systems, e.g., large aquaculture tanks, is far from trivial. This is because it is difficult to deliver sufficient concentrations of the right kind of species to biofilm-covered surfaces while carefully maintaining a suitable physiochemical environment that is healthy for its inhabitants, e.g., fish. In this work, we show that underwater microplasma bubbles (generated by a microplasma-bubble reactor that forms a dielectric barrier discharge at the gas-liquid interface with the applied voltage of 4.0 kV) act as transport vehicles to efficiently deliver reactive plasma species to the target biofilm sites on artificial and living surfaces while keeping healthy water conditions in a multispecies system. The as-generated air microplasma bubbles and plasma-activated water (PAW) both can effectively reduce the existing pathogenic biofilm load by ∼83 and 60%, respectively, after 15 min of discharge at 40 W and prevent any new biofilm from forming. The generation of underwater microplasma bubbles in a custom-made fish tank for less than a minute per day (20 s per time, twice daily) can introduce sufficient quantities of RONS into PAW to reduce the biofilm-infected area by ∼80-90% and improve the health status of Cichlasoma synspilum × Cichlasoma citrinellum blood parrot cichlid fish. Species generated include hydrogen peroxide, ozone, nitrite, nitrate, and nitric oxide. Using mimicked chemical solutions, we show that the plasma-induced nitric oxide acts as a critical bioactive species that triggers the release of cells from the biofilm and their inactivation.}, } @article {pmid31066733, year = {2019}, author = {Zhang, C and Du, C and Liao, JY and Gu, Y and Gong, Y and Pei, J and Gu, H and Yin, D and Gao, L and Pan, Y}, title = {Synthesis of magnetite hybrid nanocomplexes to eliminate bacteria and enhance biofilm disruption.}, journal = {Biomaterials science}, volume = {7}, number = {7}, pages = {2833-2840}, doi = {10.1039/c9bm00057g}, pmid = {31066733}, issn = {2047-4849}, abstract = {Bacteria can increase drug resistance by forming bacterial biofilms. Once the biofilm is formed, it becomes difficult to remove or kill the related bacteria completely by antibiotics and other antibacterial agents because these antibacterial agents cannot easily break through the biofilm matrix barrier and reach the internal bacteria. Therefore, we synthesized magnetite hybrid nanocomplexes that can penetrate and disrupt bacterial biofilms. The obtained nanocomposites are composed of multinucleated iron oxides and Ag seeds. The outer iron oxides can help the internal Ag nanoparticles penetrate the bacterial biofilms, hence killing the internal bacteria and disrupting the biofilms. We took advantage of E. coli and P. aeruginosa bacteria to test the antibacterial properties of the magnetite hybrid nanocomplexes. When planktonic E. coli and P. aeruginosa bacteria were incubated with 100 μg mL-1 magnetite hybrid nanocomplexes for 30 min, almost all the bacteria were killed. When the obtained biofilms of E. coli and P. aeruginosa were treated with magnetite hybrid nanocomplexes (10 μg mL-1 and 100 μg mL-1), the survival of E. coli and P. aeruginosa biofilms with a magnetic field showed a big decrease compared with that without a magnetic field. Therefore, the as-synthesized nanocomposites have promising potential as antimicrobial agents for killing bacteria and disrupting biofilms in the presence of a magnetic field, and thus should be further studied for a wide range of antibacterial applications.}, } @article {pmid31064142, year = {2019}, author = {Wei, C and Ding, T and Chang, C and Yu, C and Li, X and Liu, Q}, title = {Global Regulator PhoP is Necessary for Motility, Biofilm Formation, Exoenzyme Production and Virulence of Xanthomonas citri Subsp. citri on Citrus Plants.}, journal = {Genes}, volume = {10}, number = {5}, pages = {}, doi = {10.3390/genes10050340}, pmid = {31064142}, issn = {2073-4425}, abstract = {Citrus canker caused by Xanthomonas citri subsp. citri is one of the most important bacterial diseases of citrus, impacting both plant growth and fruit quality. Identifying and elucidating the roles of genes associated with pathogenesis has aided our understanding of the molecular basis of citrus-bacteria interactions. However, the complex virulence mechanisms of X. citri subsp. citri are still not well understood. In this study, we characterized the role of PhoP in X. citri subsp. citri using a phoP deletion mutant, ΔphoP. Compared with wild-type strain XHG3, ΔphoP showed reduced motility, biofilm formation, as well as decreased production of cellulase, amylase, and polygalacturonase. In addition, the virulence of ΔphoP on citrus leaves was significantly decreased. To further understand the virulence mechanisms of X. citri subsp. citri, high-throughput RNA sequencing technology (RNA-Seq) was used to compare the transcriptomes of the wild-type and mutant strains. Analysis revealed 1017 differentially-expressed genes (DEGs), of which 614 were up-regulated and 403 were down-regulated in ΔphoP. Gene ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that the DEGs were enriched in flagellar assembly, two-component systems, histidine metabolism, bacterial chemotaxis, ABC transporters, and bacterial secretion systems. Our results showed that PhoP activates the expression of a large set of virulence genes, including 22 type III secretion system genes and 15 type III secretion system effector genes, as well as several genes involved in chemotaxis, and flagellar and histidine biosynthesis. Two-step reverse-transcription polymerase chain reaction analysis targeting 17 genes was used to validate the RNA-seq data, and confirmed that the expression of all 17 genes, except for that of virB1, decreased significantly. Our results suggest that PhoP interacts with a global signaling network to co-ordinate the expression of multiple virulence factors involved in modification and adaption to the host environment during infection.}, } @article {pmid31063858, year = {2019}, author = {Misba, L and Abdulrahman, H and Khan, AU}, title = {Photodynamic efficacy of toluidine blue O against mono species and dual species bacterial biofilm.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {26}, number = {}, pages = {383-388}, doi = {10.1016/j.pdpdt.2019.05.001}, pmid = {31063858}, issn = {1873-1597}, abstract = {AIM: The purpose of this study was to investigate how Enterococcus faecalis and Streptococcus mutans behave in mono and dual species biofilm after photodynamic treatment.

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) leads to the generation of reactive oxygen species (ROS) that destroys bacterial cells in presence of a photosensitizer, visible light, and oxygen.

MATERIAL AND METHODS: We have taken Enterococcus faecalis and Streptococcus mutans as monospecies culture and their dualspecies culture biofilm. Antibacterial effect was evaluated by colony forming unit while antibiofilm action by crystal violet and congored binding assays.

RESULTS: We found that dual species biofilm are more resistant than monospecies biofilm and S. mutans shows dominance over E. faecalis in dual species biofilm, it inhibited the growth of E. faecalis in dual species biofilm. Antibiofilm efficacy of TBO also validated that dualspecies show less inhibition than monospecies biofilm this may be due to different EPS constitution in dualspecies biofilm, hence less inhibition was observed in EPS production of dualspecies biofilm than monospecies biofilm. Reactive oxygen species and singlet oxygen yield was found to be light dose dependent and antimicrobial photodynamic efficiency is directly related to the ROS production.

CONCLUSION: We conclude that dual species biofilm shows resistance over monospecies biofilm and S. mutans in dual species inhibits the growth of E. faecalis.}, } @article {pmid31062019, year = {2019}, author = {González, MJ and Da Cunda, P and Notejane, M and Zunino, P and Scavone, P and Robino, L}, title = {Fosfomycin tromethamine activity on biofilm and intracellular bacterial communities produced by uropathogenic Escherichia coli isolated from patients with urinary tract infection.}, journal = {Pathogens and disease}, volume = {77}, number = {3}, pages = {}, doi = {10.1093/femspd/ftz022}, pmid = {31062019}, issn = {2049-632X}, abstract = {Fosfomycin tromethamine (FT), an old antibiotic revived as a new strategy to overcome antibiotic resistance, is an excellent option for the treatment of lower urinary tract infection (UTI). During UTI, Escherichia coli produces biofilms and could invade the bladder epithelial cells, developing intracellular bacterial communities (IBC). The present work aimed to evaluate the activity of FT on biofilms and IBC from clinical isolates of E. coli. A total of 38 E. coli clinical UTI isolates previously characterized as biofilm and IBC producers were studied. FT susceptibility was evaluated and its activity on 48 h biofilm was determined by microtiter plate-based biofilm assay comparing three different antibiotic concentrations. Two UPEC strains were selected to evaluate FT activity on IBC in vitro using T24 bladder cells. The survival percentage of intracellular bacteria after 24 h exposure to FT was calculated and compared to the percentage of intracellular bacteria without antibiotic. All the strains were susceptible to FT. FT produced a significant reduction of biofilms at the three concentrations tested, compared to the control. However, no statistically effect on IBC was observed after 24 h of fosfomycin exposure in cell culture. FT is a good option for bacterial biofilm reduction within UTI. However, it does not affect IBC.}, } @article {pmid31061169, year = {2019}, author = {Gu, H and Lee, SW and Carnicelli, J and Jiang, Z and Ren, D}, title = {Antibiotic susceptibility of Escherichia coli cells during early-stage biofilm formation.}, journal = {Journal of bacteriology}, volume = {}, number = {}, pages = {}, doi = {10.1128/JB.00034-19}, pmid = {31061169}, issn = {1098-5530}, abstract = {Bacteria form complex multicellular structures on solid surfaces called biofilms, which allow them to survive in harsh environments. A hallmark characteristic of mature biofilms is the high-level antibiotic tolerance (up to 1,000 times) compared to planktonic cells. Here, we report our new findings that biofilm cells are not always more tolerant to antibiotics than planktonic cells in the same culture. Specifically, Escherichia coli RP437 exhibited a dynamic change in antibiotic susceptibility during its early-stage biofilm formation. This phenomenon was not strain specific. Upon initial attachment, surface-associated cells became more sensitive to antibiotics than planktonic cells. By controlling the cell adhesion and cluster size using patterned E. coli biofilms, cells involved in the interaction between cell clusters during microcolony formation were found to be more susceptible to ampicillin than cells within clusters, suggesting a role of cell-cell interactions in biofilm-associated antibiotic tolerance. After this stage, biofilm cells became less susceptible to ampicillin and ofloxacin than planktonic cells. However, when the cells were detached by sonication, both antibiotics were more effective in killing the detached biofilm cells than the planktonic cells. Collectively, these results indicate that biofilm formation involves active cellular activities in adaption to the attached life form and interactions between cell clusters to build the complex structure of a biofilm, which can render these cells more susceptible to antibiotics. These findings shed new lights on bacterial antibiotic susceptibility during biofilm formation and can guide the design of better antifouling surfaces, e.g., those with micron-scale topographic structures to interrupt cell-cell interactions.IMPORTANCE Mature biofilms are known for their high-level tolerance to antibiotics; however, antibiotic susceptibility of sessile cells during early-stage biofilm formation is not well understood. In this study, we aim to fill this knowledge gap by following bacterial antibiotic susceptibility during early-stage biofilm formation. We found that the attached cells have a dynamic change in antibiotic susceptibility, and during certain phases, they can be more sensitive to antibiotics compared to planktonic counterparts in the same culture. Using surface chemistry controlled patterned biofilm formation, cell-surface and cell-cell interactions were found to be important to biofilm-associated antibiotic tolerance. Collectively, these findings provide new insights into biofilm physiology and reveal how adaptation to the attached life form affects antibiotic susceptibility of bacterial cells.}, } @article {pmid31059933, year = {2019}, author = {Johansen, MP and Cresswell, T and Davis, J and Howard, DL and Howell, NR and Prentice, E}, title = {Biofilm-enhanced adsorption of strong and weak cations onto different microplastic sample types: Use of spectroscopy, microscopy and radiotracer methods.}, journal = {Water research}, volume = {158}, number = {}, pages = {392-400}, doi = {10.1016/j.watres.2019.04.029}, pmid = {31059933}, issn = {1879-2448}, abstract = {The adsorption of metals and other elements onto environmental plastics has been previously quantified and is known to be enhanced by surface-weathering and development of biofilms. However, further biofilm-adsorption characterisation is needed with respect to the fate of radionuclides. This study uses spectroscopy, microscopy and radiotracer methods to investigate the adsorption capacity of relatively strong and weak cations onto different microplastic sample types that were conditioned in freshwater, estuarine and marine conditions although marine data were limited. Fourier-transform infrared spectroscopy confirmed that surface oxidation chemistry changes induced by gamma irradiation were similar to those resulting from environmental exposures. Microscopy elemental mapping revealed patchy biofilm development, which contained Si, Al, and O, consistent with microbial-facilitated capture of clays. The plastics+biofilm of all sample types had measurable adsorption for Cs and Sr radiotracers, suggesting environmental plastics act broadly as a sink for the key pervasive environmental radionuclides of 137Cs and 90Sr associated with releases from nuclear activities. Adsorption onto high-density polyethylene plastic types was greater than that on polypropylene. However, in most cases, the adsorption rates of all types of plastic+biofilm were much lower than those of reference sediments and roughly consistent with their relative exchangeable surface areas.}, } @article {pmid31058104, year = {2019}, author = {Xie, Z and Meng, K and Yang, X and Liu, J and Yu, J and Zheng, C and Cao, W and Liu, H}, title = {Identification of a Quorum Sensing System Regulating Capsule Polysaccharide Production and Biofilm Formation in Streptococcus zooepidemicus.}, journal = {Frontiers in cellular and infection microbiology}, volume = {9}, number = {}, pages = {121}, doi = {10.3389/fcimb.2019.00121}, pmid = {31058104}, issn = {2235-2988}, abstract = {Streptococcus zooepidemicus is an important opportunistic pathogen of several species including humans. This organism is also well-known as the main producing strain in industrial production of hyaluronic acid (HA), which is the component of its capsule polysaccharide. How its virulence and capsule polysaccharide production is regulated remains poorly understood. Intercellular chemical signaling among bacteria provides communities of microbes the opportunity to coordinate gene expression to facilitate group behavior, such as pathogenicity, capsule polysaccharide production, etc. Yet no conserved cell-to-cell signaling system has been elucidated in S. zooepidemicus. Encoded within the genome of S. zooepidemicus is one Rgg regulator encoding gene (rgg) with low similarity to both rgg2 and rgg3 from Streptococcus pyogenes. A small ORF (named as shp) encoding a novel short hydrophobic peptide (SHP) was found in the vicinity of rgg. We found that the active form of pheromone is short and hydrophobic (LLLLKLA), corresponding to the C terminal 7 amino acids of the pre-peptide Shp, which shows divergent sequence to all peptide pheromones reported in streptococci. In response to active SHP, Rgg functions as a transcriptional activator to induce the expression of shp, forming a positive feedback circuit. Bacteria social behaviors, such as capsule polysaccharide production and biofilm formation, were significantly affected when the rgg-shp pathway was inactivated. These data provide the first demonstration that Rgg/Shp signaling pathway comprises an active quorum sensing system in S. zooepidemicus.}, } @article {pmid31057729, year = {2019}, author = {Post, SJ and Shapiro, JA and Wuest, WM}, title = {Connecting iron acquisition and biofilm formation in the ESKAPE pathogens as a strategy for combatting antibiotic resistance.}, journal = {MedChemComm}, volume = {10}, number = {4}, pages = {505-512}, doi = {10.1039/c9md00032a}, pmid = {31057729}, issn = {2040-2511}, support = {R35 GM119426/GM/NIGMS NIH HHS/United States ; }, abstract = {The rise of antibiotic resistant bacteria has become a problem of global concern. Of particular interest are the ESKAPE pathogens, species with high rates of multi-drug resistant infections. Novel antibiotic mechanisms of action are necessary to compliment traditional therapeutics. Recent research has focused on targeting virulence factors as a method of combatting infection without creating selective pressure for resistance or damaging the host commensal microbiome. Some investigations into one such virulence behavior, iron acquisition, have displayed additional effects on another virulence behavior, biofilm formation. The use of exogenous iron-chelators, gallium as an iron mimic, and inhibition of siderophore-mediated iron acquisition are all strategies for disturbing iron-homeostasis that have implicated effects on biofilms. However, the exact nature of this connection remains ambiguous. Herein we summarize these findings and identify opportunities for further investigation.}, } @article {pmid31057497, year = {2019}, author = {Igbinosa, EO and Beshiru, A}, title = {Antimicrobial Resistance, Virulence Determinants, and Biofilm Formation of Enterococcus Species From Ready-to-Eat Seafood.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {728}, doi = {10.3389/fmicb.2019.00728}, pmid = {31057497}, issn = {1664-302X}, abstract = {Enterococcus species form an important population of commensal bacteria and have been reported to possess numerous virulence factors considered significantly important in exacerbating diseases caused by them. The present study was designed to characterize antibiotic-resistant and virulent enterococci from ready-to-eat (RTE) seafood. A total of 720 RTE shrimp samples comprising sauced shrimp (n = 288), boiled shrimp (n = 216), and smoked shrimp (n = 216) obtained from open markets in Delta State, Nigeria, were assessed. Standard classical methods and polymerase chain reaction (PCR) were used in identifying the Enterococcus species. Potential virulence factors (β-hemolysis, gelatinase activity, S-layer, and biofilm formation) were assessed using standard procedures. The antibiotic susceptibility profile of the identified enterococci isolates was assayed using the Kirby-Bauer disc diffusion method. PCR was further used to screen selected antibiotic resistance and virulence genes. Prevalence of Enterococcus species from shrimp varieties is as follows: sauced, 26 (9.03%); boiled, 6 (2.78%); and smoked, 27 (12.50%), with an overall prevalence of 59 (8.19%) based on the occurrence of black hallow colonies after incubation. Enterococcus species detected include E. faecalis, 17 (28.8%); E. faecium, 29 (49.2%); E. gallinarum, 6 (10.2%); E. casseliflavus, 2 (3.4%); E. hirae, 3 (5.1%); and E. durans, 2 (3.4%). Biofilm occurrence among the shrimp varieties is as follows: 19/26 (73.1%) for sauced shrimps, 5/6 (83.3%) for boiled shrimps, and 16/27 (59.3%) for smoked shrimps. The phenotypic expression of the enterococci virulence revealed the following: S-layer, 59 (100%); gelatinase production, 19 (32.2%); and β-hemolysis, 21 (35.6%). An average of 3-11 virulence genes were detected in the Enterococcus species. The resistance profile of Enterococcus species is as follows: erythromycin, 29 (49.2%); vancomycin, 22 (37.3%); and tetracycline, 27 (45.8%). The frequency of occurrence of antibiotic resistance genes from the phenotypic resistant enterococci isolates to the macrolide, glycopeptide, and tetracycline antibiotics is as follows: ermA, 13/29 (44.8%); vanA, 14/22 (63.6%); tetA, 14/27 (51.9%); tetM, 15/27 (55.6%); ermB, 4/29 (13.8%); and vanB, 5/22 (22.7%). Findings from this study reveal the antibiotic resistance of enterococci strains of such species as E. durans, E. casseliflavus, E. gallinarum, and E. hirae. This study further revealed that RTE food products are reservoirs of potential virulent enterococci with antibiotic-resistant capabilities. This provides useful data for risk assessment and indicates that these foods may present a potential public health risk to consumers.}, } @article {pmid31055910, year = {2019}, author = {Lee, JH and Kim, YG and Khadke, SK and Yamano, A and Watanabe, A and Lee, J}, title = {Inhibition of Biofilm Formation by Candida albicans and Polymicrobial Microorganisms by Nepodin via Hyphal-Growth Suppression.}, journal = {ACS infectious diseases}, volume = {5}, number = {7}, pages = {1177-1187}, doi = {10.1021/acsinfecdis.9b00033}, pmid = {31055910}, issn = {2373-8227}, abstract = {Candida albicans is an opportunistic pathogenic yeast and is responsible for candidiasis. It readily colonizes host tissues and implant devices, and forms biofilms, which play an important role in pathogenesis and drug resistance. In this study, the antibiofilm, antihyphal, and antivirulence activities of nepodin, isolated from Rumex japonicus roots, were investigated against a fluconazole-resistant C. albicans strain and against polymicrobial-microorganism-biofilm formation. Nepodin effectively inhibited C. albicans biofilm formation without affecting its planktonic cell growth. Also, Rumex-root extract and nepodin both inhibited hyphal growth and cell aggregation of C. albicans. Interestingly, nepodin also showed antibiofilm activities against Candida glabrata, Candida parapsilosis, Staphylococcus aureus, and Acinetobacter baumannii strains and against dual biofilms of C. albicans and S. aureus or A. baumannii but not against Pseudomonas aeruginosa. Transcriptomic analysis performed by RNA-seq and qRT-PCR showed nepodin repressed the expression of several hypha- and biofilm-related genes (ECE1, HGT10, HWP1, and UME6) and increased the expression of several transport genes (CDR4, CDR11, and TPO2), which supported phenotypic changes. Moreover, nepodin reduced C. albicans virulence in a nematode-infection model and exhibited minimal cytotoxicity against the nematode and an animal cell line. These results demonstrate that nepodin and Rumex-root extract might be useful for controlling C. albicans infections and multispecies biofilms.}, } @article {pmid31055471, year = {2019}, author = {Lynch, C and O'Connor, JA and O'Brien, D and Vaughan, C and Bolton, D and Coffey, A and Lucey, B}, title = {First reported detection of biofilm formation by Campylobacter fetus during investigation of a case of prosthetic valve endocarditis.}, journal = {Journal of clinical pathology}, volume = {72}, number = {8}, pages = {554-557}, doi = {10.1136/jclinpath-2018-205677}, pmid = {31055471}, issn = {1472-4146}, mesh = {Animals ; Bacterial Adhesion ; Biofilms/*growth & development ; Campylobacter Infections/diagnosis/*microbiology/transmission ; Campylobacter fetus/*growth & development/isolation & purification ; Endocarditis, Bacterial/diagnosis/*microbiology/transmission ; Heart Valve Prosthesis/*adverse effects ; Heart Valve Prosthesis Implantation/*adverse effects/*instrumentation ; Humans ; Prosthesis-Related Infections/diagnosis/*microbiology/transmission ; Zoonoses/diagnosis/*microbiology/transmission ; }, abstract = {AIMS: Campylobacter fetus subsp fetus (CFF) can cause intestinal illness, particularly in immunocompromised humans, with the potential to cause severe systemic infections. CFF is a zoonotic pathogen with a broad host range among farm animals and humans, inducing abortion in sheep and cows. The current paper describes a strain of CFF isolated from a patient with prosthetic valve endocarditis in Mercy University Hospital, Cork, Ireland, during 2017. Only five cases of C. fetus as a cause of prosthetic valve endocarditis have been reported in the literature, with no reports of biofilm formation within the species.

METHODS: The aetiological strain was speciated and subspeciated by the VITEK 2 NH card and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry. CFF biofilm formation was analysed using a crystal violet staining method. C. jejuni National Collection of Type Cultures (NCTC) 11168 was used as a positive control organism. Strains were incubated statically in Mueller-Hinton broth and Mueller-Hinton broth supplemented with 0.025% sodium deoxycholate for 3 and 7 days at 37°C, microaerobically.

RESULTS: The CFF strain formed stronger attached biofilms on polystyrene plates on day 3 (72 hours) than the C. jejuni NCTC 11168 control strain, but were weaker than the control strain on day 7 in Mueller-Hinton broth. Monoculture of this C. fetus isolate was found to exist in three defined forms of biofilms (attached, air-liquid interface and floccules).

CONCLUSIONS: This clinically significant C. fetus isolate showed considerable biofilm-forming capability, which we suggest conferred a survivalist advantage, contributing to the genesis of infective prosthetic valve endocarditis.}, } @article {pmid31054395, year = {2019}, author = {Peng, L and Ngo, HH and Song, S and Xu, Y and Guo, W and Liu, Y and Wei, W and Chen, X and Wang, D and Ni, BJ}, title = {Heterotrophic denitrifiers growing on soluble microbial products contribute to nitrous oxide production in anammox biofilm: Model evaluation.}, journal = {Journal of environmental management}, volume = {242}, number = {}, pages = {309-314}, doi = {10.1016/j.jenvman.2019.04.084}, pmid = {31054395}, issn = {1095-8630}, abstract = {In this work, a model framework was constructed to assess and predict nitrous oxide (N2O) production, substrate and microbe interactions in an anammox biofilm bioreactor. The anammox kinetics were extended by including kinetics of autotrophic soluble microbial products (SMP) formation, which consisted of utilization-associated products (UAP) and biomass-associated products (BAP). Heterotrophic bacteria growing on UAP, BAP and decay released substance (SS) were modelled to perform four-step sequential reductions from nitrate to dinitrogen gas. N2O was modelled as an intermidiate of heterotrophic denitrification via three pathways with UAP, BAP and SS as the electron donors. The developed model framework was evaluated using long-term operational data from an anammox biofilm reactor and satisfactorily reproduced effluent nitrogen and SMP as well as N2O emission factors under different operational conditions. The modeling results revealed that N2O was mainly produced with UAP as the electron donor while BAP and SS play minor roles. Heterotrophic denitrifiers growing on UAP would significantly contribute to N2O emission from anammox biofilm reactor even though heterotrophs only account for a relatively small fraction of active biomass in the anammox biofilm. Comprehensive simulations were conducted to investigate the effects of N loading rate and biofilm thickness, which indicated that maintaining a low N loading rate and a thick biofilm thickness were essential for high total nitrogen removal efficiency and low N2O emission.}, } @article {pmid31054134, year = {2019}, author = {Babbar, A and Barrantes, I and Pieper, DH and Itzek, A}, title = {Superantigen SpeA attenuates the biofilm forming capacity of Streptococcus pyogenes.}, journal = {Journal of microbiology (Seoul, Korea)}, volume = {57}, number = {7}, pages = {626-636}, doi = {10.1007/s12275-019-8648-z}, pmid = {31054134}, issn = {1976-3794}, abstract = {Beta haemolytic Group A streptococcus (GAS) or Streptococcus pyogenes are strict human pathogens responsible for mild to severe fatal invasive infections. Even with enormous number of reports exploring the role of S. pyogenes exotoxins in its pathogenesis, inadequate knowledge on the biofilm process and the potential role of exotoxins in bacterial dissemination from matured biofilms has been a hindrance in development of effective and targeted treatments. Therefore, the present study was aimed in investigating the uncharted role of these exotoxins in biofilm process. Through our study the putative role of ciaRH in the SpeA dependent ablation of biofilm formation could be speculated and thus helping in bacterial dissemination. The seed-dispersal effect of SpeA was time and concentration dependent and seen to be consistent within various streptococcal species. Transcriptome analysis of SpeA treated S. pyogenes biofilms revealed the involvement of many transcriptional regulators (ciaRH) and response genes (luxS, shr, shp, SPy_0572), hinting towards specific mechanisms underlying the dispersal effect by SpeA. This finding opens up a discussion towards understanding a new mechanism involved in the pathogenesis of Streptococcus pyogenes and might help in understanding the bacterial infections in a better way.}, } @article {pmid31054133, year = {2019}, author = {Taha, MN and Saafan, AE and Ahmedy, A and El Gebaly, E and Khairalla, AS}, title = {Two novel synthetic peptides inhibit quorum sensing-dependent biofilm formation and some virulence factors in Pseudomonas aeruginosa PAO1.}, journal = {Journal of microbiology (Seoul, Korea)}, volume = {57}, number = {7}, pages = {618-625}, doi = {10.1007/s12275-019-8548-2}, pmid = {31054133}, issn = {1976-3794}, abstract = {Quorum sensing (QS) regulates virulence factor expression in Pseudomonas aeruginosa. Inhibiting the QS-controlled virulence factors without inhibiting the growth of P. aeruginosa is a promising approach for overcoming the widespread resistance of P. aeruginosa. This study was proposed to investigate the effects of two novel synthetic peptides on the biofilm development and virulence factor production of P. aeruginosa. The tested strain was P. aeruginosa PAO1. The results indicated that both of the synthetic peptides (LIVRHK and LIVRRK) inhibited (P < 0.05) the formation of biofilms and the production of virulence factors, including pyocyanin, protease, and rhamnolipids, without inhibiting the growth of PAO1. Additionally, we detected transcriptional changes related to QS and found a significant reduction in the levels of gene expression of lasI, lasR, rhlI, and rhlR. This study demonstrates that LIVRRK and LIVRHK are novel synthetic peptides that can act as potent inhibitors of QS-regulated virulence factors in P. aeruginosa. Moreover, these synthetic peptides have potential applications in the treatment of biofilmrelated diseases. Both peptides may be able to control chronic infections and biofilm-associated problems of P. aeruginosa.}, } @article {pmid31053580, year = {2019}, author = {Gu, D and Zhang, J and Hao, Y and Xu, R and Zhang, Y and Ma, Y and Wang, Q}, title = {Alternative Sigma Factor RpoX Is a Part of the RpoE Regulon and Plays Distinct Roles in Stress Responses, Motility, Biofilm Formation, and Hemolytic Activities in the Marine Pathogen Vibrio alginolyticus.}, journal = {Applied and environmental microbiology}, volume = {85}, number = {14}, pages = {}, doi = {10.1128/AEM.00234-19}, pmid = {31053580}, issn = {1098-5336}, abstract = {Vibrio alginolyticus is one of the most abundant microorganisms in marine environments and is also an opportunistic pathogen mediating high-mortality vibriosis in marine animals. Alternative sigma factors play essential roles in bacterial pathogens in the adaptation to environmental changes during infection and the adaptation to various niches, but little is known about them for V. alginolyticus Our previous investigation indicated that the transcript level of the gene rpoX significantly decreased in an RpoE mutant. Here, we found that rpoX was highly expressed in response to high temperature and low osmotic stress and was under the direct control of the alternative sigma factor RpoE and its own product RpoX. Moreover, transcriptome sequencing (RNA-seq) results showed that RpoE and RpoX had different regulons, although they coregulated 105 genes at high temperature (42°C), including genes associated with biofilm formation, motility, virulence, regulatory factors, and the stress response. RNA-seq and chromatin immunoprecipitation sequencing (ChIP-seq) analyses as well as electrophoretic mobility shift assays (EMSAs) revealed the distinct binding motifs of RpoE and RpoX proteins. Furthermore, quantitative real-time reverse transcription-PCR (qRT-PCR) analysis also confirmed that RpoX can upregulate genes associated with flagella, biofilm formation, and hemolytic activities at higher temperatures. rpoX abrogation does not appear to attenuate virulence toward model fish at normal temperature. Collectively, data from this study demonstrated the regulatory cascades of RpoE and an alternative sigma factor, RpoX, in response to heat and osmotic stresses and their distinct and overlapping roles in pathogenesis and stress responses in the marine bacterium V. alginolyticusIMPORTANCE The alternative sigma factor RpoE is essential for the virulence of Vibrio alginolyticus toward marine fish, coral, and other animals in response to sea surface temperature increases. In this study, we characterized another alternative sigma factor, RpoX, which is induced at high temperatures and under low-osmotic-stress conditions. The expression of rpoX is under the tight control of RpoE and RpoX. Although RpoE and RpoX coregulate 105 genes, they are programming different regulatory functions in stress responses and virulence in V. alginolyticus These findings illuminated the RpoE-RpoX-centered regulatory cascades and their distinct and overlapping regulatory roles in V. alginolyticus, which facilitates unraveling of the mechanisms by which the bacterium causes diseases in various sea animals in response to temperature fluctuations as well as the development of appropriate strategies to tackle infections by this bacterium.}, } @article {pmid31052271, year = {2019}, author = {Bahamondez-Canas, TF and Heersema, LA and Smyth, HDC}, title = {Current Status of In Vitro Models and Assays for Susceptibility Testing for Wound Biofilm Infections.}, journal = {Biomedicines}, volume = {7}, number = {2}, pages = {}, doi = {10.3390/biomedicines7020034}, pmid = {31052271}, issn = {2227-9059}, support = {DGE-1610403//National Science Foundation/ ; }, abstract = {Biofilm infections have gained recognition as an important therapeutic challenge in the last several decades due to their relationship with the chronicity of infectious diseases. Studies of novel therapeutic treatments targeting infections require the development and use of models to mimic the formation and characteristics of biofilms within host tissues. Due to the diversity of reported in vitro models and lack of consensus, this review aims to provide a summary of in vitro models currently used in research. In particular, we review the various reported in vitro models of Pseudomonas aeruginosa biofilms due to its high clinical impact in chronic wounds and in other chronic infections. We assess advances in in vitro models that incorporate relevant multispecies biofilms found in infected wounds, such as P. aeruginosa with Staphylococcus aureus, and additional elements such as mammalian cells, simulating fluids, and tissue explants in an attempt to better represent the physiological conditions found at an infection site. It is hoped this review will aid researchers in the field to make appropriate choices in their proposed studies with regards to in vitro models and methods.}, } @article {pmid31050052, year = {2019}, author = {Guo, J and Qin, S and Wei, Y and Liu, S and Peng, H and Li, Q and Luo, L and Lv, M}, title = {Silver nanoparticles exert concentration-dependent influences on biofilm development and architecture.}, journal = {Cell proliferation}, volume = {52}, number = {4}, pages = {e12616}, doi = {10.1111/cpr.12616}, pmid = {31050052}, issn = {1365-2184}, support = {//LU JIAXI International team program supported by the K.C. Wong Education Foundation and CAS/ ; QYZDJ-SSW-SLH031//the Key Research Program of Frontier Sciences, CAS/ ; 2016YFA0201200//the National Key R&D Program of China/ ; 2016YFA0400900//the National Key R&D Program of China/ ; U1632125//National Natural Science Foundation of China/ ; 21705159//National Natural Science Foundation of China/ ; 61571278//National Natural Science Foundation of China/ ; 31571014//National Natural Science Foundation of China/ ; }, abstract = {OBJECTIVES: To investigate the impact of silver nanoparticles (AgNPs) on the biofilm growth and architecture.

MATERIALS AND METHODS: Silver nitrate was reduced by d-maltose to prepare AgNPs in the presence of ammonia and sodium hydroxide. The physicochemical properties of AgNPs were characterized by transmission electron microscopy, ultraviolet-visible spectroscopy and inductively coupled plasma mass spectrometry. The development of biofilm with and without AgNPs was explored by crystal violet stain. The structures of mature biofilm were visually studied by confocal laser scanning microscopy and scanning electron microscopy. Bacterial cell, polysaccharide and protein within biofilm were assessed quantitatively by colony-counting method, phenol-sulphuric acid method and Bradford assay, respectively.

RESULTS: The spherical AgNPs (about 30 nm) were successfully synthesized. The effect of AgNPs on Pseudomonas aeruginosa biofilm development was concentration-dependent. Biofilm was more resistant to AgNPs than planktonic cells. Low doses of AgNPs exposure remarkably delayed the growth cycle of biofilm, whereas high concentration (18 μg/mL) of AgNPs fully prevented biofilm development. The analysis of biofilm architecture at the mature stage demonstrated that AgNPs exposure at all concentration led to significant decrease of cell viability within treated biofilms. However, sublethal doses of AgNPs increased the production of both polysaccharide and protein compared to control, which significantly changed the biofilm structure.

CONCLUSIONS: AgNPs exert concentration-dependent influences on biofilm development and structure, which provides new insight into the role of concentration played in the interaction between antibacterial nanoparticles and biofilm, especially, an ignored sublethal concentration associated with potential unintended consequences.}, } @article {pmid31044250, year = {2019}, author = {Alcaraz, E and García, C and Friedman, L and de Rossi, BP}, title = {The rpf/DSF signalling system of Stenotrophomonas maltophilia positively regulates biofilm formation, production of virulence-associated factors and β-lactamase induction.}, journal = {FEMS microbiology letters}, volume = {366}, number = {6}, pages = {}, doi = {10.1093/femsle/fnz069}, pmid = {31044250}, issn = {1574-6968}, abstract = {Stenotrophomonas maltophilia is a multidrug-resistant opportunistic pathogen. S. maltophilia quorum-sensing system is mediated by the diffusible signal factor (DSF), which synthesis depends on rpfF. It has been reported that rpfF disruption in S. maltophilia K279a leads to a loss of DSF synthesis, reduced levels of extracellular protease, swarming motility and virulence in the Galleria mellonella model. The aim of this work was to attain a deeper knowledge of the role of the rpf/DSF signalling system in S. maltophilia biofilm formation, phenotypic traits associated with biofilm development and virulence and antimicrobial susceptibility. To this end, comparative studies were conducted on S. maltophilia K279a and K279arpfF. The results presented here put in evidence the positive role of DSF in bacterial growth, biofilm formation, swimming and twitching motilities, DNAse, lipases and siderophores production as well as resistance to oxidative stress. Interestingly, DSF seems to be essential for the development of the spatially organised structure seen in mature biofilms. Therefore, DSF from S. maltophlia K279a positively regulates biofilm formation and virulence. Furthermore, DSF is necessary for the induction of L1 and L2 β-lactamase production in K279a. This is the first evidence of the role of the rpf/DSF signalling system in S. maltophilia β-lactam resistance.}, } @article {pmid31042554, year = {2019}, author = {de Carvalho Leonel, L and Carvalho, ML and da Silva, BM and Zamuner, S and Alberto-Silva, C and Silva Costa, M}, title = {Photodynamic Antimicrobial Chemotherapy (PACT) using methylene blue inhibits the viability of the biofilm produced by Candida albicans.}, journal = {Photodiagnosis and photodynamic therapy}, volume = {26}, number = {}, pages = {316-323}, doi = {10.1016/j.pdpdt.2019.04.026}, pmid = {31042554}, issn = {1873-1597}, abstract = {BACKGROUND: Candida albicans is an opportunistic fungus, an etiological agent of human infections, presenting high rates of morbidity and mortality. The resistance of C. albicans to conventional therapies has been reported due to the extensive use of conventional antifungals. Photodynamic antimicrobial chemotherapy (PACT) is a technique that combines a visible light with a specific wavelength and a photosensitizer, producing ROS and permanent damages in the treated cells.

METHODS: In this work, the effects of PACT, using Methylene Blue (MB), as a photosensitizer, on C. albicans development were studied.

RESULTS: Significant reduction in both cell growth and biofilm formation after PACT were observed, in a dependent manner on both MB concentration and fluence. In the presence of MB 0.02 mg/mL, it was observed inhibition in biofilm formation of ˜58, 70 and 74%, using fluences of 10, 20 and 30 J/cm2, respectively. Also, it was observed inhibition of 54, 66 and 55% in the presence of MB 0.01, 0.02 and 0.05 mg/mL, respectively in the viability of biofilm produced by C. albicans. The number of both yeast and filaments present in the structure of biofilm were reduced after PACT. Furthermore, PACT changed the growth kinetics of C. albicans. Interestingly, we demonstrated increase in the extent of lag phase and an alteration in the profile of the exponential phase after PACT.

CONCLUSIONS: Taken together, these results indicate the potential PACT effects using MB to decrease the C. albicans development.}, } @article {pmid31040831, year = {2019}, author = {Crenier, C and Sanchez-Thirion, K and Bec, A and Felten, V and Ferriol, J and González, AG and Leflaive, J and Perrière, F and Ten-Hage, L and Danger, M}, title = {Interactive Impacts of Silver and Phosphorus on Autotrophic Biofilm Elemental and Biochemical Quality for a Macroinvertebrate Consumer.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {732}, doi = {10.3389/fmicb.2019.00732}, pmid = {31040831}, issn = {1664-302X}, abstract = {Autotrophic biofilms are complex and fundamental biological compartments of many aquatic ecosystems. In particular, these biofilms represent a major resource for many invertebrate consumers and the first ecological barrier against toxic metals. To date, very few studies have investigated the indirect effects of stressors on upper trophic levels through alterations of the quality of biofilms for their consumers. In a laboratory study, we investigated the single and combined effects of phosphorus (P) availability and silver, a re-emerging contaminant, on the elemental [carbon (C):nitrogen (N):P ratios] and biochemical (fatty acid profiles) compositions of a diatom-dominated biofilm initially collected in a shallow lake. We hypothesized that (1) P and silver, through the replacement of diatoms by more tolerant primary producer species, reduce the biochemical quality of biofilms for their consumers while (2) P enhances biofilm elemental quality and (3) silver contamination of biofilm has negative effects on consumers life history traits. The quality of biofilms for consumers was assessed for a common crustacean species, Gammarus fossarum, by measuring organisms' survival and growth rates during a 42-days feeding experiment. Results mainly showed that species replacement induced by both stressors affected biofilm fatty acid compositions, and that P immobilization permitted to achieve low C:P biofilms, whatever the level of silver contamination. Gammarids growth and survival rates were not significantly impacted by the ingestion of silver-contaminated resource. On the contrary, we found a significant positive relationship between the biofilm P-content and gammarids growth. This study underlines the large indirect consequences stressors could play on the quality of microbial biomass for consumers, and, in turn, on the whole food web.}, } @article {pmid31040399, year = {2019}, author = {Hold, GL and Allen-Vercoe, E}, title = {Gut microbial biofilm composition and organisation holds the key to CRC.}, journal = {Nature reviews. Gastroenterology & hepatology}, volume = {16}, number = {6}, pages = {329-330}, doi = {10.1038/s41575-019-0148-4}, pmid = {31040399}, issn = {1759-5053}, mesh = {Biofilms ; *Colonic Neoplasms ; *Gastrointestinal Microbiome ; Humans ; Intestinal Mucosa ; }, } @article {pmid31040333, year = {2019}, author = {Melo, LDR and Ferreira, R and Costa, AR and Oliveira, H and Azeredo, J}, title = {Efficacy and safety assessment of two enterococci phages in an in vitro biofilm wound model.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {6643}, doi = {10.1038/s41598-019-43115-8}, pmid = {31040333}, issn = {2045-2322}, support = {SFRH/BPD/111653/2015//Ministry of Education and Science | Funda&#x00E7;&#x00E3;o para a Ci&#x00EA;ncia e a Tecnologia (Portuguese Science and Technology Foundation)/ ; SFRH/BPD/94648/2013//Ministry of Education and Science | Funda&#x00E7;&#x00E3;o para a Ci&#x00EA;ncia e a Tecnologia (Portuguese Science and Technology Foundation)/ ; UID/BIO/04469/2013//Ministry of Education and Science | Funda&#x00E7;&#x00E3;o para a Ci&#x00EA;ncia e a Tecnologia (Portuguese Science and Technology Foundation)/ ; POCI-01-0145-FEDER-006684//Ministry of Education and Science | Funda&#x00E7;&#x00E3;o para a Ci&#x00EA;ncia e a Tecnologia (Portuguese Science and Technology Foundation)/ ; PTDC/BBB-BSS/6471/2014//Ministry of Education and Science | Funda&#x00E7;&#x00E3;o para a Ci&#x00EA;ncia e a Tecnologia (Portuguese Science and Technology Foundation)/ ; NORTE-01-0145-FEDER-000004//Ministry of Education and Science | Funda&#x00E7;&#x00E3;o para a Ci&#x00EA;ncia e a Tecnologia (Portuguese Science and Technology Foundation)/ ; }, abstract = {Chronic wounds affect thousands of people worldwide, causing pain and discomfort to patients and represent significant economical burdens to health care systems. The treatment of chronic wounds is very difficult and complex, particularly when wounds are colonized by bacterial biofilms which are highly tolerant to antibiotics. Enterococcus faecium and Enterococcus faecalis are within the most frequent bacteria present in chronic wounds. Bacteriophages (phages) have been proposed as an efficient and alternative against antibiotic-resistant infections, as those found in chronic wounds. We have isolated and characterized two novel enterococci phages, the siphovirus vB_EfaS-Zip (Zip) and the podovirus vB_EfaP-Max (Max) to be applied during wound treatment. Both phages demonstrated lytic behavior against E. faecalis and E. faecium. Genome analysis of both phages suggests the absence of genes associated with lysogeny. A phage cocktail containing both phages was tested against biofilms formed in wound simulated conditions at a multiplicity of infection of 1.0 and a 2.5 log CFU.mL-1 reduction in the bacterial load after at 3 h of treatment was observed. Phages were also tested in epithelial cells colonized by these bacterial species and a 3 log CFU.mL-1 reduction was observed using both phages. The high efficacy of these new isolated phages against multi-species biofilms, their stability at different temperatures and pH ranges, short latent periods and non-cytotoxicity to epithelial cells suggest their therapeutic use to control infectious biofilms present in chronic wounds.}, } @article {pmid31038914, year = {2019}, author = {Nagay, BE and Dini, C and Cordeiro, JM and Ricomini-Filho, AP and de Avila, ED and Rangel, EC and da Cruz, NC and Barão, VAR}, title = {Visible-Light-Induced Photocatalytic and Antibacterial Activity of TiO2 Codoped with Nitrogen and Bismuth: New Perspectives to Control Implant-Biofilm-Related Diseases.}, journal = {ACS applied materials & interfaces}, volume = {11}, number = {20}, pages = {18186-18202}, doi = {10.1021/acsami.9b03311}, pmid = {31038914}, issn = {1944-8252}, abstract = {Biofilm-associated diseases are one of the main causes of implant failure. Currently, the development of implant surface treatment goes beyond the osseointegration process and focuses on the creation of surfaces with antimicrobial action and with the possibility to be re-activated (i.e., light source activation). Titanium dioxide (TiO2), an excellent photocatalyst used for photocatalytic antibacterial applications, could be a great alternative, but its efficiency is limited to the ultraviolet (UV) range of the electromagnetic spectrum. Since UV radiation has carcinogenic potential, we created a functional TiO2 coating codoped with nitrogen and bismuth via the plasma electrolytic oxidation (PEO) of titanium to achieve an antibacterial effect under visible light with re-activation potential. A complex surface topography was demonstrated by scanning electron microscopy and three-dimensional confocal laser scanning microscopy. Additionally, PEO-treated surfaces showed greater hydrophilicity and albumin adsorption compared to control, untreated titanium. Bismuth incorporation shifted the band gap of TiO2 to the visible region and facilitated higher degradation of methyl orange (MO) in the dark, with a greater reduction in the concentration of MO after visible-light irradiation even after 72 h of aging. These results were consistent with the in vitro antibacterial effect, where samples with nitrogen and bismuth in their composition showed the greatest bacterial reduction after 24 h of dual-species biofilm formation (Streptococcus sanguinis and Actinomyces naeslundii) in darkness with a superior effect at 30 min of visible-light irradiation. In addition, such a coating presents reusable photocatalytic potential and good biocompatibility by presenting a noncytotoxicity effect on human gingival fibroblast cells. Therefore, nitrogen and bismuth incorporation into TiO2 via PEO can be considered a promising alternative for dental implant application with antibacterial properties in darkness, with a stronger effect after visible-light application.}, } @article {pmid31038103, year = {2019}, author = {El-Khatib, M and Tetreau, G and Colletier, JP}, title = {[Porins: a vital role and a social link within the bacterial biofilm of P. stuartii].}, journal = {Medecine sciences : M/S}, volume = {35}, number = {4}, pages = {291-295}, doi = {10.1051/medsci/2019059}, pmid = {31038103}, issn = {1958-5381}, } @article {pmid31037765, year = {2019}, author = {Vinod Kumar, K and Lall, C and Raj, RV and Vijayachari, P}, title = {Coaggregation and biofilm formation of Leptospira with Staphylococcus aureus.}, journal = {Microbiology and immunology}, volume = {63}, number = {3-4}, pages = {147-150}, doi = {10.1111/1348-0421.12679}, pmid = {31037765}, issn = {1348-0421}, support = {Intramural Grant//Indian Council of Medical Research/ ; }, mesh = {Biofilms/*growth & development ; Coinfection/microbiology/pathology ; Leptospira interrogans/*growth & development ; Leptospirosis/microbiology/pathology ; Microbial Interactions/*physiology ; Microscopy, Electron, Scanning ; Skin Diseases, Bacterial/*microbiology/pathology ; Staphylococcal Infections/microbiology/pathology ; Staphylococcus aureus/*growth & development ; }, abstract = {It is not known how Leptospira react to wound or a cut infected with microbes, such as pathogenic Staphylococcus, or their common habitat on oral or nasal mucosal membranes. In the present study, Staphylococcus aureus MTCC-737 showed strong co-aggregation with leptospiral strains (>75%, visual score of + 4) in vitro. All tested strains of Leptospira were able to form biofilm with S. aureus. Scanning electron microscopy analysis revealed intertwined networks of attached cells of L. interrogans and S. aureus, thus providing evidence of a matrix-like structure. This phenomenon may have implications in Leptospira infection, which occurs via cuts and wounds of the skin.}, } @article {pmid31036689, year = {2019}, author = {Vargas-Cruz, N and Reitzel, RA and Rosenblatt, J and Chaftari, AM and Wilson Dib, R and Hachem, R and Kontoyiannis, DP and Raad, II}, title = {Nitroglycerin-Citrate-Ethanol Catheter Lock Solution Is Highly Effective for In Vitro Eradication of Candida auris Biofilm.}, journal = {Antimicrobial agents and chemotherapy}, volume = {63}, number = {7}, pages = {}, doi = {10.1128/AAC.00299-19}, pmid = {31036689}, issn = {1098-6596}, abstract = {Candida auris poses emerging risks for causing severe central line-associated bloodstream infections. We tested in vitro the ability of antifungal lock solutions to rapidly eradicate C. auris biofilms. Liposomal amphotericin B, amphotericin B deoxycholate, fluconazole, voriconazole, micafungin, caspofungin, and anidulafungin failed to completely eradicate all 10 tested C. auris biofilms. Conversely, nitroglycerin-citrate-ethanol (NiCE) catheter lock solution completely eradicated all replicates for all of C. auris biofilms tested.}, } @article {pmid31035915, year = {2019}, author = {Perera, M and Wijayarathna, D and Wijesundera, S and Chinthaka, M and Seneviratne, G and Jayasena, S}, title = {Biofilm mediated synergistic degradation of hexadecane by a naturally formed community comprising Aspergillus flavus complex and Bacillus cereus group.}, journal = {BMC microbiology}, volume = {19}, number = {1}, pages = {84}, doi = {10.1186/s12866-019-1460-4}, pmid = {31035915}, issn = {1471-2180}, support = {AP/3/2/2014/RG/12//University of Colombo/ ; }, abstract = {BACKGROUND: The hydrophobic nature of hydrocarbons make them less bioavailable to microbes, generally leading to low efficiency in biodegradation. Current bioremediation strategies for hydrocarbon contamination, uses induced mixed microbial cultures. This in-vitro study demonstrates the utilization of naturally occurring communities in suitable habitats for achieving highly efficient, synergistic degradation of hydrocarbons in a simple community structure without additives.

METHODS: Enrichment media supplemented with 1% (7652.53 mg/L) hexadecane (HXD) as the sole carbon source were inoculated with samples of soil with waste polythene, collected from a municipal landfill in order to isolate microbial communities. Gas Chromatography-Mass Spectrometry (GC-MS) analysis was performed on HXD grown co-cultures and individual counterparts after 14 days incubation and percentage degradation was calculated. Microbes were identified using 16S rRNA gene and Internal Transcribed Spacer region sequencing. Biofilm formation was confirmed through scanning electron microscopy, in the most efficient community.

RESULTS: Three mixed communities (C1, C2 and C3) that demonstrated efficient visual disintegration of the HXD layer in the static liquid cultures were isolated. The C1 community showed the highest activity, degrading > 99% HXD within 14 days. C1 comprised of a single fungus and a bacterium and they were identified as a Bacillus sp. MM1 and an Apsergillus sp. MM1. The co-culture and individual counterparts of the C1 community were assayed for HXD degradation by GC-MS. Degradation by the fungal and bacterial monocultures were 52.92 ± 8.81% and 9.62 ± 0.71% respectively, compared to 99.42 ± 0.38% by the co-culture in 14 days. This proved the synergistic behavior of the community. Further, this community demonstrated the formation of a biofilm in oil-water interface in the liquid medium. This was evidenced from scanning electron microscopy (SEM) showing the Bacillus cells attached on to Aspergillus mycelia.

CONCLUSIONS: This study demonstrates the utilization of naturally formed fungal-bacterial communities for enhanced biodegradation of hydrocarbons such as hexadecane and reports for the first time, synergistic degradation of hexadecane through biofilm formation, by a community comprising of Bacillus cereus group and Aspergillus flavus complex.}, } @article {pmid31034965, year = {2019}, author = {Yonezawa, H and Osaki, T and Hojo, F and Kamiya, S}, title = {Effect of Helicobacter pylori biofilm formation on susceptibility to amoxicillin, metronidazole and clarithromycin.}, journal = {Microbial pathogenesis}, volume = {132}, number = {}, pages = {100-108}, doi = {10.1016/j.micpath.2019.04.030}, pmid = {31034965}, issn = {1096-1208}, abstract = {The human gastric pathogen Helicobacter pylori forms biofilms in vitro and in vivo. We previously demonstrated that H. pylori biofilm formation in vitro decreased its susceptibility to clarithromycin (CAM). The aim of this study was to evaluate the effects of biofilm formation on amoxicillin (AMPC) and metronidazole (MNZ) susceptibility. In addition, we assessed the influence of biofilms of CAM resistant H. pylori on CAM susceptibility. It was shown that high levels of efflux pump gene transcripts were detected in biofilm cells of all H. pylori strains used in this study. H. pylori biofilm biomass was significantly decreased compared to initial biomass after treatment with the minimum inhibitory concentration (MIC) of AMPC. Similarly, the biofilm biomass of H. pylori decreased after treatment with MIC of MNZ, although the difference was not statistically significant. However, minimum bactericidal concentrations (MBCs) of AMPC or MNZ to biofilm cells were higher than those of planktonic cells. The biofilm biomasses of all of the CAM resistant strains were significantly decreased compared to initial biomass after treatment with 2x MIC of CAM. However, the viability of the CAM treated biofilm cells with 2x MIC of CAM was not significantly reduced compared to initial cell numbers with the exception of one strain. The viability of biofilm cells of all strains was higher than that of planktonic cells after treatment with various concentrations of CAM. These results indicate that biofilm cells were more resistant to these antibiotics than planktonic cells and that the assessment of the ability to form biofilms in H. pylori is important for eradication of this microorganism.}, } @article {pmid31034083, year = {2019}, author = {Bernardi, S and Continenza, MA and Al-Ahmad, A and Karygianni, L and Follo, M and Filippi, A and Macchiarelli, G}, title = {Streptococcus spp. and Fusobacterium nucleatum in tongue dorsum biofilm from halitosis patients: a fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) study.}, journal = {The new microbiologica}, volume = {42}, number = {2}, pages = {108-113}, pmid = {31034083}, issn = {1121-7138}, mesh = {*Biofilms ; *Fusobacterium nucleatum/physiology ; *Halitosis/microbiology ; Humans ; In Situ Hybridization, Fluorescence ; Microscopy, Confocal ; *Streptococcus/physiology ; *Tongue/microbiology ; }, abstract = {The present study involved a qualitative and quantitative evaluation of tongue dorsum biofilms sampled from halitosis patients and healthy volunteers. The aim of the study was to quantify the distribution of Streptococcus spp. and Fusobacterium nucleatum within the oral halitosis biofilm in order to highlight the role of these bacterial members in halitosis. Tongue plaque samples from four halitosis-diagnosed patients and four healthy volunteers were analyzed and compared. The visualization and quantification of the tongue dorsum biofilm was performed combining fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM). Eubacteria, Streptococcus spp. and Fusobacterium nucleatum were stained using specific fluorescent probes. For a comparison of the two tested biofilm groups the Wilcoxon rank-sum test was used. Morphological analysis by CLSM illustrated the distribution of the species which were tracked. Streptococcus spp. appeared to be enclosed within the samples and always associated to F. nucleatum. Furthermore, compared to the control group the biofilm within the halitosis group contained significantly higher proportions of F. nucleatum and Streptococcus spp., as revealed by the FISH and CLSM-analysis. The total microbial load and relative proportions of F. nucleatum and Streptococcus spp. can be considered as causative factors of halitosis and thus, as potential treatment targets.}, } @article {pmid31033962, year = {2019}, author = {Danikowski, KM and Cheng, T}, title = {Colorimetric Analysis of Alkaline Phosphatase Activity in S. aureus Biofilm.}, journal = {Journal of visualized experiments : JoVE}, volume = {}, number = {146}, pages = {}, doi = {10.3791/59285}, pmid = {31033962}, issn = {1940-087X}, abstract = {Alkaline phosphatase (ALP) is a common enzyme expressed in both prokaryotic and eukaryotic cells. It catalyzes the hydrolysis of phosphate monoesters from many molecules at basic pH and plays an indispensable role in phosphate metabolism. In humans, eukaryotic ALP is one of the most frequently used enzymatic signals in diagnosing various diseases, such as cholestasis and rickets. In S. aureus, ALP is detected exclusively on the cell membrane; it is also expressed as a secretory form as well. Yet, little is known about its function in biofilm formation. The purpose of this manuscript is to develop a quick and reliable assay to measure ALP activity in S. aureus biofilm that does not require protein isolation. Using p-nitrophenyl phosphate (pNPP) as a substrate, we measured ALP activity in S. aureus biofilm formed in 96-well tissue culture plates. Activity was based on the formation of the soluble reaction product measured by 405 nm absorbance. The high throughput nature of the 96 well tissue culture plate method provides a sensitive and reproducible method for ALP activity assays. The same experimental set up can also be extended to measure other extracellular molecular markers related to biofilm formation.}, } @article {pmid31033283, year = {2019}, author = {Benoit, DSW and Sims, KR and Fraser, D}, title = {Nanoparticles for Oral Biofilm Treatments.}, journal = {ACS nano}, volume = {13}, number = {5}, pages = {4869-4875}, doi = {10.1021/acsnano.9b02816}, pmid = {31033283}, issn = {1936-086X}, abstract = {Pathogenic oral biofilms are universal, chronic, and costly. Despite advances in understanding the mechanisms of biofilm formation and persistence, novel and effective treatment options remain scarce. Nanoparticle-mediated eradication of the biofilm matrix and resident bacteria holds great potential. In particular, nanoparticles that target specific microbial and biofilm features utilizing nontoxic materials are well-suited for clinical translation. However, much work remains to characterize the local and systemic effects of therapeutic agents that are topically applied to chronic biofilms, such as those that cause dental caries. In this Perspective, we summarize the pathogenesis of oral biofilms, describe current and future nanoparticle-mediated treatment approaches, and highlight outstanding questions that are paramount to answer for effectively targeting and treating oral biofilms.}, } @article {pmid31033028, year = {2019}, author = {Tuna, T and Kuhlmann, L and Bishti, S and Sirazitdinova, E and Deserno, T and Wolfart, S}, title = {Removal of simulated biofilm at different implant crown designs with interproximal oral hygiene aids: An in vitro study.}, journal = {Clinical oral implants research}, volume = {30}, number = {7}, pages = {627-636}, doi = {10.1111/clr.13448}, pmid = {31033028}, issn = {1600-0501}, abstract = {OBJECTIVES: To compare the removal of simulated biofilm at two different implant-supported restoration designs with various interproximal oral hygiene aids.

METHODS: Mandibular models with a missing first molar were fabricated and provided with single implant analogues (centrally or distally placed) and two different crown designs (conventional [CCD] and alternative crown design [ACD]). Occlusion spray was applied to the crowns to simulate artificial biofilm. Thirty participants (dentists, dental hygienists, and laypersons) were equally divided and asked to clean the interproximal areas with five different cleaning devices to further evaluate if there were differences in their cleaning ability. The outcome was measured via standardized photos and the cleaning ratio, representing the cleaned surfaces in relation to the respective crown surface. Statistical analysis was performed by linear mixed-effects model with fixed effects for cleaning tools, surfaces, crown design and type of participant, and random effects for crowns.

RESULTS: The mean cleaning ratio for the investigated tools and crown designs were (in%): Super floss: 76 ± 13/ACD and 57 ± 14/CCD (highest cleaning efficiency), followed by dental floss: 66 ± 13/ACD and 56 ± 15/CCD, interdental brush: 55 ± 10/ACD and 45 ± 9/CCD, electric interspace brush: 31 ± 10/ACD and 30 ± 1/CCD, microdroplet floss: 8 ± 9/ACD and 9 ± 8/CCD. There was evidence of an overall effect of each factor "cleaning tool," "surface," "crown design," and "participant" (p < 0.0001).

CONCLUSIONS: ACD allowed more removal of the artificial biofilm than CCD with Super floss, dental floss, and interdental brush. Flossing and interproximal brushing were the most effective cleaning methods. A complete removal of the artificial biofilm could not be achieved in any group.}, } @article {pmid31031431, year = {2019}, author = {Bhatwalkar, SB and Gound, SS and Mondal, R and Srivastava, RK and Anupam, R}, title = {Anti-biofilm and Antibacterial Activity of Allium sativum Against Drug Resistant Shiga-Toxin Producing Escherichia coli (STEC) Isolates from Patient Samples and Food Sources.}, journal = {Indian journal of microbiology}, volume = {59}, number = {2}, pages = {171-179}, doi = {10.1007/s12088-019-00784-3}, pmid = {31031431}, issn = {0046-8991}, abstract = {Escherichia coli (E. coli) colonizes human intestinal tract and is usually harmless to the host. However, several strains of E. coli have acquired virulent genes and could cause enteric diseases, urinary tract and even brain infections. Shiga toxin producing Escherichia coli (STEC) is an enterohaemorrhagic E. coli (EHEC) which can result in bloody diarrhoea and could potentially lead to deadly heamolytic uremic syndrome (HUS). STEC is one of the important food borne pathogens that causes food poisoning leading to diarrhoea and number of STEC outbreaks have occurred across the world. The use of standard antibiotics to treat STEC infection is not recommended as it increases the production of shiga toxin which could lead to HUS. Therefore, use of alternative approaches which include use of plant products to treat STEC infections have been gaining attention. The objective of this study was to evaluate the antibacterial and anti-biofilm activity of garlic (Allium sativum) against STEC strains isolated from various patient and food samples using in vitro assays. The microbiological isolation of STEC from various patient and food samples resulted in eight STEC isolates of which seven strains were multidrug resistant. Antibacterial assay results indicated that all the strains exhibited dose dependent sensitivity towards garlic with zone of inhibition diameters ranging from 7 to 24 mm with 15 µl of fresh garlic extract (FGE). Minimum inhibitory concentration (MIC) of FGE for isolates ranged from 30 to 140 µl/ml. Interestingly, the biofilm formation of all isolates in presence of 4% of FGE decreased by 35 to 59%. FTIR analysis indicated that treatment with 1% FGE results in compositional and content changes in the biofilm. In addition, the total carbohydrate content of biofilm was reduced by 40% upon 1% FGE treatment. The results of the present study report for the first time the antibacterial and anti-biofilm activity of garlic against STEC. The findings will enable development of novel garlic organosulfide based drugs for the prevention and treatment of STEC infections.}, } @article {pmid31029662, year = {2019}, author = {Noverr, MC and Fidel, PL}, title = {Questions remain regarding the presence of fungal species biofilm in women with vulvovaginal candidiasis.}, journal = {American journal of obstetrics and gynecology}, volume = {221}, number = {2}, pages = {169}, doi = {10.1016/j.ajog.2019.04.017}, pmid = {31029662}, issn = {1097-6868}, } @article {pmid31029348, year = {2019}, author = {Daengngam, C and Lethongkam, S and Srisamran, P and Paosen, S and Wintachai, P and Anantravanit, B and Vattanavanit, V and Voravuthikunchai, S}, title = {Green fabrication of anti-bacterial biofilm layer on endotracheal tubing using silver nanoparticles embedded in polyelectrolyte multilayered film.}, journal = {Materials science & engineering. C, Materials for biological applications}, volume = {101}, number = {}, pages = {53-63}, doi = {10.1016/j.msec.2019.03.061}, pmid = {31029348}, issn = {1873-0191}, abstract = {Endotracheal tubes (ETTs) are a common source of bacterial colonization, leading to ventilator-associated pneumonia (VAP). This research developed a biofilm-resistant ETT, following the principles of green chemistry. Using an aqueous layer-by-layer (LbL) technique, a thick polyelectrolyte multilayered film was deposited on a ventilation tube. The polyelectrolyte multilayered film accommodated silver nanoparticles (AgNPs) formed in situ by reducing Ag+ ions with Eucalyptus citriodora leaf extract. The multilayered film coating conformed to the curved surfaces of the ETT. Film thickness and silver content increased exponentially with the number of polyelectrolyte bilayer pairs, and a sufficiently high AgNPs content of 10-30%w/w was obtained at 75 to 125 bilayer films. Adhesion of the Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa was prevented by 99.9 and 99.99%, respectively, without cytotoxic effects against human lung epithelial cells (p < 0.05).}, } @article {pmid31028534, year = {2019}, author = {Perez-Tanoira, R and Aarnisalo, A and Haapaniemi, A and Saarinen, R and Kuusela, P and Kinnari, TJ}, title = {Bacterial biofilm in salivary stones.}, journal = {European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery}, volume = {276}, number = {6}, pages = {1815-1822}, doi = {10.1007/s00405-019-05445-1}, pmid = {31028534}, issn = {1434-4726}, abstract = {PURPOSE: To assess the susceptibility of salivary stones to bacterial biofilm formation, which may be involved in the development of salivary gland infection, and to investigate a relation between microbiological aspects and patient characteristics.

METHODS: This prospective study comprises of 54 patients with sialolithiasis attended in Helsinki University Hospital during 2014-2016. A total of 55 salivary stones were removed, and studied for biofilm formation using fluorescence microscopy and sonication. The isolated organisms were quantified and identified using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

RESULTS: Biofilm formation was confirmed on the surface of 39 (70.9%) stones. A total of 96 microorganisms were isolated from 45 salivary stones (81.8%). Two or more organisms were isolated in 33 (73.3%) cases. The main isolates were Streptococcus mitis/oralis (n = 27; 28.1%), followed by Streptococcus anginosus (n = 10; 9.6%), Rothia spp. (n = 8; 8.3%), Streptococcus constellatus (n = 7; 7.3%), and Streptococcus gordonii (n = 6; 6.2%). In all patients showing pre-operative (12 cases) or peri-operative (three cases) drainage of pus, the presence of biofilm was detected in microscopy (p = 0.004). Four patients showed post-operative infection, and in three of them (75.0%), the presence of biofilm was detected. Increased number of pus drainage was found among patients with reflux symptoms or use of proton-pump inhibitors.

CONCLUSIONS: Salivary stones are susceptible to bacterial biofilm formation, which could be related with the development and severity of the inflammation and the refractory nature of the disease. Sonication of salivary gland stones could be a useful method for finding the etiology of the chronic infection.}, } @article {pmid31027789, year = {2019}, author = {Ostrov, I and Sela, N and Belausov, E and Steinberg, D and Shemesh, M}, title = {Adaptation of Bacillus species to dairy associated environment facilitates their biofilm forming ability.}, journal = {Food microbiology}, volume = {82}, number = {}, pages = {316-324}, doi = {10.1016/j.fm.2019.02.015}, pmid = {31027789}, issn = {1095-9998}, abstract = {Biofilm-forming Bacillus species are often involved in contamination of dairy products and therefore present a major microbiological challenge in the field of food quality and safety. In this study, we sequenced and analyzed the genomes of milk- and non-milk-derived Bacillus strains, and evaluated their biofilm-formation potential in milk. Unlike non-dairy Bacillus isolates, the dairy-associated Bacillus strains were characterized by formation of robust submerged and air-liquid interface biofilm (pellicle) during growth in milk. Moreover, genome comparison analysis revealed notable differences in putative biofilm-associated determinants between the dairy and non-dairy Bacillus isolates, which correlated with biofilm phenotype. These results suggest that biofilm formation by Bacillus species might represent a presumable adaptation strategy to the dairy environment.}, } @article {pmid31027768, year = {2019}, author = {Pang, X and Yuk, HG}, title = {Effects of the colonization sequence of Listeria monocytogenes and Pseudomonas fluorescens on survival of biofilm cells under food-related stresses and transfer to salmon.}, journal = {Food microbiology}, volume = {82}, number = {}, pages = {142-150}, doi = {10.1016/j.fm.2019.02.002}, pmid = {31027768}, issn = {1095-9998}, abstract = {This study evaluated how the colonization sequence of Listeria monocytogenes and Pseudomonas fluorescens affects biofilm formation and biofilm cell response to food-related stress (desiccation or disinfection) as well as the transferability of L. monocytogenes to salmon products. The results showed that the colonization sequence did not affect the population of dual species biofilms. Furthermore, survival number of L. monocytogenes was 0.8 log CFU/cm2 higher when P. fluorescens was the first colonizer during desiccation or disinfectant treatment in comparison with dual-species biofilms with other colonization sequences. A lower transfer rate of L. monocytogenes biofilm cells from dual-species biofilms was observed as compared to single species biofilms. In particular, L. monocytogenes cells detached at a slower rate during transfer to 10 slices of salmon from dual-species biofilms first established by P. fluorescens. Confocal images revealed more exopolysaccharide production in dual-speciesbiofilms first established by P. fluorescens than in biofilms generated via other sequences. These results indicate that preexisting P. fluorescens biofilms on stainless steel can enhance resistance of L. monocytogenes to desiccation and disinfection, although this setup decreased the transfer rate of L. monocytogenes to salmon slices. Thus, this study highlights the risk of L. monocytogenes contamination in pre-formed Pseudomonas biofilms at salmon processing facilities.}, } @article {pmid31025881, year = {2019}, author = {Rebrošová, K and Šiler, M and Samek, O and Růžička, F and Bernatová, S and Ježek, J and Zemánek, P and Holá, V}, title = {Identification of ability to form biofilm in Candida parapsilosis and Staphylococcus epidermidis by Raman spectroscopy.}, journal = {Future microbiology}, volume = {14}, number = {}, pages = {509-517}, doi = {10.2217/fmb-2018-0297}, pmid = {31025881}, issn = {1746-0921}, abstract = {Aim: Finding rapid, reliable diagnostic methods is a big challenge in clinical microbiology. Raman spectroscopy is an optical method used for multiple applications in scientific fields including microbiology. This work reports its potential in identifying biofilm positive strains of Candida parapsilosis and Staphylococcus epidermidis. Materials & methods: We tested 54 S. epidermidis strains (23 biofilm positive, 31 negative) and 51 C. parapsilosis strains (27 biofilm positive, 24 negative) from colonies on Mueller-Hinton agar plates, using Raman spectroscopy. Results: The accuracy was 98.9% for C. parapsilosis and 96.1% for S. epidermidis. Conclusion: The method showed great potential for identifying biofilm positive bacterial and yeast strains. We suggest that Raman spectroscopy might become a useful aid in clinical diagnostics.}, } @article {pmid31025575, year = {2019}, author = {Gazzola, G and Habimana, O and Quinn, L and Casey, E and Murphy, CD}, title = {Population dynamics of a dual Pseudomonas putida-Pseudomonas fluorescens biofilm in a capillary bioreactor.}, journal = {Biofouling}, volume = {35}, number = {3}, pages = {299-307}, doi = {10.1080/08927014.2019.1598397}, pmid = {31025575}, issn = {1029-2454}, abstract = {Most biofilm studies employ single species, yet in nature biofilms exist as mixed cultures, with inevitable effects on growth and development of each species present. To investigate how related species of bacteria interact in biofilms, two Pseudomonas spp., Pseudomonas fluorescens and Pseudomonas putida, were cultured in capillary bioreactors and their growth measured by confocal microscopy and cell counting. When inoculated in pure culture, both bacteria formed healthy biofilms within 72 h with uniform coverage of the surface. However, when the bioreactors were inoculated with both bacteria simultaneously, P. putida was completely dominant after 48 h. Even when the inoculation by P. putida was delayed for 24 h, P. fluorescens was eliminated from the capillary within 48 h. It is proposed that production of the lipopeptide putisolvin by P. putida is the likely reason for the reduction of P. fluorescens. Putisolvin biosynthesis in the dual-species biofilm was confirmed by mass spectrometry.}, } @article {pmid31024468, year = {2019}, author = {Abdel-Nour, M and Su, H and Duncan, C and Li, S and Raju, D and Shamoun, F and Valton, M and Ginevra, C and Jarraud, S and Guyard, C and Kerman, K and Terebiznik, MR}, title = {Polymorphisms of a Collagen-Like Adhesin Contributes to Legionella pneumophila Adhesion, Biofilm Formation Capacity and Clinical Prevalence.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {604}, doi = {10.3389/fmicb.2019.00604}, pmid = {31024468}, issn = {1664-302X}, abstract = {Legionellosis is a severe respiratory illness caused by the inhalation of aerosolized water droplets contaminated with the opportunistic pathogen Legionella pneumophila. The ability of L. pneumophila to produce biofilms has been associated with its capacity to colonize and persist in human-made water reservoirs and distribution systems, which are the source of legionellosis outbreaks. Nevertheless, the factors that mediate L. pneumophila biofilm formation are largely unknown. In previous studies we reported that the adhesin Legionella collagen-like protein (Lcl), is required for auto-aggregation, attachment to multiple surfaces and the formation of biofilms. Lcl structure contains three distinguishable regions: An N-terminal region with a predicted signal sequence, a central region containing tandem collagen-like repeats (R-domain) and a C-terminal region (C-domain) with no significant homology to other known proteins. Lcl R-domain encodes tandem repeats of the collagenous tripeptide Gly-Xaa-Yaa (GXY), a motif that is key for the molecular organization of mammalian collagen and mediates the binding of collagenous proteins to different cellular and environmental ligands. Interestingly, Lcl is polymorphic in the number of GXY tandem repeats. In this study, we combined diverse biochemical, genetic, and cellular approaches to determine the role of Lcl domains and GXY repeats polymorphisms on the structural and functional properties of Lcl, as well as on bacterial attachment, aggregation and biofilm formation. Our results indicate that the R-domain is key for assembling Lcl collagenous triple-helices and has a more preponderate role over the C-domain in Lcl adhesin binding properties. We show that Lcl molecules oligomerize to form large supramolecular complexes to which both, R and C-domains are required. Furthermore, we found that the number of GXY tandem repeats encoded in Lcl R-domain correlates positively with the binding capabilities of Lcl and with the attachment and biofilm production capacity of L. pneumophila strains. Accordingly, the number of GXY tandem repeats in Lcl influences the clinical prevalence of L. pneumophila strains. Therefore, the number of Lcl tandem repeats could be considered as a potential predictor for virulence in L. pneumophila isolates.}, } @article {pmid31023592, year = {2019}, author = {Król, J and Nawrot, U and Bartoszewicz, M}, title = {Activity of base analogues (5-fluorouracil, 5-flucytosine) against planktonic cells and mature biofilm of Candida yeast. Effect of combination with folinic acid.}, journal = {Journal de mycologie medicale}, volume = {29}, number = {2}, pages = {147-153}, doi = {10.1016/j.mycmed.2019.04.003}, pmid = {31023592}, issn = {1773-0449}, abstract = {BACKGROUND: The increasing number of Candida infections, especially those caused by non-C. albicans species and resistant strains, is a serious medical problem.

OBJECTIVES: In this study, the antifungal activity of base analogues, 5-flucytosine (5-FC) and 5-fluorouracil (5-FU), was tested against planktonic cells as well as against mature biofilm.

METHODS: Tests were performed according the EUCAST methodology. Antibiofilm effectiveness of tested drugs was determined by the crystal violet staining method. The cytotoxicity assays was performed according to the ISO 10993-5 norm.

RESULTS: 5-FC and 5-FU were effective against fifteen fluconazole resistant Candida glabrata strains with an average minimal inhibitory concentration (MIC) of 0.152mg/L and 0.39mg/L, respectively. Folinic acid (folinate- e.g., leucovorin) is a common drug used in oncology simultaneously with 5-FU. In our tests folinate was able to lower MIC for 5-FC from 0.152 to 0.058mg/L (P<0.05). In the biofilm assay 5-FU and 5-FC alone did not induce any changes in the biomass of mature biofilm. Addition of folinate to each base analogue resulted in up to 90% reduction of biomass. Viability tests show that a concentration of 64mg/L of 5-FC and 5-FU supplemented with folinate can be fungicidal against mature biofilms of some Candida isolates. No cytotoxic effect was found for combination of FOL and 5-FC.

CONCLUSION: Therapy of 5-FU+folinate is well known in cancer treatment, in this study we reveal the beneficial effect of folinate on antifungal activity of 5-FC as well as the antifungal potential of 5-FU+folinate.}, } @article {pmid31022836, year = {2019}, author = {Flockton, TR and Schnorbus, L and Araujo, A and Adams, J and Hammel, M and Perez, LJ}, title = {Inhibition of Pseudomonas aeruginosa Biofilm Formation with Surface Modified Polymeric Nanoparticles.}, journal = {Pathogens (Basel, Switzerland)}, volume = {8}, number = {2}, pages = {}, doi = {10.3390/pathogens8020055}, pmid = {31022836}, issn = {2076-0817}, abstract = {The gram-negative bacterial pathogen Pseudomonas aeruginosa represents a prominent clinical concern. Due to the observed high levels of antibiotic resistance, copious biofilm formation, and wide array of virulence factors produced by these bacteria, new treatment technologies are required. Here, we present the development of a series of P. aeruginosa LecA-targeted polymeric nanoparticles and demonstrate the anti-adhesion and biofilm inhibitory properties of these constructs.}, } @article {pmid31022421, year = {2019}, author = {Maktabi, H and Ibrahim, M and Alkhubaizi, Q and Weir, M and Xu, H and Strassler, H and Fugolin, APP and Pfeifer, CS and Melo, MAS}, title = {Underperforming light curing procedures trigger detrimental irradiance-dependent biofilm response on incrementally placed dental composites.}, journal = {Journal of dentistry}, volume = {}, number = {}, pages = {}, doi = {10.1016/j.jdent.2019.04.003}, pmid = {31022421}, issn = {1879-176X}, abstract = {OBJECTIVES: Insufficient radiant exposure (J/cm2) may provide an early trigger in a cascade of detrimental responses on incrementally-place composite, especially the bottom layer. This study aimed to assess the influence of poor radiant exposure, the degree of conversion (%DC), water sorption/ solubility and S. mutans biofilm formation on conventional, incrementally placed composites and to establish a relationship between these factors.

METHODS: Two light units operating at 600 and 1000 mW/cm2 and four most common operator-dependent curing conditions had the radiant exposure (RE) recorded. All the specimens were subjected to S. mutans biofilm model for 14 days. The %DC, biofilm formation expressed by colony-forming units (CFU), water sorption/ solubility and surface roughness/ SEM were assessed. Data were submitted to two-way ANOVA and Tukey post-hoc test (α = 0.05). Pearson correlation was also determined.

RESULTS: The influence of RE on S. mutans CFU values and DC are dependent on the curing conditions and irradiance (p < 0.05). A negative relationship was observed between RE and biofilm formation. The operator-dependent curing conditions have shown RE reduction varying from 49.4% to 73.5% in relation to control. The difference in DC between top/bottom of cylinder varied from 13% to 21% for 1000 mW/cm2and from 29% to 53% for LCU600. The roughness, solubility and salivary sorption were greater for low RE.

CONCLUSION: Poor, deficient curing procedures provide an early trigger in a negative pathway of events for incrementally-place dental composite including a biological response by increased biofilm formation by S. mutans, a relevant factor for secondary caries development.

SIGNIFICANCE: The susceptibility to variation in the outcomes was RE -dependent. The optimization of the curing procedures ensures the maximum performance in the chain of events involved in the light curing process of resin-based materials and potentially reduce the risk factors of secondary caries development.}, } @article {pmid31021431, year = {2019}, author = {Barron, CL and Kamel-Abusalha, LB and Sethia, R and Goodman, SD and Elmaraghy, CA and Bakaletz, LO}, title = {Identification of essential biofilm proteins in middle ear fluids of otitis media with effusion patients.}, journal = {The Laryngoscope}, volume = {}, number = {}, pages = {}, doi = {10.1002/lary.28011}, pmid = {31021431}, issn = {1531-4995}, support = {R01 DC011818/DC/NIDCD NIH HHS/United States ; R01 DC011818//National Institutes of Health/ National Institute on Deafness and Other Communication Disorders/ ; }, abstract = {OBJECTIVES: Otitis media with effusion (OME) is a common disease of childhood that is largely asymptomatic. However, middle ear fluid can persist for months and negatively impact a child's quality of life. Many cases of OME remain chronic and require surgical intervention. Because biofilms are known to contribute to the persistence of many diseases, this study examined effusions collected from children with chronic OME for the presence of essential biofilm structural components, members of the DNABII family of bacterial DNA-binding proteins.

METHODS: Middle ear effusions were recovered from 38 children with chronic OME at the time of tympanostomy tube insertion. A portion of each specimen was submitted for microbiology culture. The remaining material was assessed by immunoblot to quantitate individual DNABII proteins, integration host factor (IHF), and histone-like protein (HU).

RESULTS: Sixty-five percent of effusions (24 of 37) were culture-positive for bacterial species or yeast, whereas 35% (13 of 37) were culture-negative. IHF was detected in 95% (36 of 38) at concentrations from 2 to 481 ng/μL effusion. HU was detected in 95% (36 of 38) and quantitated from 13 to 5,264 ng/μL effusion (P ≤ 0.05 compared to IHF).

CONCLUSION: Because DNABII proteins are essential structural components of bacterial biofilms, these data lend further support to our understanding that biofilms are present in the vast majority of chronic middle ear effusions, despite negative culture results. The presence and ubiquity of DNABII proteins in OME specimens indicated that these proteins can serve as an important clinical target for our novel DNABII-directed strategy to treat biofilm diseases such as chronic OME.

LEVEL OF EVIDENCE: NA Laryngoscope, 2019.}, } @article {pmid31021332, year = {2019}, author = {Gómez-Gómez, B and Arregui, L and Serrano, S and Santos, A and Pérez-Corona, T and Madrid, Y}, title = {Selenium and tellurium-based nanoparticles as interfering factors in quorum sensing-regulated processes: violacein production and bacterial biofilm formation.}, journal = {Metallomics : integrated biometal science}, volume = {11}, number = {6}, pages = {1104-1114}, doi = {10.1039/c9mt00044e}, pmid = {31021332}, issn = {1756-591X}, abstract = {A cell-to-cell communication system called quorum sensing (QS) promotes the transcription of certain target genes in bacterial cells leading to the activation of different cellular processes, some of them related to bacterial biofilm formation. The formation of bacterial biofilms favours antibiotic resistance, which is nowadays a significant public-health problem. In this study, the effect of selenium (SeNPs) and tellurium (TeNPs) nanoparticles was examined in two bacterial processes mediated by QS: violacein production by Chromobacterium violaceum and biofilm formation by Pseudomonas aeruginosa. For this purpose, quantification of the pigment production in the presence of these nanoparticles was monitored using the C. violaceum strain. Additionally, a combination of different microscopical imaging techniques was applied to examine the changes in the 3D biofilm structure of P. aeruginosa, which were quantified through performing architectural metric calculations (substratum area, cell area coverage and biovolume). SeNPs produce an 80% inhibition in the violacein production by C. violaceum and a significant effect on the P. aeruginosa biofilm architecture (a reduction of 80% in the biovolume of the bacterial biofilm was obtained). TeNPs similarly affect violacein production and the P. aeruginosa biofilm structure but at lower concentration levels. The results obtained suggest an important disruption of the QS signalling system by SeNPs and TeNPs, supporting nanotechnology as a promising tool to fight against the emerging problem of bacterial resistance related to bacterial biofilm formation.}, } @article {pmid31021282, year = {2019}, author = {Yang, Y and Hwang, EH and Park, BI and Choi, NY and Kim, KJ and You, YO}, title = {Artemisia princeps Inhibits Growth, Biofilm Formation, and Virulence Factor Expression of Streptococcus mutans.}, journal = {Journal of medicinal food}, volume = {22}, number = {6}, pages = {623-630}, doi = {10.1089/jmf.2018.4304}, pmid = {31021282}, issn = {1557-7600}, abstract = {This study was designed to determine whether the ethanol extract of Artemisia princeps could inhibit the cariogenic activity of Streptococcus mutans. The increase in acid production and biofilm formation by S. mutans were evaluated. The expression levels of virulence factor genes were determined by performing the real-time polymerase chain reaction (PCR). The bactericidal effect was tested by confocal laser scanning microscopy. The A. princeps extract was observed to inhibit the growth of S. mutans at concentrations >0.05 mg/mL (P < .05). After using the safranin staining method, we found that the A. princeps extract had an inhibitory effect against biofilm formation at a concentration of >0.05 mg/mL. These experimental results were similar to that observed with the scanning electron microscopy. The results of the confocal microscopy revealed that the A. princeps extract at high concentrations of 0.4-3.2 mg/mL showed a bactericidal effect in a concentration-dependent manner. According to the results of the real-time PCR analysis, it was observed that the A. princeps extract inhibited the expression of virulence factor genes. These results suggest that A. princeps may inhibit the cariogenic activity of S. mutans, and may be useful as an anticariogenic agent.}, } @article {pmid31020511, year = {2019}, author = {Li, X and Zhang, X and Zhao, X and Yu, B and Weng, L and Li, Y}, title = {Efficient Removal of Metolachlor and Bacterial Community of Biofilm in Bioelectrochemical Reactors.}, journal = {Applied biochemistry and biotechnology}, volume = {}, number = {}, pages = {}, doi = {10.1007/s12010-019-03014-0}, pmid = {31020511}, issn = {1559-0291}, support = {2017YFD0800704//National Key R&D Program of China/ ; 41601536 and 31500425//National Natural Science Foundation of China/ ; 16JCQNJC08800//Natural Science Foundation of Tianjin city of China/ ; 2017-05//Opening Foundation of Ministry of Education of China Key Laboratory of Pollution Processes and Environmental Criteria/ ; 2017-2018//Central Public-interest Scientific Institution Basal Research Fund/ ; }, abstract = {The microbial fuel cell (MFC) provides an inexhaustible electron acceptor to generate current and enhance the degradation of organic compounds. In MFCs with metolachlor as the sole carbon source, the degradation efficiency accelerated by 98%, with 61-76% of enhancement for the degradates, ethane sulfonic acid and oxanilic acid, respectively. According to quantifying primary metabolites of deschloro and metolachlor-2-hydroxyas, dechlorination and alcoholization were deemed as antecedent steps of metolachlor bioelectrochemical degradation. The energy recovery was infeasible by sole addition of metolachlor (at 13 ± 4 °C from equivalent weight of 0.224 mg). In MFCs with metolachlor and sodium acetate as the concomitant carbon sources, the electricity generation recovered to a level comparable to the controls, instead of increasing the removal efficiency of metolachlor. These results suggest that a low-efficiently direct electron transfer occurred between electricigens and metolachlor degraders. The Illumina sequencing showed that species of Paracoccus and Aquamicrobium played a potential degradation effect, while Comamonas sp. replaced Geobacter sp. as the predominant electricigen after addition of metolachlor. This study demonstrates that MFCs could be used as a promising alternative for treatment of chloroacetanilide herbicide contaminated wastewaters by means of a rapidly established active bacterial community. Graphical Abstract .}, } @article {pmid31020467, year = {2019}, author = {Özcan, SS and Dieser, M and Parker, AE and Balasubramanian, N and Foreman, CM}, title = {Quorum sensing inhibition as a promising method to control biofilm growth in metalworking fluids.}, journal = {Journal of industrial microbiology & biotechnology}, volume = {}, number = {}, pages = {}, doi = {10.1007/s10295-019-02181-7}, pmid = {31020467}, issn = {1476-5535}, support = {1635347//Directorate for Engineering/ ; P20GM103474//Foundation for the National Institutes of Health/ ; }, abstract = {Microbial contamination in metalworking systems is a critical problem. This study determined the microbial communities in metalworking fluids (MWFs) from two machining shops and investigated the effect of quorum sensing inhibition (QSI) on biofilm growth. In both operations, biofilm-associated and planktonic microbial communities were dominated by Pseudomonadales (60.2-99.7%). Rapid recolonization was observed even after dumping spent MWFs and meticulous cleaning. Using Pseudomonas aeruginosa PAO1 as a model biofilm organism, patulin (40 µM) and furanone C-30 (75 µM) were identified as effective QSI agents. Both agents had a substantially higher efficacy compared to α-amylase (extracellular polymeric substance degrading enzyme) and reduced biofilm formation by 63% and 76%, respectively, in MWF when compared to untreated controls. Reduced production of putatively identified homoserine lactones and quinoline in MWF treated with QS inhibitors support the effect of QSI on biofilm formation. The results highlight the effectiveness of QSI as a potential strategy to eradicate biofilms in MWFs.}, } @article {pmid31019496, year = {2019}, author = {Singh, AK and Yadav, S and Chauhan, BS and Nandy, N and Singh, R and Neogi, K and Roy, JK and Srikrishna, S and Singh, RK and Prakash, P}, title = {Classification of Clinical Isolates of Klebsiella pneumoniae Based on Their in vitro Biofilm Forming Capabilities and Elucidation of the Biofilm Matrix Chemistry With Special Reference to the Protein Content.}, journal = {Frontiers in microbiology}, volume = {10}, number = {}, pages = {669}, doi = {10.3389/fmicb.2019.00669}, pmid = {31019496}, issn = {1664-302X}, abstract = {Klebsiella pneumoniae is a human pathogen, capable of forming biofilms on abiotic and biotic surfaces. The limitations of the therapeutic options against Klebsiella pneumoniae is actually due to its innate capabilities to form biofilm and harboring determinants of multidrug resistance. We utilized a newer approach for classification of biofilm producing Klebsiella pneumoniae isolates and subsequently we evaluated the chemistry of its slime, more accurately its biofilm. We extracted and determined the amount of polysaccharides and proteins from representative bacterial biofilms. The spatial distribution of sugars and proteins were then investigated in the biofilm matrix using confocal laser scanning microscopy (CLSM). Thereafter, the extracted matrix components were subjected to sophisticated analysis incorporating Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, one-dimensional gel-based electrophoresis (SDS-PAGE), high performance liquid chromatography (HPLC), and MALDI MS/MS analysis. Besides, the quantification of its total proteins, total sugars, uronates, total acetyl content was also done. Results suggest sugars are not the only/major constituent of its biofilms. The proteins were harvested and subjected to SDS-PAGE which revealed various common and unique protein bands. The common band was excised and analyzed by HPLC. MALDI MS/MS results of this common protein band indicated the presence of different proteins within the biofilm. The 55 different proteins were identified including both cytosolic and membrane proteins. About 22 proteins were related to protein synthesis and processing while 15 proteins were identified related to virulence. Similarly, proteins related to energy and metabolism were 8 and those related to capsule and cell wall synthesis were 4. These results will improve our understanding of Klebsiella biofilm composition and will further help us design better strategies for controlling its biofilm such as techniques focused on weakening/targeting certain portions of the slime which is the most common building block of the biofilm matrix.}, } @article {pmid31019240, year = {2019}, author = {Prateeksha, and Barik, SK and Singh, BN}, title = {Nanoemulsion-loaded hydrogel coatings for inhibition of bacterial virulence and biofilm formation on solid surfaces.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {6520}, doi = {10.1038/s41598-019-43016-w}, pmid = {31019240}, issn = {2045-2322}, abstract = {The indiscriminate use of antibiotics has led to the emergence of drug-resistant bacteria which has become one of the biggest challenges of the twenty-first century for the researchers to combat and in turn search for novel targets which could lead to the development of effective and sustainable therapies. Inhibition of biofilm formation and virulence of bacterial pathogens is an emerging approach to address the challenges related to bacterial infections. To suppress the virulence and biofilm formation by Escherichia coli O157:H7 (ECOH), we developed stable nanoemulsion (NE) of Gaultheria fragrantissima Wall. essential oil's (EO) bioactive compounds, viz., eugenol (E-NE) and methyl salicylate (MS-NE) that showed significantly higher anti-biofilm and anti-virulence activities as compared to eugenol and methyl salicylate without affecting ECOH planktonic cell growth. Transcriptional analysis showed that E-NE and MS-NE reduced the expression of genes, including curli, type I fimbriae, Shiga-like toxins, quorum sensing, and ler-controlled toxins, which are needed for biofilm formation, pathogenicity, and attachment. E-NE and MS-NE loaded hydrogel coatings showed superior anti-biofilm activity against ECOH on glass, plastic and meat surfaces as compared to eugenol and methyl salicylate loaded coatings. Conclusively, NE-loaded hydrogel coatings could be used in combating ECOH infection on solid surfaces through anti-biofilm and anti-virulence strategies.}, } @article {pmid31017520, year = {2019}, author = {Pandey, S and Sarkar, S}, title = {Spatial distribution of major bacterial species and different volatile fatty acids in a two-phase anaerobic biofilm reactor with PVA gel beads as bio-carrier.}, journal = {Preparative biochemistry & biotechnology}, volume = {49}, number = {7}, pages = {704-717}, doi = {10.1080/10826068.2019.1605525}, pmid = {31017520}, issn = {1532-2297}, abstract = {Conventional completely mixed anaerobic treatment systems limit the chances of the different species of bacteria to spatially group together according to their mutual cooperation and as a result, show a lower efficiency and vulnerability towards shock situations. It is interesting to know about the stratification of the different bacterial species participating in the degradation process and the intermediates that they produce. In this study, we established and optimized a two-phase anaerobic packed bed biofilm reactor system (AnPBR) with porous PVA gel beads used as bio-carriers and ran the reactor system in a steady state to observe the VFAs produced along with the microbial diversity of the predominant species at different stages of the reactor system. We observed that acetate and butyrate were the predominant intermediate VFAs while concentrations of other VFAs such that propionic acid were low. Acetobacterium and Clostridium were found to be the most abundant bacterial species in acidogenic reactor while methanogenic reactor was highly enriched with Methanobacterium and Methanosarcina. Apart from the above, syntrophic populations such as Syntrophobactor wolinii were also observed to be dominant in both the reactors - especially towards the end of acidogenic reactor and the initial part of the methanogenic reactor.}, } @article {pmid31015909, year = {2019}, author = {Nguyen, TV and Peszko, MT and Melander, RJ and Melander, C}, title = {Using 2-aminobenzimidazole derivatives to inhibit Mycobacterium smegmatis biofilm formation.}, journal = {MedChemComm}, volume = {10}, number = {3}, pages = {456-459}, doi = {10.1039/c9md00025a}, pmid = {31015909}, issn = {2040-2511}, abstract = {Biofilm formation by mycobacteria can lead to enhanced antibiotic tolerance. Herein, we report on the identification of a series of 2-aminobenzimidazole (2-ABI) derivatives that potently inhibit biofilm formation by Mycobacterium smegmatis.}, } @article {pmid31015652, year = {2019}, author = {Tavares, ER and Gionco, B and Morguette, AEB and Andriani, GM and Morey, AT and do Carmo, AO and de Pádua Pereira, U and Andrade, G and de Oliveira, AG and Pinge-Filho, P and Nakamura, CV and Yamauchi, LM and Yamada-Ogatta, SF}, title = {Phenotypic characteristics and transcriptome profile of Cryptococcus gattii biofilm.}, journal = {Scientific reports}, volume = {9}, number = {1}, pages = {6438}, doi = {10.1038/s41598-019-42896-2}, pmid = {31015652}, issn = {2045-2322}, abstract = {In this study, we characterized Cryptococcus gattii biofilm formation in vitro. There was an increase in the density of metabolically active sessile cells up to 72 h of biofilm formation on polystyrene and glass surfaces. Scanning electron microscopy and confocal laser scanning microscopy analysis revealed that in the early stage of biofilm formation, yeast cells adhered to the abiotic surface as a monolayer. After 12 h, extracellular fibrils were observed projecting from C. gattii cells, connecting the yeast cells to each other and to the abiotic surface; mature biofilm consisted of a dense network of cells deeply encased in an extracellular polymeric matrix. These features were also observed in biofilms formed on polyvinyl chloride and silicone catheter surfaces. We used RNA-Seq-based transcriptome analysis to identify changes in gene expression associated with C. gattii biofilm at 48 h compared to the free-floating planktonic cells. Differential expression analysis showed that 97 and 224 transcripts were up-regulated and down-regulated in biofilm, respectively. Among the biological processes, the highest enriched term showed that the transcripts were associated with cellular metabolic processes, macromolecule biosynthetic processes and translation.}, } @article {pmid31015181, year = {2019}, author = {Ding, X and Wei, D and Guo, W and Wang, B and Meng, Z and Feng, R and Du, B and Wei, Q}, title = {Biological denitrification in an anoxic sequencing batch biofilm reactor: Performance evaluation, nitrous oxide emission and microbial community.}, journal = {Bioresource technology}, volume = {285}, number = {}, pages = {121359}, doi = {10.1016/j.biortech.2019.121359}, pmid = {31015181}, issn = {1873-2976}, abstract = {The present study evaluated the performance of biological denitrification in an anoxic sequencing batch biofilm reactor (ASBBR) and its nitrous oxide (N2O) emission. After 90 days operation, the effluent chemical oxygen demand and total nitrogen removal efficiencies high of 94.8% and 95.0%, respectively. Both polysaccharides and protein contents were reduced in bound EPS (TB-EPS) and loosely bound EPS (LB-EPS) after biofilm formation. According to typical cycle, N2O release rate was related to the free nitrous acid (FNA) concentration with the maximum value of 3.88 μg/min and total conversion rate of 1.27%. Two components were identified from EEM-PARAFAC model in soluble microbial products (SMP). Protein-like substances for component 1 changed significantly in denitrification process, whereas humic-like and fulvic acid-like substances for component 2 remained relatively stable. High-throughput sequencing results showed that Lysobacter, Tolumonas and Thauera were the dominant genera, indicating the co-existence of autotrophic and heterotrophic denitrifiers in ASBBR.}, } @article {pmid31014001, year = {2019}, author = {Brust, FR and Boff, L and da Silva Trentin, D and Pedrotti Rozales, F and Barth, AL and Macedo, AJ}, title = {Macrocolony of NDM-1 Producing Enterobacterhormaechei subsp. oharae Generates Subpopulations with Different Features Regarding the Response of Antimicrobial Agents and Biofilm Formation.}, journal = {Pathogens (Basel, Switzerland)}, volume = {8}, number = {2}, pages = {}, doi = {10.3390/pathogens8020049}, pmid = {31014001}, issn = {2076-0817}, support = {1871-25511/13-4//Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul/ ; 408578/2013-0//Conselho Nacional de Desenvolvimento Científico e Tecnológico/ ; 443150/2014-1//Conselho Nacional de Desenvolvimento Científico e Tecnológico/ ; doctoral fellowship//Coordenação de Aperfeiçoamento de Pessoal de Nível Superior/ ; 465718/2014-0//Instituto Nacional de Ciência e Tecnologia/ ; }, abstract = {Enterobacter cloacae complex has been increasingly recognized as a nosocomial pathogen representing the third major Enterobacteriaceae species involved with infections. This study aims to evaluate virulence and antimicrobial susceptibility of subpopulations generated from macrocolonies of NDM-1 producing Enterobacter hormaechei clinical isolates. Biofilm was quantified using crystal violet method and fimbrial genes were investigated by PCR. Susceptibility of antimicrobials, alone and combined, was determined by minimum inhibitory concentration and checkerboard assays, respectively. Virulence and efficacy of antimicrobials were evaluated in Galleria mellonella larvae. Importantly, we verified that some subpopulations that originate from the same macrocolony present different biofilm production ability and distinct susceptibility to meropenem due to the loss of blaNDM-1 encoding plasmid. A more in-depth study was performed with the 798 macrocolony subpopulations. Type 3 fimbriae were straightly related with biofilm production; however, virulence in larvae was not statistically different among subpopulations. Triple combination with meropenem-rifampicin-polymyxin B showed in vitro synergistic effect against all subpopulations; while in vivo this treatment showed different efficacy rates for 798-1S and 798-4S subpopulations. The ability of multidrug resistant E. hormaechei isolates in generating bacterial subpopulations presenting different susceptible and virulence mechanisms are worrisome and may explain why these infections are hardly overcome.}, } @article {pmid31013388, year = {2019}, author = {Chevalier, M and Doglio, A and Rajendran, R and Ramage, G and Prêcheur, I and Ranque, S}, title = {Inhibition of adhesion-specific genes by Solidago virgaurea extract causes loss of Candida albicans biofilm integrity.}, journal = {Journal of applied microbiology}, volume = {127}, number = {1}, pages = {68-77}, doi = {10.1111/jam.14289}, pmid = {31013388}, issn = {1365-2672}, abstract = {AIMS: Candida albicans biofilms are commonly associated with severe oral infections. We previously discovered that a crude extract from the Solidago virgaurea plant (SV extract) was a potent inhibitor of C. albicans biofilm formation. Here, we further investigate the mechanisms underlying C. albicans biofilm inhibition by the SV extract.

METHODS AND RESULTS: The SV extract was shown to inhibit laboratory and clinical C. albicans isolates adherence and hyphal transition on inert support and epithelial human cells, without affecting viability and growth of planktonic yeasts. Interestingly, RT-PCR-based experiments demonstrated that some key genes involved in adhesion and hyphal morphological switch (e.g. Hwp1p, Ece1p, Als3p) were strongly down-regulated by the SV extract. Moreover, antimicrobial synergy testing (checkerboard assay) demonstrated that antifungal effects of miconazole, nystatin or a common antiseptic mouthwash were synergistically improved when used in combination with the SV extract.

CONCLUSIONS: The SV extract prevents C. albicans biofilm formation through direct inhibition of key adherence and hyphae-associated genes.

Biofilm is considered as a key virulence factor of C. albicans infection. Our discovery of an inhibitor specifically acting on genes involved in biofilm formation paves the way for the future development of a new class of antifungal product.}, } @article {pmid31013054, year = {2019}, author = {Zhang, H and Wang, D and Zuo, X and Gao, C}, title = {UV-Responsive Multilayers with Multiple Functions for Biofilm Destruction and Tissue Regeneration.}, journal = {ACS applied materials & interfaces}, volume = {11}, number = {19}, pages = {17283-17293}, doi = {10.1021/acsami.9b04428}, pmid = {31013054}, issn = {1944-8252}, abstract = {The increasing demands of surgical implantation highlight the significance of anti-infection of medical devices, especially antibiofilm contamination on the surface of implants. The biofilms developed by colonized microbes will largely hinder the adhesion of host cells, leading to failure in long-term applications. In this work, UV-responsive multilayers were fabricated by stepwise assembly of poly(pyrenemethyl acrylate- co-acrylic acid) (P(PA- co-AA)) micelles and chitosan on different types of substrates. Under UV irradiation, the cleavage of pyrene ester bonds in the P(PA- co-AA) molecules resulted in the increase of roughness and hydrophilicity of the multilayers. During this process, reactive oxygen species were generated in situ within 10 s, which destroyed the biofilms of Staphylococcus aureus, leading to the degradation of the bacterial matrix. The antibacterial rate was above 99.999%. The UV-irradiated multilayers allowed the attachment and proliferation of fibroblasts, endothelial cells, and smooth muscle cells, benefiting tissue integration of the implants. When poly(dimethylsiloxane) slices with the multilayers were implanted in vivo and irradiated by UV, the density of bacteria and the inflammatory level (judging from the number of neutrophils) decreased significantly. Moreover, formation of neo blood vessels surrounding the implants was observed after implantation for 7 days. These results reveal that the photoresponsive multilayers endow the implants with multifunctions of simultaneous antibiofilm and tissue integration, shedding light for applications in surface modification of implants in particular for long-term use.}, } @article {pmid31011774, year = {2019}, author = {Liu, J and Li, W and Zhu, X and Zhao, H and Lu, Y and Zhang, C and Lu, Z}, title = {Surfactin effectively inhibits Staphylococcus aureus adhesion and biofilm formation on surfaces.}, journal = {Applied microbiology and biotechnology}, volume = {103}, number = {11}, pages = {4565-4574}, doi = {10.1007/s00253-019-09808-w}, pmid = {31011774}, issn = {1432-0614}, support = {31571887//National Natural Science Foundation of China/ ; CX 16-1058//Jiangsu Agricultural Science and Technology Innovation Fund/ ; }, abstract = {Biosurfactants are amphiphilic compounds that composed of hydrophilic and hydrophobic moieties, which possess the ability of self-organizing between phases, reducing the interfacial tension, and forming aggregates such as micelles. This spontaneous process results in significant changes in surface properties that directly influence the adherence of microorganisms. In this study, the ability of surfactin, a biosurfactant produced by Bacillus subtilis in reducing adhesion and disrupting the presence of biofilm of Staphylococcus aureus (S. aureus) on several surfaces, was investigated. Significant biofilm removal was observed on glass, polystyrene, and stainless steel surfaces. Furthermore, we explored the probable mechanism about how surfactin affected S. aureus biofilm formation. Based on our findings, surfactin had a significant effect on the polysaccharides production and especially decreased the percentage of alkali-soluble polysaccharide in biofilms. It also down-regulated the expression of icaA and icaD significantly, which are necessary for the important constituents to take shape of staphylococcal biofilm. In addition, it was found that the lipopeptide affected the quorum sensing (QS) system in S. aureus through regulating the auto inducer 2 (AI-2) activity, which has been reported to be negative for biofilm formation in S. aureus. These above properties could be applied in developing surfactin as a potential pre-coating agent on material surfaces to prevent S. aureus biofilm formation.}, } @article {pmid31010902, year = {2019}, author = {Cassin, EK and Tseng, BS}, title = {Pushing beyond the envelope: the potential roles of OprF in Pseudomonas aeruginosa biofilm formation and pathogenicity.}, journal = {Journal of bacteriology}, volume = {}, number = {}, pages = {}, doi = {10.1128/JB.00050-19}, pmid = {31010902}, issn = {1098-5530}, support = {K22 AI121097/AI/NIAID NIH HHS/United States ; }, abstract = {The ability of Pseudomonas aeruginosa to form biofilms, which are communities of cells encased in a self-produced extracellular matrix, protects the cells from antibiotics and the host immune response. While some biofilm matrix components, such as exopolysaccharides and extracellular DNA, are relatively well characterized, the extracellular matrix proteins remain understudied. Multiple proteomic analyses of the P. aeruginosa soluble biofilm matrix and outer membrane vesicles, which are a component of the matrix, have identified OprF as an abundant matrix protein. To date, the few reports on the effects of oprF mutations on biofilm formation are conflicting, and little is known about the potential role of OprF in the biofilm matrix. The majority of OprF studies focus on the protein as a cell-associated porin. As a component of the outer membrane, OprF assumes dual conformations and is involved in solute transport, as well as cell envelope integrity. Here we review the current literature on OprF in P. aeruginosa, discussing how the structure and function of the cell-associated and matrix-associated protein may affect biofilm formation and pathogenesis in order to inform future research on this understudied matrix protein.}, } @article {pmid31010041, year = {2019}, author = {Ostrov, I and Paz, T and Shemesh, M}, title = {Robust Biofilm-Forming Bacillus Isolates from the Dairy Environment Demonstrate an Enhanced Resistance to Cleaning-in-Place Procedures.}, journal = {Foods (Basel, Switzerland)}, volume = {8}, number = {4}, pages = {}, doi = {10.3390/foods8040134}, pmid = {31010041}, issn = {2304-8158}, support = {4210343//Israeli Dairy Board/ ; }, abstract = {One of the main strategies for maintaining the optimal hygiene level in dairy processing facilities is regular cleaning and disinfection, which is incorporated in the cleaning-in-place (CIP) regimes. However, a frail point of the CIP procedures is their variable efficiency in eliminating biofilm bacteria. In the present study, we evaluated the susceptibility of strong biofilm-forming dairy Bacillus isolates to industrial cleaning procedures using two differently designed model systems. According to our results, the dairy-associated Bacillus isolates demonstrate a higher resistance to CIP procedures, compared to the non-dairy strain of B. subtilis. Notably, the tested dairy isolates are highly persistent to different parameters of the CIP operations, including the turbulent flow of liquid (up to 1 log), as well as the cleaning and disinfecting effects of commercial detergents (up to 2.3 log). Moreover, our observations indicate an enhanced resistance of poly-γ-glutamic acid (PGA)-overproducing B. subtilis, which produces high amounts of proteinaceous extracellular matrix, to the CIP procedures (about 0.7 log, compared to the wild-type non-dairy strain of B. subtilis). We therefore suggest that the enhanced resistance to the CIP procedures by the dairy Bacillus isolates can be attributed to robust biofilm formation. In addition, this study underlines the importance of evaluating the efficiency of commercial cleaning agents in relation to strong biofilm-forming bacteria, which are relevant to industrial conditions. Consequently, we believe that the findings of this study can facilitate the assessment and refining of the industrial CIP procedures.}, } @article {pmid31007867, year = {2019}, author = {Zhang, Y and Shi, W and Song, Y and Wang, J}, title = {Metatranscriptomic analysis of an in vitro biofilm model reveals strain-specific interactions among multiple bacterial species.}, journal = {Journal of oral microbiology}, volume = {11}, number = {1}, pages = {1599670}, doi = {10.1080/20002297.2019.1599670}, pmid = {31007867}, issn = {2000-2297}, abstract = {Interactions among bacteria can affect biofilm properties. Method: Here, we investigated the role of different bacteria in functional dysbiosis of an in vitro polymicrobial subgingival plaque model using both 16S rRNA and metatranscriptomic sequencing. Results: We found that high-virulence Porphyromonas gingivalis W83 had greater effects on the symbiotic species than the low-virulence P. gingivalis ATCC33277, and that Prevotella intermedia exacerbated the effects of W83. P. gingivalis significantly influenced the expression of genes related to metabolic pathways and quorum sensing of commensal oral species in a strain-specific manner. P. intermedia exerted synergistic effects with P. gingivalis W83 but antagonistic effects with strain ATCC33277, which may regulate the expression of virulence factors of P. gingivalis through the clp regulator. Discussion: The interaction networks indi