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26 Jun 2019 at 01:31
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Bibliography on: Biofilm


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Wikipedia: Biofilm A biofilm is any group of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPS). The EPS components are produced by the cells within the biofilm and are typically a polymeric conglomeration of extracellular DNA, proteins, and polysaccharides. Because they have three-dimensional structure and represent a community lifestyle for microorganisms, biofilms are frequently described metaphorically as cities for microbes. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium. Biofilms can be present on the teeth of most animals as dental plaque, where they may cause tooth decay and gum disease. Microbes form a biofilm in response to many factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics. When a cell switches to the biofilm mode of growth, it undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.

Created with PubMed® Query: biofilm[title] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-06-24

Nakamura H, Shimizu T, Takatani A, et al (2019)

Initial human T-cell leukemia virus type 1 infection of the salivary gland epithelial cells requires a biofilm-like structure.

Virus research pii:S0168-1702(19)30101-7 [Epub ahead of print].

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.

RevDate: 2019-06-24

Mendis HC, Ozcan A, Santra S, et al (2019)

A novel Zn chelate (TSOL) that moves systemically in citrus plants inhibits growth and biofilm formation of bacterial pathogens.

PloS one, 14(6):e0218900 pii:PONE-D-19-05957.

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'.

RevDate: 2019-06-24

Soler-Arango J, Figoli C, Muraca G, et al (2019)

The Pseudomonas aeruginosa biofilm matrix and cells are drastically impacted by gas discharge plasma treatment: A comprehensive model explaining plasma-mediated biofilm eradication.

PloS one, 14(6):e0216817 pii:PONE-D-18-34815.

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.

RevDate: 2019-06-24

MacKenzie KD, Wang Y, Musicha P, et al (2019)

Parallel evolution leading to impaired biofilm formation in invasive Salmonella strains.

PLoS genetics, 15(6):e1008233 pii:PGENETICS-D-19-00304 [Epub ahead of print].

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.

RevDate: 2019-06-24

Wang Y, Wang Y, Liu B, et al (2019)

pdh modulate virulence through reducing stress tolerance and biofilm formation of Streptococcus suis serotype 2.

Virulence, 10(1):588-599.

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.

RevDate: 2019-06-24

Perkowski K, Baltaza W, Conn DB, et al (2019)

Examination of oral biofilm microbiota in patients using fixed orthodontic appliances in order to prevent risk factors for health complications.

Annals of agricultural and environmental medicine : AAEM, 26(2):231-235.

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.

RevDate: 2019-06-24

Singh VK, Mishra A, B Jha (2019)

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.

Frontiers in microbiology, 10:1269.

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.

RevDate: 2019-06-24

Pathirana RU, McCall AD, Norris HL, et al (2019)

Filamentous Non-albicans Candida Species Adhere to Candida albicans and Benefit From Dual Biofilm Growth.

Frontiers in microbiology, 10:1188.

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.

RevDate: 2019-06-24

Wang J, Liu Q, Ma S, et al (2019)

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.

Bioresource technology pii:S0960-8524(19)30821-1 [Epub ahead of print].

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.

RevDate: 2019-06-23

Bellich B, Distefano M, Syrgiannis Z, et al (2019)

The polysaccharide extracted from the biofilm of Burkholderia multivorans strain C1576 binds hydrophobic species and exhibits a compact 3D-structure.

International journal of biological macromolecules pii:S0141-8130(19)33271-4 [Epub ahead of print].

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.

RevDate: 2019-06-23

Cruzado-Bravo MLM, Silva NCC, Rodrigues MX, et al (2019)

Phenotypic and genotypic characterization of Staphylococcus spp. isolated from mastitis milk and cheese processing: Study of adherence and biofilm formation.

Food research international (Ottawa, Ont.), 122:450-460.

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.

RevDate: 2019-06-22

Wang J, Liu Q, Hu H, et al (2019)

Insight into mature biofilm quorum sensing in full-scale wastewater treatment plants.

Chemosphere, 234:310-317 pii:S0045-6535(19)31227-5 [Epub ahead of print].

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.

RevDate: 2019-06-22

Luo JH, Wu M, Liu J, et al (2019)

Microbial chromate reduction coupled with anaerobic oxidation of methane in a membrane biofilm reactor.

Environment international, 130:104926 pii:S0160-4120(19)31394-7 [Epub ahead of print].

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.

RevDate: 2019-06-22

Sánchez MC, Ribeiro-Vidal H, Esteban-Fernández A, et al (2019)

Antimicrobial activity of red wine and oenological extracts against periodontal pathogens in a validated oral biofilm model.

BMC complementary and alternative medicine, 19(1):145 pii:10.1186/s12906-019-2533-5.

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.

RevDate: 2019-06-21

Short B, Brown J, Delaney C, et al (2019)

Candida auris exhibits resilient biofilm characteristics in vitro: implications for environmental persistence.

The Journal of hospital infection pii:S0195-6701(19)30260-9 [Epub ahead of print].

Surfaces within healthcare play a key role in the transmission of drug-resistant pathogens. Candida auris is an emerging multi-drug resistant yeast which has the ability to 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 remain viable 14 days' post treatment. The ability of C. auris to adhere and persist on environmental surfaces emphasises our need to better understand the biology of this fungal pathogen.

RevDate: 2019-06-21

Ramos-Vivas J, Chapartegui-González I, Fernández-Martínez M, et al (2019)

Biofilm formation by multidrug resistant Enterobacteriaceae strains isolated from solid organ transplant recipients.

Scientific reports, 9(1):8928 pii:10.1038/s41598-019-45060-y.

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.

RevDate: 2019-06-21

Tassinari E, Duffy G, Bawn M, et al (2019)

Microevolution of antimicrobial resistance and biofilm formation of Salmonella Typhimurium during persistence on pig farms.

Scientific reports, 9(1):8832 pii:10.1038/s41598-019-45216-w.

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.

RevDate: 2019-06-20

Zhong H, Wang H, Tian Y, et al (2019)

Treatment of polluted surface water with nylon silk carrier-aerated biofilm reactor (CABR).

Bioresource technology, 289:121617 pii:S0960-8524(19)30847-8 [Epub ahead of print].

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.

RevDate: 2019-06-20

Lee TH, Jung MK, Kim TK, et al (2019)

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.

Gastrointestinal endoscopy pii:S0016-5107(19)31952-2 [Epub ahead of print].

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).

RevDate: 2019-06-20

George J, PM Halami (2019)

Presence of extracellular DNA & protein in biofilm formation by gentamicin-resistant Lactobacillus plantarum.

The Indian journal of medical research, 149(2):257-262.

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.

RevDate: 2019-06-20

Pepoyan AZ, Manvelyan AM, Balayan MH, et al (2019)

Low-Dose Electron-Beam Irradiation for the Improvement of Biofilm Formation by Probiotic Lactobacilli.

Probiotics and antimicrobial proteins pii:10.1007/s12602-019-09566-1 [Epub ahead of print].

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.

RevDate: 2019-06-20

De-la-Pinta I, Cobos M, Ibarretxe J, et al (2019)

Effect of biomaterials hydrophobicity and roughness on biofilm development.

Journal of materials science. Materials in medicine, 30(7):77 pii:10.1007/s10856-019-6281-3.

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.

RevDate: 2019-06-20

Stacchi C, Del Lupo V, Berton F, et al (2019)

Aspergillus fumigatus biofilm formation on different bone substitutes used in maxillary sinus augmentation: an in vitro analysis.

International journal of implant dentistry, 5(1):22 pii:10.1186/s40729-019-0175-5.

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.

RevDate: 2019-06-20

Khalifehzadeh S, Haghanifar S, Jenabian N, et al (2019)

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 of dental research, dental clinics, dental prospects, 13(1):51-56.

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.

RevDate: 2019-06-20

Zhou G, Peng H, Wang YS, et al (2019)

Enhanced synergistic effects of xylitol and isothiazolones for inhibition of initial biofilm formation by Pseudomonas aeruginosa ATCC 9027 and Staphylococcus aureus ATCC 6538.

Journal of oral science, 61(2):255-263.

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.

RevDate: 2019-06-20

Arnaouteli S, Matoz-Fernandez DA, Porter M, et al (2019)

Pulcherrimin formation controls growth arrest of the Bacillus subtilis biofilm.

Proceedings of the National Academy of Sciences of the United States of America pii:1903982116 [Epub ahead of print].

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.

RevDate: 2019-06-19

Palmioli A, Sperandeo P, Polissi A, et al (2019)

Targeting bacterial biofilm: a new LecA multivalent ligand with inhibitory activity.

Chembiochem : a European journal of chemical biology [Epub ahead of print].

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.

RevDate: 2019-06-19

Pickering AC, Vitry P, Prystopiuk V, et al (2019)

Host-specialized fibrinogen-binding by a bacterial surface protein promotes biofilm formation and innate immune evasion.

PLoS pathogens, 15(6):e1007816 pii:PPATHOGENS-D-19-00126 [Epub ahead of print].

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.

RevDate: 2019-06-19

Flament-Simon SC, Duprilot M, Mayer N, et al (2019)

Association Between Kinetics of Early Biofilm Formation and Clonal Lineage in Escherichia coli.

Frontiers in microbiology, 10:1183.

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.

RevDate: 2019-06-19

Keogh D, Lam LN, Doyle LE, et al (2019)

Correction for Keogh et al., "Extracellular Electron Transfer Powers Enterococcus faecalis Biofilm Metabolism".

mBio, 10(3): pii:mBio.01080-19.

RevDate: 2019-06-19

Cepas V, López Y, Gabasa Y, et al (2019)

Inhibition of Bacterial and Fungal Biofilm Formation by 675 Extracts from Microalgae and Cyanobacteria.

Antibiotics (Basel, Switzerland), 8(2): pii:antibiotics8020077.

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.

RevDate: 2019-06-18

Heuschkel I, Hoschek A, Schmid A, et al (2019)

Data on mixed trophies biofilm for continuous cyclohexane oxidation to cyclohexanol using Synechocystis sp. PCC 6803.

Data in brief, 25:104059 pii:104059.

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.

RevDate: 2019-06-18

Rodríguez López AL, Lee MR, Wang NB, et al (2019)

Small-molecule morphogenesis modulators enhance the ability of 14-helical β-peptides to prevent Candida albicans biofilm formation.

Antimicrobial agents and chemotherapy pii:AAC.02653-18 [Epub ahead of print].

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.

RevDate: 2019-06-18

Fu TK, Ng SK, Chen YE, et al (2019)

Rhamnose Binding Protein as an Anti-Bacterial Agent-Targeting Biofilm of Pseudomonas aeruginosa.

Marine drugs, 17(6): pii:md17060355.

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.

RevDate: 2019-06-17

Liang D, Li H, Xu X, et al (2019)

Rational Design of Peptides with Enhanced Antimicrobial and Anti-biofilm Activities against Cariogenic Bacterium Streptococcus mutans.

Chemical biology & drug design [Epub ahead of print].

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 cytotoxicty 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. This article is protected by copyright. All rights reserved.

RevDate: 2019-06-17

Melian C, Segli F, Gonzalez R, et al (2019)

Lactocin AL705 as quorum sensing inhibitor to control Listeria monocytogenes biofilm formation.

Journal of applied microbiology [Epub ahead of print].

AIMS: The control of Listeria monocytogenes biofilm formation using lactocin AL705 bacteriocin at sub-MICs through an anti-quorum 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. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of lactocin AL705 purified extract against the pathogen was determined. Bacteriocin sub-MICs were used to evaluate biofilm reduction. Concentrations between 2·5 to 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 AU ml-1) were investigated as quorum sensing (QS) inhibitors using V. harveyi as reporter strain, a significant reduction of 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: Anti-listerial 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 microorganisms as a QS inhibition represents an effective strategy to control pathogens as well as an environmentally-friendly sanitation method to mitigate post-processing food contamination. This article is protected by copyright. All rights reserved.

RevDate: 2019-06-16

Zhao Y, Liu D, Huang W, et al (2019)

Insights into biofilm carriers for biological wastewater treatment processes: Current state-of-the-art, challenges, and opportunities.

Bioresource technology pii:S0960-8524(19)30849-1 [Epub ahead of print].

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.

RevDate: 2019-06-16

Moraes JO, Cruz EA, Pinheiro Í, et al (2019)

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.

Food microbiology, 83:95-103.

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.

RevDate: 2019-06-16

García-Sánchez L, Melero B, Jaime I, et al (2019)

Biofilm formation, virulence and antimicrobial resistance of different Campylobacter jejuni isolates from a poultry slaughterhouse.

Food microbiology, 83:193-199.

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.

RevDate: 2019-06-14

Dawas A, Abu-Salih S, Sabbah I, et al (2019)

Controlling nitritation in a continuous split-feed/aeration biofilm nitrifying bioreactor.

Bioresource technology, 288:121599 pii:S0960-8524(19)30829-6 [Epub ahead of print].

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.

RevDate: 2019-06-14

Manilal A, Shewangizaw M, Mama M, et al (2019)

Methicillin-resistant Staphylococcus aureus colonization in HIV patients of Arba Minch province, Ethiopia: Carriage rates, antibiotic resistance, and biofilm formation.

Acta microbiologica et immunologica Hungarica [Epub ahead of print].

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.

RevDate: 2019-06-14

Shivaee A, Mohammadzadeh R, Shahbazi S, et al (2019)

Time-variable expression levels of mazF, atlE, sdrH, and bap genes during biofilm formation in Staphylococcus epidermidis.

Acta microbiologica et immunologica Hungarica [Epub ahead of print].

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.

RevDate: 2019-06-14

Ariafar MN, Iğci N, Akçelik M, et al (2019)

Investigation of the effect of different environmental conditions on biofilm structure of Salmonella enterica serotype Virchow via FTIR spectroscopy.

Archives of microbiology pii:10.1007/s00203-019-01681-5 [Epub ahead of print].

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.

RevDate: 2019-06-14

Zhou Y, X Gao (2019)

Characterization of Biofilm Formed by Phenanthrene-Degrading Bacteria on Rice Root Surfaces for Reduction of PAH Contamination in Rice.

International journal of environmental research and public health, 16(11): pii:ijerph16112002.

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.

RevDate: 2019-06-13

Zheng M, Zhu H, Han Y, et al (2019)

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.

Bioresource technology, 288:121590 pii:S0960-8524(19)30820-X [Epub ahead of print].

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.

RevDate: 2019-06-13

Zeng R, Xu H, Liu Y, et al (2019)

miR-146a inhibits biofilm-derived Cutibacterium acnes induced inflammatory reactions in human keratinocytes.

The Journal of investigative dermatology pii:S0022-202X(19)31634-3 [Epub ahead of print].

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.

RevDate: 2019-06-13

Sanawar H, Pinel I, Farhat NM, et al (2018)

Enhanced biofilm solubilization by urea in reverse osmosis membrane systems.

Water research X, 1:100004 pii:100004.

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.

RevDate: 2019-06-13

Gomes F, Martins N, Ferreira ICFR, et al (2019)

Anti-biofilm activity of hydromethanolic plant extracts against Staphylococcus aureus isolates from bovine mastitis.

Heliyon, 5(5):e01728 pii:e01728.

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.

RevDate: 2019-06-13

Singhal N, Maurya AK, Singh NS, et al (2019)

Antimicrobial resistance and its relationship with biofilm production and virulence-related factors in Yersinia enterocolitica biotype 1A.

Heliyon, 5(5):e01777 pii:e01777.

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.

RevDate: 2019-06-13

Zaatout N, Ayachi A, M Kecha (2019)

Interaction of primary mammary bovine epithelial cells with biofilm-forming staphylococci associated with subclinical bovine mastitis.

Iranian journal of veterinary research, 20(1):27-32.

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.

RevDate: 2019-06-13

Navidifar T, Amin M, M Rashno (2019)

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.

Infection and drug resistance, 12:1099-1111 pii:199993.

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.

RevDate: 2019-06-12

Meza-Villezcas A, Gallego-Hernández AL, Yildiz FH, et al (2019)

Effect of antimicrobial nanocomposites on Vibrio cholerae lifestyles: Pellicle biofilm, planktonic and surface-attached biofilm.

PloS one, 14(6):e0217869 pii:PONE-D-19-05430.

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.

RevDate: 2019-06-12

Salman M, Rizwana R, Khan H, et al (2019)

Synergistic effect of silver nanoparticles and polymyxin B against biofilm produced by Pseudomonas aeruginosa isolates of pus samples in vitro.

Artificial cells, nanomedicine, and biotechnology, 47(1):2465-2472.

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.

RevDate: 2019-06-12

Alavi M, N Karimi (2019)

Ultrasound assisted-phytofabricated Fe3O4 NPs with antioxidant properties and antibacterial effects on growth, biofilm formation, and spreading ability of multidrug resistant bacteria.

Artificial cells, nanomedicine, and biotechnology, 47(1):2405-2423.

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.

RevDate: 2019-06-12

García-Rodríguez JP, Amezquita-Garcia HJ, Escamilla-Alvarado C, et al (2019)

Biofilm microbial composition changes due to different surface chemical modifications of activated carbon cloths in the biotransformation of 4-nitrophenol.

Biodegradation pii:10.1007/s10532-019-09880-z [Epub ahead of print].

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.

RevDate: 2019-06-12

Zou H, Y Wang (2019)

Functional collaboration of biofilm-cathode electrode and microbial fuel cell for biodegradation of methyl orange and simultaneous bioelectricity generation.

Environmental science and pollution research international pii:10.1007/s11356-019-05617-w [Epub ahead of print].

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.

RevDate: 2019-06-12

Devadas SM, Nayak UY, Narayan R, et al (2019)

2,5-Dimethyl-4-hydroxy-3(2H)-furanone as an Anti-biofilm Agent Against Non-Candida albicans Candida Species.

Mycopathologia pii:10.1007/s11046-019-00341-y [Epub ahead of print].

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.

RevDate: 2019-06-12

Dzianach PA, Dykes GA, Strachan NJC, et al (2019)

Challenges of biofilm control and utilization: lessons from mathematical modelling.

Journal of the Royal Society, Interface, 16(155):20190042.

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.

RevDate: 2019-06-11

Pourhajibagher M, Ghorbanzadeh R, A Bahador (2019)

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.

Photodiagnosis and photodynamic therapy pii:S1572-1000(19)30001-8 [Epub ahead of print].

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.

RevDate: 2019-06-11

Nicastro LK, Tursi SA, Le LS, et al (2019)

Cytotoxic curli intermediates form during Salmonella biofilm development.

Journal of bacteriology pii:JB.00095-19 [Epub ahead of print].

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.

RevDate: 2019-06-11

Lotlikar SR, Gallaway E, Grant T, et al (2019)

Polymeric Composites with Silver (I) Cyanoximates Inhibit Biofilm Formation of Gram-Positive and Gram-Negative Bacteria.

Polymers, 11(6): pii:polym11061018.

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.

RevDate: 2019-06-10

Yang S, Guo B, Shao Y, et al (2019)

The value of floc and biofilm bacteria for anammox stability when treating ammonia-rich digester sludge thickening lagoon supernatant.

Chemosphere, 233:472-481 pii:S0045-6535(19)31209-3 [Epub ahead of print].

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.

RevDate: 2019-06-10

Liu J, Jiang J, Zong J, et al (2019)

Antibacterial and anti-biofilm effects of fatty acids extract of dried Lucilia sericata larvae against Staphylococcus aureus and Streptococcus pneumoniae in vitro.

Natural product research [Epub ahead of print].

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.

RevDate: 2019-06-10

Lahiri D, Dash S, Dutta R, et al (2019)

Elucidating the effect of anti-biofilm activity of bioactive compounds extracted from plants.

Journal of biosciences, 44(2):.

RevDate: 2019-06-10

Liu L, Ye C, Soteyome T, et al (2019)

Inhibitory effects of two types of food additives on biofilm formation by foodborne pathogens.

MicrobiologyOpen [Epub ahead of print].

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.

RevDate: 2019-06-10

Yunda E, F Quilès (2019)

In situ spectroscopic analysis of Lactobacillus rhamnosus GG flow on an abiotic surface reveals a role for nutrients in biofilm development.

Biofouling [Epub ahead of print].

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.

RevDate: 2019-06-09

Pousti M, Lefèvre T, Amirdehi MA, et al (2019)

A surface spectroscopy study of a Pseudomonas fluorescens biofilm in the presence of an immobilized air bubble.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 222:117163 pii:S1386-1425(19)30553-0 [Epub ahead of print].

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.

RevDate: 2019-06-09

Niavarzi S, Pourhajibagher M, Khedmat S, et al (2019)

Effect of ultrasonic activation on the efficacy of antimicrobial photodynamic therapy: Evaluation of penetration depth of photosensitizer and elimination of Enterococcus faecalis biofilm.

Photodiagnosis and photodynamic therapy pii:S1572-1000(19)30112-7 [Epub ahead of print].

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.

RevDate: 2019-06-08

Shah MS, Qureshi S, Kashoo Z, et al (2019)

Methicillin resistance genes and in vitro biofilm formation among Staphylococcus aureus isolates from bovine mastitis in India.

Comparative immunology, microbiology and infectious diseases, 64:117-124.

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.

RevDate: 2019-06-07

Rajasekharan SK, Lee JH, J Lee (2019)

Aripiprazole repurposed as an inhibitor of biofilm formation, and sterol biosynthesis in multi-drug resistant Candida albicans.

International journal of antimicrobial agents pii:S0924-8579(19)30133-5 [Epub ahead of print].

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.

RevDate: 2019-06-07

Kreth J, Ferracane JL, Pfeifer CS, et al (2019)

At the Interface of Materials and Microbiology: A Call for the Development of Standardized Approaches to Assay Biomaterial-Biofilm Interactions.

Journal of dental research [Epub ahead of print].

RevDate: 2019-06-07

Dell'Olmo E, Gaglione R, Pane K, et al (2019)

Fighting multidrug resistance with a fruit extract: anti-cancer and anti-biofilm activities of Acca sellowiana.

Natural product research [Epub ahead of print].

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.

RevDate: 2019-06-07

Shakibaie M, Hajighasemi E, Adeli-Sardou M, et al (2019)

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.

IET nanobiotechnology, 13(4):377-381.

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.

RevDate: 2019-06-06

Kłodzińska SN, Pletzer D, Rahanjam N, et al (2019)

Hyaluronic acid-based nanogels improve in vivo compatibility of the anti-biofilm peptide DJK-5.

Nanomedicine : nanotechnology, biology, and medicine pii:S1549-9634(19)30106-6 [Epub ahead of print].

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 194nm 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.

RevDate: 2019-06-06

Mendoza MV, RT Sáez (2019)

Modelling biofilm anaerobic reactor with effluent from hydrolytic/acidogenic reactor as substrate.

Water science and technology : a journal of the International Association on Water Pollution Research, 79(8):1534-1540.

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.

RevDate: 2019-06-06

Kriswandini IL, Rahardjo MB, Budi HS, et al (2019)

The difference in biofilm molecular weight in Streptococcus mutans and Aggregatibacter actinomycetemcomitans induced by sucrose and soy protein (glycine soja).

Indian journal of dental research : official publication of Indian Society for Dental Research, 30(2):273-276.

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).

RevDate: 2019-06-06

Le Mauff F, Bamford NC, Alnabelseya N, et al (2019)

Molecular mechanism of Aspergillus fumigatus biofilm disruption by fungal and bacterial glycoside hydrolases.

The Journal of biological chemistry pii:RA119.008511 [Epub ahead of print].

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 multi-functional 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.

RevDate: 2019-06-05

Pinto M, Langer TM, Hüffer T, et al (2019)

The composition of bacterial communities associated with plastic biofilms differs between different polymers and stages of biofilm succession.

PloS one, 14(6):e0217165 pii:PONE-D-19-01490.

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.

RevDate: 2019-06-05

Pires JG, Braga AS, Andrade FB, et al (2019)

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 of applied oral science : revista FOB, 27:e20180514 pii:S1678-77572019000100454.

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.

RevDate: 2019-06-05

Távora FFF, Chocano APC, Oliveira DG, et al (2019)

Beneficial Effects of Ethyl-Cyanoacrylate Coating Against Candida Albicans Biofilm Formation.

Brazilian dental journal, 30(3):266-271.

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.

RevDate: 2019-06-05

Iribarnegaray V, Navarro N, Robino L, et al (2019)

Magnesium-doped zinc oxide nanoparticles alter biofilm formation of Proteus mirabilis.

Nanomedicine (London, England) [Epub ahead of print].

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.

RevDate: 2019-06-05

Turner SD (2019)

Commentary on: Deposition of Host Matrix Proteins on Breast Implant Surfaces Facilitates Staphylococcus Epidermidis Biofilm Formation: In Vitro Analysis.

Aesthetic surgery journal pii:5511426 [Epub ahead of print].

RevDate: 2019-06-05

Siebert C, Lindgren H, Ferré S, et al (2019)

Francisella tularensis: FupA mutation contributes to fluoroquinolone resistance by increasing vesicle secretion and biofilm formation.

Emerging microbes & infections, 8(1):808-822.

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.

RevDate: 2019-06-04

Teh AHT, Lee SM, GA Dykes (2019)

Growth in the presence of specific antibiotics induces biofilm formation a Campylobacter jejuni strain sensitive to them but not in resistant strains.

Journal of global antimicrobial resistance pii:S2213-7165(19)30130-4 [Epub ahead of print].

OBJECTIVE: Campylobacter 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: In this study 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 was investigated.

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

CONCLUSION: The ability of certain antibiotics to induce biofilm formation by aC. jejuni strain tested is of concern with respect to the effective control of disease caused by this pathogen but further work is required to confirm how widespread this feature is.

RevDate: 2019-06-04

Maczynska B, Secewicz A, Smutnicka D, et al (2019)

In vitro efficacy of gentamicin released from collagen sponge in eradication of bacterial biofilm preformed on hydroxyapatite surface.

PloS one, 14(6):e0217769 pii:PONE-D-18-35190.

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.

RevDate: 2019-06-04

Bukhari S, B Karabucak (2019)

The Antimicrobial Effect of Bioceramic Sealer on an 8-week Matured Enterococcus faecalis Biofilm Attached to Root Canal Dentinal Surface.

Journal of endodontics pii:S0099-2399(19)30293-6 [Epub ahead of print].

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.

RevDate: 2019-06-10

Pu Y, Ngan WY, Yao Y, et al (2019)

Could benthic biofilm analyses be used as a reliable proxy for freshwater environmental health?.

Environmental pollution (Barking, Essex : 1987), 252(Pt A):440-449 pii:S0269-7491(18)35245-X [Epub ahead of print].

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.

RevDate: 2019-06-03

Shin DS, YB Eom (2019)

Zerumbone inhibits Candida albicans biofilm formation and hyphal growth.

Canadian journal of microbiology [Epub ahead of print].

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 suggested that zerumbone possessed antifungal and anti-biofilm activity which inhibited biofilm formation and eradicated preformed biofilm. Notably, zerumbone considerably reduced carbohydrate and DNA contents of biofilm matrix. In addition, zerumbone showed anti-virulence 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.

RevDate: 2019-06-03

Panmanee W, Su S, Schurr MJ, et al (2019)

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.

PloS one, 14(6):e0216401 pii:PONE-D-18-32141.

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.

RevDate: 2019-06-10

Lavery LA, Bhavan K, DK Wukich (2019)

Biofilm and diabetic foot ulcer healing: all hat and no cattle.

Annals of translational medicine, 7(7):159.

RevDate: 2019-06-03

Brilhante RSN, Aguiar L, Sales JA, et al (2019)

Ex vivo biofilm-forming ability of dermatophytes using dog and cat hair: an ethically viable approach for an infection model.

Biofouling [Epub ahead of print].

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.

RevDate: 2019-06-03

Ikezaki S, Cho T, Nagao JI, et al (2019)

Mild Heat Stress Affects on the Cell Wall Structure in Candida albicans Biofilm.

Medical mycology journal, 60(2):29-37.

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.

RevDate: 2019-06-10

Albayaty YN, Thomas N, Jambhrunkar M, et al (2019)

Enzyme responsive copolymer micelles enhance the anti-biofilm efficacy of the antiseptic chlorhexidine.

International journal of pharmaceutics, 566:329-341 pii:S0378-5173(19)30429-6 [Epub ahead of print].

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.

RevDate: 2019-06-01

Mahdinia E, Demirci A, A Berenjian (2019)

Biofilm reactors as a promising method for vitamin K (menaquinone-7) production.

Applied microbiology and biotechnology pii:10.1007/s00253-019-09913-w [Epub ahead of print].

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.

RevDate: 2019-06-01

Picco DCR, Marangoni-Lopes L, Parisotto TM, et al (2019)

Activity of Carbonic Anhydrase VI is Higher in Dental Biofilm of Children with Caries.

International journal of molecular sciences, 20(11): pii:ijms20112673.

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.

RevDate: 2019-06-01

Simonetti G, Palocci C, Valletta A, et al (2019)

Anti-Candida Biofilm Activity of Pterostilbene or Crude Extract from Non-Fermented Grape Pomace Entrapped in Biopolymeric Nanoparticles.

Molecules (Basel, Switzerland), 24(11): pii:molecules24112070.

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.

RevDate: 2019-06-01

Heersema LA, HDC Smyth (2019)

A Multispecies Biofilm In Vitro Screening Model of Dental Caries for High-Throughput Susceptibility Testing.

High-throughput, 8(2): pii:ht8020014.

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.

RevDate: 2019-06-10

Rajivgandhi G, Maruthupandy M, Muneeswaran T, et al (2019)

Biosynthesized silver nanoparticles for inhibition of antibacterial resistance and biofilm formation of methicillin-resistant coagulase negative Staphylococci.

Bioorganic chemistry, 89:103008 pii:S0045-2068(19)30488-2 [Epub ahead of print].

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.

RevDate: 2019-06-10

Tahrioui A, Duchesne R, Bouffartigues E, et al (2019)

Extracellular DNA release, quorum sensing, and PrrF1/F2 small RNAs are key players in Pseudomonas aeruginosa tobramycin-enhanced biofilm formation.

NPJ biofilms and microbiomes, 5:15 pii:88.

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.

RevDate: 2019-06-10

Abbas HA, Elsherbini AM, MA Shaldam (2019)

Glyceryl trinitrate blocks staphyloxanthin and biofilm formation in Staphylococcus aureus.

African health sciences, 19(1):1376-1384.

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.


RJR Experience and Expertise


Robbins holds BS, MS, and PhD degrees in the life sciences. He served as a tenured faculty member in the Zoology and Biological Science departments at Michigan State University. He is currently exploring the intersection between genomics, microbial ecology, and biodiversity — an area that promises to transform our understanding of the biosphere.


Robbins has extensive experience in college-level education: At MSU he taught introductory biology, genetics, and population genetics. At JHU, he was an instructor for a special course on biological database design. At FHCRC, he team-taught a graduate-level course on the history of genetics. At Bellevue College he taught medical informatics.


Robbins has been involved in science administration at both the federal and the institutional levels. At NSF he was a program officer for database activities in the life sciences, at DOE he was a program officer for information infrastructure in the human genome project. At the Fred Hutchinson Cancer Research Center, he served as a vice president for fifteen years.


Robbins has been involved with information technology since writing his first Fortran program as a college student. At NSF he was the first program officer for database activities in the life sciences. At JHU he held an appointment in the CS department and served as director of the informatics core for the Genome Data Base. At the FHCRC he was VP for Information Technology.


While still at Michigan State, Robbins started his first publishing venture, founding a small company that addressed the short-run publishing needs of instructors in very large undergraduate classes. For more than 20 years, Robbins has been operating The Electronic Scholarly Publishing Project, a web site dedicated to the digital publishing of critical works in science, especially classical genetics.


Robbins is well-known for his speaking abilities and is often called upon to provide keynote or plenary addresses at international meetings. For example, in July, 2012, he gave a well-received keynote address at the Global Biodiversity Informatics Congress, sponsored by GBIF and held in Copenhagen. The slides from that talk can be seen HERE.


Robbins is a skilled meeting facilitator. He prefers a participatory approach, with part of the meeting involving dynamic breakout groups, created by the participants in real time: (1) individuals propose breakout groups; (2) everyone signs up for one (or more) groups; (3) the groups with the most interested parties then meet, with reports from each group presented and discussed in a subsequent plenary session.


Robbins has been engaged with photography and design since the 1960s, when he worked for a professional photography laboratory. He now prefers digital photography and tools for their precision and reproducibility. He designed his first web site more than 20 years ago and he personally designed and implemented this web site. He engages in graphic design as a hobby.

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This is a must read book for anyone with an interest in invasion biology. The full title of the book lays out the author's premise — The New Wild: Why Invasive Species Will Be Nature's Salvation. Not only is species movement not bad for ecosystems, it is the way that ecosystems respond to perturbation — it is the way ecosystems heal. Even if you are one of those who is absolutely convinced that invasive species are actually "a blight, pollution, an epidemic, or a cancer on nature", you should read this book to clarify your own thinking. True scientific understanding never comes from just interacting with those with whom you already agree. R. Robbins

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Collection of publications by R J Robbins

Reprints and preprints of publications, slide presentations, instructional materials, and data compilations written or prepared by Robert Robbins. Most papers deal with computational biology, genome informatics, using information technology to support biomedical research, and related matters.

Research Gate page for R J Robbins

ResearchGate is a social networking site for scientists and researchers to share papers, ask and answer questions, and find collaborators. According to a study by Nature and an article in Times Higher Education , it is the largest academic social network in terms of active users.

Curriculum Vitae for R J Robbins

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Curriculum Vitae for R J Robbins

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