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26 Jan 2022 at 01:31
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Bibliography on: Biofilm


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RJR: Recommended Bibliography 26 Jan 2022 at 01:31 Created: 


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 28392838[PMID] NOT 31293528[PMID] NOT 29372251[PMID] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)


RevDate: 2022-01-20

Pani A, Valeria L, Dugnani S, et al (2022)

Erdosteine enhances antibiotic activity against bacteria within biofilm.

International journal of antimicrobial agents pii:S0924-8579(22)00019-X [Epub ahead of print].

Bacterial biofilms form on inert or living surfaces and display high levels of resistance to antibiotics, making it difficult to eradicate biofilm-related infections. Erdosteine, a thiol-based drug used in the treatment of acute and chronic respiratory diseases, has multiple pharmacodynamic properties (mucolytic, anti-inflammatory, antioxidant) which suggest that it may have potential in controlling biofilm-related infections. This in vitro study aimed to evaluate the effects of erdosteine in combination with different antibiotics against methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA) biofilms. Biofilm production/mass and bacterial viability were measured using crystal violet absorbance and resorufin resonance, respectively, in young (6-h) and mature (24-h) biofilms incubated with antibiotics (at concentrations from 0 to 200 times the minimum inhibitory concentration [MIC]) for 24 h in the absence or presence of erdosteine (2, 5, and 10 mg/liter). In 6-h MRSA biofilms, vancomycin and linezolid displayed concentration-dependent reductions in biofilm mass and viability, which was enhanced in the presence of increasing concentrations of erdosteine. Similar results were seen for amoxicillin-clavulanate and levofloxacin against 6-h MSSA biofilms. Antibiotics alone had reduced efficacy against 24-h biofilms, while the effect of the erdosteine-antibiotic combination was significantly greater against 24-h biofilms (MRSA and MSSA). These results suggest that erdosteine enhances the activity of the antibiotic by facilitating its penetration into biofilms and by disrupting the extracellular polymeric substance matrix; this should be confirmed with further studies. The potential clinical value of erdosteine in treating biofilm-related infections warrants further investigation.

RevDate: 2022-01-20

Sandhya M, Huang Y, Li J, et al (2022)

Biofilm-mediated bioremediation is a powerful tool for the removal of environmental pollutants.

Chemosphere pii:S0045-6535(22)00098-4 [Epub ahead of print].

Biofilm-mediated bioremediation is an attractive approach for the elimination of environmental pollutants, because of its wide adaptability, biomass, and excellent capacity to absorb, immobilize, or degrade contaminants. Biofilms are assemblages of individual or mixed microbial cells adhering to a living or non-living surface in an aqueous environment. Biofilm-forming microorganisms have excellent survival under exposure to harsh environmental stressors, can compete for nutrients, exhibit greater tolerance to pollutants compared to free-floating planktonic cells, and provide a protective environment for cells. Biofilm communities are thus capable of sorption and metabolization of organic pollutants and heavy metals through a well-controlled expression pattern of genes governed by quorum sensing. The involvement of quorum sensing and chemotaxis in biofilms can enhance the bioremediation kinetics with the help of signaling molecules, the transfer of genetic material, and metabolites. This review provides in-depth knowledge of the process of biofilm formation in microorganisms, their regulatory mechanisms of interaction, and their importance and application as powerful bioremediation agents in the biodegradation of environmental pollutants, including hydrocarbons, pesticides, and heavy metals.

RevDate: 2022-01-20

Su X, Cheng X, Wang Y, et al (2022)

Effect of different D-amino acids on biofilm formation of mixed microorganisms.

Water science and technology : a journal of the International Association on Water Pollution Research, 85(1):116-124.

This study aimed to determine the effects of D-tyrosine, D-aspartic acid, D-tryptophan and D-leucine on biofilm formation of mixed microorganisms. Results showed that, in the attachment stage, D-amino acids caused significant reduction in adhesion efficiency of mixed microorganisms to the membrane surface. Moreover, D-amino acids have a promoting effect on the reversible adhesion of mixed microorganisms. The addition of D-amino acid generally inhibited the biofilm biomass, of which D-tyrosine has the best inhibition effect. With the effect of D-tyrosine, D-aspartic acid, D-tryptophan and D-leucine, the protein in extracellular polymeric substance (EPS) decreased by 8.21%, 7.65%, 3.51% and 11.31%, respectively. The carbohydrates in EPS decreased by 29.53%, 21.44%, 14.60% and 10.54%, respectively. The results of excitation-emission matrix spectra (EEMs) suggested that the structural properties of the tyrosine-like proteins, tryptophan-like protein and humic-like acid might have changed by the D-amino acids.

RevDate: 2022-01-20

Parker CW, Teixeira MM, Singh NK, et al (2022)

Genomic Characterization of Parengyodontium torokii sp. nov., a Biofilm-Forming Fungus Isolated from Mars 2020 Assembly Facility.

Journal of fungi (Basel, Switzerland), 8(1): pii:jof8010066.

A fungal strain (FJII-L10-SW-P1) was isolated from the Mars 2020 spacecraft assembly facility and exhibited biofilm formation on spacecraft-qualified Teflon surfaces. The reconstruction of a six-loci gene tree (ITS, LSU, SSU, RPB1 and RPB2, and TEF1) using multi-locus sequence typing (MLST) analyses of the strain FJII-L10-SW-P1 supported a close relationship to other known Parengyodontium album subclade 3 isolates while being phylogenetically distinct from subclade 1 strains. The zig-zag rachides morphology of the conidiogenous cells and spindle-shaped conidia were the distinct morphological characteristics of the P. album subclade 3 strains. The MLST data and morphological analysis supported the conclusion that the P. album subclade 3 strains could be classified as a new species of the genus Parengyodontium and placed in the family Cordycipitaceae. The name Parengyodontium torokii sp. nov. is proposed to accommodate the strain, with FJII-L10-SW-P1 as the holotype. The genome of the FJII-L10-SW-P1 strain was sequenced, annotated, and the secondary metabolite clusters were identified. Genes predicted to be responsible for biofilm formation and adhesion to surfaces were identified. Homology-based assignment of gene ontologies to the predicted proteome of P. torokii revealed the presence of gene clusters responsible for synthesizing several metabolic compounds, including a cytochalasin that was also verified using traditional metabolomic analysis.

RevDate: 2022-01-20

Netsch A, Horn H, M Wagner (2021)

On-Line Monitoring of Biofilm Accumulation on Graphite-Polypropylene Electrode Material Using a Heat Transfer Sensor.

Biosensors, 12(1): pii:bios12010018.

Biofilms growing on electrodes are the heart piece of bioelectrochemical systems (BES). Moreover, the biofilm morphology is key for the efficient performance of BES and must be monitored and controlled for a stable operation. For the industrial use of BES (i.e., microbial fuel cells for energy production), monitoring of the biofilm accumulation directly on the electrodes during operation is desirable. In this study a commercially available on-line heat transfer biofilm sensor is applied to a graphite-polypropylene (C-PP) pipe and compared to its standard version where the sensor is applied to a stainless-steel pipe. The aim was to investigate the transferability of the sensor to a carbonaceous material (C-PP), that are preferably used as electrode materials for bioelectrochemical systems, thereby enabling biofilm monitoring directly on the electrode surface. The sensor signal was correlated to the gravimetrically determined biofilm thickness in order to identify the sensitivity of the sensor for the detection and quantification of biofilm on both materials. Results confirmed the transferability of the sensor to the C-PP material, despite the sensor sensitivity being decreased by a factor of approx. 5 compared to the default biofilm sensor applied to a stainless-steel pipe.

RevDate: 2022-01-20

Lang KN, Sculean A, Eick S, et al (2022)

A novel in vitro periodontal pocket model to evaluate the effect of root surface instrumentation on biofilm-epithelial cell interactions.

Clinical oral investigations [Epub ahead of print].

OBJECTIVE: To develop a novel in vitro periodontal pocket model for evaluating the effect of two different root surface instrumentation modalities on biofilm-epithelial cell interactions.

MATERIALS AND METHODS: An artificial periodontal pocket model was created using an impression material. Dentin discs were prepared and incubated for 3.5 days with a biofilm consisting of 12 bacterial strains. Then, the discs were inserted into the pocket model and instrumented for 10 s or 10 strokes either with ultrasonics (US) or hand instruments (HI). Subsequently, a glass slide coated with epithelial cells was placed in close vicinity to the discs. After incubation of the pocket model in a 5% CO2 atmosphere for 6 h, residual bacteria of the biofilm as well as bacteria adhering to or invaded into epithelial cells were determined using colony-forming unit (cfu) counts and real-time PCR. Further, as a parameter of the pro-inflammatory cell response, interleukin (IL)-8 expression was determined by ELISA.

RESULTS: Compared to untreated control, HI reduced the cfu counts by 0.63 log10 (not significant) and US by 1.78 log10 (p = 0.005) with a significant difference between the treatment modalities favoring US (p = 0.048). By trend, lower detection levels of Tannerella forsythia were detected in the US group compared to HI. Concerning the interaction with epithelial cells, half of the control and the HI samples showed epithelial cells with attaching or invading bacteria, while US displayed bacteria only in two out of eight samples. In addition, US resulted in significantly lower IL-8 secretion by epithelial cells compared to the untreated control. Between HI and controls, no statistically significant difference in IL-8 secretion was found.

CONCLUSION: This newly developed in vitro model revealed in terms of biofilm-epithelial cell interaction after root surface instrumentation that compared to hand curettes, ultrasonic instrumentation appeared to be more effective in removing bacterial biofilm and in decreasing the inflammatory response of epithelium to biofilm.

CLINICAL RELEVANCE: Ultrasonic instrumentation might be more advantageous to reduce cellular inflammatory response than hand instruments.

RevDate: 2022-01-20

Uranga C, Nelson KE, Edlund A, et al (2021)

Tetramic Acids Mutanocyclin and Reutericyclin A, Produced by Streptococcus mutans Strain B04Sm5 Modulate the Ecology of an in vitro Oral Biofilm.

Frontiers in oral health, 2:796140.

The human oral microbiome consists of diverse microbes actively communicating and interacting through a variety of biochemical mechanisms. Dental caries is a major public health issue caused by fermentable carbohydrate consumption that leads to dysbiosis of the oral microbiome. Streptococcus mutans is a known major contributor to caries pathogenesis, due to its exceptional ability to form biofilms in the presence of sucrose, as well as to its acidophilic lifestyle. S. mutans can also kill competing bacteria, which are typically health associated, through the production of bacteriocins and other small molecules. A subset of S. mutans strains encode the muc biosynthetic gene cluster (BGC), which was recently shown to produce the tetramic acids, mutanocyclin and reutericyclins A, B, and C. Reutericyclin A displayed strong antimicrobial activity and mutanocyclin appeared to be anti-inflammatory; however the effect of these compounds, and the carriage of muc by S. mutans, on the ecology of the oral microbiota is not known, and was examined here using a previously developed in vitro biofilm model derived from human saliva. While reutericyclin significantly inhibited in vitro biofilm formation and acid production at sub-nanomolar concentrations, mutanocyclin did not present any activity until the high micromolar range. 16S rRNA gene sequencing revealed that reutericyclin drastically altered the biofilm community composition, while mutanocyclin showed a more specific effect, reducing the relative abundance of cariogenic Limosilactobacillus fermentum. Mutanocyclin or reutericyclin produced by the S. mutans strains amended to the community did not appear to affect the community in the same way as the purified compounds, although the results were somewhat confounded by the differing growth rates of the S. mutans strains. Regardless of the strain added, the addition of S. mutans to the in vitro community significantly increased the abundance of S. mutans and Veillonella infantium, only. Overall, this study illustrates that reutericyclin A and mutanocyclin do impact the ecology of a complex in vitro oral biofilm; however, further research is needed to determine the extent to which the production of these compounds affects the virulence of S. mutans.

RevDate: 2022-01-20

Zhou P, Manoil D, Belibasakis GN, et al (2021)

Veillonellae: Beyond Bridging Species in Oral Biofilm Ecology.

Frontiers in oral health, 2:774115.

The genus Veillonella comprises 16 characterized species, among which eight are commonly found in the human oral cavity. The high abundance of Veillonella species in the microbiome of both supra- and sub-gingival biofilms, and their interdependent relationship with a multitude of other bacterial species, suggest veillonellae to play an important role in oral biofilm ecology. Development of oral biofilms relies on an incremental coaggregation process between early, bridging and later bacterial colonizers, ultimately forming multispecies communities. As early colonizer and bridging species, veillonellae are critical in guiding the development of multispecies communities in the human oral microenvironment. Their ability to establish mutualistic relationships with other members of the oral microbiome has emerged as a crucial factor that may contribute to health equilibrium. Here, we review the general characteristics, taxonomy, physiology, genomic and genetics of veillonellae, as well as their bridging role in the development of oral biofilms. We further discuss the role of Veillonella spp. as potential "accessory pathogens" in the human oral cavity, capable of supporting colonization by other, more pathogenic species. The relationship between Veillonella spp. and dental caries, periodontitis, and peri-implantitis is also recapitulated in this review. We finally highlight areas of future research required to better understand the intergeneric signaling employed by veillonellae during their bridging activities and interspecies mutualism. With the recent discoveries of large species and strain-specific variation within the genus in biological and virulence characteristics, the study of Veillonella as an example of highly adaptive microorganisms that indirectly participates in dysbiosis holds great promise for broadening our understanding of polymicrobial disease pathogenesis.

RevDate: 2022-01-20

Wagenknecht DR, RL Gregory (2021)

Analyses of the Effects of Arginine, Nicotine, Serotype and Collagen-Binding Proteins on Biofilm Development by 33 Strains of Streptococcus mutans.

Frontiers in oral health, 2:764784.

Streptococcus mutans serotype k strains comprise <3% of oral isolates of S. mutans but are prominent in diseased cardiovascular (CV) tissue. Collagen binding protein (CBP) genes, cbm and cnm, are prevalent in serotype k strains and are associated with endothelial cell invasion. Nicotine increases biofilm formation by serotype c strains of S. mutans, but its effects on serotype k strains and strains with CBP are unknown. Saliva contains arginine which alters certain properties of the extracellular polysaccharides (EPS) in S. mutans biofilm. We examined whether nicotine and arginine affect sucrose-induced biofilm of S. mutans serotypes k (n = 23) and c (n = 10) strains with and without CBP genes. Biofilm mass, metabolism, bacterial proliferation, and EPS production were assessed. Nicotine increased biomass and metabolic activity (p < 0.0001); arginine alone had no effect. The presence of a CBP gene (either cbm or cnm) had a significant effect on biofilm production, but serotype did not. Nicotine increased bacterial proliferation and the effect was greater in CBP + strains compared to strains lacking CBP genes. Addition of arginine with nicotine decreased both bacterial mass and EPS compared to biofilm grown in nicotine alone. EPS production was greater in cnm + than cbm + strains (p < 0.0001). Given the findings of S. mutans in diseased CV tissue, a nicotine induced increase in biofilm production by CBP + strains may be a key link between tobacco use and CV diseases.

RevDate: 2022-01-20

Taylor ES, Gomez GF, Moser EAS, et al (2021)

Effect of a Tea Polyphenol on Different Levels of Exposure of Nicotine and Tobacco Extract on Streptococcus mutans Biofilm Formation.

Frontiers in oral health, 2:737378.

Objective: The purpose of this study was to compare the effects of different levels of nicotine and tobacco extract exposure on Streptococcus mutans biofilm formation and the inhibitory effect of the polyphenol epigallocatechin-3 gallate (EGCG) found in green tea. This study addressed the results of biofilm assays with EGCG and varying relative concentrations of nicotine and tobacco extract consistent with primary, secondary and tertiary levels of smoking exposure. Primary smoking exposure to nicotine has been demonstrated to significantly increase biofilm formation, while EGCG has been demonstrated to reduce S. mutans biofilm formation. Methods: S. mutans was treated with varying levels of nicotine or cigarette smoke condensate (CSC) concentrations (0-32 mg/ml and 0-2 mg/ml, respectively) in Tryptic Soy broth supplemented with 1% sucrose for different lengths of time simulating primary, secondary and tertiary smoking exposure with and without 0.25 mg/ml EGCG. The amount of total growth and biofilm formed was determined using a spectrophotometric crystal violet dye staining assay. Results: For both nicotine and CSC, primary exposure displayed overall significantly less growth compared to secondary exposure. For nicotine, secondary exposure demonstrated significantly greater growth than tertiary exposure levels. Overall, significantly greater total bacterial growth and biofilm formation in the presence of nicotine and CSC was observed in the absence of EGCG than in the presence of EGCG. However, biofilm growth was not significantly different among different concentrations of CSC. Conclusion: The results of this study help illustrate that nicotine-induced S. mutans biofilm formation is reduced by the presence of EGCG. This provides further evidence of the potential beneficial properties of polyphenols.

RevDate: 2022-01-20

Albaghdadi SZ, Altaher JB, Drobiova H, et al (2021)

In vitro Characterization of Biofilm Formation in Prevotella Species.

Frontiers in oral health, 2:724194.

Background: Periodontitis, a chronic inflammatory oral infection is the outcome of disturbances in the homeostasis of the oral biofilm microbiota. A number of studies have found the occurrence of Prevotella species in elevated levels in periodontitis compared to healthy subjects. Even though different aspects of Prevotella as part of oral biofilm have been studied, in vitro biofilms formed by these species have not been characterized systematically. The objective of this study was to characterize biofilms formed by several Prevotella species and further to assess biofilm inhibition and detachment of preformed biofilms. Methods: Biofilms were grown in 24-well plates containing brucella broth in anaerobic conditions for 3 days, and were quantified using crystal violet staining. Images of SYTO 9 Green fluorescent stained biofilms were captured using confocal microscopy. Biofilm inhibition and detachment by proteinase and DNase I was tested. The biochemical characterization included quantification of proteins and DNA in the biofilms and biofilm-supernatants. Results: Prevotella loescheii, Prevotella oralis and Prevotella nigrescens showed highest biofilm formation. P. nigrescens formed significantly higher amounts of biofilms than P. loescheii (P = 0.005) and P. oralis (P = 0.0013). Inhibition of biofilm formation was significant only in the case of P. oralis when treated with proteinase (P = 0.037), whereas with DNase I treatment, the inhibition was not significant (P = 0.531). Overall, proteinase was more effective in biofilm detachment than DNase I. Protein and DNA content were higher in biofilm than the supernatant with the highest amounts found in P. nigrescens biofilm and supernatants. P. oralis biofilms appeared to secrete large amounts of proteins extracellularly into the biofilm-supernatants. Conclusion: Significant differences among Prevotella species to form biofilms may imply their variable abilities to get integrated into oral biofilm communities. Of the species that were able to grow as biofilms, DNase I and proteinase inhibited the biofilm growth or were able to cause biofilm detachment.

RevDate: 2022-01-20

Giordani B, Parolin C, B Vitali (2021)

Lactobacilli as Anti-biofilm Strategy in Oral Infectious Diseases: A Mini-Review.

Frontiers in medical technology, 3:769172.

The spread of biofilm-related diseases in developed countries has led to increased mortality rates and high health care costs. A biofilm is a community of microorganisms that is irreversibly attached to a surface, behaving very differently from planktonic cells and providing resistance to antimicrobials and immune response. Oral diseases are an excellent example of infection associated with the formation of highly pathogenic biofilms. It is generally accepted that, when the oral homeostasis is broken, the overgrowth of pathogens is facilitated. Among them, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans are the main etiological agents of periodontitis, while Streptococcus mutans is strongly associated with the onset of dental caries. Other microorganisms, such as the fungus Candida albicans, may also be present and contribute to the severity of infections. Since the common antibiotic therapies usually fail to completely eradicate biofilm-related oral diseases, alternative approaches are highly required. In this regard, the topical administration of probiotics has recently gained interest in treating oral diseases. Thus, the present mini-review focuses on the possibility of using Lactobacillus spp. as probiotics to counteract biofilm-mediated oral infections. Many evidence highlight that Lactobacillus living cells can impede the biofilm formation and eradicate mature biofilms of different oral pathogens, by acting through different mechanisms. Even more interestingly, lactobacilli derivatives, namely postbiotics (soluble secreted products) and paraprobiotics (cell structural components) are able to trigger anti-biofilm effects too, suggesting that they can represent a novel and safer alternative to the use of viable cells in the management of biofilm-related oral diseases.

RevDate: 2022-01-20

Bao J, Xie L, Ma Y, et al (2021)

Proteomic and Transcriptomic Analyses Indicate Reduced Biofilm-Forming Abilities in Cefiderocol-Resistant Klebsiella pneumoniae.

Frontiers in microbiology, 12:778190.

The advent of cefiderocol provides hope for the clinical treatment of multi-drug resistant gram-negative bacteria (GNB), especially those with carbapenem resistance. Resistance of Klebsiella pneumoniae to cefiderocol can be enhanced by acclimatization. In the present study, we collected cefiderocol resistant K. pneumoniae isolates during a 36-day acclimatization procedure while increasing the cefiderocol concentration in the culture medium. Strains were studied for changes in their biological characteristics using proteomics and transcriptomics. A decrease in biofilm formation ability was the main change observed among the induced isolates. Downregulation of genes involved in biofilm formation including hdeB, stpA, yhjQ, fba, bcsZ, uvrY, bcsE, bcsC, and ibpB were the main factors that reduced the biofilm formation ability. Moreover, downregulation of siderophore transporter proteins including the iron uptake system component efeO, the tonB-dependent receptor fecA, and ferric iron ABC transporter fbpA may be among the determining factors leading to cefiderocol resistance and promoting the reduction of biofilm formation ability of K. pneumoniae. This is the first study to investigate cefiderocol resistance based on comprehensive proteomic and transcriptomic analyses.

RevDate: 2022-01-20

Zhang L, Yang W, Chu Y, et al (2021)

The Inhibition Effect of Linezolid With Reyanning Mixture on MRSA and its Biofilm is More Significant than That of Linezolid Alone.

Frontiers in pharmacology, 12:766309 pii:766309.

Methicillin-resistant Staphylococcus aureus (MRSA) is a superbacterium, and when it forms biofilms, it is difficult to treat even with the first-line of antibiotic linezolid (LNZ). Reyanning mixture (RYN), a compound-based Chinese medicine formula, has been found to have inhibitory effects on biofilms. This study aims to explore the synergistic inhibitory effect and corresponding mechanisms of their (LNZ&RYN) combination on the planktonic as well as biofilm cells of MRSA. Broth microdilution and chessboard methods were employed for the determination of minimum inhibitory concentrations (MICs) and synergistic concentration of LNZ&RYN, respectively. The effect of the combined medication on biofilm and mature biofilm of MRSA were observed by biofilm morphology and permeability experiments, respectively. To unveil the molecular mechanism of action of the synergistic combination of LNZ and RYN, RT-PCR based biofilm-related gene expression analysis and ultra-high pressure liquid chromatography-time-of-flight mass spectrometry based endogenous metabonomic analysis were deployed. The results indicated that 1/16RYN as the best combined dose reduced LNZ (4 μg/ml) to 2 μg/ml. The combined treatment inhibited living MRSA before and after biofilm formation, removed the residual structure of dead bacteria in MRSA biofilms and affected the shape and size of bacteria, resulting in the improvement of biofilm permeability. The mechanism was that biofilm-related genes such as agrC, atlA, and sarA, as well as amino acid uptake associated with the metabolism of 3-dehydrocarnitine, kynurenine, L-leucine, L-lysine and sebacic acid were inhibited. This study provides evidence for the treatment of MRSA and its biofilms with LNZ combined with RYN.

RevDate: 2022-01-19

Pant N, Wallis SC, Roberts JA, et al (2022)

In vitro effect of synovial fluid from patients undergoing arthroplasty surgery on MRSA biofilm formation.

The Journal of antimicrobial chemotherapy pii:6511742 [Epub ahead of print].

BACKGROUND: Bacterial biofilm is a key component in the pathogenesis of prosthetic joint infection (PJI). Synovial fluid has been shown to have inhibitory activity against planktonic bacteria. However, the contribution of synovial fluid in prevention of Staphylococcus aureus (including MRSA) planktonic and biofilm forms is unknown.

OBJECTIVES: To test the antibacterial and antibiofilm activities of synovial fluid, including that containing cefazolin, against MSSA and MRSA.

MATERIALS AND METHODS: We determined the antiplanktonic and antibiofilm activities of synovial fluid collected from patients given preoperative cefazolin while undergoing elective arthroplasty surgery. MICs of cefazolin were determined for planktonic and biofilm cultures of biofilm-forming strains of MSSA and MRSA.

RESULTS: Synovial fluid inhibited planktonic and biofilm cultures of MSSA and MRSA. Cefazolin-containing synovial fluid had greater antibacterial and antibiofilm activities than the same cefazolin concentration in glucose LB (GLB) broth. MSSA and MRSA MICs of cefazolin suspended in synovial fluid were 0.7 mg/L. The MICs of cefazolin diluted in GLB broth were higher, measuring 1.4 mg/L for MSSA and 23 mg/L for MRSA.

CONCLUSIONS: Synovial fluid containing cefazolin inhibited biofilm- and planktonic-state MRSA cultures. This may explain the apparent effect of cefazolin in the prevention of MRSA PJI.

RevDate: 2022-01-19

Chen MY, Alexiev A, VJ McKenzie (2022)

Bacterial biofilm thickness and fungal-inhibitory bacterial richness both prevent establishment of the amphibian fungal pathogen, Batrachochytrium dendrobatidis.

Applied and environmental microbiology [Epub ahead of print].

Host-associated microbial biofilms can provide protection against pathogen establishment. In many host-microbe symbioses (including, but not limited to: humans, plants, insects, and amphibians), there is a correlation between host-associated microbial diversity and pathogen infection risk. Diversity may prevent infection by pathogens through sampling effects and niche complementarity- but an alternative hypothesis may be that microbial biomass is confounded with diversity, and that host-associated biofilms are deterring pathogen establishment through space pre-emption. In this study, we use the amphibian system as a model for host-microbe-pathogen interactions to ask two questions: (1) is bacterial richness confounded with biofilm thickness or cell density, and (2) to what extent does biofilm thickness, cell density, and bacterial richness each deter the establishment of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd)? To answer these questions, we built a custom biofilm microcosm that mimics the host-environment interface by allowing nutrients to diffuse out of a fine-pore biofilm scaffolding. This created a competitive environment in which bacteria and the fungal pathogen compete for colonization space. We then challenged bacterial biofilms ranging in community richness, biofilm thickness, bacterial cell density, and Bd-inhibitory metabolite production with live Bd zoospores to determine how Bd establishment success on membranes vary. We found that biofilm thickness and Bd-inhibitory isolate richness work in complement to reduce Bd establishment success. This work underscores that physical aspects of biofilm communities can play a large role in pathogen inhibition and in many studies, these traits are not studied. IMPORTANCE Our finding highlights the fact that diversity, as measured through 16S rDNA sequencing, may obscure the true mechanisms behind microbe-mediated pathogen defence, and that physical space occupation by biofilm-forming symbionts may significantly contribute to pathogen protection. These findings have implications across a wide range of host-microbe systems, since 16S rDNA sequencing is a standard tool used across many microbial systems. Further, our results are potentially relevant to many host-pathogen systems, since host-associated bacterial biofilms are ubiquitous.

RevDate: 2022-01-18

Ribeiro IP, Pinto JG, Souza BMN, et al (2022)

4Antimicrobial photodynamic therapy with curcumin on methicillin-resistant Staphylococcus aureus biofilm.

Photodiagnosis and photodynamic therapy pii:S1572-1000(22)00018-7 [Epub ahead of print].

Healthcare-Associated Infections (HAI) affect approximately 1.5 million individuals worldwide. Among the causes of HAIs in Latin America, Staphylococcus aureus presents a severe danger due to its rapid spread and ease of developing antibiotic resistance. Upon acquiring methicillin resistance, it receives the classification Methicillin-Resistant Staphylococcus aureus (MRSA), responsible for 40 to 60% of HAIs. The increase in resistant microorganisms led to the search for alternative methods, such as antimicrobial Photodynamic Therapy (aPDT), forming Reactive Oxygen Species (ROS), leading bacterial cells to death. The objective of this work was to evaluate in vitro the antimicrobial action of PDT with curcumin in MRSA biofilm. The strains were induced to form biofilm and incubated with curcumin for 20 minutes, irradiated with LED (Light Emitting Diode) 450 nm, at 110 mW/cm2, 50 J/cm2 for 455 seconds, subsequently counting the Colony Forming Units, Scanning Electron Microscopy (SEM) micrographs, Confocal Microscopy images, Resazurin dye test, ROS quantification to assess the effect of PDT on biofilm. The results show that PDT with curcumin reduced the biofilm growth of the MRSA strain. In addition, confocal microscopy showed that curcumin was internalized by S. aureus in the cells at the concentration used, and when isolated, curcumin and the irradiation parameter did not show cytotoxicity. The study demonstrated that the PDT in the established parameters reduced the growth of the MRSA strain biofilm, making it a relevant alternative possibility for the inactivation of this strain.

RevDate: 2022-01-18

Bilal H, Tait JR, Lang Y, et al (2022)

Simulated intravenous versus inhaled tobramycin with and without intravenous ceftazidime evaluated against hypermutable Pseudomonas aeruginosa via a dynamic biofilm model and mechanism-based modeling.

Antimicrobial agents and chemotherapy [Epub ahead of print].

Acute exacerbations of chronic respiratory infections in patients with cystic fibrosis are highly challenging due to hypermutable Pseudomonas aeruginosa, biofilm formation and resistance emergence. We aimed to systematically evaluate the effects of intravenous versus inhaled tobramycin with and without intravenous ceftazidime. Two hypermutable P. aeruginosa isolates, CW30 (MICCAZ 0.5mg/L, MICTOB 2mg/L) and CW8 (MICCAZ 2mg/L, MICTOB 8mg/L), were investigated for 120h in dynamic in vitro biofilm studies. Treatments were: intravenous ceftazidime 9g/day (33% lung fluid penetration); intravenous tobramycin 10mg/kg 24-hourly (50% lung fluid penetration); inhaled tobramycin 300mg 12-hourly, and both ceftazidime-tobramycin combinations. Total and less-susceptible planktonic and biofilm bacteria were quantified over 120h. Mechanism-based modeling was performed. All monotherapies were ineffective for both isolates, with regrowth of planktonic (≥4.7log10 CFU/mL) and biofilm (>3.8log10 CFU/cm2) bacteria, and resistance amplification by 120h. Both combination treatments demonstrated synergistic or enhanced bacterial killing of planktonic and biofilm bacteria. With the combination simulating tobramycin inhalation, planktonic bacterial counts of the two isolates at 120h were 0.47% and 36% of those for the combination with intravenous tobramycin; for biofilm bacteria the corresponding values were 8.2% and 13%. Combination regimens achieved substantial suppression of resistance of planktonic and biofilm bacteria compared to each antibiotic in monotherapy for both isolates. Mechanism-based modeling well described all planktonic and biofilm counts, and indicated synergy of the combination regimens despite reduced activity of tobramycin in biofilm. Combination regimens of inhaled tobramycin with ceftazidime hold promise to treat acute exacerbations caused by hypermutable P. aeruginosa strains and warrant further investigation.

RevDate: 2022-01-18

Blasco L, Bleriot I, González de Aledo M, et al (2022)

«Development of an anti-Acinetobacter baumannii biofilm phage cocktail: Genomic Adaptation to the Host».

Antimicrobial agents and chemotherapy [Epub ahead of print].

The need for alternatives to antibiotic therapy due to the emergence of multidrug resistant bacteria (MDR), such as the nosocomial pathogen Acinetobacter baumannii, has led to the recovery of phage therapy. In addition, phages can be combined in cocktails to increase the host range. In this study, the evolutionary mechanism of adaptation was utilized in order to develop a phage adapted to A. baumannii, named phage Ab105-2phiΔCI404ad, from a mutant lytic phage, Ab105-2phiΔCI, previously developed by our group. The whole genome sequence of phage Ab105-2phiΔCI404ad was determined, showing that four genomic rearrangements events occurred in the tail morphogenesis module affecting the ORFs encoding the host receptor binding sites. As a consequence of the genomic rearrangements, 10 ORFs were lost and four new ORFs were obtained, all encoding tail proteins; two inverted regions were also derived from these events. The adaptation process increased the host range of the adapted phage by almost three folds. In addition, a depolymerase-expressing phenotype, indicated by formation of a halo, which was not observed in the ancestral phage, was obtained in 81% of the infected strains. A phage cocktail was formed by combining this phage with the A. baumannii phage vB_AbaP_B3, known to express a depolymerase. Both the individual phages and the phage cocktail showed strong antimicrobial activity against 5 clinical strains and 1 reference strain of A. baumannii tested. However, in all cases resistance to the bacterial strains was also observed. The antibiofilm activity of the individual phages and the cocktail was assayed. The phage cocktail displayed strong antibiofilm activity.

RevDate: 2022-01-17

Tan Q, Ai Q, He Y, et al (2022)

P. aeruginosa biofilm activates the NLRP3 inflammasomes in vitro.

Microbial pathogenesis pii:S0882-4010(21)00653-7 [Epub ahead of print].

The ability of P.aeruginosa to form biofilms renders common treatments inefficient, thereby promoting chronic infection. Inflammasomes activate caspase-1, which is important for the maturation of IL-1β and IL-18 and evoke an inflammatory response. We aimed to investigate the activation of inflammasomes induced by P.aeruginosa biofilm. THP-1 cells were mock-infected or infected with PAO1 biofilms. Protein levels of caspase-1 p20, pro-caspase-1, caspase-4 p20, and pro-caspase-4 in THP-1 macrophages were determined by Western blotting. The expression of NLRC4 and NLRP3 was measured by RT-PCR. The production of IL-1β and IL-18 was monitored using ELISA. P. aeruginosa biofilm significantly elevated caspase-1 levels, and decreased NLRC4 levels. Additionally, caspase-4 and NLRP3 levels were significantly increased. P.aeruginosa biofilm significantly enhanced IL-1β and IL-18 production. We concluded that P. aeruginosa biofilm induced the production of IL-1β and IL-18, possibly via NLRP3 inflammasomes, rather than NLRC4 inflammasomes.

RevDate: 2022-01-17

Wen L, Huang L, Wang Y, et al (2022)

Facet-engineered hematite boosts microbial electrogenesis by synergy of promoting electroactive biofilm formation and extracellular electron transfer.

The Science of the total environment pii:S0048-9697(22)00244-3 [Epub ahead of print].

Hematite has been proven to be an excellent material for enhancing extracellular electron transfer (EET) in microbial bioelectrochemical systems (BESs). However, the effect of hematite with different exposed facets on microbial EET remains unclear. Here, we synthesized two types of hematite nanoparticles with high {100} and {001} facet exposure (Hem_{100} and Hem_{001}), respectively, which were coated on ITO electrode to stimulate the microbial EET in the BESs. The results showed that the maximum biocurrent density of commercial hematite nanoparticles (Hem_NPs), Hem_{100} and Hem_{001} electrodes reached 73.33 ± 5.68, 129.33 ± 9.12 and 287.00 ± 19.89 μA cm-2 from three replicates of each treatment, respectively. The current generation achieved from the Hem_{001} electrode was nearly 199-times higher than that of the blank ITO electrode (1.44 ± 0.10 μA cm-2). The electrochemical measurements showed that the lowest charge transfer resistance (Rct) was observed for the Hem_{001}, and the promoted biofilm formation and EPS secretion on the Hem_{001} electrode were also revealed, which could contribute the high performance of this electrode. Moreover, metagenomic analysis revealed that Hem_{001} might facilitate the microbial EET by stimulating the expression of genes related to cytochrome c and conductive nanowires. This study not only provides a new strategy to enhance microbial electrogenesis but also expands the knowledge of the effect of facet on microbial EET, helping to develop more efficient electrode materials in the future.

RevDate: 2022-01-17

Xie J, Meng Z, Han X, et al (2022)

Cholesterol Microdomain Enhances the Biofilm Eradication of Antibiotic Liposomes.

Advanced healthcare materials [Epub ahead of print].

Resistance and tolerance of biofilms to antibiotics is the greatest challenge in the treatment of bacterial infections. Therefore, developing an effective strategy against biofilms is a top priority. Liposomes are widely used as antibiotic drug carriers; however, common liposomes lack affinity for biofilms. Herein, we created biofilm-targeted antibiotic liposomes by simply adjusting their cholesterol content. The tailored liposomes exhibited significantly enhanced bacterial inhibition and biofilm eradication effects that were positively correlated with the cholesterol content of liposomes. Our experiments further demonstrated that this enhanced effect can be ascribed to the effective drug release through the pores, which are formed by the combination of cholesterol microdomains in liposomal lipid bilayers with membrane-damaged toxins in biofilms. Consequently, liposome encapsulation with a high cholesterol concentration improved noticeably the pharmacodynamics and biocompatibility of antibiotics after pulmonary administration. This work may provide a new direction for the development of anti-biofilm formulations that can be widely used for the treatment of infections caused by bacterial biofilms. This article is protected by copyright. All rights reserved.

RevDate: 2022-01-17

Alarcón-Vivero M, Moena NR, Gonzalez F, et al (2022)

Anaerobic biofilm enriched with an ammonia tolerant methanogenic consortium to improve wastewater treatment in the fishing industry.

Biotechnology letters [Epub ahead of print].

The digestion efficiency of liquid industrial wastes increases when using bioreactors colonized by microbial biofilms. High concentrations of proteins derived from the fish processing industry lead to the production of ammonia, which inhibits methane production. Two bioreactors were constructed to compare methanogenic activity: one enriched with mMPA (methylaminotrofic methane production archaea) consortia (control bioreactor), and the second with NH3 tolerant consortia (treatment bioreactor). Ammonia tolerant activity was assessed by applying an ammonia shock (755 mg NH3/L). Methane production, consumption of total organic carbon (TOC) and the taxonomic composition of bacteria and archaea was evaluated using 16S rDNA in the acclimatization, ammonia shock, and recovery phases.The ammonia shock significantly affected both methane production and the consumption of TOC in the control reactor (p < 0.05) and taxonomical composition of the microbial consortia (OTU). These values remained constant in the treatment reactor. The analysis of biofilm composition showed a predominance of Methanosarcinaceae (Methanomethylovorans sp., and probably two different species of Methanosarcina sp.) in bioreactors. These results demonstrate that using acclimated biofilms enriched with ammonia tolerant methanogens control the inhibitory effect of ammonia on methanogenesis.

RevDate: 2022-01-17

Wang X, He Y, Deng Y, et al (2022)

A diguanylate cyclase regulates biofilm formation in Rhodococcus sp. NJ-530 from Antarctica.

3 Biotech, 12(1):27.

Biofilms represent a protective survival mode in which bacteria adapt themselves to the natural environment for survival purposes. Biofilm formation is regulated by 3,5-cyclic diguanylic acid (c-di-GMP), which is a universal second messenger molecule in bacteria. Diguanylate cyclase (DGC) catalyses c-di-GMP intracellular synthesis, which plays important roles in bacterial adaptation to the natural environment. In this study, the DGC gene was first cloned from Antarctic Rhodococcus sp. NJ-530. DGC contained 948 nucleotides and encoded 315 amino acids with a molecular weight of 34.6 KDa and an isoelectric point of 5.58. qRT-PCR demonstrated that the DGC expression level was significantly affected by lower salinity and temperature. Consistently, more biofilm formation occurred under the same stress. It has been shown that Rhodococcus sp. NJ-530 can adapt to the extreme environment in Antarctica, which is closely related to biofilm formation. These results provide an important reference for studying the adaptive mechanism of Antarctic microorganisms to this extreme environment.

Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-021-03093-z.

RevDate: 2022-01-16

He Y, Luckett J, Begines B, et al (2021)

Ink-jet 3D printing as a strategy for developing bespoke non-eluting biofilm resistant medical devices.

Biomaterials, 281:121350 pii:S0142-9612(21)00706-7 [Epub ahead of print].

Chronic infection as a result of bacterial biofilm formation on implanted medical devices is a major global healthcare problem requiring new biocompatible, biofilm-resistant materials. Here we demonstrate how bespoke devices can be manufactured through ink-jet-based 3D printing using bacterial biofilm inhibiting formulations without the need for eluting antibiotics or coatings. Candidate monomers were formulated and their processability and reliability demonstrated. Formulations for in vivo evaluation of the 3D printed structures were selected on the basis of their in vitro bacterial biofilm inhibitory properties and lack of mammalian cell cytotoxicity. In vivo in a mouse implant infection model, Pseudomonas aeruginosa biofilm formation on poly-TCDMDA was reduced by ∼99% when compared with medical grade silicone. Whole mouse bioluminescence imaging and tissue immunohistochemistry revealed the ability of the printed device to modulate host immune responses as well as preventing biofilm formation on the device and infection of the surrounding tissues. Since 3D printing can be used to manufacture devices for both prototyping and clinical use, the versatility of ink-jet based 3D-printing to create personalised functional medical devices is demonstrated by the biofilm resistance of both a finger joint prosthetic and a prostatic stent printed in poly-TCDMDA towards P. aeruginosa and Staphylococcus aureus.

RevDate: 2022-01-16

Li S, Liu SY, Chan SY, et al (2022)

Biofilm matrix cloaks bacterial quorum sensing chemoattractants from predator detection.

The ISME journal [Epub ahead of print].

Microbes often secrete high levels of quorum sensing (QS) autoinducers into the environment to coordinate gene expression and biofilm formation, but risk detection and subsequent predation by bacterivorous predators. With such prominent signaling molecules acting as chemoattractants that diffuse into the environment at alarmingly high concentrations, it is unclear if bacterial cells can mask their chemical trails from predator detection. Here, we describe a microbial-based anti-detection adaptation, termed as "biofilm cloak", where the biofilm prey produced biofilm matrix exopolysaccharides that "locked" and reduced the leaching of autoinducers into the milieu, thereby concealing their trails to the detection by the bacterivorous Caenorhabditis elegans nematode. The exopolysaccharides act as common good for the non-producers to hide their autoinducers from predator detection. Deficiency in chemosensory gene odr-10 in mutant animals abrogated their ability to detect autoinducers and migrate toward their prey in a directed manner, which led to lower population growth rate of animals. Hence, restriction of bacterial communication activities to the confinements of biofilms is a novel approach for predator evasion, which plays a fundamental role in shaping ecological dynamics of microbial communities and predator-prey interactions.

RevDate: 2022-01-16

Cao L, Zhu G, Tao J, et al (2022)

Iron carriers promote biofilm formation and p-nitrophenol degradation.

Chemosphere pii:S0045-6535(22)00090-X [Epub ahead of print].

Vertical baffled biofilm reactors (VBBR) equipped with Plastic-carriers and Fe-carriers were employed to explore the effect of biofilm carriers on biofilm formation and p-nitrophenol (PNP) degradation. The results showed that Fe-carriers enhanced biofilm formation and PNP degradation. The maximum thickness of biofilm grown on the Fe-carriers was 1.5-fold higher than that on the Plastic-carriers. The Fe-VBBR reached a maximum rate of PNP removal at 13.02 μM L-1 h-1 with less sodium acetate addition (3 mM), while the maximum rate of PNP removal was 11.53 μM L-1 h-1 with more sodium acetate addition (6 mM) in the Plastic-based VBBR. High-throughput sequencing suggested that the Fe-VBBR had a higher biodiversity of the bacterial community in evenness, and the Achromobacter genus and Xanthobacteraceae family were as main PNP degraders. Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology analysis suggested more abundances of iron uptake genes were expressed to transport iron into the cytoplasm under an iron-limited condition in two VBBRs, and the metabolic pathway of PNP degradation went through 4-nitrocatechol and 1,2,4-benzenetriol. Our results provide a new insight for iron enhancing biofilm formation and PNP degradation.

RevDate: 2022-01-15

Tatta ER, R Kumavath (2022)

Attenuation of Enterococcus faecalis biofilm formation by Rhodethrin: A combinatorial study with an antibiotic.

Microbial pathogenesis pii:S0882-4010(22)00014-6 [Epub ahead of print].

The nosocomial pathogen Enterococcus faecalis critically implicated in the hospital environment. Its major virulence attributes biofilm formation and antibiotic resistance. The novel therapeutics are required to inhibit E. faecalis biofilm formation and virulence. Thus combinatorial and drug repurposing has been promising approaches to tackling biofilm-associated infections. Here, we have used a bacterium that produced indole terpenoid Rhodethrin (Rdn) with a combination of known antibiotic chloramphenicol (Chpl) against E. faecalis (ATCC 19433). The fractional inhibitory concentration index (FICI) values showed between 0.25 and 0.33 synergistic activities. The exopolysaccharides (EPSs) production significant decrease with Rdn (34.6 ± 4.6%), Chpl (31.0 ± 5.2%), and combination (Rdn-Chpl) (76.0 ± 4.5%) (p > 0.05). However, the biofilm interruption can attenuate of total biofilm was shown with Rdn (39.7 ± 5.1%), Chpl (32.6 ± 4.7%), and Rdn-Chpl (69.0 ± 5.3%), (p > 0.05). The microscopic observations reveal that the gradually unstructured biofilm architecture in E. faecalis. Furthermore, in silico, studies on biofilm-associated proteins (GelE, LuxS), virulence regulating (SprE), and cell division (FtsZ) have resulted in high and reasonable binding affinity, respectively. Thus, our results suggested that the synergism of Rdn-Chpl has the potential to function as a combinatorial antibiotic accelerates in treating vancomycin-resistant Enterococcus faecalis infections.

RevDate: 2022-01-15

Ahmed B, Jailani A, Lee JH, et al (2022)

Effect of halogenated indoles on biofilm formation, virulence, and root surface colonization by Agrobacterium tumefaciens.

Chemosphere pii:S0045-6535(22)00092-3 [Epub ahead of print].

Agrobacterium tumefaciens is a plant pathogen that causes crown gall disease in several plant species by transferring its T-DNA to the host genome. Its chemotactic response to a range of chemical compounds released by hosts facilitates its colonization to host surfaces, and thus, novel anti-agrobacterium compounds are needed to prevent its biofilm formation. Here, we investigated 83 indole derivatives against A. tumefaciens, and based on the screening, 4-chloroindole, 6-iodoindole, and 5-chloro-2-methyl indole were selected as candidates that at 50 μg mL-1 significantly inhibited the adherence and biofilm formation of A. tumefaciens to abiotic (nitrocellulose and polystyrene) and biotic (roots of Brassica juncea) surfaces. Furthermore, they reduced bacterial growth in a time and concentration-dependent manner and significantly reduced log CFU mL-1 and survival (%). Changes in biofilm morphologies and biomasses, thicknesses, and substratum coverages were determined, and 2-D and 3-D analyses were performed using a crystal violet assay and bright field, CLSM, and SEM microscopies. Virulence factors such as swimming motility, exopolysaccharide, and exo-protease production, and cell surface hydrophobicity were markedly inhibited by the three compounds. Transcriptional analysis showed multi-fold downregulation of biofilm, virulence, motility, and stress-related genes; however, the degrees of these downregulations were variably affected. B. juncea seed germination was only severely affected by 4-chloroindole. This study demonstrates the promising antibiofilm and antivirulence activities of the three indole derivatives tested and their potentials for targeting and curbing A. tumefaciens infections.

RevDate: 2022-01-15

Klein E, Weiler J, Wagner M, et al (2022)

Enrichment of phosphate-accumulating organisms (PAOs) in a microfluidic model biofilm system by mimicking a typical aerobic granular sludge feast/famine regime.

Applied microbiology and biotechnology [Epub ahead of print].

Wastewater treatment using aerobic granular sludge has gained increasing interest due to its advantages compared to conventional activated sludge. The technology allows simultaneous removal of organic carbon, nitrogen, and phosphorus in a single reactor system and is independent of space-intensive settling tanks. However, due to the microscale, an analysis of processes and microbial population along the radius of granules is challenging. Here, we introduce a model system for aerobic granular sludge on a small scale by using a machine-assisted microfluidic cultivation platform. With an implemented logic module that controls solenoid valves, we realized alternating oxic hunger and anoxic feeding phases for the biofilms growing within. Sampling during ongoing anoxic cultivation directly from the cultivation channel was achieved with a robotic sampling device. Analysis of the biofilms was conducted using optical coherence tomography, fluorescence in situ hybridization, and amplicon sequencing. Using this setup, it was possible to significantly enrich the percentage of polyphosphate-accumulating organisms (PAO) belonging to the family Rhodocyclaceae in the community compared to the starting inoculum. With the aid of this miniature model system, it is now possible to investigate the influence of a multitude of process parameters in a highly parallel way to understand and efficiently optimize aerobic granular sludge-based wastewater treatment systems.Key points• Development of a microfluidic model to study EBPR.• Feast-famine regime enriches polyphosphate-accumulating organisms (PAOs).• Microfluidics replace sequencing batch reactors for aerobic granular sludge research.

RevDate: 2022-01-15

Louis M, Clamens T, Tahrioui A, et al (2022)

Pseudomonas aeruginosa Biofilm Dispersion by the Human Atrial Natriuretic Peptide.

Advanced science (Weinheim, Baden-Wurttemberg, Germany) [Epub ahead of print].

Pseudomonas aeruginosa biofilms cause chronic, antibiotic tolerant infections in wounds and lungs. Numerous recent studies demonstrate that bacteria can detect human communication compounds through specific sensor/receptor tools that modulate bacterial physiology. Consequently, interfering with these mechanisms offers an exciting opportunity to directly affect the infection process. It is shown that the human hormone Atrial Natriuretic Peptide (hANP) both prevents the formation of P. aeruginosa biofilms and strongly disperses established P. aeruginosa biofilms. This hANP action is dose-dependent with a strong effect at low nanomolar concentrations and takes effect in 30-120 min. Furthermore, although hANP has no antimicrobial effect, it acts as an antibiotic adjuvant. hANP enhances the antibiofilm action of antibiotics with diverse modes of action, allowing almost full biofilm eradication. The hANP effect requires the presence of the P. aeruginosa sensor AmiC and the AmiR antiterminator regulator, indicating a specific mode of action. These data establish the activation of the ami pathway as a potential mechanism for P. aeruginosa biofilm dispersion. hANP appears to be devoid of toxicity, does not enhance bacterial pathogenicity, and acts synergistically with antibiotics. These data show that hANP is a promising powerful antibiofilm weapon against established P. aeruginosa biofilms in chronic infections.

RevDate: 2022-01-15

Kütük D, A Temiz (2022)

Biofilm formation potential of Bacillus toyonensis and Pseudomonas aeruginosa on the stainless steel test surfaces in a model dairy batch system.

Folia microbiologica [Epub ahead of print].

Bacillus toyonensis (a Gram-positive bacterium) and Pseudomonas aeruginosa (a Gram-negative bacterium) isolated from the different surfaces of a dairy plant in our previous study were selected as the test bacteria for the present study. These two test bacteria were investigated in terms of their attachment on the stainless steel test surfaces in a model dairy batch system. After incubation at 5 °C and 20 °C for 6 h, 12 h, and 24 h, stainless steel plates were examined using cultural counts, profilometer, scanning electron microscopy (SEM), and fluorescent microscopy. Also, the test plates were subjected to a cleaning/disinfection procedure used in the dairy plant. Tests were employed before and after the cleaning/disinfection procedures. Cell wall characteristics and holding temperature were found to be significant for the attachment of the test bacteria to stainless steel test surfaces. In the study, the effect of the holding temperature varied depending on the type and characteristics of the bacteria. The adhesion ability of P. aeruginosa was higher than that of B. toyonensis. Increases in the holding temperature may increase the adhesion ability of the bacteria. Milk growth medium was found to be more successful in preventing the attachment ability of P. aeruginosa compared to B. toyonensis. This indicates that the chemical characteristic of the contact material may affect adhesion. The adhered bacterial cells were entirely removed by means of the cleaning/disinfection treatment. Therefore, the adhesion of bacterial cells could be explained as "initial phase of biofilm formation." It can be concluded that the microorganism cell adhesion on the surface is followed by biofilm formation, and this situation lasts for many years. These results reveal the importance of controlling biofilm formation in dairy plants from the beginning.

RevDate: 2022-01-15

Fenati RA, Locock K, Qu Y, et al (2019)

Oxacillin Coupled G-Quadruplexes as a Novel Biofilm-Specific Antibiotic for Staphylococcus aureus Biofilms.

ACS applied bio materials, 2(7):3002-3008.

One of the most important traits of pathogenic microbial biofilms is their high tolerance to conventional antimicrobial agents, which is partially due to the presence of metabolically inactive and transiently resistant persister cells. Here, we use guanine-rich DNA structures known as G-quadruplexes (G4s) coupled with the β-lactam antibiotic, oxacillin (OX), and loaded with an iron-containing protoporphyrin IX (hemin), as OXG4/hemin complex biofilm-specific antibiotic agents. By coupling the OX to the G4, to form an OXG4/hemin complex, the diffusion of the OX was facilitated into the biofilm. Further, by utilizing the known oxidizing behavior (peroxidase-mimicking) of the G4/hemin complex, the entire system was found to be highly effectively against Staphylococcus aureus biofilms. By using G4 structures to penetrate biofilms, this work paves the way for an entirely new DNA-based therapy for biofilm eradication.

RevDate: 2022-01-15

Chen L, Yang Y, Zhang P, et al (2019)

Degradable Supramolecular Photodynamic Polymer Materials for Biofilm Elimination.

ACS applied bio materials, 2(7):2920-2926.

In this work, we fabricated a degradable supramolecular photodynamic polymer (SPP) with an enhanced efficiency of biofilm elimination. The small-molecule photosensitizer, a cationic porphyrin derivative, was grafted to a block polymer backbone (BPB) through a host-guest interaction and metal coordination. The locally enriched cationic photosensitizer in SPP endows a high efficiency to disrupt biofilms due to the generated reactive oxygen species (ROS) around the bacteria under white light illumination, while reducing the cytotoxicity to mammalian cells. After cucurbit[7]uril was added as a competitive agent, the photosensitizer could be disassociated from the BPB and the antibacterial ability was reduced; also the SPP could be further degraded. As a consequence, the supramolecular photodynamic polymer may become a very promising material for biofilm elimination with an enhanced antibacterial efficacy and degradability to fight against drug-resistant bacteria.

RevDate: 2022-01-14

Zhang R, Ali A, Su J, et al (2021)

Synergistic removal of fluoride, calcium, and nitrate in a biofilm reactor based on anaerobic microbially induced calcium precipitation.

Journal of hazardous materials, 428:128102 pii:S0304-3894(21)03071-5 [Epub ahead of print].

Fluoride (F-) and calcium (Ca2+) are primary causes of skeleton fluorosis and scaling, posing a grievous threat to aquatic lives and public health. Therefore, a novel strategy for polluted groundwater in immobilized biofilm reactor based on the anaerobic microbial induced calcium precipitation (MICP) was proposed, in which loofah was used as a multifunctional strain Cupriavidus sp. W12 growth carrier. Effects of different hydraulic retention time (HRT), initial F-concentration, and pH on the synchronous removal of pollutants were examined. Under stable operation conditions, the highest efficiencies for Ca2+, F-, and nitrate (NO3--N) reached 76.73%, 94.92%, and 100%, respectively. Furthermore, gas chromatography (GC), Fluorescence excitation-emission matrix (EEM), X-ray diffraction (XRD), Scanning electron microscope-energy dispersive spectroscope (SEM-EDS), and Fourier transform infrared spectrometer (FTIR) comprehensively clarified the mechanism of pollutants removal. The results elucidated that the removal of various pollutants was achieved through a combination of anaerobic MICP, adsorption, and co-precipitation. Besides, high-throughput sequencing analysis showed that Cupriavidus had a predominant proportion of 42.36% in the reactor and had stability against pH impact. As the first application of a biofilm reactor based on anaerobic MICP, it put forward a new insight for efficient defluorination and decalcification.

RevDate: 2022-01-14

Wang S, Xu M, Jin B, et al (2022)

Electrochemical and microbiological response of exoelectrogenic biofilm to polyethylene microplastics in water.

Water research, 211:118046 pii:S0043-1354(22)00009-4 [Epub ahead of print].

Exoelectrogenic biofilm and the associated microbial electrochemical processes have recently been intensively studied for water treatment, but their response to and interaction with polyethylene (PE) microplastics which are widespread in various aquatic environments has never been reported. Here, we investigated how and to what extent PE microplastics would affect the electrochemistry and microbiology of exoelectrogenic biofilm in both microbial fuel cells (MFCs) and microbial electrolysis cells (MECs). When the PE microplastics concentration was increased from 0 to 75 mg/L in the MECs, an apparent decline in the maximum current density (from 1.99 to 0.74 A/m2) and abundance of electroactive bacteria (EAB) in the exoelectrogenic biofilm was noticed. While in the MFCs, the current output was not significantly influenced and the abundance of EAB lightly increased at 25 mg/L microplastics. In addition, PE microplastics restrained the viability of the exoelectrogenic biofilms in both systems, leading to a higher system electrode resistance. Moreover, the microbial community richness and the microplastics-related operational taxonomic units decreased with PE microplastics. Furthermore, the electron transfer-related genes (e.g., pilA and mtrC) and cytochrome c concentration decreased after adding microplastics. This study provides the first glimpse into the influence of PE microplastics on the exoelectrogenic biofilm with the potential mechanisms revealed at the gene level, laying a methodological foundation for the future development of efficient water treatment technologies.

RevDate: 2022-01-14

You R, Kwon OY, Woo HJ, et al (2022)

Hovenia Monofloral Honey can Attenuate Enterococcus faecalis Mediated Biofilm Formation and Inflammation.

Food science of animal resources, 42(1):84-97.

We evaluated the anti-biofilm formation and anti-inflammatory activity of Hovenia monofloral honey (HMH) against Enterococcus faecalis. Co-culture of HMH with E. faecalis attenuated the biofilm formation of E. faecalis on a polystyrene surface. In addition, HMH effectively eradicated the established E. faecalis biofilm. HMH significantly attenuated E. faecalis growth but did not affect the production of extracellular polymeric substances on E. faecalis, indicating that reduction of E. faecalis biofilm is a result of HMH-mediated killing of E. faecalis. Furthermore, we found that HMH can effectively attenuate E. faecalis-induced expression of a proinflammatory interleukin-8 (IL-8) in HT-29 cells. Interestingly, treatment of HMH significantly attenuated the E. faecalis-mediated expression of Toll-like receptor-2 (TLR-2) and its adaptor molecules, myeloid differentiation primary response 88 (MyD88), in HT-29 cells. In addition, E. faecalis-induced mitogen-activated protein kinases (MAPKs) phosphorylation was significantly attenuated by HMH administration. Furthermore, HMH-mediated anti-inflammatory efficacy (0.2 mg/mL of HMHs) had an equal extent of inhibitory efficacy as 5 μM of MyD88 inhibitor to attenuate E. faecalis-mediated IL-8 expression in HT-29 cells. These results suggest that HMH could effectively inhibit E. faecalis-mediated gastrointestinal inflammation through regulating the TLR-2/MyD88/MAPKs signaling pathways. Collectively, our data suggest that HMH could be developed as a potential natural agent to control E. faecalis-mediated biofilm formation and inflammation.

RevDate: 2022-01-14

El-Telbany M, A El-Sharaki (2022)

Antibacterial and anti-biofilm activity of silver nanoparticles on multi-drug resistance pseudomonas aeruginosa isolated from dental-implant.

Journal of oral biology and craniofacial research, 12(1):199-203.

Aim: The aim of this study was to isolate multi-drug-resistant p. aeruginosa from dental implant, and control the growth and biofilm of isolated p. aeruginosa by silver nanoparticles.

Materials and methods: Thirty specimens from patients with Peri-implantitis were taken for isolation of p. aeruginosa. Bacterial samples were obtained from the infected peri-implant pocket with sterile paper points (size 30-45 mm). Samples were cultured for isolation of Multi-drug resistance P. aeruginosa. Phenotypical identification was done by the VITEK 2 system. DNA was extracted from the isolates and 16S rDNA-based PCR assay was used to confirm the identification. Susceptibility of isolated p. aeruginosa to 16 antibiotics was evaluated using the VITEK 2 system. The growth inhibition of isolated bacteria by AgNPs was tested by disk-diffusion method. The microtiter plate assay was used to estimate the capacity of P. aeruginosa to from biofilms. Antibiofilm activity of AgNPs was determined by microtiter plate assay.

Results: Three P. aeruginosa were successfully isolated from 30 clinical specimens. P. aeruginoas isolates were resistance to most of used antibiotics. Silver nanoparticles exerted an inhibitory effect on all isolated bacteria. All tested concentration of AgNPS exhibited a greatest anti-biofilm activity against multi-drug resistance (MDR) p. aeruginosa.

Conclusion: Current findings highlight the role of AgNPS in growth inhibition of P. aeruginosa and reveal a potential application of AgNPS in eradication of p. aeruginosa biofilms.

RevDate: 2022-01-14

Zou P, Cao P, Liu J, et al (2022)

Comparisons of the killing effect of direct current partially mediated by reactive oxygen species on Porphyromonas gingivalis and Prevotella intermedia in planktonic state and biofilm state - an in vitro study.

Journal of dental sciences, 17(1):459-467.

Background/purpose: Bacterial biofilms formed on the surface of tissues and biomaterials are major causes of chronic infections in humans. Among them, Porphyromonas gingivalis (P. gingivalis) and Prevotella intermedia (P. intermedia) are anaerobic pathogens causing dental infections associated with periodontitis. In this study, we evaluated the killing effect and underlying mechanisms of direct current (DC) as an antimicrobial method in vitro.

Materials and methods: We chose P. gingivalis and P. intermedia in different states to make comparisons of the killing effect of DC. By viable bacteria counting, fluorescent live/dead staining, reactive oxygen species (ROS) assay, addition of ROS scavenger DMTU and mRNA expression assay of ROS scavenging genes, the role of ROS in the killing effect was explored.

Results: The planktonic and biofilm states of two bacteria could be effectively killed by low-intensity DC. For the killing effect of 1000 μA DC, there were significant differences whether on planktonic P. gingivalis and P. intermedia (mean killing values: 2.40 vs 2.62 log10 CFU/mL) or on biofilm state of those (mean killing values: 0.63 vs 0.98 log10 CFU/mL). 1000 μA DC greatly induced ROS production and the mRNA expression of ROS scavenging genes. DMTU could partially decrease the killing values of DC and downregulate corresponding gene's expression.

Conclusion: 1000 μA DC can kill P. gingivalis and P. intermedia in two states by promoting overproduction of ROS, and P. intermedia is more sensitive to DC than P. gingivalis. These findings indicate low-intensity DC may be a promising approach in treating periodontal infections.

RevDate: 2022-01-14

Komalsingsakul A, Srisatjaluk RL, P Senawongse (2022)

Effect of brushing on surface roughness, fluoride release, and biofilm formation with different tooth-colored materials.

Journal of dental sciences, 17(1):389-398.

Background/purpose: Tooth brushing, material mechanical ageing procedure, is the most effective way in removing biofilm. The purpose of this study was to investigate the surface roughness, fluoride-release, and S. mutans biofilm formation on various tooth-colored restorative materials before and after brushing.

Materials and methods: Discs of materials, a nanocomposite (Filtek Z350XT; CO), a giomer (Beautifil II; GIOMER), a resin-modified glass-ionomer material (Fuji II LC; RMGI), and a conventional glass-ionomer material (Fuji IX GP Extra; GI), were prepared, polished with abrasive discs (SofLex), and divided into brushed and not brushed groups. The surface roughness of specimens was observed using a contact profilometer, fluoride-release was measured using a fluoride-specific ion electrode, and S. mutans biofilm formation, biovolume and live/dead cells, was observed under a confocal laser scanning microscope.

Results: Higher roughness was observed on GI and RMGI than on CO and GIOMER. Brushing had no effect on the roughness. The fluoride-release of GI and RMGI was higher than that of GIOMER. The fluoride-release decreased after brushing in all materials. The biovolume of S. mutans was not significantly different between GIOMER, RMGI and GI, while CO showed the highest. Brushing resulted in a higher biovolume for all materials, except CO, which showed no change. After brushing, all the tested materials demonstrated identical biovolumes. There were no significant differences in live/dead cells among all groups.

Conclusion: Brushing demonstrated a negative effect on the fluoride-release and biovolume of S. mutans biofilms for all tested materials except nanocomposites.

RevDate: 2022-01-14

Holguin-Loya B, Soto-Barreras U, Martinez-Martinez R, et al (2022)

Relationship between fluoride exposure and count of Streptococcus mutans in supragingival biofilm of mexican scholar children.

Journal of dental sciences, 17(1):211-216.

Background/purpose: The use of fluoride is known to reduce the risk of dental caries. There is limited information on the relationship between Streptococcus mutans (S. mutans) and fluoride exposure. This study investigated the association between the count of S. mutans on supragingival biofilm and fluoride exposure of scholar children.

Materials and methods: In this cross-sectional study, 56 children from 9 to 11 years of age were selected. Fluoride concentration in drinking water, urine and saliva of each participant were assessed. The count of S. mutans was estimated by calculating the DNA copy number through a quantitative real time polymerase chain reaction (qPCR) assay. Also, sociodemographic data, oral and general health information and variables related to caries risk were evaluated. A stepwise multiple linear regression was performed in all caries related predictor variables with the count of S. mutans as the dependent variable.

Results: The multiple linear regression analysis showed that the concentration of fluoride in saliva (β = -3.029, p < 0.001) and urine (β = -2.057, p = 0.017), time of last visit to the dentist (β = 1.968, p = 0.001), plaque index (β = 1.637, p = 0.006) and number of surfaces with codes 3-6 (D3-6MFS) of ICDAS II criteria (β = 0.283, p = 0.076) were significantly associated with the count of S. mutans (Adjusted R square = 0.427, p < 0.001).

Conclusion: Fluoride levels in urine and saliva were negatively associated with the count of S. mutans in supragingival biofilm. Plaque index, D3-6MFS and time of last visit to the dentist showed a positive association.

RevDate: 2022-01-14

Farshadzadeh Z, Pourhajibagher M, Taheri B, et al (2022)

Antimicrobial and anti-biofilm potencies of dermcidin-derived peptide DCD-1L against Acinetobacter baumannii: an in vivo wound healing model.

BMC microbiology, 22(1):25.

BACKGROUND: The global emergence of Acinetobacter baumannii resistance to most conventional antibiotics presents a major therapeutic challenge and necessitates the discovery of new antibacterial agents. The purpose of this study was to investigate in vitro and in vivo anti-biofilm potency of dermcidin-1L (DCD-1L) against extensively drug-resistant (XDR)-, pandrug-resistant (PDR)-, and ATCC19606-A. baumannii.

METHODS: After determination of minimum inhibitory concentration (MIC) of DCD-1L, in vitro anti-adhesive and anti-biofilm activities of DCD-1L were evaluated. Cytotoxicity, hemolytic activity, and the effect of DCD-1L treatment on the expression of various biofilm-associated genes were determined. The inhibitory effect of DCD-1L on biofilm formation in the model of catheter-associated infection, as well as, histopathological examination of the burn wound sites of mice treated with DCD-1L were assessed.

RESULTS: The bacterial adhesion and biofilm formation in all A. baumannii isolates were inhibited at 2 × , 4 × , and 8 × MIC of DCD-1L, while only 8 × MIC of DCD-1L was able to destroy the pre-formed biofilm in vitro. Also, reduce the expression of genes involved in biofilm formation was observed following DCD-1L treatment. DCD-1L without cytotoxic and hemolytic activities significantly reduced the biofilm formation in the model of catheter-associated infection. In vivo results showed that the count of A. baumannii in infected wounds was significantly decreased and the promotion in wound healing by the acceleration of skin re-epithelialization in mice was observed following treatment with 8 × MIC of DCD-1L.

CONCLUSIONS: Results of this study demonstrated that DCD-1L can inhibit bacterial attachment and biofilm formation and prevent the onset of infection. Taking these properties together, DCD-1L appears as a promising candidate for antimicrobial and anti-biofilm drug development.

RevDate: 2022-01-14

Dai X, Yu Y, Wei X, et al (2019)

Peptide-Conjugated CuS Nanocomposites for NIR-Triggered Ablation of Pseudomonas aeruginosa Biofilm.

ACS applied bio materials, 2(4):1614-1622.

The Gram-negative bacteria Pseudomonas aeruginosa is one famous bacterial strain owing to its ability to effectively form biofilms, which is a front-line mechanism of bacterial tolerance. Herein, the near-infrared-induced nanocomposites were one-step prepared by modifying copper sulfide nanoparticle with peptide to effectively eradicate Pseudomonas aeruginosa biofilm through electrostatic interaction, photodynamic effect and photothermal effect. These nanocomposites could rapidly adhere to the surface of bacteria, and irreversible damage the bacterial membrane under near-infrared laser irradiation. Furthermore, the nanocomposites could selectively eliminate bacteria over mammalian cell without distinct toxicity to NIH 3T3 cells. The nanocomposites will exert a far-reaching impact on the future design of biocompatible near-infrared-induced antibacterial agents, exhibiting its potential applications in Gram-negative bacteria and biofilm infections.

RevDate: 2022-01-13

Sterniša M, Sabotič J, A Klančnik (2022)

A novel approach using growth curve analysis to distinguish between antimicrobial and anti-biofilm activities against Salmonella.

International journal of food microbiology, 364:109520 pii:S0168-1605(21)00480-3 [Epub ahead of print].

Salmonella spp. are a commonly identified cause of outbreaks of food-borne diseases. Despite much research, there remains the need to find new antimicrobial and anti-biofilm agents against Salmonella. For this, it is necessary to distinguish between these two aspects. Agents that influence biofilm formation should not affect bacterial growth, to thus avoid further promotion of the development of resistance. In this study, we present the use of growth curves of Salmonella Infantis to simultaneously determine antimicrobial and anti-biofilm activities, for the screening for anti-Salmonella activities of 42 aqueous fungal extracts. The extract from Pseudohydnum gelatinosum showed good antimicrobial activity, and that from Pleurotus ostreatus showed good anti-biofilm activity. In extracts from Infundibulicybe geotropa and Infundibulicybe gibba, both activities were determined after fractionation. The antimicrobial activity was associated with protein-rich fractions and mediated by l-amino acid oxidase activity. The fractionation did not allow determination of the anti-biofilm active fraction, so further studies are needed to define these compounds. Growth curve analysis of S. Infantis is shown here to provide a fast and simple approach to distinguish between antimicrobial and anti-biofilm activities in a high-throughput setting, such that it can be easily implemented in screening and further bioassay-based purification of novel alternatives to antibiotics.

RevDate: 2022-01-13

Bhowmik P, Rajagopal S, Hmar RV, et al (2022)

Validated In Silico Model for Biofilm Formation in Escherichia coli.

ACS synthetic biology [Epub ahead of print].

Using Escherichia coli as the representative biofilm former, we report here the development of an in silico model built by simulating events that transform a free-living bacterial entity into self-encased multicellular biofilms. Published literature on ∼300 genes associated with pathways involved in biofilm formation was curated, static maps were created, and suitably interconnected with their respective metabolites using ordinary differential equations. Precise interplay of genetic networks that regulate the transitory switching of bacterial growth pattern in response to environmental changes and the resultant multicomponent synthesis of the extracellular matrix were appropriately represented. Subsequently, the in silico model was analyzed by simulating time-dependent changes in the concentration of components by using the R and python environment. The model was validated by simulating and verifying the impact of key gene knockouts (KOs) and systematic knockdowns on biofilm formation, thus ensuring the outcomes were comparable with the reported literature. Similarly, specific gene KOs in laboratory and pathogenic E. coli were constructed and assessed. MiaA, YdeO, and YgiV were found to be crucial in biofilm development. Furthermore, qRT-PCR confirmed the elevation of expression in biofilm-forming clinical isolates. Findings reported in this study offer opportunities for identifying biofilm inhibitors with applications in multiple industries. The application of this model can be extended to the health care sector specifically to develop novel adjunct therapies that prevent biofilms in medical implants and reduce emergence of biofilm-associated resistant polymicrobial-chronic infections. The in silico framework reported here is open source and accessible for further enhancements.

RevDate: 2022-01-13

García-Bonillo C, Texidó R, Reyes-Carmenaty G, et al (2020)

Study of the Human Albumin Role in the Formation of a Bacterial Biofilm on Urinary Devices Using QCM-D.

ACS applied bio materials, 3(5):3354-3364.

Catheter-associated urinary tract infections (CAUTIs) are the most common health care-associated infections due to rapid bacterial colonization+ and biofilm formation in urinary catheters. This behavior has been extensively documented in medical devices. However, there is a few literature works on CAUTI providing a model that allows the exhaustive study of biofilm formation in a urinary environment. The development of an effective model would be helpful to identify the factors that promote the biofilm formation and identify strategies to avoid it. In this work, we have developed a model to test biofilm formation on urinary medical device surfaces by simulating environmental and physical conditions using a quartz crystal microbalance with dissipation (QCM-D) module with an uropathogenic strain. Moreover, we used the developed model to study the role of human albumin present in artificial urine at high concentrations because of renal failure or heart-diseases in patients. Despite model limitations using artificial urine, these tests show that human albumin can be considered as a promoter of biofilm formation on hydrophobic surfaces, being a possible risk factor to developing a CAUTI.

RevDate: 2022-01-13

Bugari RA, Başchir AS, Turcin LA, et al (2021)

Adenoidal bacterial biofilm in pediatric rhinosinusitis.

Romanian journal of morphology and embryology = Revue roumaine de morphologie et embryologie, 62(2):481-489.

The aim of the study was to observe, using scanning electron microscopy (SEM), the ratio of bacterial biofilm coverage of adenoidal tissue in children diagnosed with chronic rhinosinusitis (CR), compared to the ratio of adenoid bacterial biofilm coverage in children diagnosed with obstructive sleep apnea (OSA). We also performed histopathological and immunohistochemical tests to correlate the results with the images obtained from SEM. We estimated, using an image analysis program, the coverage ratio with bacterial biofilm on the surface of the lymphatic tissue. Adenoid vegetation extracted from children with CR had a higher percentage of bacterial biofilm coverage compared to the group diagnosed with OSA. In the nasopharynx of children with CR, the bacterial biofilm had a constant role of infection generator, and adenoidectomy was the only effective therapeutic procedure to relieve the symptoms. Allergy tests were performed in all children to establish a link between CR, OSA and allergic rhinitis.

RevDate: 2022-01-13

Sanchez-Vizuete P, Dergham Y, Bridier A, et al (2022)

The coordinated population redistribution between Bacillus subtilis submerged biofilm and liquid-air pellicle.

Biofilm, 4:100065 pii:S2590-2075(21)00023-X.

Bacillus subtilis is a widely used bacterial model to decipher biofilm formation, genetic determinants and their regulation. For several years, studies were conducted on colonies or pellicles formed at the interface with air, but more recent works showed that non-domesticated strains were able to form thick and structured biofilms on submerged surfaces. Taking advantage of time-lapse confocal laser scanning microscopy, we monitored bacterial colonization on the surface and observed an unexpected biphasic submerged biofilm development. Cells adhering to the surface firstly form elongated chains before being suddenly fragmented and released as free motile cells in the medium. This switching coincided with an oxygen depletion in the well which preceded the formation of the pellicle at the liquid-air interface. Residual bacteria still associated with the solid surface at the bottom of the well started to express matrix genes under anaerobic metabolism to build the typical biofilm protruding structures.

RevDate: 2022-01-13

Palencia SL, García A, M Palencia (2022)

Multiple surface interaction mechanisms direct the anchoring, co-aggregation and formation of dual-species biofilm between Candida albicans and Helicobacter pylori.

Journal of advanced research, 35:169-185 pii:S2090-1232(21)00062-X.

Introduction: Polymicrobial biofilms have a significant impact on pathogenesis of infectious microorganisms. Many human diseases are affected by colonization of multi-species communities affecting negatively the treatments and increase the risks for the health. In particular, in the epithelium of the stomach co-existence between C. albicans and H. pylori has been described, which has been associated to a synergistic effect on ulcer pathogenesis.

Objective: The objective of this work was to advance in the understanding of surface interaction between H. pylori and C. albicans for the formation of polymicrobial biofilms.

Methods: Studies of microbial surfaces both bacterium, yeast and co-cultures of them were carried out by infrared spectroscopy, deconvolution analysis, transmission and scanning electron microscopies, and optic microscopy. Additional methods were used to contrast the results as dynamic light scattering, contact angle, agarose gel electrophoresis and gene amplification.

Results: Several surface interaction mechanisms promote the anchoring of H. pylori on C. albicans, cell co-aggregation, and polymicrobial biofilm formation, main identified interactions were: (i) hydrophobic interactions between non-polar peptide chains and lipid structures, characterized by θw among 84.9 ± 1.6 (γ = 22.78 mJ/m2 with 95.3 of dispersive contribution) and 76.6 ± 3.8 (γ = 17.34 mJ/m2, 40.2 of dispersive contribution) for C. albicans and H. pylori, respectively, (ii) hydrogen bonds between surface components of yeast and bacterium (e.g., -S-H⋅⋅⋅NH2- or -S-H⋅⋅⋅O[bond, double bond]CO-) and (iii) thiol-mediated surface interactions identified by displacements to lower wavenumbers (Δv = 5 cm-1). Evidence of internalization and electrostatic interactions were not evidenced. All observations were congruent with the biofilm formation, including the identification of small-size biostructures (i.e., 122-459 nm) associated with extracellular proteins, extracellular DNA, or outer membrane vesicles were observed characteristic of biofilm formation.

Conclusion: It is concluded that biofilm is formed by co-aggregation after anchoring of H. pylori on C. albicans. Several surface interactions were associated with the prevalence of H. pylori, the possibility to find C. albicans in the stomach epithelium infected by H. pylori, but also, strength interactions could be interfering in experimental observations associated with bacterial-DNA detection in culture mixtures.

RevDate: 2022-01-13

da Conceição Aquino de Sá M, Filho JTRR, Alcantara ME, et al (2022)

Analysis of Gtpases Rab 5 and Rab 7 expression from macrophages infected with biofilm-producing and non biofilm-producing strains of Corynebacterium pseudotuberculosis.

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] [Epub ahead of print].

Corynebacterium pseudotuberculosis is a facultative intracellular pathogen that uses various mechanisms to survive within macrophages. In phagocytosis, this survival can be attributed to the ability to inhibit phagosome-lysosome fusion. In this fusion, some proteins, including Rabs GTPases, are involved in the maturation process and are responsible for regulating membrane vesicle trafficking. Thus, to better understand these mechanisms, the capacity of biofilm-producing and non biofilm-producing strains of Corynebacterium pseudotuberculosis for modulating the expression of endosomal proteins GTPases Rab 5 and Rab 7 was evaluated in an in vitro study of infection of goat macrophages. Blood was collected from ten Canindé goats, infected with biofilm-producing and non biofilm-producing strains of C. pseudotuberculosis. Blood cells were separated in colloidal silica-polyvinylpyrrolidone gradients (GE Healthcare®). These cells were maintained at 37 °C, with 5% of CO2. After differentiation, macrophages were infected with the mentioned strains. The bacterial pellets were marked with Rab 5 and Rab 7 antibodies, and their expression was observed by flow cytometry. Both strains of C. pseudotuberculosis (biofilm-producing and non biofilm-producing) were observed to be capable of altering the expression of Rab proteins in macrophages cultivated in vitro. Macrophages from the animals infected with the biofilm-producing strain had an increase in the expression of Rab 5 protein, mainly when these macrophages were treated with the non biofilm-producing strain. The same mechanism was shown to function with Rab 7 protein, however at a lower intensity of expression when compared with Rab 5.

RevDate: 2022-01-13

Yan Y, Soraru C, Keller V, et al (2020)

Antibacterial and Biofilm-Preventive Photocatalytic Activity and Mechanisms on P/F-Modified TiO2 Coatings.

ACS applied bio materials, 3(9):5687-5698.

Photocatalytic antibacterial and biofilm-preventive activity in liquid of heavy-metal-free coatings based on a phosphorus (P)- and fluorine (F)-modified TiO2 photocatalyst has been investigated. They reveal significantly higher immediate and longer-term (biofilm-preventive) inactivation capacity than a reference coating made of the commercial photocatalyst TiO2 P25 on three bacterial species differing in cell wall type and ability to resist oxidative stress (Escherichia coli, Staphylococcus epidermidis, Pseudomonas fluorescens) (up to more than 99% reduction of colonization on P/F-modified TiO2 coating compared to about 50% on P25 TiO2 coating for 10 min UV-A illumination). This results from the P- and F-induced improvement of photocatalyst properties and from the smoother surface topography, which shortens reactive oxygen species (ROS) diffusion to the outer membrane of the targeted adhered bacteria. Decrease in ROS-related impairment of cell wall, respiratory, and enzymatic activities confirms the loss of ROS throughout the bacterial cell degradation. Staphylococcus epidermidis and Pseudomonas fluorescens are less sensitive than Escherichia coli, with a probable relation to the bacterial oxygen stress defense mechanism. The coating antibacterial efficacy was highly affected by phosphate ions and the richness in dissolved oxygen of the reaction medium.

RevDate: 2022-01-13

Chen M, Zhang S, Z He (2020)

Controlled Block Polypeptide Composed of d-Type Amino Acids: A Therapeutics Delivery Platform to Inhibit Biofilm Formation of Drug-Resistant Bacteria.

ACS applied bio materials, 3(9):6343-6350.

Antibiotic resistance of bacteria has been widely developed due to biofilm protection and separating the bacteria from antibiotics. The phenomenon of biofilm inhibition or disassembly by d-amino acids (DAAs) has been reported recently, while it was also challenged by some other scientists. Presuming DAAs work for biofilms on the surface of bacteria, delivery of the DAAs to disease sites is important while small DAAs are easily removed by kidney. To resolve the above issues, it is urgent to develop a biofilm inhibitor. To achieve this goal, we synthesized d-type polypeptides via NCA ring-opening polymerization with the initiator of HMDS to generate poly(CBZ-l-lysine)33-block-poly(d-phenylalanine)14. After deprotection, the resultant polypeptides were converted into amphiphilic poly(l-lysine)33-block-poly(d-phenylalanine)14, which can be self-assembled into well-defined homogeneous nanoparticles capable of capsulizing penicillin G. For the molecular weight of polypeptides resulting in various bioeffects, we prepared similar-sized polypeptides of an l-type equivalent polypeptide as control. The data from microbial experiments indicated that poly(l-lysine)33-block-poly(d-phenylalanine)14 can inhibit biofilm formation of Bacillus subtilis at a low final concentration (24 μg/mL), much stronger than poly(l-lysine)40-block-poly(l-phenylalanine)19 at the same concentration. This is the first report in that synthetic d-type polypeptides can inhibit biofilms of bacteria. Poly(l-lysine)33-block-poly(d-phenylalanine)14 can be assembled into well-defined, biostable homogeneous nanoparticles. This research provides a potential solution to overcome bacteria antibiotic resistance from small molecules to material sciences and gives a unique angle to understand the current dispute if DAAs can disassemble the biofilms. Additionally, these nanoparticles have great potential in the development of nanomedicines with a longer circulation time in blood and this discovery has implications in developing antimicrobial nanodevices for therapy and basic scientific interest.

RevDate: 2022-01-13

Ostrov I, Polishchuk I, Shemesh M, et al (2019)

Superhydrophobic Wax Coatings for Prevention of Biofilm Establishment in Dairy Food.

ACS applied bio materials, 2(11):4932-4940.

Microbial contamination of dairy products caused by biofilm-forming bacteria is of great concern to the dairy industry, a leading sector impacted by food loss. Previous reports have emphasized that preventing biofilm formation on work surfaces of dairy equipment would be a more desirable option than treating it. However, there is currently no available technology that could completely prevent such biofilm formation without causing detrimental side effects. Here, we demonstrate that a bioinspired approach, exploiting superhydrophobic paraffin/fluorinated wax surfaces, can be efficiently employed to prevent dairy-associated biofilm formation. Our results showed that under conditions relevant to dairy food production (continuous flow of milk in the presence of substrates relevant to the dairy industry), biofilm development by strong biofilm-forming dairy Bacillus isolates was effectively mitigated (up to 97-99% inhibition) on the tested wax surfaces. This, coupled with the ability of these wax surfaces to retain their structure and functionality after prolonged exposure to milk, without producing any negative effects on milk quality, makes the technology potentially applicable in the dairy industry.

RevDate: 2022-01-12

Nair S, Li C, Mou S, et al (2022)

A novel phage indirectly regulates diatom growth by infecting diatom-associated biofilm-forming bacterium.

Applied and environmental microbiology [Epub ahead of print].

Algae and heterotrophic bacteria have close and intricate interactions, which are regulated by multiple factors in the natural environment. Phages are the major factor determining bacterial mortality. However, their impacts on the algae-associated bacteria and thus on the algae-bacteria interactions are poorly understood. Here, we obtained a diatom-associated bacterium Stappia indica SNL01 that could form biofilm and had an inhibitory effect on the growth of diatom Thalassiosira pseudonana. Meanwhile, the phage SI01 with a double-stranded circular DNA genome (44,247 bp) infecting S. indica SNL01 was isolated. Phylogenetic analysis revealed that phage SI01 represents a novel member of the Podoviridae family. The phage contained multiple lysis genes encoding for cell wall lysing muramidase and spore cortex lysing SleB, as well as depolymerase-like tail spike protein. By lysing the host bacterium and inhibiting the formation of biofilm, this phage could indirectly promote the growth of the diatom. Our results shed new insights into how phages indirectly regulate algal growth by infecting bacteria closely associated with algae or in the phycosphere. IMPORTANCE The impact of phage infection on the algae-bacteria relationship in the ocean is poorly understood. Here, a novel phage infecting the diatom-associated bacterium Stappia indica SNL01 was isolated. This bacterium could form biofilm and had a negative effect on diatom growth. We revealed that this phage contained multiple lysis genes and could inhibit the formation of bacterial biofilm, thus indirectly promoting diatom growth. This study implicates that phages are not only important regulators of bacteria but also have substantial indirect effects on algae as well as the algae-bacteria relationship.

RevDate: 2022-01-12

Oliveira F, Lima T, Correia A, et al (2022)

Involvement of the Iron-Regulated Loci hts and fhuC in Biofilm Formation and Survival of Staphylococcus epidermidis within the Host.

Microbiology spectrum [Epub ahead of print].

Staphylococcus epidermidis is a major nosocomial pathogen with a remarkable ability to persist on indwelling medical devices through biofilm formation. Nevertheless, it remains intriguing how this process is efficiently achieved under the host's harsh conditions, where the availability of nutrients, such as essential metals, is scarce. Following our previous identification of two iron-regulated loci putatively involved in iron transport, hts and fhuC, we assessed here their individual contribution to both bacterial physiology and interaction with host immune cells. Single deletions of the hts and fhuC loci led to marked changes in the cell iron content, which were partly detrimental for planktonic growth and strongly affected biofilm formation under iron-restricted conditions. Deletion of each of these two loci did not lead to major changes in S. epidermidis survival within human macrophages or in an ex vivo human blood model of bloodstream infection. However, the lack of either hts or fhuC loci significantly impaired bacterial survival in vivo in a murine model of bacteremia. Collectively, this study establishes, for the first time, the pivotal role of the iron-regulated loci hts and fhuC in S. epidermidis biofilm formation and survival within the host, providing relevant information for the development of new targeted therapeutics against this pathogen. IMPORTANCE Staphylococcus epidermidis is one of the most important nosocomial pathogens and a major cause of central line-associated bloodstream infections. Once in the bloodstream, this bacterium must surpass severe iron restriction in order to survive and establish infection. Surprisingly, very little is known about the iron acquisition mechanisms in this species. This study represents the first report on the involvement of the S. epidermidis iron-regulated loci hts and fhuC in biofilm formation under host relevant conditions and, most importantly, in survival within the host. Ultimately, these findings highlight iron acquisition and these loci in particular, as potential targets for future therapeutic strategies against biofilm-associated S. epidermidis infections.

RevDate: 2022-01-12

Hwang HJ, Li XH, Kim SK, et al (2022)

Anthranilate Acts as a Signal to Modulate Biofilm Formation, Virulence, and Antibiotic Tolerance of Pseudomonas aeruginosa and Surrounding Bacteria.

Microbiology spectrum [Epub ahead of print].

Anthranilate is a diffusible molecule produced by Pseudomonas aeruginosa and accumulates as P. aeruginosa grows. Anthranilate is an important intermediate for the synthesis of tryptophan and the Pseudomonas quinolone signal (PQS), as well as metabolized by the anthranilate dioxygenase complex (antABC operon products). Here we demonstrate that anthranilate is a key factor that modulates the pathogenicity-related phenotypes of P. aeruginosa and other surrounding bacteria in the environment, such as biofilm formation, antibiotic tolerance, and virulence. We found that the anthranilate levels in P. aeruginosa cultures rapidly increased in the stationary phase and then decreased again, forming an anthranilate peak. Biofilm formation, antibiotic susceptibility, and virulence of P. aeruginosa were significantly altered before and after this anthranilate peak. In addition, these phenotypes were all modified by the mutation of antABC and exogenous addition of anthranilate. Anthranilate also increased the antibiotic susceptibility of other species of bacteria, such as Escherichia coli, Salmonella enterica, Bacillus subtilis, and Staphylococcus aureus. Before the anthranilate peak, the low intracellular anthranilate level was maintained through degradation from the antABC function, in which induction of antABC was also limited to a small extent. The premature degradation of anthranilate, due to its high levels, and antABC expression early in the growth phase, appears to be toxic to the cells. From these results, we propose that by generating an anthranilate peak as a signal, P. aeruginosa may induce some sort of physiological change in surrounding cells. IMPORTANCE Pseudomonas aeruginosa is a notorious pathogen with high antibiotic resistance, strong virulence, and ability to cause biofilm-mediated chronic infection. We found that these characteristics change profoundly before and after the time when anthranilate is produced as an "anthranilate peak". This peak acts as a signal that induces physiological changes in surrounding cells, decreasing their antibiotic tolerance and biofilm formation. This study is important in that it provides a new insight into how microbial signaling substances can induce changes in the pathogenicity-related phenotypes of cells in the environment. In addition, this study shows that anthranilate can be used as an adjuvant to antibiotics.

RevDate: 2022-01-12

Le PH, Nguyen DHK, Aburto-Medina A, et al (2020)

Nanoscale Surface Roughness Influences Candida albicans Biofilm Formation.

ACS applied bio materials, 3(12):8581-8591.

The microbial contamination of surfaces presents a significant challenge due to the adverse effects associated with biofilm formation, particularly on implantable devices. Here, the attachment and biofilm formation of the opportunistic human pathogen, Candida albicans ATCC 10231, were studied on surfaces with decreasing magnitudes of nanoscale roughness. The nanoscale surface roughness of nonpolished titanium, polished titanium, and glass was characterized according to average surface roughness, skewness, and kurtosis. Nonpolished titanium, polished titanium, and glass possessed average surface roughness (Sa) values of 350, 20, and 2.5 nm; skewness (Sskw) values of 1.0, 4.0, and 1.0; and (Skur) values of 3.5, 16, and 4, respectively. These unique characteristics of the surface nanoarchitecture were found to play a key role in limiting C. albicans attachment and modulating the functional phenotypic changes associated with biofilm formation. Our results suggest that surfaces with a specific combination of surface topographical parameters could prevent the attachment and biofilm formation of C. albicans. After 7 days, the density of attached C. albicans cells was recorded to be 230, 70, and 220 cells mm-2 on nonpolished titanium, polished titanium, and glass surfaces, respectively. Despite achieving a very low attachment density, C. albicanscells were only observed to produce hyphae associated with biofilm formation on nonpolished titanium surfaces, possessing the highest degree of surface roughness (Sa = 350 nm). This study provides a more comprehensive picture of the impact of surface architectures on C. albicans attachment, which is beneficial for the design of antifungal surfaces.

RevDate: 2022-01-12

Zhu J, Wang M, Zhang H, et al (2020)

Effects of Hydrophilicity, Adhesion Work, and Fluid Flow on Biofilm Formation of PDMS in Microfluidic Systems.

ACS applied bio materials, 3(12):8386-8394.

Polydimethylsiloxane (PDMS) has been the most widely used material in microfluidic systems, especially for cell biology applications. However, the antibacterial performance of PDMS in flow conditions has never been reported in the literature. In this paper, we analyzed the effects of contact angle (CA), adhesion force (work), and surface free energy on the antibacterial activities of PDMS by varying the ratio of curing agents (crosslinking degree) and surface modification with oxygen plasma. The results show that the Young's modulus has no particular effects on bacterial adhesion compared to the CAs of samples. For the first time, we analyzed the adhesion work (AW) effect on biofilm formation, and we found that biofilms tend to form on the surface with less AW. Furthermore, we analyzed the dual effect of hydrophilicity and shear force induced by fluid flow on the bacterial adhesion in PDMS microfluidic systems. We found that at low flow rates in microfluidic conditions, the adhesion of the bacteria on the PDMS surface is inhibited when the fluid flow exceeds a certain value. It required higher shear force to inhibit bacterial adhesion on the hydrophilic surface than on the hydrophobic surface. Therefore, hydrophilicity might be the dominant factor affecting bacterial adhesion.

RevDate: 2022-01-12

Deepika MS, Thangam R, Sundarraj S, et al (2020)

Co-delivery of Diverse Therapeutic Compounds Using PEG-PLGA Nanoparticle Cargo against Drug-Resistant Bacteria: An Improved Anti-biofilm Strategy.

ACS applied bio materials, 3(1):385-399.

Controlling biofilms of bacteria is a challenging aspect because of their drug-resistance potentials against a range of antibiotics, demanding the development of active anti-biofilm agents. Rutin (R), a natural antioxidant, and benzamide (B), a synthetic antibacterial agent, have several pharmacological and antibacterial abilities. Herein, we developed PEG-PLGA NPs that synergistically carried rutin and benzamide as drug candidates, while displaying therapeutic and anti-biofilm functions. These drug delivery NPs were synthesized by the oil-in-water emulsion (O/W) solvent evaporation technique. The obtained NPs were characterized by UV-vis, FT-IR, SEM, TEM, and DLS measurements. Confocal laser scanning microscopy was employed to evaluate the anti-biofilm capabilities against Staphylococcus aureus and Pseudomonas aeruginosa and further quantified the levels of residual biofilm constituents such as protein and exopolysaccharide (EPS). Drug release experiments showed the controlled release of rutin-benzamide (RB) for several days. Antibacterial analyses showed that the minimum inhibitory concentration (MIC) of NPs was at least two times lower than that of the free drugs. RB-PEG-PLGA NPs revealed that they targeted biofilm-forming bacteria through the disruption of the membrane and biofilm surface and were observed to be nontoxic when tested using human erythrocytes and human cell lines. In vivo evaluations in zebrafish showed that the NPs did not alter the antioxidant functions and histological features of tissues. On the basis of results obtained, it is substantiated that the rutin-benzamide-loaded nanocarrier offers potential anti-biofilm therapy due to its high anti-biofilm activity and biocompatibility.

RevDate: 2022-01-12

Zhang S, Liang X, Gadd GM, et al (2020)

Superhydrophobic Coatings for Urinary Catheters To Delay Bacterial Biofilm Formation and Catheter-Associated Urinary Tract Infection.

ACS applied bio materials, 3(1):282-291.

In this research, a multilayered superhydrophobic coating for urinary catheters was synthesized by a layer-by-layer deposition technique. A mussel-inspired polydopamine coating was utilized as a platform for the in situ anchoring of silver nanoparticles followed by hydrophobic modification with 1H,1H,2H,2H-perfluorodecanethiol. Benefiting from the synergistic effect of hierarchical micro/nanostructures and antibacterial silver nanoparticles, the prepared catheters exhibited excellent superhydrophobicity and prolonged antibacterial activity against Escherichia coli WT F1693 and Proteus mirabilis WT F1697. Compared with commercial all-silicone and silver-alloy-hydrogel catheters, the superhydrophobic catheter exhibited significant antibiofilm activities in both static and dynamic models. In an in vitro bladder model, bacterial migration along the outer catheter was effectively delayed, reducing biomass accumulation by up to 55 and 90% compared with all-silicone and silver-alloy-hydrogel catheters. Encrustations in the catheter lumen were also retarded, extending the lifetime of silicone catheters from ∼40 to ∼100 h. The superhydrophobic catheter also exhibited good biocompatibility to the L929 mouse fibroblasts, therefore providing a promising direction for the future design of urinary catheters.

RevDate: 2022-01-12

Li P, Liu S, Zhang G, et al (2020)

Design of pH-Responsive Dissociable Nanosystem Based on Carbon Dots with Enhanced Anti-biofilm Property and Excellent Biocompatibility.

ACS applied bio materials, 3(2):1105-1115.

Bacterial biofilm poses a serious threat to human health, leading to increased and prolonged bacterial infections. How to solve the problem of eliminating biofilms effectively and rapidly while being nontoxic to normal cells is still a challenge. Here, we design a pH-sensitive anti-biofilm nanosystem formed by self-assembly between negatively charged carboxyl groups of poly(ethylene glycol_-COOH-polyethylenimine-2,3-dimethylmaleic anhydride (PPD) and positively charged amines on the surface of carbon dots derived from the ashes of calcined l-lysine powder (CDLys) (PPD@CDLys for short). The outmost copolymer could make PPD@CDLys facilely diffuse into the dense biofilm and reverse to be positively charged via hydrolysis, which lead to the acid-triggered disassembly of the nanosystem. After hydrolyzation, PPD would turn into a biocidal cationic polymer, which is prone to attaching on bacteria inside the biofilm and efficiently killing them. In addition, the released CDLys could induce intracellular reactive oxygen species (ROS) across the whole biofilm to degrade the matrix of extracellular polymer substances and kill resident bacteria deep into the biofilm. Finally, the prepared nanosystem effectively inhibits the formation of Staphylococcus aureus biofilm and rapidly destroys the mature biofilm by the synergy antibacterial effects of the cation and ROS. We also evaluate the biocompatibility of the nanocomposites. The results show that PPD@CQDLys has no toxicity to L929 and 3T3 cells and exhibits a zero hemolytic rate even when the concentration is up to 2000 μg/mL. The outstanding biocompatibility coupled with rapid anti-biofilm ability of the nanosystem presents an opportunity for it to be utilized as an effective pH-responsive and targetable anti-biofilm agent for controlling bacterial infections.

RevDate: 2022-01-12

Difloe-Geisert JC, Fiedler S, Kulik EM, et al (2022)

Interdental biofilm reduction and composition after use of an activated and inactivated side-to-side toothbrush - a proof-of-principle clinical study.

Clinical oral investigations [Epub ahead of print].

OBJECTIVES: To evaluate interdental biofilm reduction and composition after powered toothbrushing with a side-to-side (sonic) toothbrush compared to manual toothbrushing following single brushing exercises in periodontally healthy young adults.

MATERIALS AND METHODS: All participants brushed with a side-to-side toothbrush without toothpaste in four different modes: toothbrush (a) inactivated without instruction (OFF-NI), (b) activated without instruction (ON-NI), (c) inactivated with instruction (OFF-I), and (d) activated with instruction (ON-I) at consecutive visits (single brushing exercises). Before and after brushing, the Approximal Plaque Index (API) was assessed at three interdental spaces and plaque samples were taken from two interdental sites. Biofilm reduction and composition were analyzed microbiologically by total bacterial load and 16S rRNA sequencing.

RESULTS: Thirty participants (age: 22.9 ± 2.5 years) completed the study. Most participants showed no or incomplete plaque removal assessed by API following single brushing exercises, while the frequency of API reduction was higher after ON-NI compared to OFF-I (p = 0.023). Irrespective of the brushing mode, a significant reduction of total bacterial load was detected with lower bacterial counts after OFF-NI compared to ON-NI (p = 0.008) and ON-I (p = 0.007). Biofilm composition showed slight changes in the relative abundances of bacterial taxa, regardless of the brushing mode.

CONCLUSIONS: Manual and powered toothbrushing with a side-to-side toothbrush, with and without instruction, showed incomplete interdental biofilm removal in periodontally healthy young adults following single brushing exercises.

CLINICAL RELEVANCE: Data has to be validated in further studies on other groups, however, in periodontally healthy young adults, additional devices seem to be necessary for sufficient interdental cleaning.

RevDate: 2022-01-12

Shreya , Jain G, Srinkhala , et al (2021)

Comparative Evaluation of Antimicrobial Efficacy of Calcium Hydroxide, Triple Antibiotic Paste, and 2% Chlorhexidine Combined with 0.5% Cetrimide against Enterococcus faecalis Biofilm-Infected Dentin Model: An In vitro Study.

Journal of pharmacy & bioallied sciences, 13(Suppl 2):S1538-S1543.

Background: Enterococcus faecalis is the most common and important microorganism found in infected root canals associated with persistent periapical periodontitis and failing endodontically treated tooth. Intracanal medicaments used after chemomechanical preparation of an infected root canal play a vital in eradication of this microorganism and pave the way for long-term success of endodontic therapy. Hence, the present in vitro study was conducted to assess the antimicrobial efficacy of calcium hydroxide (Ca(OH)2), triple antibiotic paste (metronidazole 400 mg + minocycline 100 mg + ciprofloxacin 500 mg), and 2% chlorhexidine (CHX) combined with 0.5% cetrimide on eradication of E. faecalis biofilm.

Materials and Methods: Eighty dentin specimens were taken and infected extraorally with E. faecalis to induce microbial colonization. The specimens were then divided into four groups of twenty each based on medicaments used and further subdivided into two subgroups based on assessment of live cells done either immediately after the elimination of the medicament or after 24-h incubation in brain-heart infusion (BHI) medium: Group I specimens were treated with Ca(OH)2, Group II with triple antibiotic paste, Group III with 2% CHX combined with 0.5% cetrimide, and Group IV with saline (control) for 7 days at 37°C. Assessment of live cells was done using confocal microscope.

Results: 2% CHX combined with 0.5% cetrimide (Group III) and triple antibiotic paste (Group II) showed a statistically significant result with high antimicrobial efficacy and lower percentage of live cells as compared to Ca(OH)2 (Group I). The mean percentage of live cells in Group I immediately after elimination of medicaments was 64.7%, in Group II was 1.52%, in Group III was 1.49%, and in Group IV was 83.4%. After 24 h of incubation in BHI medium, 2% CHX combined with 0.5% cetrimide (Group III) showed a statistically significant (p < 0.05) result of 1.27% mean live cells as compared to 84.2% in Ca(OH)2 (Group I), 1.82% in triple antibiotic paste (Group II), and 94.2% in saline (Group IV control).

Conclusion: 2% CHX combined with 0.5% cetrimide exhibited maximum antimicrobial efficacy with least number of mean live cells followed by triple antibiotic paste as compared to Ca(OH)2. Based on these findings, 2% CHX combined with 0.5% cetrimide was most effective in eradicating E. faecalis from the extraorally infected dentine biofilm.

RevDate: 2022-01-12

Al-Marri T, Al-Marri A, Al-Zanbaqi R, et al (2021)

Multidrug resistance, biofilm formation, and virulence genes of Escherichia coli from backyard poultry farms.

Veterinary world, 14(11):2869-2877.

Background and Aim: Backyard chicken flocks have traditionally been regarded as an essential food source in developed countries; however, they may act as reservoirs and spread various zoonotic bacterial pathogens. This study was designed to investigate the prevalence, phenotypic resistance, biofilm formation (BF), and pathotypes of Escherichia coli isolates from backyard poultry farms.

Materials and Methods: Cloacal swabs (n=150) and internal organs (n=150) were collected from 30 backyard chicken flocks; 20 of them were experiencing systemic infection, and the other ten were apparently healthy. Samples were bacteriologically examined for E. coli isolation. Isolates were identified biochemically by the VITEK® 2 COMPACT system (BioMérieux, France). For molecular identification, 16S rRNA was amplified and sequenced. Ten antimicrobials were selected for E. coli antimicrobial susceptibility testing. The minimum inhibitory concentration for each antimicrobial was determined. The extended-spectrum β-lactamase activity in isolates was investigated using cephalosporin/clavulanate combination disks. The ability of isolates for BF was determined by the microtiter plate method. Thirteen virulence genes linked to different E. coli pathotypes and two serotype-related genes were investigated by real-time polymerase chain reaction.

Results: Eighty-six E. coli strains were isolated from 30 backyard chicken flocks. The isolates were biochemically identified to the species level. Genetically, sequences of the 16S rRNA gene showed >98% identity with E. coli in the National Center for Biological Information database. The frequency of isolation from diseased flocks was significantly higher (p<0.05) than apparently healthy flocks; 63.9% of the isolates were recovered from cloacal swabs and 36.04% were recovered from internal organs. E. coli isolates showed high resistance to ampicillin (AMP; 75.6%), gentamicin (39.5%), and tetracycline (29.1%). However, none of the isolates were resistant to imipenem. A variable drug resistance profile for E. coli isolates was reported. Twenty-one (24.4%) isolates were sensitive to all ten antimicrobials. Seven (8.1%) isolates were resistant only to AMP, and 28 (32.6%) were resistant to two antimicrobials, whereas the remaining 30 (34.9%) isolates showed multidrug resistance (MDR). Of the 86 isolates, 8 (9.3%) were confirmed as extended-spectrum β-lactamase (ESBL)-producing E. coli by the combination disk diffusion method. All ESBL isolates were MDR with an MDR index of 0.5-0.6. Fifty-seven (66.3%) isolates were capable of forming biofilms; 22 (25.6%) of them were strong biofilm producers, 24 (27.9%) moderate producers, and 11 (12.8%) weak producers. A statistically significant pairwise correlation was obtained for MDR versus BF (r=0.512) and MDR index versus BF (r=0.556). Based on virulence gene profiles, five pathotypes were identified, including enteropathogenic E. coli (39.5%), avian pathogenic E. coli (32.53%), enterohemorrhagic E. coli (EHEC; 9.3%), enterotoxigenic E. coli (ETEC; 5.8%), and enteroaggregative E. coli (EAEC; 1.2%). The lower frequency of EAEC and ETEC was statistically significant than other pathotypes. Three isolates were identified as O157 based on the detection of the rbfO157 gene.

Conclusion: This study reported a high prevalence of MDR, suggesting the misuse of antimicrobials in backyard chicken farms. The emergence of ESBL and EHEC isolates in backyard chickens is a public health concern. Furthermore, the backyard flocks environment may harbor different pathogenic bacteria that may enhance the persistence of infection and the transmission to in-contact humans. Regular monitoring for the occurrence of MDR and the zoonotic pathotypes among E. coli in backyard chicken flocks is recommended, as these bacteria can transmit to humans through food products or contaminated environments.

RevDate: 2022-01-11

Ye Z, Silva DM, Traini D, et al (2022)

An adaptable microreactor to investigate the influence of interfaces on Pseudomonas aeruginosa biofilm growth.

Applied microbiology and biotechnology [Epub ahead of print].

Biofilms are ubiquitous and notoriously difficult to eradicate and control, complicating human infections and industrial and agricultural biofouling. However, most of the study had used the biofilm model that attached to solid surface and developed in liquid submerged environments which generally have neglected the impact of interfaces. In our study, a reusable dual-chamber microreactor with interchangeable porous membranes was developed to establish multiple growth interfaces for biofilm culture and test. Protocol for culturing Pseudomonas aeruginosa (PAO1) on the air-liquid interface (ALI) and liquid-liquid interface (LLI) under static environmental conditions for 48 h was optimized using this novel device. This study shows that LLI model biofilms are more susceptible to physical disruption compared to ALI model biofilm. SEM images revealed a unique "dome-shaped" microcolonies morphological feature, which is more distinct on ALI biofilms than LLI. Furthermore, the study showed that ALI and LLI biofilms produced a similar amount of extracellular polymeric substances (EPS). As differences in biofilm structure and properties may lead to different outcomes when using the same eradication approaches, the antimicrobial effect of an antibiotic, ciprofloxacin (CIP), was chosen to test the susceptibility of a 48-h-old P. aeruginosa biofilms grown on ALI and LLI. Our results show that the minimum biofilm eradication concentration (MBEC) of 6-h CIP exposure for ALI and LLI biofilms is significantly different, which are 400 μg/mL and 200 μg/mL, respectively. These results highlight the importance of growth interface when developing more targeted biofilm management strategies, and our novel device provides a promising tool that enables manipulation of realistic biofilm growth. KEY POINTS: • A novel dual-chamber microreactor device that enables the establishment of different interfaces for biofilm culture has been developed. • ALI model biofilms and LLI model biofilms show differences in resistance to physical disruption and antibiotic susceptibility.

RevDate: 2022-01-11

Keefe BF, LE Bermudez (2022)

Environment in the lung of cystic fibrosis patients stimulates the expression of biofilm phenotype in Mycobacterium abscessus.

Journal of medical microbiology, 71(1):.

Introduction. Pulmonary infections caused by organisms of the Mycobacterium abscessus complex are increasingly prevalent in populations at risk, such as patients with cystic fibrosis, bronchiectasis and emphysema.Hypothesis. M. abscessus infection of the lung is not observed in immunocompetent individuals, which raises the possibility that the compromised lung environment is a suitable niche for the pathogen to thrive in due to the overproduction of mucus and high amounts of host cell lysis.Aim. Evaluate the ability of M. abscessus to form biofilm and grow utilizing in vitro conditions as seen in immunocompromised lungs of patients.Methodology. We compared biofilm formation and protein composition in the presence and absence of synthetic cystic fibrosis medium (SCFM) and evaluated the bacterial growth when exposed to human DNA.Results. M. abscessus is capable of forming biofilm in SCFM. By eliminating single components found in the medium, it became clear that magnesium works as a signal for the biofilm formation, and chelation of the divalent cations resulted in the suppression of biofilm formation. Investigation of the specific proteins expressed in the presence of SCFM and in the presence of SCFM lacking magnesium revealed many different proteins between the conditions. M. abscessus also exhibited growth in SCFM and in the presence of host cell DNA, although the mechanism of DNA utilization remains unclear.Conclusions. In vitro conditions mimicking the airways of patients with cystic fibrosis appear to facilitate M. abscessus establishment of infection, and elimination of magnesium from the environment may affect the ability of the pathogen to establish infection.

RevDate: 2022-01-11

Herzberg M, Berglin M, Eliahu S, et al (2021)

Efficient Prevention of Marine Biofilm Formation Employing a Surface-Grafted Repellent Marine Peptide.

ACS applied bio materials, 4(4):3360-3373.

Creation of surfaces resistant to the formation of microbial biofilms via biomimicry has been heralded as a promising strategy to protect a range of different materials ranging from boat hulls to medical devices and surgical instruments. In our current study, we describe the successful transfer of a highly effective natural marine biofilm inhibitor to the 2D surface format. A series of cyclic peptides inspired by the natural equinatoxin II protein produced by Beadlet anemone (Actinia equine) have been evaluated for their ability to inhibit the formation of a mixed marine microbial consortium on polyamide reverse osmosis membranes. In solution, the peptides are shown to effectively inhibit settlement and biofilm formation in a nontoxic manner down to 1 nM concentrations. In addition, our study also illustrates how the peptides can be applied to disperse already established biofilms. Attachment of a hydrophobic palmitic acid tail generates a peptide suited for strong noncovalent surface interactions and allows the generation of stable noncovalent coatings. These adsorbed peptides remain attached to the surface at significant shear stress and also remain active, effectively preventing the biofilm formation over 24 h. Finally, the covalent attachment of the peptides to an acrylate surface was also evaluated and the prepared coatings display a remarkable ability to prevent surface colonization at surface loadings of 55 ng/cm2 over 48 h. The ability to retain the nontoxic antibiofilm activity, documented in solution, in the covalent 2D-format is unprecedented, and this natural peptide motif displays high potential in several material application areas.

RevDate: 2022-01-11

Dai X, Ma J, Chen N, et al (2021)

MSNs-Based Nanocomposite for Biofilm Imaging and NIR-Activated Chem/Photothermal/Photodynamic Combination Therapy.

ACS applied bio materials, 4(3):2810-2820.

Bacterial infections caused by biofilms are severe clinical problems, resulting in high drug resistance by limiting the penetration of antibiotics. Herein, a near-infrared (NIR)-activated chem/photodynamic/photothermal combined therapeutic agent is proposed by loading fluorescein isothiocyanate (FITC), ultrasmall copper sulfide nanoparticles (Cu2-xSNPs), and ε-polylysine (PLL) onto mesoporous silica nanoparticles (MSNs) through a layer-by-layer self-assembly approach. FITC-doped MSNs are prepared to monitor the permeability and accumulation of nanocomposites into biofilms. MSNs can also act as hosts for the synthesis of ultrasmall Cu2-xSNPs, which has effective photodynamic and photothermal ablation against bacteria under NIR light irradiation. Moreover, biodegradable PLL introduced can not only enhance adhesion toward the bacterial surface to increase the effectiveness of phototherapy but also damage bacteria through electrostatic interaction. As a result, the prepared nanocomposites could not only penetrate biofilms but also ablate biofilms through combined chem/photodynamic/photothermal effects under NIR light irradiation. Furthermore, the nanocomposites could treat bacterial infections in vivo with negligible tissue toxicity. Overall, the finely designed nanocomposites are anticipated to display promising applications in imaging-guided chem/photodynamic/photothermal combined therapy for bacterial infections.

RevDate: 2022-01-11

Chen Z, Srivastava P, Zarazúa-Osorio B, et al (2022)

Bacillus subtilis Histidine Kinase KinC Activates Biofilm Formation by Controlling Heterogeneity of Single-Cell Responses.

mBio [Epub ahead of print].

In Bacillus subtilis, biofilm and sporulation pathways are both controlled by a master regulator, Spo0A, which is activated by phosphorylation via a phosphorelay-a cascade of phosphotransfer reactions commencing with autophosphorylation of histidine kinases KinA, KinB, KinC, KinD, and KinE. However, it is unclear how the kinases, despite acting via the same regulator, Spo0A, differentially regulate downstream pathways, i.e., how KinA mainly activates sporulation genes and KinC mainly activates biofilm genes. In this work, we found that KinC also downregulates sporulation genes, suggesting that KinC has a negative effect on Spo0A activity. To explain this effect, with a mathematical model of the phosphorelay, we revealed that unlike KinA, which always activates Spo0A, KinC has distinct effects on Spo0A at different growth stages: during fast growth, KinC acts as a phosphate source and activates Spo0A, whereas during slow growth, KinC becomes a phosphate sink and contributes to decreasing Spo0A activity. However, under these conditions, KinC can still increase the population-mean biofilm matrix production activity. In a population, individual cells grow at different rates, and KinC would increase the Spo0A activity in the fast-growing cells but reduce the Spo0A activity in the slow-growing cells. This mechanism reduces single-cell heterogeneity of Spo0A activity, thereby increasing the fraction of cells that activate biofilm matrix production. Thus, KinC activates biofilm formation by controlling the fraction of cells activating biofilm gene expression. IMPORTANCE In many bacterial and eukaryotic systems, multiple cell fate decisions are activated by a single master regulator. Typically, the activities of the regulators are controlled posttranslationally in response to different environmental stimuli. The mechanisms underlying the ability of these regulators to control multiple outcomes are not understood in many systems. By investigating the regulation of Bacillus subtilis master regulator Spo0A, we show that sensor kinases can use a novel mechanism to control cell fate decisions. By acting as a phosphate source or sink, kinases can interact with one another and provide accurate regulation of the phosphorylation level. Moreover, this mechanism affects the cell-to-cell heterogeneity of the transcription factor activity and eventually determines the fraction of different cell types in the population. These results demonstrate the importance of intercellular heterogeneity for understanding the effects of genetic perturbations on cell fate decisions. Such effects can be applicable to a wide range of cellular systems.

RevDate: 2022-01-11

Suttasattakrit K, Khamkeaw A, Tangwongsan C, et al (2021)

Ionic Silver and Electrical Treatment for Susceptibility and Disinfection of Escherichia coli Biofilm-Contaminated Titanium Surface.

Molecules (Basel, Switzerland), 27(1): pii:molecules27010180.

In this work, surface disinfection and biofilm susceptibility were investigated by applying ionic silver of 0.4-1.6 µg/mL and cathodic voltage-controlled electrical treatment of 1.8 V and a current of 30 mA to Escherichia coli (E. coli) ATCC 25922 biofilm-contaminated titanium substrates. Herein, it is evident that the treatment exhibited the potential use to enhance the susceptibility of bacterial biofilms for surface disinfection. In vitro studies have demonstrated that the ionic silver treatment of 60 min significantly increased the logarithmic reduction (LR) of bacterial populations on disinfectant-treated substrates and the electrical treatment enhanced the silver susceptibility of E. coli biofilms. The LR values after the ionic silver treatments and the electric-enhanced silver treatments were in the ranges of 1.94-2.25 and 2.10-2.73, respectively. The treatment was also associated with morphological changes in silver-treated E. coli cells and biofilm-contaminated titanium surfaces. Nevertheless, the treatments showed no cytotoxic effects on the L929 mouse skin fibroblast cell line and only a slight decrease in pH was observed during the electrical polarization of titanium substrate.

RevDate: 2022-01-11

Wang X, Li W, Xu M, et al (2021)

The Microbial Diversity and Biofilm-Forming Characteristic of Two Traditional Tibetan Kefir Grains.

Foods (Basel, Switzerland), 11(1): pii:foods11010012.

In this study, a high-throughput sequencing technique was used to analyze bacterial and fungal diversity of two traditional Tibetan kefir grains from Linzhi (K1) and Naqu (K2) regions. Comparative bioinformatic analyses indicated that Lactobacillus kefiranofaciens, L. kefiri and Kluyveromyces marxianus were the main dominant strains in K1 and K2. In order to research the relationship of the growth of kefir grains, the biofilm and the extracellular polysaccharides (EPS) produced by microorganisms, the proliferation rate of kefir grains, the yield and chemical structure of EPS and the optimal days for biofilm formation were determined. The results showed that the growth rate, the yield of EPS and the biofilm formation ability of K1 were higher than K2, and the optimal day of their biofilm formation was the same in 10th day. Additionally, the live cells, dead cells and EPS in biofilm formation of K1 and K2 were observed by fluorescence microscope to clarify the formation process of kefir grains. To determine the influence of microbial interactions on biofilm and the formation of kefir grains, the essential role of microbial quorum sensing needs further attention.

RevDate: 2022-01-11

Pleva P, Bartošová L, Máčalová D, et al (2021)

Biofilm Formation Reduction by Eugenol and Thymol on Biodegradable Food Packaging Material.

Foods (Basel, Switzerland), 11(1): pii:foods11010002.

Biofilm is a structured community of microorganisms adhering to surfaces of various polymeric materials used in food packaging. Microbes in the biofilm may affect food quality. However, the presence of biofilm can ensure biodegradation of discarded packaging. This work aims to evaluate a biofilm formation on the selected biodegradable polymer films: poly (lactic acid) (PLA), poly (butylene adipate-co-terephthalate) (PBAT), and poly (butylene succinate) (PBS) by selected bacterial strains; collection strains of Escherichiacoli, Staphylococcusaureus; and Bacillus pumilus, Bacillussubtilis, Bacillustequilensis, and Stenotrophomonasmaltophilia isolated from dairy products. Three different methods for biofilm evaluation were performed: the Christensen method, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and fluorescence microscopy. High biofilm formation was confirmed on the control PBS film, whereas low biofilm formation ability was observed on the PLA polymer sample. Furthermore, the films with incorporated antimicrobial compounds (thymol or eugenol) were also prepared. Antimicrobial activity and also reduction in biofilm formation on enriched polymer films were determined. Therefore, they were all proved to be antimicrobial and effective in reducing biofilm formation. These films can be used to prepare novel active food packaging for the dairy industry to prevent biofilm formation and enhance food quality and safety in the future.

RevDate: 2022-01-10

Shu Y, D Liang (2022)

Effect of tetracycline on nitrogen removal in Moving Bed Biofilm Reactor (MBBR) System.

PloS one, 17(1):e0261306 pii:PONE-D-21-34743.

The effect of tetracycline (TC) on nitrogen removal in wastewater treatment plants has become a new problem. This study investigated the effects of TC on nitrogen removal using a Moving Bed Biofilm Reactor system. The results showed that there was no significant effect on nitrogen removal performance when the concentration of TC was 5 mg/L, and that the total nitrogen (TN) removal efficiency could reach 75-77%. However, when the concentration of TC increased to 10 mg/L, the denitrification performance was affected and the TN removal efficiency decreased to 58%. The abundance of denitrifying bacteria such as those in the genus Thauera decreased, and TC-resistant bacteria gradually became dominant. At a TC concentration of 10 mg/L, there were also increases and decreases, respectively, in the abundance of resistance and denitrification functional genes. The inhibitory effect of TC on denitrification was achieved mainly by the inhibition of nitrite-reducing bacteria.

RevDate: 2022-01-10

Shadvar P, Mirzaie A, S Yazdani (2022)

Fabrication and optimization of amoxicillin-loaded niosomes: An appropriate strategy to increase antimicrobial and anti-biofilm effects against multidrug-resistant strains of Staphylococcus aureus.

Drug development and industrial pharmacy [Epub ahead of print].

In this study, different formulations of amoxicillin-loaded niosomes were fabricated using the thin-film hydration method and their physicochemical properties were determined using scanning electron microscopy (SEM), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FTIR). The optimum prepared niosomes had a spherical morphology with an average size of 170.6 ± 6.8 nm and encapsulation efficiency of 65.78 ± 1.45%. The drug release study showed that the release rate of amoxicillin from niosome containing amoxicillin was slow and 47 ± 1% of the drug was released within 8 hours, while 97 ± 0.5% of the free drug was released. In addition, amoxicillin-loaded niosome increased the antimicrobial activity by 2-4 folds against multidrug-resistant (MDR) Staphylococcus aureus strains using broth microdilution assay. Moreover, at ½ minimum inhibitory concentrations, amoxicillin-loaded niosome significantly enhanced the anti-biofilm activity compared to free amoxicillin. Amoxicillin-loaded niosome had negligible cytotoxicity against HEK-293 normal cell line compared to free amoxicillin. The free niosomes exhibited no toxicity against HEK-293 cells and presented a biocompatible nanoscale delivery system. Based on the results, it can be concluded that amoxicillin-loaded niosome can be used as a promising candidate for enhancing antimicrobial and anti-biofilm effects against MDR strains of S. aureus.

RevDate: 2022-01-10

Kurbatfinski N, Goodman SD, LO Bakaletz (2022)

A Humanized Monoclonal Antibody Potentiates Killing by Antibiotics of Diverse Biofilm-Forming Respiratory Tract Pathogens.

Antimicrobial agents and chemotherapy [Epub ahead of print].

New strategies to treat diseases wherein biofilms contribute significantly to pathogenesis are needed as biofilm-resident bacteria are highly recalcitrant to antibiotics due to physical biofilm architecture and a canonically quiescent metabolism, among many additional attributes. We, and others, have shown that when biofilms are dispersed or disrupted, bacteria released from biofilm residence are in a distinct physiologic state that, in part, renders these bacteria highly sensitive to killing by specific antibiotics. We sought to demonstrate the breadth of ability of a recently humanized monoclonal antibody against an essential biofilm structural element (DNABII protein) to disrupt biofilms formed by respiratory tract pathogens and potentiate antibiotic-mediated killing of bacteria released from biofilm residence. Biofilms formed by six respiratory tract pathogens were significantly disrupted by the humanized monoclonal antibody in a dose- and time-dependent manner, as corroborated by CLSM imaging. Bacteria newly released from the biofilms of 3 of 6 species were significantly more sensitive than their planktonic counterparts to killing by 2 of 3 antibiotics currently used clinically and were now also equally as sensitive to killing by the 3rd antibiotic. The remaining 3 pathogens were significantly more susceptible to killing by all 3 antibiotics. A humanized monoclonal antibody directed against protective epitopes of a DNABII protein effectively released six diverse respiratory tract pathogens from biofilm residence in a phenotypic state that was now as, or significantly more, sensitive to killing by three antibiotics currently indicated for use clinically. These data support this targeted, combinatorial, species-agnostic therapy to mitigate chronic bacterial diseases.

RevDate: 2022-01-10

Sikder A, Chaudhuri A, Mondal S, et al (2021)

Recent Advances on Stimuli-Responsive Combination Therapy against Multidrug-Resistant Bacteria and Biofilm.

ACS applied bio materials, 4(6):4667-4683.

The widespread occurrence of infections from multidrug-resistant (MDR) bacteria is a global health problem. It has been amplified over the past few years due to the increase in adaptive traits in bacteria and lack of advanced treatment strategies. Because of the low bioavailability and limited penetration at infected sites, the existing antibiotics often fail to resist bacterial growth. Recently, developed stimuli-responsive drug delivery systems and combinatorial therapeutic systems based on nanoparticles, metal-organic frameworks, hydrogels, and organic chromophores offer the ability to improve the therapeutic efficacy of antibiotics by reducing drug resistance and other side effects. These therapeutic systems have been designed with the relevant chemical and physical properties that respond to specific triggers resulting in spatiotemporal controlled release and site-specific transportability. This review highlights the latest development of single and dual/multistimuli-responsive antibiotic delivery systems for combination therapies to treat MDR bacterial infections and biofilm eradication.

RevDate: 2022-01-10

Zhang K, Raju C, Zhong W, et al (2021)

Cationic Glycosylated Block Co-β-peptide Acts on the Cell Wall of Gram-Positive Bacteria as Anti-biofilm Agents.

ACS applied bio materials, 4(5):3749-3761.

Antimicrobial resistance is a global threat. In addition to the emergence of resistance to last resort drugs, bacteria escape antibiotics killing by forming complex biofilms. Strategies to tackle antibiotic resistance as well as biofilms are urgently needed. Wall teichoic acid (WTA), a generic anionic glycopolymer present on the cell surface of many Gram-positive bacteria, has been proposed as a possible therapeutic target, but its druggability remains to be demonstrated. Here we report a cationic glycosylated block co-β-peptide that binds to WTA. By doing so, the co-β-peptide not only inhibits biofilm formation, it also disperses preformed biofilms in several Gram-positive bacteria and resensitizes methicillin-resistant Staphylococcus aureus to oxacillin. The cationic block of the co-β-peptide physically interacts with the anionic WTA within the cell envelope, whereas the glycosylated block forms a nonfouling corona around the bacteria. This reduces physical interaction between bacteria-substrate and bacteria-biofilm matrix, leading to biofilm inhibition and dispersal. The WTA-targeting co-β-peptide is a promising lead for the future development of broad-spectrum anti-biofilm strategies against Gram-positive bacteria.

RevDate: 2022-01-10

Woodhouse I, Nejati S, Selvamani V, et al (2021)

Flexible Microneedle Array Patch for Chronic Wound Oxygenation and Biofilm Eradication.

ACS applied bio materials, 4(7):5405-5415.

Chronic nonhealing wounds are a growing socioeconomic problem that affects more than 6 million people annually solely in the United States. These wounds are colonized by bacteria that often develop into biofilms that act as a physical and chemical barrier to therapeutics and tissue oxygenation leading to chronic inflammation and tissue hypoxia. Although wound debridement and vigorous mechanical abrasion techniques are often used by clinical professionals to manage and remove biofilms from wound surfaces, such methods are highly nonselective and painful. In this study, we have developed a flexible polymer composite microneedle array that can overcome the physicochemical barriers (i.e., bacterial biofilm) present in chronic nonhealing wounds and codeliver oxygen and bactericidal agents. The polymeric microneedles are made by using a facile UV polymerization process of polyvinylpyrrolidone and calcium peroxide onto a flexible polyethylene terephthalate substrate for conformable attachment onto different locations of the human body surface. The microneedles effectively elevate the oxygen levels from 8 to 12 ppm once dissolved over the course of 2 h while also providing strong bactericidal effects on both liquid and biofilm bacteria cultures of both Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacterial strains commonly found in dermal wounds. Furthermore, the results from the ex vivo assay on a porcine wound model indicated successful insertion of the microneedles into the tissue while also providing effective bactericidal properties against both Gram-positive and Gram-negative within the complex tissue matrix. Additionally, the microneedles demonstrate high levels of cytocompatibility with less than 10% of apoptosis throughout 6 days of continuous exposure to human dermal fibroblast cells. The demonstrated flexible microneedle array can provide a better approach for increasing the effectiveness of topical tissue oxygenation as well as the treatment of infected wounds with intrinsically antibiotic resistant biofilms.

RevDate: 2022-01-10

Fan X, Zhu SS, Zhang XX, et al (2021)

Revisiting the Microscopic Processes of Biofilm Formation on Organic Carriers: A Study under Variational Shear Stresses.

ACS applied bio materials, 4(7):5529-5541.

The microscopic process of biofilm development on carriers is critical for interfacial regulation of biofilms in attached-growth wastewater treatment. However, the process under shear stress has not been well understood. The study purposed to revisit the processes of biofilm formation on organic carriers under different shear stresses with special highlights on bacterial reversible adhesion and pioneers in the microbial community. Biofilm formation on high-density polyethylene, polyamide, acrylonitrile butadiene styrene plastic, polyvinyl chloride, and polycarbonate carriers under shear stresses ranging from 1.0 to 2.5 Pa was investigated using Couette-Taylor reactors. Employing extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the bacterial reversible adhesion regions ranging from 3.74 ± 0.20 to 5.51 ± 0.24 nm on an organic carrier were quantified for the first time, elucidating significant differences among different carriers (p < 0.01). The colonization of pioneers in the microbial community was significantly altered by shear stress rather than carrier properties (p < 0.01). In particular, the diversity of the biofilm microbial community was pronouncedly enhanced by a higher shear stress (p < 0.01). XDLVO analysis suggested that extracellular polymeric substances had a negative feedback on subsequent microbial adhesion and biofilm development, especially the transition from reversible to irreversible bacterial adhesion. This study contributed to a better understanding of the biofilm formation process at the microscopic scale and shed light on micro-interfacial manipulation for biofilm accumulation or renewal.

RevDate: 2022-01-10

Gao H, Wang J, Wu H, et al (2021)

Biofilm-Integrated Glycosylated Membrane for Biosuccinic Acid Production.

ACS applied bio materials, 4(10):7517-7523.

Biofilm-based cell-immobilized fermentation technology is regarded as the technique with the most potential for biobased product (chemicals, biofuelss materials, etc.) production in industry. Glycosylated membrane can mimic natural extracellular matrix (ECM) and improve cell adhesion and biofilm formation based on carbohydrate-microbial lectin interaction. Here, we applied glycosylated membrane with rhamnose modified surface for constructing Actinobacillus succinogenes biofilm and producing biosuccinic acid. Polymer hollow fiber (PHF) membrane surface was first modified by glycosylation based on physical adsorption approach. The approach is simple, green, and suitable for scale-amplification. Then, the microbial biofilm formed dramatically on the modified membrane surface. And for subsequent biosuccinic acid production, the maximum titer of succinic acid reached 67.3 g/L, and the yield was 0.82 g/g. Compared with free cell fermentation, the titer and yield increased by 18% and 9% in this biofilm-based cell-immobilized fermentation system, respectively. Importantly, the production efficiency of biosuccinic acid increased obviously for subsequent biofilm-based cell-immobilized fermentation. In addition, the biofilm-integrated glycosylated membrane showed high reusability for succinic acid production. This result is important for developing biofilms for a wide range of applications in bioproduct (chemicals, biofuels, materials, etc.) production.

RevDate: 2022-01-10

Seferji KA, Susapto HH, Khan BK, et al (2021)

Green Synthesis of Silver-Peptide Nanoparticles Generated by the Photoionization Process for Anti-Biofilm Application.

ACS applied bio materials, 4(12):8522-8535.

An alarming increase in antibiotic-resistant bacterial strains is driving clinical demand for new antibacterial agents. One of the oldest antimicrobial agents is elementary silver (Ag), which has been used for thousands of years. Even today, elementary Ag is used for medical purposes such as treating burns, wounds, and microbial infections. In consideration of the effectiveness of elementary Ag, the present researchers generated effective antibacterial/antibiofilm agents by combining elementary Ag with biocompatible ultrashort peptide compounds. The innovative antibacterial agents comprised a hybrid peptide bound to Ag nanoparticles (IVFK/Ag NPs). These were generated by photoionizing a biocompatible ultrashort peptide, thus reducing Ag ions to form Ag NPs with a diameter of 6 nm. The IVFK/Ag NPs demonstrated promising antibacterial/antibiofilm activity against reference Gram-positive and Gram-negative bacteria compared with commercial Ag NPs. Through morphological changes in Escherichia coli and Staphylococcus aureus, we proposed that the mechanism of action for IVFK/Ag NPs derives from their ability to disrupt bacterial membranes. In terms of safety, the IVFK/Ag NPs demonstrated biocompatibility in the presence of human dermal fibroblast cells, and concentrations within the minimal inhibitory concentration had no significant effect on cell viability. These results demonstrated that hybrid peptide/Ag NPs hold promise as a biocompatible material with strong antibacterial/antibiofilm properties, allowing them to be applied across a wide range of applications in tissue engineering and regenerative medicine.

RevDate: 2022-01-10

Oliveira F, Lima T, Correia A, et al (2021)

Siderophore-Mediated Iron Acquisition Plays a Critical Role in Biofilm Formation and Survival of Staphylococcus epidermidis Within the Host.

Frontiers in medicine, 8:799227.

Iron acquisition through siderophores, a class of small, potent iron-chelating organic molecules, is a widely spread strategy among pathogens to survive in the iron-restricted environment found in the host. Although these molecules have been implicated in the pathogenesis of several species, there is currently no comprehensive study addressing siderophore production in Staphylococcus epidermidis. Staphylococcus epidermidis is an innocuous skin commensal bacterium. The species, though, has emerged as a leading cause of implant-associated infections, significantly supported by an inherent ability to form biofilms. The process of adaptation from skin niche environments to the hostile conditions during invasion is yet not fully understood. Herein, we addressed the possible role of siderophore production in S. epidermidis virulence. We first identified and deleted a siderophore homolog locus, sfaABCD, and provided evidence for its involvement in iron acquisition. Our findings further suggested the involvement of siderophores in the protection against oxidative stress-induced damage and demonstrated the in vivo relevance of a siderophore-mediated iron acquisition during S. epidermidis infections. Conclusively, this study addressed, for the first time in this species, the underlying mechanisms of siderophore production, highlighting the importance of a siderophore-mediated iron acquisition under host relevant conditions and, most importantly, its contribution to survival within the host.

RevDate: 2022-01-10

Hou X, Yuan K, Huang Z, et al (2021)

Effects of Bleaching Associated with Er:YAG and Nd:YAG Laser on Enamel Structure and Bacterial Biofilm Formation.

Scanning, 2021:6400605.

Objective: To compare the effects of bleaching associated with Er:YAG and Nd:YAG laser on enamel structure and mixed biofilm formation on teeth surfaces.

Materials and Methods: Sixty-eight enamel samples were randomly divided into four groups (n = 17), control, Opalescence Boost only, Opalescence Boost plus Er: YAG laser, and Opalescence Boost plus Nd:YAG laser. The structure was observed using SEM after bleaching. Subsequently, the treated enamel samples were also cultured in suspensions of Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus, and Fusobacterium nucleatum (Fn) for 24 and 48 h. Biofilm formation was quantified by crystal violet staining, and the structure was visualized by confocal laser scanning microscopy. The data were analyzed using the Kruskal-Wallis method.

Results: The enamel structure significantly changed after bleaching. There was no obvious difference in the biofilm formation after 24 h; however, after 48 hours, the amount of biofilm increased significantly. Remarkably, the amount was significantly higher on enamel bleached only, however, there was no significant difference between samples bleached with Er:YAG or Nd:YAG laser compared to the control.

Conclusions: Bleaching only appeared to markedly promote biofilm formation after 48 h, and the biofilms on samples bleached with Er:YAG or Nd:YAG laser did not change significantly, showing that bleaching with Er:YAG or Nd:YAG laser can be safely applied in clinical practice.

RevDate: 2022-01-10

Ma Z, Li NA, Ning C, et al (2021)

A Novel LysR Family Factor STM0859 is Associated with The Responses of Salmonella Typhimurium to Environmental Stress and Biofilm Formation.

Polish journal of microbiology, 70(4):479-487.

Salmonella enterica subsp. enterica serovar Typhimurium (ST) is an intracellularly parasitic bacterium. This zoonotic pathogen causes food poisoning and thus imposes a severe threat to food safety. Here, to understand the regulatory roles of the novel transcription factor STM0859 on the response of ST to environmental stress and biofilm formation, the STM0859 gene-deficient strain and the complementation strain ΔSTM0859/STM0859 were generated, respectively. Then, its capacity of responding to environmental stresses and biofilm (BF) formation ability under different stresses, including acid, alkali, high salt, cholate, and oxidative stresses was tested. We further analyzed the interaction between the STM0859 protein and the promoter of the acid stress response-related gene rcsB by performing an electrophoresis mobility shift assay (EMSA). The results showed that acid resistance and BF formation capacities of ST-ΔSTM0859 strain were significantly weaker, as compared with those of Salmonella Typhimurium SL1344 (ST-SL1344) wild strain (p < 0.01). Quantitative qRT-PCR analysis showed that the expression levels of acid stress and BF formation-related genes, rcsB and rpoS, of ST-ΔSTM0859 strain were significantly reduced at the transcription levels, while the transcription levels of these genes were fully restored in complementation strain ST-ΔSTM0859/STM0859. The results of EMSA showed that STM0859 was capable of binding the promoter DNA fragments of the rcsB gene, suggesting that STM0859 can promote the transcription of the rcsB gene through interaction with its promoter, thereby exerting an indirectly regulatory role on the adaptive responses to acid stress and BF formation of ST. This study provided new insights into the regulatory mechanisms of the LysR family factors on the tolerances of ST under adverse environmental stresses.

RevDate: 2022-01-10

Chen F, Zhang J, Ji HJ, et al (2021)

Deinococcus radiodurans Exopolysaccharide Inhibits Staphylococcus aureus Biofilm Formation.

Frontiers in microbiology, 12:712086.

Deinococcus radiodurans is an extremely resistant bacterium against extracellular stress owing to on its unique physiological functions and the structure of its cellular constituents. Interestingly, it has been reported that the pattern of alteration in Deinococcus proportion on the skin is negatively correlated with skin inflammatory diseases, whereas the proportion of Staphylococcus aureus was increased in patients with chronic skin inflammatory diseases. However, the biological mechanisms of deinococcal interactions with other skin commensal bacteria have not been studied. In this study, we hypothesized that deinococcal cellular constituents play a pivotal role in preventing S. aureus colonization by inhibiting biofilm formation. To prove this, we first isolated cellular constituents, such as exopolysaccharide (DeinoPol), cell wall (DeinoWall), and cell membrane (DeinoMem), from D. radiodurans and investigated their inhibitory effects on S. aureus colonization and biofilm formation in vitro and in vivo. Among them, only DeinoPol exhibited an anti-biofilm effect without affecting bacterial growth and inhibiting staphylococcal colonization and inflammation in a mouse skin infection model. Moreover, the inhibitory effect was impaired in the Δdra0033 strain, a mutant that cannot produce DeinoPol. Remarkably, DeinoPol not only interfered with S. aureus biofilm formation at early and late stages but also disrupted a preexisting biofilm by inhibiting the production of poly-N-acetylglucosamine (PNAG), a key molecule required for S. aureus biofilm formation. Taken together, the present study suggests that DeinoPol is a key molecule in the negative regulation of S. aureus biofilm formation by D. radiodurans. Therefore, DeinoPol could be applied to prevent and/or treat infections or inflammatory diseases associated with S. aureus biofilms.

RevDate: 2022-01-10

Joseph B, L Steier (2022)

Bioluminescence and ventilator-associated pneumonia caused by oral biofilm in ICU during COVID-19 -Is there a possible relationship?.

Medical hypotheses, 159:110760.

Ventilator-associated pneumonia (VAP) has been claiming many lives in the intensive care unit (ICU) during COVID-19. Oral biofilm and bacterial contamination that can be passed on from the oral cavity to the lungs during endotracheal intubation has been found to be the main culprit. Bioluminescence-based assays are emerging as potential clinical diagnostics methods. Hence, we hypothesize that the bioluminescent imaging technique can be used in the ICU to determine the load of biofilm-associated with patients undergoing endotracheal intubation. Early detection of such infections and their management can effectively bring down mortality and influence the death rate in ICU caused due to VAP. Government agencies and policymakers should be made to take this issue of deaths in the ICU due to VAP more seriously and act judiciously to methods such as bioluminescence based on sound scientific evidence.

RevDate: 2022-01-10

Astuti Febria F, R Aziza (2022)

Exopolysaccharides-Producing Biofilm Bacteria from Submerged Seawater Substrate for Bioremediation of Heavy Metal Contamination.

Pakistan journal of biological sciences : PJBS, 25(1):9-14.

Background and Objective: The coastal environment is often polluted by various toxic compounds such as heavy metals. Exposure to these toxic compounds causes coastal bacteria to adapt so that they can be used as bioremediation agents for heavy metals. This study aims for finding and screening the ability of bacteria to produce exopolysaccharide biofilms and then determine the characteristics of bacterial isolates as agents candidates for heavy metal bioremediation in the coastal environment. Materials and Methods: Samples were collected on submerged seawater substrate from Bungus Coastal, Padang and West Sumatra, on the wet area that was exposed by seawater (on the rocks, on the wood and the ship, the lower out part on the ship that exposed to seawater). Bacterial isolation process using Marine Agar Medium. The isolate discovered then observed and purified. Furthermore, Congo Red Agar was used for bacteria screening for detecting EPS produced by biofilm bacteria. Results: The results of the isolation, found 9 bacterial isolates attached to the substrate submerged seawater. The screening results showed that isolates K4, K5 and K7 were positive as biofilm-forming bacteria as indicated by the colour change of the bacterial colonies to black on Congo Red Media after 24 hrs incubation. The characteristics of the three bacterial isolates were gram-negative, with cocci and bacilli cells form. Conclusion: Three isolates of positive exopolysaccharide biofilm bacteria that 1 isolate gram-negative coccus (K4) and the other 2 isolates (K5 and K7) were bacillus. Then, the 3 isolates can be used for remediation of metal contamination research in aquatic.

RevDate: 2022-01-10

Tagua VG, Molina-Henares MA, Travieso ML, et al (2022)

C-di-GMP and biofilm are regulated in Pseudomonas putida by the CfcA/CfcR two-component system in response to salts.

Environmental microbiology [Epub ahead of print].

In Pseudomonas putida KT2440, cfcR encodes an orphan multidomain response regulator with diguanylate cyclase activity, which is responsible for the synthesis of c-di-GMP, a second messenger key in the transition from planktonic to sessile bacterial lifestyles. When overexpressed, cfcR enhances biofilm formation and causes other phenotype alterations. The cfcA gene, encoding a membrane-anchored multisensory CHASE3/GAF hybrid histidine kinase (HK), is required to develop this pleiotropic phenotype. Here we show autophosphorylation of CfcA through HisKA/HATPase_c domains and then transfer of the phosphoryl group to an internal receiver (REC) domain. CfcA REC domains are nonessential for phosphotransfer from CfcA~P to the REC domain of CfcR. CfcA~P also phosphorylates the REC domain of CfcD, a second HK encoded in the same gene cluster as CfcA, which negatively regulates the CfcA/CfcR pathway. To evaluate the impact of CfcA domains on CfcR activity, a battery of mutants with in-frame domain deletions was generated, whose CfcA protein locations were also examined. CfcA membrane anchorage contributes to protein stability and CfcR activation. Salt enhances c-di-GMP levels through CfcR, a response which is hampered by alteration of a presumed ligand binding motif in the CHASE3 sensor domain. Thus in P. putida, c-di-GMP is salt-regulated through the CfcA/CfcR/CfcD system. This article is protected by copyright. All rights reserved.

RevDate: 2022-01-10

Vishakha K, Das S, Das SK, et al (2022)

Antibacterial, anti-biofilm, and anti-virulence potential of tea tree oil against leaf blight pathogen Xanthomonas oryzae pv. oryzae instigates disease suppression.

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] [Epub ahead of print].

Bacterial leaf blight (BLB) disease, caused by Xanthomonas oryzae pv. oryzae (Xoo), causes major annual economic losses around the world. Inorganic copper compounds and antibiotics are conventionally used to control BLB disease. They often cause environmental pollution, contributing to adverse effects on human health. Therefore, research is now leading to the search for alternative control methods. Tea tree oil (TTO) is obtained from a traditional medicinal plant, Melaleuca alternifolia, with antibacterial properties. In this study, we found that TTO showed antibacterial activity against Xoo with a minimum inhibitory concentration (MIC) of 18 mg/ml. These antagonistic activities were not limited only to planktonic cells, as further studies have shown that TTO effectively eradicated sessile cells of Xoo in both initial and mature biofilms. Furthermore, it was also observed that TTO reduced various key virulence properties of Xoo, such as swimming, swarming motility, and the production of extracellular polymeric substances, xanthomonadin, and exoenzymes. TTO triggered ROS generation with cell membrane damage as an antibacterial mode of action against Xoo. The in silico study revealed that 1,8-cineole of TTO was effectively bound to two essential proteins, phosphoglucomutase and peptide deformylase, responsible for the synthesis of EPS and bacterial survival, respectively. These antibacterial and anti-virulence activities of TTO against Xoo were further confirmed by an ex vivo virulence assay where TTO significantly reduced the lesion length caused by Xoo on rice leaves. All these data concluded that TTO could be a safe, environment-friendly alternative approach for the comprehensive management of BLB disease.

RevDate: 2022-01-09

Zheng Y, Lu X, Liu B, et al (2022)

Novel FabI inhibitor disrupts the biofilm formation of MRSA through down-regulating the expression of quorum-sensing regulatory genes.

Microbial pathogenesis pii:S0882-4010(22)00004-3 [Epub ahead of print].

OBJECTIVES: The aim of this study was to explore the antibiofilm and antivirulence efficacy of benzylaniline 4k against MRSA.

METHODS: The clinical MRSA strains were identified and used to evaluate their potential to form biofilm using crystal violet assay. The minimal inhibitory concentration (MIC) was determined using broth microdilution method. The expression of genes was detected using quantitative real-time PCR (qRT-PCR). Rabbit blood hemolytic assay was used to observe the inhibitory ability of alpha-hemolysin (Hla).

RESULTS: Compound 4k showed potent antibacterial activity against 16 clinical MRSA with an MIC50 of 1.25 mg/L and MIC90 of 2.25 mg/L. The value of minimum biofilm eradication concentration (MBEC) against MRSA2858 biofilm was of 1.5 mg/L, close to its MIC, superior to those of vancomycin and erythromycin. Compound 4k eradicated the formation of biofilm through inhibiting the gene expression of branched-chain fatty acid synthesis, down-regulating the expression of quorum-sensing (QS) regulatory genes (norA, agrA, icaA, hla), decreasing the level of hemolysis in a dose-dependent manner, and inhibiting rabbit blood hemolysis by 86.9% at a concentration of 1.25 mg/L. In a mouse model of abdominal infection, compound 4k was more effective than vancomycin in reducing bacterial load.

CONCLUSIONS: These results suggested that compound 4k could be developed as promising an anti-MRSA agent through affecting quorum-sensing system.

RevDate: 2022-01-09

Zhang X, Miao Y, Yu D, et al (2022)

Culturing partial denitrification biofilm in side stream incubator with ordinary activated sludge as inoculum: one step closer to mainstream Anammox upgrade.

Bioresource technology pii:S0960-8524(22)00008-6 [Epub ahead of print].

Recently, adding carriers into anoxic zone is proposed for mainstream Anammox upgrade, which relied on the denitrifiers responsible for partial denitrification (PD) to generate essential nitrite for Anammox bacteria. Still, their low abundance in the naturally formed biofilm leads to insufficient nitrite supply. This study investigated the sequential culturing of PD biofilm. By inoculating ordinary activated sludge, the PD process was quickly established within 54-day. During that, decreasing carbon to nitrogen ratio and anoxic duration in order might be effective strategies. Adding carriers shifted the microbial community, especially the proliferation of Flavobacterium. When solely using the mature PD biofilm, high nitrate to nitrite transformation ratio (> 70%) was obtained. Meanwhile, both nitrate-reducing and nitrite-generating processes slowed down and lasted ∼90 min. In addition, abundant Simplicispira candidate for PD was detected in biofilm. This study also suggests that regularly harvesting PD-related functional bacteria from a side-stream incubator promotes mainstream Anammox upgrade.

RevDate: 2022-01-09

Dong Y, Feng D, Song GL, et al (2022)

The effect of a biofilm-forming bacterium Tenacibaculum mesophilum D-6 on the passive film of stainless steel in the marine environment.

The Science of the total environment pii:S0048-9697(21)07988-2 [Epub ahead of print].

The microbiologically influenced corrosion of 304 stainless steel in the presence of a marine biofilm-forming bacterium Tenacibaculum mesophilum D-6 was systematically investigated by means of electrochemical techniques and surface analyses to reveal the effect of the selective attachment and adsorption of the biofilms on the passivity breakdown of the stainless steel. It was found that the T. mesophilum D-6 was electroactive and could oxidize low valent cations and metal, facilitating the local dissolution of the passive film and the substrate in the film defects, nearly doubling the surface roughness. The biofilms of T. mesophilum D-6 with mucopolysaccharide secreta and chloride ions tended to preferentially adsorb at the defects of the passive film on the steel, yielding non-homogeneous microbial aggregates and local Cl- enrichment there. The adsorption of the bacteria and chloride ions reduced the thickness of passive film by 23.9%, and generate more active sites for pitting corrosion on the passive film and more semiconducting carrier acceptors in the film. The maximum current density of the 304 SS in the presence of T. mesophilum D-6 was over one order of magnitude higher than that in the sterile medium, and the largest pit was deepened 3 times.

RevDate: 2022-01-08

Desmond P, Huisman KT, Sanawar H, et al (2022)

Controlling the hydraulic resistance of membrane biofilms by engineering biofilm physical structure.

Water research, 210:118031 pii:S0043-1354(21)01225-2 [Epub ahead of print].

The application of membrane technology for water treatment and reuse is hampered by the development of a microbial biofilm. Biofilm growth in micro-and ultrafiltration (MF/UF) membrane modules, on both the membrane surface and feed spacer, can form a secondary membrane and exert resistance to permeation and crossflow, increasing energy demand and decreasing permeate quantity and quality. In recent years, exhaustive efforts were made to understand the chemical, structural and hydraulic characteristics of membrane biofilms. In this review, we critically assess which specific structural features of membrane biofilms exert resistance to forced water passage in MF/UF membranes systems applied to water and wastewater treatment, and how biofilm physical structure can be engineered by process operation to impose less hydraulic resistance ("below-the-pain threshold"). Counter-intuitively, biofilms with greater thickness do not always cause a higher hydraulic resistance than thinner biofilms. Dense biofilms, however, had consistently higher hydraulic resistances compared to less dense biofilms. The mechanism by which density exerts hydraulic resistance is reported in the literature to be dependant on the biofilms' internal packing structure and EPS chemical composition (e.g., porosity, polymer concentration). Current reports of internal porosity in membrane biofilms are not supported by adequate experimental evidence or by a reliable methodology, limiting a unified understanding of biofilm internal structure. Identifying the dependency of hydraulic resistance on biofilm density invites efforts to control the hydraulic resistance of membrane biofilms by engineering internal biofilm structure. Regulation of biofilm internal structure is possible by alteration of key determinants such as feed water nutrient composition/concentration, hydraulic shear stress and resistance and can engineer biofilm structural development to decrease density and therein hydraulic resistance. Future efforts should seek to determine the extent to which the concept of "biofilm engineering" can be extended to other biofilm parameters such as mechanical stability and the implication for biofilm control/removal in engineered water systems (e.g., pipelines and/or, cooling towers) susceptible to biofouling.

RevDate: 2022-01-08

Unsal T, Wang D, Kijkla P, et al (2022)

Food-grade D-limonene enhanced a green biocide in the mitigation of carbon steel biocorrosion by a mixed-culture biofilm consortium.

Bioprocess and biosystems engineering [Epub ahead of print].

Microbiologically influenced corrosion (MIC), or microbial biocorrosion, is caused directly by microbial metabolic activities/products or induced by microbial biofilm's damage of a protective film that exposes a solid surface to a pre-existing corrosive environment. MIC causes billions of dollars of losses in various industrial processes, especially in oil and gas and water utilities. The mitigation of problematic industrial microbes typically relies on biocides whose discharges can cause environmental problems. Thus, more effective biocide applications are desired to minimize environmental impact. D-Limonene, a citrus peel oil, generally regarded as safe (GRAS), was used to enhance the popular biodegradable tetrakis hydroxymethyl phosphonium sulfate (THPS) biocide. An oilfield mixed-culture biofilm was grown anaerobically in enriched artificial seawater containing C1018 carbon steel coupons for 7 days at 37 °C. One hundred ppm (w/w) D-limonene reduced general heterotrophic bacteria (GHB) and acid-producing bacteria (APB) effectively, leading to 5.4-log and 6.0-log reductions in sessile GHB and APB cell counts, respectively, compared to no treatment control. The combination of 100 ppm D-limonene + 100 ppm THPS achieved extra 1.0-log SRB, 0.6-log GHB and 0.5-log APB reductions in sessile cell counts, which led to extra 58% reduction in microbial corrosion mass loss (1.2 vs. 0.5 mg/cm2) and extra 30% reductions in maximum pit depth (11.5 vs. 8.1 µm), compared to 100 ppm THPS-only treatment. Linear polarization resistance and potentiodynamic polarization (PDP) corrosion data supported mass loss and pitting data. Mixed-culture biofilms on carbon steel coupons after 7 day incubation at 37 °C showing enhanced biocide treatment outcome using D-limonene + THPS: A no treatment, B 100 ppm D-limonene, C 100 ppm THPS, D 100 ppm D-limonene + 100 ppm THPS.

RevDate: 2022-01-08

Pang Y, Wang S, Tao J, et al (2022)

Mechanism of berberine hydrochloride interfering with biofilm formation of Hafnia alvei.

Archives of microbiology, 204(2):126.

The mechanism of berberine hydrochloride (BBH) inhibiting the biofilm formation of Hafnia alvei was investigated in this study. The antibiofilm potential of BBH was evaluated by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) as well as crystal violet staining. The quorum-sensing (QS) inhibition was revealed by determination of QS-related genes expression and related signal molecules production using real-time quantitative PCR (RT-qPCR) and high performance liquid chromatography (HPLC). The binding of BBH to receptor proteins was simulated by molecular docking and molecular dynamics simulations. It was found that BBH at sub-minimum inhibitory concentrations (sub-MICs) significantly reduced the biofilm formation of H. alvei in a dose dependent manner. BBH inhibited the bacterial swimming motility, decreased the transcription of halI and halR genes, and reduced the production of signal molecule C14-HSL. It bound to HalR protein mainly through Van der Waals force and electrostatic interaction force. Based on these results, it was concluded that BBH inhibits the biofilm formation of H. alvei and the mechanism is related to its interference with QS through down-regulating the expression of halI and halR genes.

RevDate: 2022-01-08

Mangalea MR, BR Borlee (2022)

The NarX-NarL two-component system regulates biofilm formation, natural product biosynthesis, and host-associated survival in Burkholderia pseudomallei.

Scientific reports, 12(1):203.

Burkholderia pseudomallei is a saprophytic bacterium endemic throughout the tropics causing severe disease in humans and animals. Environmental signals such as the accumulation of inorganic ions mediates the biofilm forming capabilities and survival of B. pseudomallei. We have previously shown that B. pseudomallei responds to nitrate and nitrite by inhibiting biofilm formation and altering cyclic di-GMP signaling. To better understand the roles of nitrate-sensing in the biofilm inhibitory phenotype of B. pseudomallei, we created in-frame deletions of narX (Bp1026b_I1014) and narL (Bp1026b_I1013), which are adjacent components of a conserved nitrate-sensing two-component system. We observed transcriptional downregulation in key components of the biofilm matrix in response to nitrate and nitrite. Some of the most differentially expressed genes were nonribosomal peptide synthases (NRPS) and/or polyketide synthases (PKS) encoding the proteins for the biosynthesis of bactobolin, malleilactone, and syrbactin, and an uncharacterized cryptic NRPS biosynthetic cluster. RNA expression patterns were reversed in ∆narX and ∆narL mutants, suggesting that nitrate sensing is an important checkpoint for regulating the diverse metabolic changes occurring in the biofilm inhibitory phenotype. Moreover, in a macrophage model of infection, ∆narX and ∆narL mutants were attenuated in intracellular replication, suggesting that nitrate sensing contributes to survival in the host.

RevDate: 2022-01-08

Chandrasekharan S, Chinnasamy G, S Bhatnagar (2022)

Sustainable phyto-fabrication of silver nanoparticles using Gmelina arborea exhibit antimicrobial and biofilm inhibition activity.

Scientific reports, 12(1):156.

Increase in bacterial resistance to commonly used antibiotics is a major public health concern generating interest in novel antibacterial treatments. Aim of this scientific endeavor was to find an alternative efficient antibacterial agent from non-conventional plant source for human health applications. We used an eco-friendly approach for phyto-fabrication of silver nanoparticles (AgNPs) by utilizing logging residue from timber trees Gmelina arborea (GA). GC-MS analysis of leaves, barks, flowers, fruits, and roots was conducted to determine the bioactive compounds. Biosynthesis, morphological and structural characterization of GA-AgNPs were undertaken by UV-Vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD). GA-AgNPs were evaluated for antibacterial, antibiofilm, antioxidant, wound healing properties and their toxicity studies were carried out. Results identified the presence of terpenoids, sterols, aliphatic alcohols, aldehydes, and flavonoids in leaves, making leaf extract the ideal choice for phyto-fabrication of silver nanoparticles. The synthesis of GA-AgNPs was confirmed by dark brown colored colloidal solution and spectral absorption peak at 420 nm. Spherical, uniformly dispersed, crystalline GA-AgNPs were 34-40 nm in diameter and stable in solutions at room temperature. Functional groups attributed to the presence of flavonoids, terpenoids, and phenols that acted as reducing and capping agents. Antibacterial potency was confirmed against pathogenic bacteria Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus by disc diffusion assay, MIC and MBC assay, biofilm inhibition assay, electron-microscopy, cell staining and colony counting techniques. The results from zone of inhibition, number of ruptured cells and dead-cell-count analysis confirmed that GA-AgNPs were more effective than GA-extract and their bacteria inhibition activity level increased further when loaded on hydrogel as GA-AgNPs-PF127, making it a novel distinguishing feature. Antioxidant activity was confirmed by the free radical scavenging assays (DPPH and ABTS). Wound healing potential was confirmed by cell scratch assay in human dermal fibroblast cell lines. Cell-proliferation study in human chang liver cell lines and optical microscopic observations confirmed non-toxicity of GA-AgNPs at low doses. Our study concluded that biosynthesized GA-AgNPs had enhanced antibacterial, antibiofilm, antioxidant, and wound healing properties.

RevDate: 2022-01-08

Elekhnawy E, Negm WA, El-Aasr M, et al (2022)

Histological assessment, anti-quorum sensing, and anti-biofilm activities of Dioon spinulosum extract: in vitro and in vivo approach.

Scientific reports, 12(1):180.

Pseudomonas aeruginosa is an opportunistic bacterium causing several health problems and having many virulence factors like biofilm formation on different surfaces. There is a significant need to develop new antimicrobials due to the spreading resistance to the commonly used antibiotics, partly attributed to biofilm formation. Consequently, this study aimed to investigate the anti-biofilm and anti-quorum sensing activities of Dioon spinulosum, Dyer Ex Eichler extract (DSE), against Pseudomonas aeruginosa clinical isolates. DSE exhibited a reduction in the biofilm formation by P. aeruginosa isolates both in vitro and in vivo rat models. It also resulted in a decrease in cell surface hydrophobicity and exopolysaccharide quantity of P. aeruginosa isolates. Both bright field and scanning electron microscopes provided evidence for the inhibiting ability of DSE on biofilm formation. Moreover, it reduced violacein production by Chromobacterium violaceum (ATCC 12,472). It decreased the relative expression of 4 quorum sensing genes (lasI, lasR, rhlI, rhlR) and the biofilm gene (ndvB) using qRT-PCR. Furthermore, DSE presented a cytotoxic activity with IC50 of 4.36 ± 0.52 µg/ml against human skin fibroblast cell lines. For the first time, this study reports that DSE is a promising resource of anti-biofilm and anti-quorum sensing agents.

RevDate: 2022-01-07

Chou KT, Lee DD, Chiou JG, et al (2022)

A segmentation clock patterns cellular differentiation in a bacterial biofilm.

Cell, 185(1):145-157.e13.

Contrary to multicellular organisms that display segmentation during development, communities of unicellular organisms are believed to be devoid of such sophisticated patterning. Unexpectedly, we find that the gene expression underlying the nitrogen stress response of a developing Bacillus subtilis biofilm becomes organized into a ring-like pattern. Mathematical modeling and genetic probing of the underlying circuit indicate that this patterning is generated by a clock and wavefront mechanism, similar to that driving vertebrate somitogenesis. We experimentally validated this hypothesis by showing that predicted nutrient conditions can even lead to multiple concentric rings, resembling segments. We additionally confirmed that this patterning mechanism is driven by cell-autonomous oscillations. Importantly, we show that the clock and wavefront process also spatially patterns sporulation within the biofilm. Together, these findings reveal a biofilm segmentation clock that organizes cellular differentiation in space and time, thereby challenging the paradigm that such patterning mechanisms are exclusive to plant and animal development.

RevDate: 2022-01-07

Wang H, Yu P, Schwarz C, et al (2022)

Phthalate Esters Released from Plastics Promote Biofilm Formation and Chlorine Resistance.

Environmental science & technology [Epub ahead of print].

Phthalate esters (PAEs) are commonly released from plastic pipes in some water distribution systems. Here, we show that exposure to a low concentration (1-10 μg/L) of three PAEs (dimethyl phthalate (DMP), di-n-hexyl phthalate (DnHP), and di-(2-ethylhexyl) phthalate (DEHP)) promotes Pseudomonas biofilm formation and resistance to free chlorine. At PAE concentrations ranging from 1 to 5 μg/L, genes coding for quorum sensing, extracellular polymeric substances excretion, and oxidative stress resistance were upregulated by 2.7- to 16.8-fold, 2.1- to 18.9-fold, and 1.6- to 9.9-fold, respectively. Accordingly, more biofilm matrix was produced and the polysaccharide and eDNA contents increased by 30.3-82.3 and 10.3-39.3%, respectively, relative to the unexposed controls. Confocal laser scanning microscopy showed that PAE exposure stimulated biofilm densification (volumetric fraction increased from 27.1 to 38.0-50.6%), which would hinder disinfectant diffusion. Biofilm densification was verified by atomic force microscopy, which measured an increase of elastic modulus by 2.0- to 3.2-fold. PAE exposure also stimulated the antioxidative system, with cell-normalized superoxide dismutase, catalase, and glutathione activities increasing by 1.8- to 3.0-fold, 1.0- to 2.0-fold, and 1.2- to 1.6-fold, respectively. This likely protected cells against oxidative damage by chlorine. Overall, we demonstrate that biofilm exposure to environmentally relevant levels of PAEs can upregulate molecular processes and physiologic changes that promote biofilm densification and antioxidative system expression, which enhance biofilm resistance to disinfectants.


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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An examination of the research and translational application to prevent and treat biofilm-associated diseases In the decade since the first edition of Microbial Biofilms was published, the interest in this field has expanded, spurring breakthrough research that has advanced the treatment of biofilm-associated diseases. This second edition takes the reader on an exciting, extensive review of bacterial and fungal biofilms, ranging from basic molecular interactions to innovative therapies, with particular emphasis on the division of labor in biofilms, new approaches to combat the threat of microbial biofilms, and how biofilms evade the host defense.

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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

short personal version

Curriculum Vitae for R J Robbins

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RJR Picks from Around the Web (updated 11 MAY 2018 )