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Bibliography on: Biofilm

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ESP: PubMed Auto Bibliography 23 May 2019 at 01:34 Created: 

Biofilm

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

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

Citations The Papers (from PubMed®)

RevDate: 2019-05-22

Huang TC, Chen CJ, Chen CC, et al (2019)

Enhancing osteoblast functions on biofilm-contaminated titanium alloy by concentration-dependent use of methylene blue-mediated antimicrobial photodynamic therapy.

Photodiagnosis and photodynamic therapy pii:S1572-1000(19)30076-6 [Epub ahead of print].

The concentration of methylene blue (MB) photosensitizer could affect the eradication efficacy of antimicrobial photodynamic therapy (aPDT) in the treatment of contaminated implants, which is linked to the osseointegration of the implant. This was the first report of evaluating osteoblast functions on the contaminated SLA (sandblasting, large-grit and acid-etching) Ti alloy surfaces after the concentration-dependent use of MB-aPDT. Totally 1,164 SLA discs were randomly distributed for the analyses of antibacterial efficacy and osteoblast functions. Gram-negative (Aggregatibacter actinomycetemcomitans; A. actinomycetemcomitans) or Gram-positive (Streptococcus mutans; S. mutans) adhered on disc samples was subjected to aPDT with different MB concentrations (200, 250, 300, 350, and 400 μg/mL) using 660 nm diode laser with maximum output 80 mW for 1 min irradiation (4.8 J/cm2). Bactericidal effect was examined by viability, morphology, and lipopolysaccharide (LPS) assays. The disinfected disc surfaces by MB-aPDT to support osteoblast-like MG63 attachment, proliferation, differentiation, and mineralization were assessed for the predetermined culture time intervals. The statistical differences between the means were performed using a one-way analysis of variance (ANOVA) with a post hoc Scheffe test. The results of the morphology observation and bacterial survival examination consistently indicated a remarkably lower quantity of bacterial colonies on biofilm-contaminated surfaces after the aPDT treatment with higher MB concentration. Similarly, the higher MB concentration in aPDT resulted in the lower LPS amounts remaining on the A. actinomycetemcomitans-contaminated surfaces. Intriguingly, the expression of osteoblast cultured on disinfected surfaces using aPDT with higher MB concentration was comparable to the control without contamination. Within the limits of this in vitro model, this formulation of 400 μg/mL MB used in aPDT may be not only the lethal concentration against the 2 bacteria-contaminated implants, but it could also enhance the osteoblast functions on the contaminated implants. Nevertheless, the efficacy in the clinical practice for peri-implantitis therapy remains to be studied.

RevDate: 2019-05-22

Feng R, Zhao G, Yang Y, et al (2019)

Enhanced biological removal of intermittent VOCs and deciphering the roles of sodium alginate and polyvinyl alcohol in biofilm formation.

PloS one, 14(5):e0217401 pii:PONE-D-19-08641.

Developing a robust biofilm is a prerequisite for a biotrickling filter to obtain the good performance in removing volatile organic compounds (VOCs). But the biofilm formation can be seriously disturbed under intermittent loading condition due to carbon starvation stress in idle time. In this study, a biotrickling filter, with its packing materials being modified by 3% sodium alginate and 5% polyvinyl alcohol (v/v = 1:3), was employed to treat intermittent VOCs. Results showed that the removal efficiencies of toluene, ethylbenzene, p-xylene, m-xylene, and o-xylene was significantly enhanced in the BTF compared to the control one. Under relatively lower inlet loading, nearly complete removal of the five pollutants was achieved. A quantitative analysis showed that the concentration of total organic compound (TOC) in the leachate maintained at a high level, and had a strongly positive correlation with the divergence of microbial communities. The capacity of biofilm formation in the BTF was approximately four-fold higher than the control BTF, while the quantity of EPS secreted was more than ten-fold. EPS comprised largely of protein, and to less extent, polysaccharide. The biofilm formed on the modified packing materials maintained higher levels of microbial diversity and stability, even when modifiers were complete depleted or the VOCs inlet loading was increased. This study highlights the importance of packing materials for reducing the gap in performance between laboratory and industrial applications of BTFs.

RevDate: 2019-05-22

Huang MY, Woolford CA, May G, et al (2019)

Circuit diversification in a biofilm regulatory network.

PLoS pathogens, 15(5):e1007787 pii:PPATHOGENS-D-19-00221.

Genotype-phenotype relationships can vary extensively among members of a species. One cause of this variation is circuit diversification, the alteration of gene regulatory relationships among members of a species. Circuit diversification is thought to be a starting point for the circuit divergence or rewiring that occurs during speciation. How widespread is circuit diversification? Here we address this question with the fungal pathogen Candida albicans, which forms biofilms rich in distinctive hyphal cells as a prelude to infection. Our understanding of the biofilm/hyphal regulatory network comes primarily from studies of one clinical isolate, strain SC5314, and its marked derivatives. We used CRISPR-based methods to create mutations of four key biofilm transcription factor genes-BCR1, UME6, BRG1, and EFG1 -in SC5314 and four additional clinical isolates. Phenotypic analysis revealed that mutations in BCR1 or UME6 have variable impact across strains, while mutations in BRG1 or EFG1 had uniformly severe impact. Gene expression, sampled with Nanostring probes and examined comprehensively for EFG1 via RNA-Seq, indicates that regulatory relationships are highly variable among isolates. Our results suggest that genotype-phenotype relationships vary in this strain panel in part because of differences in control of BRG1 by BCR1, a hypothesis that is supported through engineered constitutive expression of BRG1. Overall, the data show that circuit diversification is the rule, not the exception, in this biofilm/hyphal regulatory network.

RevDate: 2019-05-22

Abbondante S, E Pearlman (2019)

Breaching bacterial biofilm with neutrophil α-mannosidase.

RevDate: 2019-05-22

Laulund ASB, Trøstrup H, Lerche CJ, et al (2019)

Synergistic effect of immunomodulatory S100A8/A9 and ciprofloxacin against Pseudomonas aeruginosa biofilm in a murine chronic wound model.

Pathogens and disease pii:5497298 [Epub ahead of print].

The majority of chronic wounds are associated with bacterial biofilms recalcitrant to antibiotics and host responses.Immunomodulatory S100A8/A9 is suppressed in P. aeruginosa biofilms infected wounds. We aimed at investigating a possible additive effect between S100A8/A9 and ciprofloxacin against biofilms.

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

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

CONCLUSION: The observed ciprofloxacin augmenting effect of S100A8/A9 in vivo was not confirmed by checkerboard analysis indicating dependence of host cells for the S100A8/A9 effect. S100A8/A9 and ciprofloxacin is a promising therapy for optimizing chronic wound treatment.

RevDate: 2019-05-22

Daood U, Burrow MF, CKY Yiu (2019)

Effect of a novel quaternary ammonium silane cavity disinfectant on cariogenic biofilm formation.

Clinical oral investigations pii:10.1007/s00784-019-02928-7 [Epub ahead of print].

OBJECTIVE: Evaluate effect of quaternary ammonium silane (QAS) cavity disinfectant on cariogenic biofilm.

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

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

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

CLINICAL SIGNIFICANCE: Available data demonstrated use of QAS as potential antibacterial cavity disinfectant in adhesive dentistry. Experimental QAS can effectively eliminate caries-forming bacteria, when used inside a prepared cavity, and can definitely overcome problems associated with present available cavity disinfectants.

RevDate: 2019-05-22

Montazeri A, Salehzadeh A, H Zamani (2019)

Effect of silver nanoparticles conjugated to thiosemicarbazide on biofilm formation and expression of intercellular adhesion molecule genes, icaAD, in Staphylococcus aureus.

Folia microbiologica pii:10.1007/s12223-019-00715-1 [Epub ahead of print].

Biofilm formation is regarded as an important factor in the establishment of infections caused by Staphylococcus aureus. In the present study, phenotypic and molecular assays were used to evaluate antibiofilm potential of thiosemicarbazide (Tsc) conjugated with silver nanoparticles (Ag NPs) and functionalized by glutamic acid (Ag@Glu/Tsc NPs) against methicillin-resistant S. aureus (MRSA). Ag NPs were synthesized using precipitation method and conjugated to Tsc using glutamic acid. The NPs were characterized using SEM and FTIR spectroscopy analyses. Then, antibiofilm potential of the prepared NPs against MRSA strains was evaluated using phenotypic method and their effects on the expression of biofilm-associated genes icaA and icaD. Finally, the genes involved with the synthesis of intercellular adhesion molecules were determined. According to the results, Ag@Glu/Tsc NPs inhibited biofilm formation of MRSA strains up to 76.7% compared with the control. In addition, expression of the biofilm-associated genes icaA and icaD reduced by 66.7% and 60.3%, respectively in the presence of sub-inhibitory concentration of Ag@Glu/Tsc NPs. In conclusion, Ag@Glu/Tsc NPs could be considered as a potent antibacterial agent to inhibit bacterial biofilms.

RevDate: 2019-05-22

Dance DA, Wuthiekanun V, Sarovich D, et al (2019)

Pan-drug-resistant and biofilm-producing strain of Burkholderia pseudomallei: first report of melioidosis from a diabetic patient in Yogyakarta, Indonesia [Letter].

International medical case reports journal, 12:117-118 pii:205245.

RevDate: 2019-05-22

Pisithkul T, Schroeder JW, Trujillo EA, et al (2019)

Metabolic Remodeling during Biofilm Development of Bacillus subtilis.

mBio, 10(3): pii:mBio.00623-19.

Biofilms are structured communities of tightly associated cells that constitute the predominant state of bacterial growth in natural and human-made environments. Although the core genetic circuitry that controls biofilm formation in model bacteria such as Bacillus subtilis has been well characterized, little is known about the role that metabolism plays in this complex developmental process. Here, we performed a time-resolved analysis of the metabolic changes associated with pellicle biofilm formation and development in B. subtilis by combining metabolomic, transcriptomic, and proteomic analyses. We report surprisingly widespread and dynamic remodeling of metabolism affecting central carbon metabolism, primary biosynthetic pathways, fermentation pathways, and secondary metabolism. Most of these metabolic alterations were hitherto unrecognized as biofilm associated. For example, we observed increased activity of the tricarboxylic acid (TCA) cycle during early biofilm growth, a shift from fatty acid biosynthesis to fatty acid degradation, reorganization of iron metabolism and transport, and a switch from acetate to acetoin fermentation. Close agreement between metabolomic, transcriptomic, and proteomic measurements indicated that remodeling of metabolism during biofilm development was largely controlled at the transcriptional level. Our results also provide insights into the transcription factors and regulatory networks involved in this complex metabolic remodeling. Following upon these results, we demonstrated that acetoin production via acetolactate synthase is essential for robust biofilm growth and has the dual role of conserving redox balance and maintaining extracellular pH. This report represents a comprehensive systems-level investigation of the metabolic remodeling occurring during B. subtilis biofilm development that will serve as a useful road map for future studies on biofilm physiology.IMPORTANCE Bacterial biofilms are ubiquitous in natural environments and play an important role in many clinical, industrial, and ecological settings. Although much is known about the transcriptional regulatory networks that control biofilm formation in model bacteria such as Bacillus subtilis, very little is known about the role of metabolism in this complex developmental process. To address this important knowledge gap, we performed a time-resolved analysis of the metabolic changes associated with bacterial biofilm development in B. subtilis by combining metabolomic, transcriptomic, and proteomic analyses. Here, we report a widespread and dynamic remodeling of metabolism affecting central carbon metabolism, primary biosynthetic pathways, fermentation pathways, and secondary metabolism. This report serves as a unique hypothesis-generating resource for future studies on bacterial biofilm physiology. Outside the biofilm research area, this work should also prove relevant to any investigators interested in microbial physiology and metabolism.

RevDate: 2019-05-22

Liu X, Yan Y, Wu H, et al (2019)

Biological and transcriptomic studies reveal hfq is required for swimming, biofilm formation and stress response in Xanthomonas axonpodis pv. citri.

BMC microbiology, 19(1):103 pii:10.1186/s12866-019-1476-9.

BACKGROUND: Hfq is a widely conserved bacterial RNA-binding protein which generally mediates the global regulatory activities involv ed in physiological process and virulence. The goal of this study was to characterize the biological function of hfq gene in Xanthomonas axonpodis pv. citri (Xac), the causal agent of citrus canker disease.

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

CONCLUSIONS: The study demonstrated that hfq was involved in multiple biological processes in Xac. The results could serve as initiate points for identifying regulatory sRNAs and genes controlled by Hfq-sRNA interactions in Xac.

RevDate: 2019-05-21

Jannadi H, Correa W, Zhang Z, et al (2019)

Antimicrobial peptides Pep19-2.5 and Pep19-4LF inhibited Streptococcus mutans growth and biofilm formation.

Microbial pathogenesis pii:S0882-4010(18)32083-7 [Epub ahead of print].

With this study, we investigated the effect of synthetic antimicrobial peptides Pep19-2.5 and Pep194LF alone or in combination with antibiotics on S. mutans growth and biofilm formation/disruption. We also examined the cytotoxic effect of each peptide on monocytes. S. mutans was cultured in the presence of different concentrations of each peptide. We showed that Pep19-2.5 and Pep19-4LF were able to significantly (p ≤ 0.01) inhibit the growth of S. mutans. The synthetic peptides also decreased biofilm formation by S. mutans. Furthermore, both peptides reduced the viability of S. mutans in already formed biofilms. The combination of each peptide with antibiotics (penicillin/streptomycin, P/S) produced additive interactions which inhibited S. mutans growth and biofilm formation. Pep19-2.5 and Pep19-4LF were nontoxic, as they did not decrease monocyte viability and did not increase the lactate dehydrogenase activity of the exposed cells. In conclusion, synthetic peptides Pep19-2.5 and Pep19-4LF did inhibit S. mutans growth and its capacity to form biofilm. Both peptides were found to be nontoxic to monocytes. These data provide new insight into the efficacy of synthetic peptides Pep19-2.5 and Pep19-4LF against S. mutans. These peptides may thus be useful in controlling the adverse effects of this cariogenic bacterium in human.

RevDate: 2019-05-21

Rizzato C, Torres J, Kasamatsu E, et al (2019)

Potential Role of Biofilm Formation in the Development of Digestive Tract Cancer With Special Reference to Helicobacter pylori Infection.

Frontiers in microbiology, 10:846.

Bacteria are highly social organisms that communicate via signaling molecules and can assume a multicellular lifestyle to build biofilm communities. Until recently, complications from biofilm-associated infection have been primarily ascribed to increased bacterial resistance to antibiotics and host immune evasion, leading to persistent infection. In this theory and hypothesis article we present a relatively new argument that biofilm formation has potential etiological role in the development of digestive tract cancer. First, we summarize recent new findings suggesting the potential link between bacterial biofilm and various types of cancer to build the foundation of our hypothesis. To date, evidence has been particularly convincing for colorectal cancer and its precursor, i.e., polyps, pointing to several key individual bacterial species, such as Bacteroides fragilis, Fusobacterium nucleatum, and Streptococcus gallolyticus subsp. Gallolyticus. Then, we further extend this hypothesis to one of the most common bacterial infection in humans, Helicobacter pylori (Hp), which is considered a major cause of gastric cancer. Thus far, there has been no direct evidence linking in vivo Hp gastric biofilm formation to gastric carcinogenesis. Yet, we synthesize the information to support an argument that biofilm associated-Hp is potentially more carcinogenic, summarizing biological characteristics of biofilm-associated bacteria. We also discuss mechanistic pathways as to how Hp or other biofilm-associated bacteria control biofilm formation and highlight recent findings on Hp genes that influence biofilm formation, which may lead to strain variability in biofilm formation. This knowledge may open a possibility of developing targeted intervention. We conclude, however, that this field is still in its infancy. To test the hypothesis rigorously and to link it ultimately to gastric pathologies (e.g., premalignant lesions and cancer), studies are needed to learn more about Hp biofilms, such as compositions and biological properties of extracellular polymeric substance (EPS), presence of non-Hp microbiome and geographical distribution of biofilms in relation to gastric gland types and structures. Identification of specific Hp strains with enhanced biofilm formation would be helpful not only for screening patients at high risk for sequelae from Hp infection, but also for development of new antibiotics to avoid resistance, regardless of its association with gastric cancer.

RevDate: 2019-05-21

Berne C, YV Brun (2019)

The two chemotaxis clusters in Caulobacter crescentus play different roles in chemotaxis and biofilm regulation.

Journal of bacteriology pii:JB.00071-19 [Epub ahead of print].

The holdfast polysaccharide adhesin is crucial for irreversible cell adhesion and biofilm formation in Caulobacter crescentus Holdfast production is tightly controlled via developmental regulators, as well as via environmental and physical signals. Here we identify a novel mode of regulation of holdfast synthesis that involves chemotaxis proteins. We characterized the two identified chemotaxis clusters of C. crescentus and showed that only the previously characterized, major cluster is involved in chemotactic response towards different carbon sources. However, both chemotaxis clusters encoded in the C. crescentus genome play a role in biofilm formation and holdfast production, by regulating the expression of hfiA, the gene encoding the holdfast inhibitor HfiA. We show that CheA and CheB proteins act in an antagonistic manner: while the two CheA proteins negatively regulate hfiA expression, the CheB proteins are positive regulators, thus providing a modulation of holdfast synthesis and surface attachment.IMPORTANCEChemosensory systems constitute major signal transduction pathways in bacteria. These systems are involved in chemotaxis and other cell responses to environment conditions, such as production of adhesins to enable irreversible adhesion to a surface and surface colonization. The C. crescentus genome encodes two complete chemotaxis clusters. Here we characterized the second, novel chemotaxis-like cluster. While only the major chemotaxis cluster is involved in chemotaxis, both chemotaxis systems modulate C. crescentus adhesion by controlling expression of the holdfast synthesis inhibitor HfiA. Here, we identify a new level in holdfast regulation, providing new insights into the control of adhesin production that leads to the formation of biofilms in response to the environment.

RevDate: 2019-05-20

Stoodley P (2019)

CORR Insights®: Is Implant Coating With Tyrosol- and Antibiotic-loaded Hydrogel Effective in Reducing Cutibacterium (Propionibacterium) acnes Biofilm Formation? A Preliminary In Vitro Study.

Clinical orthopaedics and related research [Epub ahead of print].

RevDate: 2019-05-20

Volejníková A, Melicherčík P, Nešuta O, et al (2019)

Antimicrobial peptides prevent bacterial biofilm formation on the surface of polymethylmethacrylate bone cement.

Journal of medical microbiology [Epub ahead of print].

PURPOSE: Antibiotic-loaded polymethylmethacrylate-based bone cement has been implemented in orthopaedics to cope with implant-related infections associated with the formation of bacterial biofilms. In the context of emerging bacterial resistance to current antibiotics, we examined the efficacy of short antimicrobial peptide-loaded bone cement in inhibiting bacterial adhesion and consequent biofilm formation on its surface.

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

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

CONCLUSION: The results showed that the antibiofilm activity of these peptides was comparable to that of the antibiotics, but the peptides exhibited broader specificity than the antibiotics. Given the rapid development of antibiotic resistance, antimicrobial peptides show promise as a substitute for antibiotics for loading into bone cements.

RevDate: 2019-05-20

Perez LRR (2019)

Equal, but different: Fluctuant biofilm formation and its impact on polymyxin B susceptibility among a clonal spreading of KPC-2-producing Klebsiella pneumoniae isolates.

Infection control and hospital epidemiology pii:S0899823X19001065 [Epub ahead of print].

RevDate: 2019-05-20

Colomer-Winter C, Lemos JA, AL Flores-Mireles (2019)

Biofilm Assays on Fibrinogen-coated Silicone Catheters and 96-well Polystyrene Plates.

Bio-protocol, 9(6):.

Biofilm formation is a well-known bacterial strategy that protects cells from hostile environments. During infection, bacteria found in a biofilm community are less sensitive to antibiotics and to the immune response, often allowing them to colonize and persist in the host niche. Not surprisingly, biofilm formation on medical devices, such as urinary catheters, is a major problem in hospital settings. To be able to eliminate such biofilms, it is important to understand the key bacterial factors that contribute to their formation. A common practice in the lab setting is to study biofilms grown in laboratory media. However, these media do not fully reflect the host environment conditions, potentially masking relevant biological determinants. This is the case during urinary catheterization, where a key element for Enterococcus faecalis and Staphylococcus aureus colonization and biofilm formation is the release of fibrinogen (Fg) into the bladder and its deposition on the urinary catheter. To recapitulate bladder conditions during catheter-associated urinary tract infection (CAUTI), we have developed a fibrinogen-coated catheter and 96-well plate biofilm assay in urine. Notably, enterococcal biofilm factors identified in these in vitro assays proved to be important for biofilm formation in vivo in a mouse model of CAUTI. Thus, the method described herein can be used to uncover biofilm-promoting factors that are uniquely relevant in the host environment, and that can be exploited to develop new antibacterial therapies.

RevDate: 2019-05-20

Khider M, Hansen H, Hjerde E, et al (2019)

Exploring the transcriptome of luxI- and ΔainS mutants and the impact of N-3-oxo-hexanoyl-L- and N-3-hydroxy-decanoyl-L-homoserine lactones on biofilm formation in Aliivibrio salmonicida.

PeerJ, 7:e6845 pii:6845.

Background: Bacterial communication through quorum sensing (QS) systems has been reported to be important in coordinating several traits such as biofilm formation. In Aliivibrio salmonicida two QS systems the LuxI/R and AinS/R, have been shown to be responsible for the production of eight acyl-homoserine lactones (AHLs) in a cell density dependent manner. We have previously demonstrated that inactivation of LitR, the master regulator of the QS system resulted in biofilm formation, similar to the biofilm formed by the AHL deficient mutant ΔainSluxI- . In this study, we aimed to investigate the global gene expression patterns of luxI and ainS autoinducer synthases mutants using transcriptomic profiling. In addition, we examined the influence of the different AHLs on biofilm formation.

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

Conclusion: These findings imply that the LuxI and AinS autoinducer synthases play a critical role in the regulation of biofilm formation, EPS production, and motility.

RevDate: 2019-05-20

Samad A, Khan AA, Sajid M, et al (2019)

Assessment of biofilm formation by pseudomonas aeruginosa and hydrodynamic evaluation of microtiter plate assay.

JPMA. The Journal of the Pakistan Medical Association, 69(5):666-671.

OBJECTIVE: To assess the biofilm formation in clinical and environmental isolates of Pseudomonas aeruginosa and to evaluate the hydrodynamics in microtiter plate assay and compare it with conventional assays for biofilm formation.

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

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

CONCLUSIONS: Microtiter plate assay was found to be a reliable method to detect biofilm forming pseudomonas aeruginosa isolates which further provides a base for development of methods to detect biofilms readily and accurately.

RevDate: 2019-05-19

Aiyer KS, BS Vijayakumar (2019)

An improvised microtiter dish biofilm assay for non-invasive biofilm detection on microbial fuel cell anodes and studying biofilm growth conditions.

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] pii:10.1007/s42770-019-00091-5 [Epub ahead of print].

Microbial life is predominantly observed as biofilms, which are a sessile aggregation of microbial cells formed in response to stress conditions. The microtiter dish biofilm formation assay is one of the most important methods of studying biofilm formation. In this study, the assay has been improvised to allow easy detection of biofilm formation on different substrata. The method has then been used to study growth conditions that affect biofilm formation, viz., the effect of pH, temperature, shaking conditions, and the carbon source provided. Glass, cellulose acetate, and carbon cloth materials were used as substrata to study biofilm development under the above conditions. The method was then extended to determine biofilm formation on the anodes of a microbial fuel cell in order to study the effect of biofilm formation on power production. A high correlation was observed between biofilm formation and power density (r = 0.951). When the electrode containing a biofilm was replaced with another electrode without biofilm, the average power density dropped from 59.55 to 5.76 mW/m2. This method offers an easy way to study the suitability of different materials to support biofilm formation. Growth conditions determining biofilm formation can be studied using this method. This method also offers a non-invasive way to determine biofilm formation on anodes of microbial fuel cells and preserves the anode for further studies.

RevDate: 2019-05-18

Liang C, Zhang L, Nord NB, et al (2019)

Dose-dependent effects of acetate on the biodegradation of pharmaceuticals in moving bed biofilm reactors.

Water research, 159:302-312 pii:S0043-1354(19)30334-3 [Epub ahead of print].

Moving bed biofilm reactors (MBBR) are promising as a post-treatment for removing pharmaceuticals from wastewater. However, the effect of easily degradable carbon sources on the degradation of pharmaceuticals is unclear. This study shows the influence of acetate on the degradation of 26 pharmaceuticals in an MBBR was dose- and compound-dependent: while the degradation of venlafaxine, tramadol and ciprofloxacin was promoted (increase of reaction rate constant (k) by 133%, 212%, 55%) by acetate, its presence caused negative effects on the removal of ibuprofen, citalopram and diclofenac (decrease of k by 76%, 57%, 44%). The deconjugation of acetyl-sulfadiazine was clearly slowed down (decrease of k by 75%) by the dosed acetate, probably due to feedback inhibition by abundant acetate. 17 out of 25 tested compounds were found to be independent of the acetate dosage, which suggested dosing acetate induced minor effects on most of pharmaceuticals' removal. Enrichment of S- or first eluted enantiomer of 4 β-blockers and the metabolite metoprolol acid was observed. Both non-enantioselective (rapid at elevated compound concentration) and enantioselective enzymes (slower and predominant at lower compound concentration) played a part in the biodegradation. High doses of acetate slowed down the enantiomeric enrichment of atenolol, metoprolol, propranolol and metoprolol acid, which demonstrated that the acetate is able to up- or down-regulate enzymes involved in the enantioselective degradation of β-blockers and thus reveals a complex co-metabolism relationship between transformation pathways of pharmaceuticals and carbon source.

RevDate: 2019-05-18

Campbell M, Zhao W, Fathi R, et al (2019)

Title:Rhamnus prinoides (gesho): A source of diverse anti-biofilm activity.

Journal of ethnopharmacology pii:S0378-8741(18)32185-8 [Epub ahead of print].

Rhamnus prinoides (gesho) is an evergreen shrub from East Africa traditionally used for the treatment of illnesses including atopic dermatitis, ear, nose and throat infections, pneumonia, arthritis, brucellosis, flu, indigestion and fatigue.

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

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

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

CONCLUSION: Gesho leaf ethanol extract contains chemicals with anti-biofilm and bactericidal activities. This work lends support to the traditional use of gesho for treating topical infections and warrants further investigation into Rhamnus prinoides as a source of antibacterial and anti-biofilm agents.

RevDate: 2019-05-18

Carvajal J, M Carvajal (2019)

Further Clarification About "Back to Basics: Could the Preoperative Skin Antiseptic Agent Help Prevent Biofilm-Related Capsular Contracture?".

Aesthetic surgery journal pii:5491530 [Epub ahead of print].

RevDate: 2019-05-17

Senpuku H, Mohri S, Mihara M, et al (2019)

Effects of 7S globulin 3 derived from the adzuki bean [Vigna angularis] on the CSP- and eDNA- dependent biofilm formation of Streptococcus mutans.

Archives of oral biology, 102:256-265 pii:S0003-9969(18)30447-3 [Epub ahead of print].

OBJECTIVE: Streptococcus mutans is a principal bacterium that forms pathogenic biofilm involved in the development of dental caries. S. mutans possesses a quorum sensing system (QS) stimulated by competence stimulating peptide (CSP), which is associated with bacteriocin production, genetic competency and biofilm formation. Inhibiting CSP-dependent QS is one of the aims leading to the inhibition of biofilm formation and is useful for establishing new prevention systems for dental caries.

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

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

CONCLUSION: It was suggested that 7S3 might be a safe and useful material to prevent pathogenic activities in the biofilm formation of S. mutans.

RevDate: 2019-05-17

Lin CJ, Hou YH, YL Chen (2019)

The histone acetyltransferase GcnE regulates conidiation and biofilm formation in Aspergillus fumigatus.

Medical mycology pii:5491293 [Epub ahead of print].

Histone modifications play a crucial role in eukaryotic gene regulation. The Spt-Ada-Gcn5-acetyltransferase (SAGA) complex controls histone acetylation, with Gcn5 (GcnE) acting as the acetyltransferase. In the Aspergillus species, GcnE has been shown to regulate asexual development and secondary metabolism. Apart from this, GcnE is required for pathogenicity in plant fungal pathogen A. flavus; however, the role of GcnE in the pathogenicity of human pathogenic fungus A. fumigatus is unknown. In this study, we uncovered the key roles of GcnE in A. fumigatus conidiation, stress responses, and biofilm formation. We observed that deletion of gcnE resulted in aberrant conidiation in which conidiophores displayed abnormal phialide formation. In addition, the ΔgcnE mutant grew slightly faster under limited nitrogen sources (1 mM of ammonium or nitrate) compared to the wild type. The ΔgcnE mutant exhibited increased susceptibility to cell wall-perturbing agents, H2O2 and menadione but enhanced tolerance to LiCl. Furthermore, we showed that GcnE is involved in biofilm formation, and overexpression of adherence-related genes such as somA or uge3 partially rescued biofilm formation defects in the ΔgcnE mutant background. Interestingly, GcnE was not required for virulence in a neutropenic murine model of invasive aspergillosis. These results suggest that GcnE is critical for conidiation and biofilm formation but not virulence in A. fumigatus.

RevDate: 2019-05-17

Sato A, Yamaguchi T, Hamada M, et al (2019)

Morphological and Biological Characteristics of Staphylococcus aureus Biofilm Formed in the Presence of Plasma.

Microbial drug resistance (Larchmont, N.Y.) [Epub ahead of print].

Characteristics of Staphylococcus aureus infections include biofilm formation, leading to the spread of bacteria to the bloodstream causing sepsis and metastatic infections. In particular, in methicillin-resistant S. aureus (MRSA) infections, biofilm formation critically hampers treatment and causes poor prognosis. We explored the biofilm formation of MRSA in the presence or absence of plasma and compared morphological characteristics, accumulation of antibiotics, and resistance to bactericidal activity, using continuous optimizing confocal reflection microscopy. Addition of plasma significantly increased biofilm formation, which is characterized by an uneven surface and aggregation of bacteria (hereafter plasma biofilm). The flow-cell system, which enabled a continuous supply of plasma, accelerated biofilm formation in both the tested strains of MRSA (BAA1556 and N315). Accumulation of green fluorescence-labeled vancomycin was observed within 5 minutes in the plasma-free biofilm, but not in the plasma biofilm. Delay of accumulation was also observed for daptomycin in plasma biofilm. Plasma biofilm bacteria were more resistant to anti-MRSA antibiotics than plasma-free biofilm bacteria. These data demonstrate that the plasma biofilm of S. aureus is substantially different from the plasma-free biofilm. Plasma biofilm, especially in the flow-cell system, could be a clinically relevant model to analyze MRSA infections and treatment.

RevDate: 2019-05-17

André CB, Chan DC, M Giannini (2018)

Antibacterial-containing dental adhesives' effects on oral pathogens and on Streptococcus mutans biofilm: Current perspectives.

American journal of dentistry, 31(Sp Is B):37B-41B.

PURPOSE: To describe the literature findings regarding commercially available antibacterial-containing dental adhesives and the futures perspectives of this field.

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

CLINICAL SIGNIFICANCE: Antibacterial-containing dental adhesives may have therapeutic effects, working as an additional source to reduce recurrent caries development in patients with high-risk of caries, and consequently the reduction in restoration replacements.

RevDate: 2019-05-17

Ali SE, Songe MM, I Skaar (2019)

Colorimetric assay for the in vitro evaluation of Saprolegnia biofilm inhibitors.

Journal of fish diseases [Epub ahead of print].

A quantitative and reproducible 96-well microtiter method that is easily adaptable for the screening of Saprolegnia biofilm inhibitors is described. As opposed to other methods previously developed for the screening of Saprolegnia inhibitors on spore germination or mycelial growth, this technique is of particular significance as it investigates potential inhibitors against surface-attached mycelial mats of Saprolegnia spp. (biofilm). In this study, we have investigated the effects of propionic acid (PPA) on reducing the viability of induced Saprolegnia biofilms using colorimetric MTS assay based on the reduction of tetrazolium salts. Viability of Saprolegnia hyphae in treated biofilms was reduced significantly following treatment with different PPA concentrations. The effect was enhanced after combining each of the tested PPA concentrations with 500 mg/L of boric acid (BA). However, the percentage of non-viable hyphae was still higher in 200 mg L-1 bronopol-treated biofilms (positive control) following 6- and 12-hr exposure. Similar results were observed using other recently described fluorescence-based assays for viability.

RevDate: 2019-05-17

Dubois T, Tremblay YDN, Hamiot A, et al (2019)

A microbiota-generated bile salt induces biofilm formation in Clostridium difficile.

NPJ biofilms and microbiomes, 5:14 pii:87.

Clostridium difficile is a major cause of nosocomial infections. Bacterial persistence in the gut is responsible for infection relapse; sporulation and other unidentified mechanisms contribute to this process. Intestinal bile salts cholate and deoxycholate stimulate spore germination, while deoxycholate kills vegetative cells. Here, we report that sub-lethal concentrations of deoxycholate stimulate biofilm formation, which protects C. difficile from antimicrobial compounds. The biofilm matrix is composed of extracellular DNA and proteinaceous factors that promote biofilm stability. Transcriptomic analysis indicates that deoxycholate induces metabolic pathways and cell envelope reorganization, and represses toxin and spore production. In support of the transcriptomic analysis, we show that global metabolic regulators and an uncharacterized lipoprotein contribute to deoxycholate-induced biofilm formation. Finally, Clostridium scindens enhances biofilm formation of C. difficile by converting cholate into deoxycholate. Together, our results suggest that deoxycholate is an intestinal signal that induces C. difficile persistence and may increase the risk of relapse.

RevDate: 2019-05-17

Passos da Silva D, Matwichuk ML, Townsend DO, et al (2019)

The Pseudomonas aeruginosa lectin LecB binds to the exopolysaccharide Psl and stabilizes the biofilm matrix.

Nature communications, 10(1):2183 pii:10.1038/s41467-019-10201-4.

Pseudomonas aeruginosa biofilms are composed of exopolysaccharides (EPS), exogenous DNA, and proteins that hold these communities together. P. aeruginosa produces lectins LecA and LecB, which possess affinities towards sugars found in matrix EPS and mediate adherence of P. aeruginosa to target host cells. Here, we demonstrate that LecB binds to Psl, a key matrix EPS, and this leads to increased retention of both cells and EPS in a growing biofilm. This interaction is predicted to occur between the lectin and the branched side chains present on Psl. Finally, we show that LecB coordinates Psl localization in the biofilm. This constitutes a unique function for LecB and identifies it as a matrix protein that contributes to biofilm structure through EPS interactions.

RevDate: 2019-05-17

Oprei A, Zlatanović S, M Mutz (2019)

Grazers superimpose humidity effect on stream biofilm resistance and resilience to dry-rewet stress.

The Science of the total environment, 659:841-850.

Temperate low order streams increasingly experience intermittency and drying due to climate change. In comparison to well-studied Mediterranean streams, drying events in canopied temperate streams occur under higher ambient humidity which probably affects the metabolic response to drying. Previous work on drying sediments (in temperate streams) did not consider the interactions of trophic levels. We hypothesized that preservation of sediment moisture due to high humidity increases resistance to drying in temperate streambed biofilms and fast resilience of biofilm activity after flow resumption. We also expected the presence of macroinvertebrate grazers to modulate the biofilm response to dry-rewet stress. Following a two-level factorial design in 24 microcosms, we tested the effect of drying intensity (moderate and intense) and grazer presence and absence (P. antipodarum) on the activity of biofilm colonizing shallow hyporheic sediment. We measured the community respiration over a drying period of 27 days, a single rewetting event and a follow-up of three days. Grazer presence stimulated biofilm community respiration (CRmic) in the permanently wet control, but decreased biofilm resistance to desiccation (<0.2% of pre-disturbed activity), regardless of drying intensity. In the absence of grazers, higher atmospheric humidity in moderately drying microcosms resulted in maintaining a film of adhesive water and low CRmic (29% of pre-disturbed respiration) until the end of the drying period. After flow resumption, the CRmic increased within 8 h, achieving 79-83% of pre-disturbed respiration (no grazers) and 15-41% (with grazers), respectively. Results show that short dry periods in temperate streams, even under high humidity, impact the streambed biofilm community negatively. The complex response and strong effect of grazer presence indicates that experiments including interactions of trophic levels and settings mimicking environmental factors during dry-rewet stress are needed.

RevDate: 2019-05-17

Ramírez-Vargas CA, Arias CA, Carvalho P, et al (2019)

Electroactive biofilm-based constructed wetland (EABB-CW): A mesocosm-scale test of an innovative setup for wastewater treatment.

The Science of the total environment, 659:796-806.

Constructed wetlands (CWs) performance enhancement can be done with intensification strategies. A recent strategy still in study is the coupling with Microbial Electrochemical Technologies (MET). An alternative system using electro-conductive biofilters instead of electrodes and circuits used in MET, resulted in the development of a Microbial Electrochemical-based CW (METland). This system relies on electroactive bacteria (EAB) metabolism to transfer electrons to an electro-conductive material, thus boosting substrate consumption, and diminishing electron availability for biomass build-up and methane generation. In previous studies this biofilters have shown an improvement in biodegradation rates in comparison with subsurface flow CW. However, this set-up is still in development, hence there are uncertainties regarding the dynamics involve in the removal of pollutants. Considering that, this work aimed at establishing the capacity and removal kinetics of organic matter and nutrients in an Electroactive Biofilm-Based CW (EABB-CW). Two electro-conductive materials were tested (PK-A and PK-LSN) in planted and non-planted mesocosms and compared with sand. The systems were operated in a continuous upflow mode for 32 weeks and fed with real wastewater. The electro-conductive systems reached removal efficiencies up to 88% for BOD5, 90% for COD, 46% for NH4-N, and 86% for PO4-P. Organic matter removal in electro-conductive systems was possible even at loading rates 10-fold higher than recommended for horizontal flow CWs. First-order area-based removal constants (k), calculated for organic matter and nutrients are higher than values typically reported for saturated CW and in certain cases comparable with vertical flow CW. The organic removal was correlated with electron current densities measures, as indicator of the presence of EAB. The tested EABB-CW profiles as a promising CW type for the removal of organic matter and PO4-P with margin for modifications to improve nitrogen removal. Future studies with pilot/real scale systems are proposed to validate the findings of this study.

RevDate: 2019-05-16

Hogan S, Kasotakis E, Maher S, et al (2019)

A novel medical device coating prevents Staphylococcus aureus biofilm formation on medical device surfaces.

FEMS microbiology letters pii:5490329 [Epub ahead of print].

Prevention of device related infections due to Staphylococcus aureus biofilms on devices represents a significant challenge. Such infections have recently been shown to be dependent on the coagulation pathway via activation of pro-thrombin and fibrin production. Three direct-thrombin inhibitors, argatroban, hirudin and dabigatran, were examined to determine their effect on preventing S. aureus biofilm on plastic biochip surfaces under shear stress using an in vivo relevant model of infection. Surface functionalization of polyurethane discs via dityrosine covalent crosslinking with hirudin was performed and changes in bacterial density and microscopic appearances determined. The three direct-thrombin inhibitors prevented S. aureus biofilm formation on plasma-coated surfaces treated with these agents. Coating of polyurethane with one of these agents, hirudin, significantly inhibited biofilm formation on the modified surface. These findings reveal the exciting potential for coating biomaterial surfaces with direct thrombin inhibitors to prevent staphylococcal binding and subsequent device-related infections.

RevDate: 2019-05-16

Reda FM (2019)

Antibacterial and anti-adhesive efficiency of Pediococcus acidilactici against foodborne biofilm producer Bacillus cereus attached on different food processing surfaces.

Food science and biotechnology, 28(3):841-850 pii:518.

This study aimed to assess the biofilm formation by Bacillus cereus on two novel surfaces namely: aluminum and cold steel in comparison study with stainless steel and polystyrene. Also, it aimed to study the inhibitory effect of a new strain Pediococcus acidilactici against biofilm formation by B. cereus grown on these surfaces. In this study, B. cereus M50 isolated from milky machine surface was selected as the highest biofilm producer. The number of M50 cells adhered to aluminum and stainless steel surfaces were more than that adhered to polystyrene and cold steel, respectively. The antimicrobial, anti-adhesive and SEM studies revealed that the P. acidilactici P12 culture and its cell free filtrate showed a significant potential inhibition of biofilm formation of M50 on all tested surfaces under different conditions. These results demonstrated that P. acidilactici strain are considered a new biotreatment for biofilm destruction of food borne pathogens, food biopreservation and food safety.

RevDate: 2019-05-16

Yang CH, Su PW, Moi SH, et al (2019)

Biofilm Formation in Acinetobacter Baumannii: Genotype-Phenotype Correlation.

Molecules (Basel, Switzerland), 24(10): pii:molecules24101849.

Strains of Acinetobacter baumannii are commensal and opportunistic pathogens that have emerged as problematic hospital pathogens due to its biofilm formation ability and multiple antibiotic resistances. The biofilm-associated pathogens usually exhibit dramatically decreased susceptibility to antibiotics. This study was aimed to investigate the correlation of biofilm-forming ability, antibiotic resistance and biofilm-related genes of 154 A. baumannii isolates which were collected from a teaching hospital in Taiwan. Biofilm-forming ability of the isolates was evaluated by crystal violet staining and observed by scanning electron microscopy. Antibiotic susceptibility was determined by disc diffusion method and minimum inhibitory concentration; the biofilm-related genes were screened by polymerase chain reaction. Results showed that among the 154 tested isolates, 15.6% of the clinical isolates were weak biofilm producers, while 32.5% and 45.4% of them possessed moderate and strong biofilm formation ability, respectively. The experimental results revealed that the multiple drug resistant isolates usually provided a higher biofilm formation. The prevalence of biofilm related genes including bap, blaPER-1, csuE and ompA among the isolated strains was 79.2%, 38.3%, 91.6%, and 68.8%, respectively. The results indicated that the antibiotic resistance, the formation of biofilm and the related genes were significantly correlated. The results of this study can effectively help to understand the antibiotic resistant mechanism and provides the valuable information to the screening, identification, diagnosis, treatment and control of clinical antibiotic-resistant pathogens.

RevDate: 2019-05-15

Mosteller TM, JR Bishop (1993)

Sanitizer Efficacy Against Attached Bacteria in a Milk Biofilm.

Journal of food protection, 56(1):34-41.

Pseudomonas fluorescens , Yersinia enterocolitica , and Listeria monocytogenes were shown to readily attach to both rubber and Teflon® surfaces. Sanitizer efficacy testing done in the laboratory with nonadherent bacteria could lead to false assumptions as to the sanitizer's true effectiveness under processing conditions where cells may be attached. The objectives in this study were: (a) evaluate the efficacy of in-use concentrations of sanitizers on bacteria attached to gasket materials, (b) compare bacterial attachment to rubber and Teflon® gaskets, (c) examine different methods of enumeration, and (d) compare sanitizer efficacy on attached and suspended bacteria. The goal reduction for all of the sanitizers tested was ≥3 log cycles or 99.9%. Results indicated that iodophor, hypochlorite, acid anionic, peroxyacetic acid, fatty acid, and quaternary ammonium sanitizers failed to provide an adequate reduction in the numbers of attached bacteria at levels of 104 to 105/mm2 in most cases. The test organisms attached in slightly higher numbers to the rubber surface versus Teflon®. Plate counts, impedance microbiology, and the direct epifluorescent filter technique were tested as methods of enumeration. Impedance microbiology was the best method of enumeration, since it allowed the estimation of both reversibly and irreversibly attached bacteria. The efficacy of sanitizers versus a bacterial suspensions resulted in a ≥ 5 log-cycle reduction. The same concentrations were relatively ineffective against the attached bacteria. The goal reduction was reached on the Teflon® surface with the iodophor, hypochlorite, and fatty acid sanitizers with a log-cycle reduction in the number of Yersinia enterocolitica of 3.09, 3.19, and 3.31, respectively. Pseudomonas fluorescens was reduced by 3.16 on both the rubber and Teflon® surfaces when exposed to the hypochlorite sanitizer.

RevDate: 2019-05-15

Tobudic S, Kern S, Kussmann M, et al (2019)

Effect of Peritoneal Dialysis Fluids on Activity of Teicoplanin Against Methicillin-Resistant Staphylococcus aureus Biofilm.

Peritoneal dialysis international : journal of the International Society for Peritoneal Dialysis, 39(3):293-294.

RevDate: 2019-05-15

Čabarkapa I, Čolović R, Đuragić O, et al (2019)

Anti-biofilm activities of essential oils rich in carvacrol and thymol against Salmonella Enteritidis.

Biofouling [Epub ahead of print].

The aim of the present study was to determine the bioactive compounds in four essential oils (EO's) from Origanum heracleoticum, Origanum vulgare, Thymus vulgaris and Thymus serpyllum and to assess their antimicrobial and anti-biofilm activity against Salmonella Enteritidis. Strains were previously characterized depending on the expression of the extracellular matrix components cellulose and curli fimbriae as rdar (red, dry and rough) and bdar morphotype (brown, dry and rough). This study revealed that the EO's and EOC's (carvacrol and thymol) investigated showed inhibition of biofilm formation at sub-minimum inhibitory concentration. Comparing the efficacy of EO's and EOC's in the inhibition of biofilm formation between the strains with different morphotype (rdar and bdar) did not show a statistically significant difference. Results related to the effectiveness of EO's and EOC's (the essential oil components, carvacrol and thymol) on eradication of preformed 48 h old biofilms indicated that biofilm reduction occurred in a dose-dependent manner over time.

RevDate: 2019-05-15

Bernard C, Lemoine V, Hoogenkamp MA, et al (2019)

Candida albicans enhances initial biofilm growth of Cutibacterium acnes under aerobic conditions.

Biofouling [Epub ahead of print].

Candida albicans and Cutibacterium acnes are opportunistic pathogens that co-colonize the human body. They are involved in biofilm-related infections of implanted medical devices. The objective of this study was to evaluate the ability of these species to interact and form polymicrobial biofilms. SEM imaging and adhesion assays showed that C. acnes adhesion to C. albicans did not have a preference for a specific morphological state of C. albicans; bacteria adhered to both hyphal and yeast forms of C. albicans. C. albicans did not influence growth of C. acnes under anaerobic growth conditions, however under aerobic growth condition, C. albicans enhanced early C. acnes biofilm formation. This favorable impact of C. albicans was not mediated by secreted compounds accumulating in the medium, but required the presence of metabolically active C. albicans. The ability of these microorganisms to interact together could modulate the physiopathology of infections.

RevDate: 2019-05-15

Fu KM, Liao MH, Zhou HT, et al (2019)

[Operation Characteristics of the Biofilm CANON Reactor During the Temperature Reduction Process].

Huan jing ke xue= Huanjing kexue, 40(3):1412-1418.

The focus of this paper, was low temperature, high ammonia nitrogen wastewater. The operation characteristics of the biofilm CANON process during the temperature reduction process were determined, by continuously adjusting different operating conditions. The aim was to explore the methods needed for the CANON process to obtain stable shortcut nitrification and a good nitrogen removal effect, when the influent NH4+-N concentration is high and the temperature low. The results showed that, ① compared with the biofilm CANON reactor temperature changing from medium to low temperature directly (30℃±1℃→19℃), it was more conducive to adapt the nitrogen-removing bacteria to the low-temperature environment, while the temperature was gradually lowered. Moreover, the extent of each reduction should be minimized. Besides, the operating conditions should be adjusted to ensure the nitrogen removal effect. ② The temperature was gradually reduced to about 19℃ after 25 d, and then decreased to about 15℃ after another 18 d. The NH4+-N and TN removal rates could be respectively stable at 90% and 70% over a long period of time. The TN removal rate and removal load could still reach 72.52% and 0.78 kg·(m3·d)-1, respectively, even when the temperature dropped to 12℃. ③ When adapting biological CANON sludge during the temperature reduction process, shortcut nitrification should be given priority. A stable shortcut nitrification effect should be obtained by maintaining a certain concentration of residual NH4+-N, and by strictly controlling the DO concentration to restrain NOB activity.

RevDate: 2019-05-15

Zhu L, Gong T, Wood TL, et al (2019)

σ54 -Dependent Regulator DVU2956 Switches Desulfovibrio vulgaris from Biofilm Formation to Planktonic Growth and Regulates Hydrogen Sulfide Production.

Environmental microbiology [Epub ahead of print].

Microbiologically influenced corrosion causes $1011 in damage per year, and biofilms formed by sulfate-reducing bacteria (SRB) are the major culprit. However, little is known about the regulation of SRB biofilm formation. Using Desulfovibrio vulgaris as a model SRB organism, we compared the transcriptomes of biofilm and planktonic cells and identified that the gene for σ54 -dependent regulator DVU2956 is repressed in biofilms. Utilizing a novel promoter that is primarily transcribed in biofilms (Pdvu0304), we found production of DVU2956 inhibits biofilm formation by 70%. Corroborating this result, deleting dvu2956 increased biofilm formation, and this biofilm phenotype could be complemented. By producing proteins in biofilms from genes controlled by DVU2956 (dvu2960 and dvu2962), biofilm formation was inhibited almost completely. A second round of RNA-seq for the production of DVU2956 revealed DVU2956 influences electron transport via an Hmc complex (high-molecular weight cytochrome c encoded by dvu0531-dvu0536) and the Fe-only hydrogenase (encoded by dvu1769, hydA, and dvu1770, hydB) to control H2 S production. Corroborating these results, producing DVU2956 in biofilms decreased H2 S production by half, deleting dvu2956 increased H2 S production by 131 ± 5%, and producing DVU2956 in the dvu2956 strain reduced H2 S production. Therefore, DVU2956 maintains SRB in the planktonic state and reduces H2 S formation. This article is protected by copyright. All rights reserved.

RevDate: 2019-05-15

Banerjee A, Bardhan R, Chowdhury M, et al (2019)

Characterization of beta-lactamase and biofilm producing Enterobacteriaceae isolated from organized and backyard farm ducks.

Letters in applied microbiology [Epub ahead of print].

The present study was undertaken to detect the occurrence of beta-lactamase and biofilm producing Enterobacteriaceae in healthy ducks. A total 202 cloacal swabs were collected from ducks kept in organized (n=92) and backyard (n=110) farms in West Bengal (India). The ducks had no history of antibiotic intake. Among the 87 phenotypically beta-lactamase producing E. coli, 19 (17·43%), six (5·05%) and 15 (13·76%) isolates possessed blaTEM , blaSHV and blaCTX-M , respectively. Whereas, five (38·46%) Salmonella isolates were found to harbour blaCTX-M . In K. pneumoniae 10(33·33%), three (13·33%), four (13·33%) isolates possessed blaTEM , blaSHV and blaCTX-M , respectively. The sequences of selected PCR products were found 98% cognate with blaCTX-M-9, blaSHV-12 and blaTEM-1 . Beta-lactamase producing E. coli isolates belonged to 14 different serogroups such as O1, O2, O3, O5, O7, O8, O35, O83, O84, O88, O119, O128, O145 and O157. Moreover, 87 E. coli (79·82%), six Samonella (46·15%) and 13 K. pneumoniae (43·33%) isolates were detected as AmpC producers possessing blaAmpC . Majority of E. coli (46·79%), Salmonella (46·15%) and K. pneumoniae (70%) isolates were detected as biofilm producers and possessed the associated genes (csgA, sdiA, rcsA, rpoS). Significantly higher occurrence of beta-lactamase and biofilm producing Enterobacteriaceae isolates was detected in backyard ducks than organized farms. This article is protected by copyright. All rights reserved.

RevDate: 2019-05-15

Dos Santos DMS, Pires JG, Silva AB, et al (2019)

Protective Effect of 4% Titanium Tetrafluoride Varnish on Dentin Demineralization Using a Microcosm Biofilm Model.

Caries research pii:000499317 [Epub ahead of print].

This study evaluated the effect of titanium tetrafluoride (TiF4) varnish on the development of dentin carious lesions. Bovine root dentin samples were treated for 6 h with: (A) 4% TiF4 varnish (2.45% F); (B) 5.42% sodium fluoride (NaF) varnish (2.45% F); (C) 2% chlorhexidine (CHX) gel - positive control; (D) placebo varnish; or (E) untreated - negative control (n = 4 × biological triplicate, n = 12). Treated dentin samples were exposed to human saliva mixed with McBain saliva (1:50) for the first 8 h in 24-well plates. Thereafter, the medium was removed, and McBain saliva containing 0.2% sucrose was applied for 16 h. From days 2 to 5, McBain saliva with sucrose was replaced daily (37°C, 5% CO2). The demineralization was measured using transverse microradiography, while the effect on biofilm was analyzed using viability, extracellular polysaccharide (EPS), and lactic acid production assays. The data were statistically analyzed (p < 0.05). All treatments (fluorides and CHX) significantly reduced the biofilm viability compared to placebo varnish and negative control. However, none of them was able to reduce the colony-forming unit counting for total microorganism, total streptococci, and Streptococcus mutans. NaF significantly reduced the number of Lactobacillus sp. compared to negative control. No effect was seen on lactic acid production neither on EPS synthesis, except that CHX significantly reduced the amount of insoluble EPS. Both fluorides were able to reduce dentin demineralization compared to placebo varnish and negative control; TiF4 had a better effect in reducing mineral loss and lesion depth than NaF. Therefore, TiF4 varnish has the best protective effect on dentin carious lesion formation using this model.

RevDate: 2019-05-15

Matysik A, KA Kline (2019)

Streptococcus pyogenes capsule promotes microcolony-independent biofilm formation.

Journal of bacteriology pii:JB.00052-19 [Epub ahead of print].

Biofilms play an important role in the pathogenesis of Group A Streptococcus (GAS), a gram-positive pathogen responsible for a wide range infections and significant public health impact. Although most GAS serotypes are able to form biofilms, there is large heterogeneity between individual strains in biofilm formation, as measured by standard crystal violet assays. It is generally accepted that biofilm formation includes initial adhesion of bacterial cells to a surface, followed by microcolony formation, biofilm maturation, and extensive production of extracellular matrix that links together proliferating cells and provides a scaffold for the three-dimensional biofilm structure. However, our studies show that for GAS strain JS95, microcolony formation is not an essential step in static biofilm formation, and instead, biofilm can be effectively formed from slow-growing or non-replicating late exponential or early stationary planktonic cells, via sedimentation and fixation of GAS chains into biofilms. In addition, we show that the GAS capsule specifically contributes to the alternative, sedimentation-initiated biofilms. Microcolony-independent, sedimentation biofilms are similar in morphology and 3-D structure to biofilms initiated by actively dividing planktonic bacteria. We conclude that GAS can form biofilms by an alternate, non-canonical mechanism that does not require transition from microcolony formation to biofilm maturation, and which may be obscured by biofilm phenotypes that arise via the classical biofilm maturation processes.IMPORTANCEThe static biofilm assay is a common tool for easy biomass quantification of biofilm forming bacteria. However, S. pyogenes biofilm formation as measured by the static assay is strain dependent and yields heterogeneous results for different strains of the same serotype. In this study, we show that two independent mechanisms, for which the protective capsule contributes opposing functions, may contribute to static biofilm formation. We propose that separation of these mechanisms for biofilm formation might uncover previously unappreciated biofilm phenotypes that may otherwise be masked in the classic static assay.

RevDate: 2019-05-15

Wan D, Li Q, Chen J, et al (2019)

Simultaneous bio-electrochemical reduction of perchlorate and electro-disinfection in a novel Moving-Bed Biofilm Reactor (MBBR) based on proton-exchange membrane electrolysis.

The Science of the total environment, 679:288-297 pii:S0048-9697(19)31992-8 [Epub ahead of print].

A novel Moving-Bed Biofilm Reactor (MBBR), based on proton-exchange membrane electrolysis, was developed and tested for perchlorate transformation. The bacteria growing on the carrier in the cathode chamber could use in situ-generated hydrogen to reduce perchlorate to chloride via electrolysis; the resulting chloride ions and chloride ions in raw water were then oxidized into chlorine by anode reaction to disinfect the final effluent and improve water quality. For a ClO4- concentration of 10.00 ± 0.08 mg/L in the influent, at hydraulic retention times (HRTs) of 4.0, 2.0, and 1.5 h, the optimal applied currents (OACs) were 130, 240, and 270 mA, with a corresponding removal efficiencies of 99.90 ± 0.21, 96.70 ± 0.36, and 78.50 ± 0.24%, respectively. Active chlorine concentration was in the range of 0.063-0.096 mg/L, contributing to simultaneous electro-disinfection. Along the water flow direction, OH- generated by the cathode could be neutralized in the anode chamber; thus, the final effluent pH was kept a balance with the influent pH. Proteobacteria, Bacteroidetes, and Firmicutes were the dominant bacteria in the MBBR. The maximum value of current efficiency (13.32 ± 0.69%) was obtained at 100 mA and an HRT of 4.0 h, which was in accordance with the abundance of Thauera.

RevDate: 2019-05-15

Wall G, Montelongo-Jauregui D, Vidal Bonifacio B, et al (2019)

Candida albicans biofilm growth and dispersal: contributions to pathogenesis.

Current opinion in microbiology, 52:1-6 pii:S1369-5274(18)30097-3 [Epub ahead of print].

The fungal species Candida albicans is most frequently associated with biofilm formation in immune-compromised and medically compromised patients, and it is now firmly established that biofilm formation represents a major virulence factor during candidiasis. A growing body of evidence has demonstrated that C. albicans biofilm development is a highly regulated and coordinated process, where adhesive interactions, morphogenetic conversions, and consortial behavior play significant roles. Cells within the biofilms are protected from environmental stresses including host immune defenses and antifungal treatment, which carries important clinical consequences for the treatment of biofilm-associated infections. Dispersal of cells from biofilms represents one of the hallmarks of the biofilm life-style, and in the case of C. albicans dispersed cells are responsible for candidemia and dissemination leading to the establishment of invasive disease.

RevDate: 2019-05-15

Girish VM, Liang H, Aguilan JT, et al (2019)

Anti-biofilm activity of garlic extract loaded nanoparticles.

Nanomedicine : nanotechnology, biology, and medicine pii:S1549-9634(19)30093-0 [Epub ahead of print].

The emergence and widespread distribution of multi-drug resistant bacteria is considered as a major public health concern. The inabilities to curb severe infections due to antibiotic resistance have increased healthcare costs as well as patient morbidity and mortality. Bacterial biofilms formed by drug-resistant bacteria add additional challenges to treatment. This study describes a sol-gel based nanoparticle system loaded with garlic extract (GE-np) that exhibits: i) slow and sustained release of garlic components; ii) stabilization of the active components; and iii) significant enhancement of antimicrobial and antibiofilm activity relative to the free garlic extract. Also, GE-np were efficient in penetrating and disrupting the well-established methicillin-resistant Staphylococcus aureus (MRSA) biofilms. Overall, the study suggests that GE-np might be a promising candidate for the treatment of chronic infections due to biofilm forming drug-resistant bacteria.

RevDate: 2019-05-14

Nagel C, Machulla A, Zahn S, et al (2019)

Several One-Domain Zinc Finger µ-Proteins of Haloferax Volcanii Are Important for Stress Adaptation, Biofilm Formation, and Swarming.

Genes, 10(5): pii:genes10050361.

Zinc finger domains are highly structured and can mediate interactions to DNA, RNA, proteins, lipids, and small molecules. Accordingly, zinc finger proteins are very versatile and involved in many biological functions. Eukaryotes contain a wealth of zinc finger proteins, but zinc finger proteins have also been found in archaea and bacteria. Large zinc finger proteins have been well studied, however, in stark contrast, single domain zinc finger µ-proteins of less than 70 amino acids have not been studied at all, with one single exception. Therefore, 16 zinc finger µ-proteins of the haloarchaeon Haloferax volcanii were chosen and in frame deletion mutants of the cognate genes were generated. The phenotypes of mutants and wild-type were compared under eight different conditions, which were chosen to represent various pathways and involve many genes. None of the mutants differed from the wild-type under optimal or near-optimal conditions. However, 12 of the 16 mutants exhibited a phenotypic difference under at least one of the four following conditions: Growth in synthetic medium with glycerol, growth in the presence of bile acids, biofilm formation, and swarming. In total, 16 loss of function and 11 gain of function phenotypes were observed. Five mutants indicated counter-regulation of a sessile versus a motile life style in H. volcanii. In conclusion, the generation and analysis of a set of deletion mutants demonstrated the high importance of zinc finger µ-proteins for various biological functions, and it will be the basis for future mechanistic insight.

RevDate: 2019-05-14

Foster LL, Yusa SI, K Kuroda (2019)

Solution-Mediated Modulation of Pseudomonas aeruginosa Biofilm Formation by a Cationic Synthetic Polymer.

Antibiotics (Basel, Switzerland), 8(2): pii:antibiotics8020061.

Bacterial biofilms and their associated infections are a continuing problem in the healthcare community. Previous approaches utilizing anti-biofilm coatings suffer from short lifetimes, and their applications are limited to surfaces. In this research, we explored a new approach to biofilm prevention based on the hypothesis that changing planktonic bacteria behavior to result in sub-optimal biofilm formation. The behavior of planktonic Pseudomonas aeruginosa exposed to a cationic polymer was characterized for changes in growth behavior and aggregation behavior, and linked to resulting P. aeruginosa biofilm formation, biomass, viability, and metabolic activity. The incubation of P. aeruginosa planktonic bacteria with a cationic polymer resulted in the aggregation of planktonic bacteria, and a reduction in biofilm development. We propose that cationic polymers may sequester planktonic bacteria away from surfaces, thereby preventing their attachment and suppressing biofilm formation.

RevDate: 2019-05-14

Guo X, Li B, Zhao R, et al (2019)

Performance and bacterial community of moving bed biofilm reactors with various biocarriers treating primary wastewater effluent with a low organic strength and low C/N ratio.

Bioresource technology, 287:121424 pii:S0960-8524(19)30654-6 [Epub ahead of print].

A laboratory-scale sequencing batch reactor (SBR) and two moving bed biofilm reactors (MBBRs) with different types of biocarriers were operated to treat the effluent of chemically enhanced primary sedimentation (CEPS). Due to the low organic strength and low carbon/nitrogen ratio of the CEPS effluent, COD and NH4+-N were effectively removed by the MBBRs but not by the SBR. Of the two MBBRs, MBBR2 filled with LEVAPOR biocarrier cubes performed even better than MBBR1 filled with K3 polystyrene biocarriers. The continuous decline of the sludge concentration in the SBR and the high and stable biomass content in MBBR2 contributed to their performances. High-throughput sequencing analysis showed that the reactors had selective effects on the bacterial community structure. Principal coordinate analysis indicated the different dynamic successions in the three reactors. Network analysis showed different community composition and diversity that were highly suggestive of different bacterial interactions among the three bioreactors.

RevDate: 2019-05-13

Panariello BHD, Garcia BA, S Duarte (2019)

Daily Phototherapy with Red Light to Regulate Candida albicans Biofilm Growth.

Journal of visualized experiments : JoVE.

Here, we present a protocol to assess the outcomes of per diem red light treatment on the growth of Candida albicans biofilm. To increase the planktonic growth of C. albicans SN425, the inoculums grew on Yeast Nitrogen Base media. For biofilm formation, RPMI 1640 media, which have high concentrations of amino acids, were applied to help biofilm growth. Biofilms of 48 h were treated twice a day for a period of 1 min with a non-coherent light device (red light; wavelength = 635 nm; energy density = 87.6 J·cm-2). As a positive control (PC), 0.12% chlorhexidine (CHX) was applied, and as a negative control (NC), 0.89% NaCl was applied to the biofilms. Colony forming units (CFU), dry-weight, soluble and insoluble exopolysaccharides were quantified after treatments. Briefly, the protocol presented here is simple, reproducible and provides answers regarding viability, dry-weight and extracellular polysaccharide amounts after red light treatment.

RevDate: 2019-05-13

Mai HN, Hong SH, Kim SH, et al (2019)

Effects of different finishing/polishing protocols and systems for monolithic zirconia on surface topography, phase transformation, and biofilm formation.

The journal of advanced prosthodontics, 11(2):81-87.

PURPOSE: The purpose of this study was to evaluate the effects of various protocols and systems for finishing and polishing monolithic zirconia on surface topography, phase transformation, and bacterial adhesion.

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

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

CONCLUSION: Stepwise surface treatment of monolithic zirconia, combined with careful polishing system selection, is essential to obtaining optimal microstructural and biological surface results.

RevDate: 2019-05-12

Pillot G, Davidson S, Auria R, et al (2019)

Production of Current by Syntrophy Between Exoelectrogenic and Fermentative Hyperthermophilic Microorganisms in Heterotrophic Biofilm from a Deep-Sea Hydrothermal Chimney.

Microbial ecology pii:10.1007/s00248-019-01381-z [Epub ahead of print].

To study the role of exoelectrogens within the trophic network of deep-sea hydrothermal vents, we performed successive subcultures of a hyperthermophilic community from a hydrothermal chimney sample on a mix of electron donors in a microbial fuel cell system. Electrode (the electron acceptor) was swapped every week to enable fresh development from spent media as inoculum. The MFC at 80 °C yielded maximum current production increasing from 159 to 247 mA m-2 over the subcultures. The experiments demonstrated direct production of electric current from acetate, pyruvate, and H2 and indirect production from yeast extract and peptone through the production of H2 and acetate from fermentation. The microorganisms found in on-electrode communities were mainly affiliated to exoelectrogenic Archaeoglobales and Thermococcales species, whereas in liquid media, the communities were mainly affiliated to fermentative Bacillales and Thermococcales species. The work shows interactions between fermentative microorganisms degrading complex organic matter into fermentation products that are then used by exoelectrogenic microorganisms oxidizing these reduced compounds while respiring on a conductive support. The results confirmed that with carbon cycling, the syntrophic relations between fermentative microorganisms and exoelectrogens could enable some microbes to survive as biofilm in extremely unstable conditions. Graphical Abstract Schematic representation of cross-feeding between fermentative and exoelectrogenic microbes on the surface of the conductive support. B, Bacillus/Geobacillus spp.; Tc, Thermococcales; Gg, Geoglobus spp.; Py, pyruvate; Ac, acetate.

RevDate: 2019-05-12

Edel M, Horn H, J Gescher (2019)

Biofilm systems as tools in biotechnological production.

Applied microbiology and biotechnology pii:10.1007/s00253-019-09869-x [Epub ahead of print].

The literature provides more and more examples of research projects that develop novel production processes based on microorganisms organized in the form of biofilms. Biofilms are aggregates of microorganisms that are attached to interfaces. These viscoelastic aggregates of cells are held together and are embedded in a matrix consisting of multiple carbohydrate polymers as well as proteins. Biofilms are characterized by a very high cell density and by a natural retentostat behavior. Both factors can contribute to high productivities and a facilitated separation of the desired end-product from the catalytic biomass. Within the biofilm matrix, stable gradients of substrates and products form, which can lead to a differentiation and adaptation of the microorganisms' physiology to the specific process conditions. Moreover, growth in a biofilm state is often accompanied by a higher resistance and resilience towards toxic or growth inhibiting substances and factors. In this short review, we summarize how biofilms can be studied and what most promising niches for their application can be. Moreover, we highlight future research directions that will accelerate the advent of productive biofilms in biology-based production processes.

RevDate: 2019-05-12

Su JF, Zhang YM, Liang DH, et al (2019)

Performance and microbial community of an immobilized biofilm reactor (IBR) for Mn(II)-based autotrophic and mixotrophic denitrification.

Bioresource technology, 286:121407 pii:S0960-8524(19)30637-6 [Epub ahead of print].

An immobilized biofilm reactor (IBR) was established to treat nitrate using different electron donors. A novel material, Fe3O4@Cu/PVA, was synthesized as an adsorbent and bacterial immobilized carrier in the reactor. The optimum condition of nitrate removal were pH 7.0, hydraulic retention time (HRT) of 10 h under autotrophic and mixotrophic conditions. Strain H-117 in the mixotrophic reactor had better adaptability to changes in the initial pH. The metabolism in the mixotrophic reactor was more vigorous than that in autotrophic reactor. The microbial communities and structures were evaluated to determine the nitrate removal mechanisms in this system. Microbial analyses demonstrated that different electron donor could influence the bacterial abundance and species in the IBR system. Proteobacteria was the most dominant phylum in all IBRs and accounted for more than 50% of the total phyla. Pseudomonas and Rhizobium were the dominant contributor to the effective removal of nitrate in the IBRs.

RevDate: 2019-05-12

Ahmed W, Tian X, R Delatolla (2019)

Nitrifying moving bed biofilm reactor: Performance at low temperatures and response to cold-shock.

Chemosphere, 229:295-302 pii:S0045-6535(19)30839-2 [Epub ahead of print].

In contrast with suspended growth systems, attached growth technologies such as the moving bed biofilm reactors (MBBR) have recently demonstrated significant nitrification rates at temperatures as low as 1 °C. The purpose of this study was to investigate the performance of the nitrifying MBBR system at elevated municipal concentrations with exposures to low temperatures and cold-shock conditions down to 1 °C using an enhanced temperature-controlled room. A removal rate of 98.44 ± 4.69 gN·m-3·d-1 was identified as the intrinsic rate of nitrifying MBBR systems at 1 °C and was proposed as the conservative rate for low temperature design. A temperature threshold at which attached growth nitrification displayed a significant decrease in kinetics was identified between 2 °C and 4 °C. Arrhenius correction coefficients of 1.086 and 1.09 previously applied for low temperature nitrifying MBBR systems resulted in conservative modeled removal rates on average 21% lower than the measured rates. Thus, an Arrhenius correction coefficient of 1.049 is proposed between the temperatures of 10 °C and 4 °C and another correction coefficient of 1.149 to model rates at 1 °C. For the transition from 4 °C to 1 °C, the adjustment of a previously reported Theta model is proposed in this study to account for exposure time at low temperatures; with the modified model showing strong correlation with measured rates (R2 = 0.88). Finally, a comparison of nitrification kinetics between MBBR systems acclimatized to 1 °C and systems that are cold-shocked to 1 °C demonstrated that shocked removal rates are 21% lower.

RevDate: 2019-05-11

Bermejo P, Sánchez MC, Llama-Palacios A, et al (2019)

Biofilm formation on dental implants with different surface micro-topography: an in vitro study.

Clinical oral implants research [Epub ahead of print].

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

RESULTS: A biofilm, located mainly at the peak and lateral areas of the implant threads, was observed on both implant surfaces, with a greater biomass and a greater live/dead ratio in moderate-, compared to minimal-roughness surface implants. Statistically significant higher values of total bacteria (mean difference=2.61x107 CFU/mL; 95% confidence interval - CI [1.91x106 ; 5.02x107 ]; p=0.036), F. nucleatum (mean difference=4.43x106 CFU/mL; 95% CI [1.06x106 ; 7.80x106 ]; p=0.013) and A. actinomycetemcomitans (mean difference=2.55x107 CFU/mL; 95% CI [1.07x107 ; 4.04x107 ]; p=0.002) were found in the moderate-, compared to minimal-roughness surface dental implants.

CONCLUSIONS: Implants with moderate-roughness surfaces accumulated more bacterial biomass and significant higher number of pathogenic bacteria (F. nucleatum and A. actinomycetemcomitans), when compared to implants with minimal-roughness surfaces, within a similar biofilm structure. This article is protected by copyright. All rights reserved.

RevDate: 2019-05-11

Alves AR, Sequeira AM, Â Cunha (2019)

Increase of bacterial biosurfactant production by co-cultivation with biofilm-forming bacteria.

Letters in applied microbiology [Epub ahead of print].

Considering that bacterial biosurfactants (BSFs) are released as secondary metabolites involved in biotic relations within mixed bacterial assemblages, the hypothesis that the co-cultivation of BSF producing bacteria with biofilm-forming strains would enhance BSF synthesis was tested. Environmental BSF producing strains of Bacillus licheniformis and Pseudomonas sp. were cultivated with reference biofilm-forming strains (Pseudomonas aeruginosa and Listeria innocua). BSF production and quorum quenching effects were tested in solid media. Tensioactive and anionic BSFs were also quantified in cell-free extracts (CFEs). BSF production increased in co-cultures with inducer strains although this was not demonstrated by all screening methods. Increased concentrations of anionic BSF were detected in CFEs of co-cultures in which Pseudomonas aeruginosa was included as inducer, which is in accordance with the observation of larger halos in cetyl trimethylammonium bromide-methylene blue agar. The results demonstrate that co-cultivation positively affects the efficiency of BSF production and that higher production yields may be attained by selecting convenient inducer partners in designed consortia. This article is protected by copyright. All rights reserved.

RevDate: 2019-05-11

Zeng Z, Zang W, Wang W, et al (2019)

Biofilm formation in Pseudoalteromonas lipolytica is related to IS5-like insertions in the capsular polysaccharide operon.

FEMS microbiology ecology pii:5488432 [Epub ahead of print].

Bacterial capsular polysaccharides (CPSs) participate in environmental adaptation in diverse bacteria species. However, the role and regulation of CPS production in marine bacteria have remained largely unexplored. We previously reported that both wrinkled and translucent Pseudoalteromonas lipolytica variants with altered polysaccharide production were generated in pellicle biofilm-associated cells. In this study, we observed that translucent variants were generated at a rate of ∼20% in colony biofilms of P. lipolytica cultured on HSLB agar plates for 12 days. The DNA sequencing results revealed that nearly 90% of these variants had an IS5-like element inserted within the coding or promoter regions of nine genes in the cps operon. In contrast, IS5 insertion into the cps operon was not detected in planktonic cells. Furthermore, we demonstrated that the IS5 insertion event inactivated CPS production, which leads to a translucent colony morphology. The CPS-deficient variants showed an increased ability to form attached biofilms but exhibited reduced resistance to sublethal concentrations of antibiotics. Moreover, deleting the DNA repair gene recA significantly decreased the frequency of occurrence of CPS-deficient variants during biofilm formation. Thus, IS insertion into the cps operon is an important mechanism for the production of genetic variants during biofilm formation of marine bacteria.

RevDate: 2019-05-11

Peng C, Gao Y, Fan X, et al (2019)

Enhanced biofilm formation and denitrification in biofilters for advanced nitrogen removal by rhamnolipid addition.

Bioresource technology pii:S0960-8524(19)30617-0 [Epub ahead of print].

Denitrification biofilters (DNBFs) are widely used in advanced nitrogen removal of wastewater with low C/N and effective biofilm formation is critical to their long-term operation. Hereby the influence of rhamnolipid addition in DNBFs was investigated for the first time. Gradient concentrations (0, 20, 40, 80, 120 mg/L) of rhamnolipid were applied to investigate nitrogen removal, biofilm properties and microbial community of lab-scale DNBFs. A significant increase of nitrogen removal was observed in rhamnolipid-treated DNBFs (p < 0.05). Total solid (TS), extracellular polymeric substances (EPS) and adhesion force of biofilms in DNBF with 120 mg/L rhamnolipid reached the maximum, which were 2.17, 2.15 and 3.36 times of those in the control, respectively. Moreover, rhamnolipid exhibited an improvement in abundance of Simplicispira and Gemmatimonas which were responsible for enhanced biofilm formation and denitrification. The results suggested that rhamnolipid addition can be a novel strategy to improve the start-up and denitrification performance of DNBFs.

RevDate: 2019-05-10

Gou Y, Liu W, Wang J, et al (2019)

CRISPR-Cas9 knockout of qseB induced asynchrony between motility and biofilm formation in Escherichia coli.

Canadian journal of microbiology [Epub ahead of print].

Generally, there is a tight regulation between cell motility and biofilm formation. The two-component system (TCS) of QseBC serves as a bridge for bacterial signal transmission, in which QseB acts as a response regulator to regulate bacterial motility, biofilm and virulence. The interaction mechanisms between QseBC and their functions have been generally studied, but the regulation of QseB on bacterial motility and biofilm formation is unknown. In this study, CRISPR-Cas9 system was used to construct the strain of Escherichia coli MG1655ΔqseB (ΔqseB strain), and the effects of gene qseB on the changes of motility and biofilm formation of Wild-type (WT) were determined. The motility assay results showed that the ΔqseB strain had higher (p<0.05) mobility than that of the WT strain. Nevertheless, there was no difference in the biofilm formation between ΔqseB and WT. The real-time quantitative PCR (qRT-PCR) illustrated that deletion of qseB in the WT strain down-regulated the expression of the type I pili gene fimA. Therefore, we might conclude that the ΔqseB induced the down-regulation of fimA, which led to asynchrony between motility and biofilm formation in E. coli, which provide a new insight into the functional importance of QseB in regulating the cell motility and biofilm.

RevDate: 2019-05-09

Mehta M, Allen-Gipson D, Mohapatra S, et al (2019)

Study on the therapeutic index and synergistic effect of Chitosan-Zinc Oxide nanomicellar composites for drug-resistant bacterial biofilm inhibition.

International journal of pharmaceutics pii:S0378-5173(19)30356-4 [Epub ahead of print].

The synergistic effectiveness of chitosan with zinc oxide nanomicelles (CZNPs) on broad spectrum of multidrug resistance (MDR) was previously evidenced in our labs, requiring elucidation of the therapeutic index (TI) for safe in vivo use. This in vitro assessment estimated the effective dose (ED50) of micellar CZNPs for eradication of the MDR Enterococcus faecium 1449 model and the corresponding cytotoxic dose (LD50) against rat small intestinal epithelial cells as functions of TI. In order to visually determine the mechanistic effects of micellar CZNPs on bacterial biofilm size reduction, LIVE/DEAD viability assay was used in conjunction with advanced fluorescence imaging and 3D confocal microscopy. Biofilm quantification was performed through the measure of the fluorescence intensity, using the Biotek Synergy Neo2 for calculating the ED50. To generate the LD50, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay was implemented. Quantification results revealed, at the same concentration (200 µg/mL), micellar CZNPs had average biofilm reduction of approximately 50.22% at 24 hours (ED50 = 199.13 µg/mL, LD50 = 240.20 µg/mL, TI = 1.2062), compared to chitosan (15.66%) and ZnO (13.94%) alone. Conclusively, the ED50 of micellar CZNPs on MDR bacterial biofilms (199.13 µg/mL) as a function of TI reveals a promising nanotherapeutic agent in comparison to either Chitosan or ZnO alone.

RevDate: 2019-05-09

Guo D, Yang Z, Zheng X, et al (2019)

Thymoquinone Inhibits Biofilm Formation and Attachment-Invasion in Host Cells of Vibrio parahaemolyticus.

Foodborne pathogens and disease [Epub ahead of print].

Vibrio parahaemolyticus is a halophilic Gram-negative foodborne pathogen that is widely distributed in marine environments. It can cause acute gastroenteritis and other diseases. This study aimed to investigate the antivirulence activity of thymoquinone (TQ) on V. parahaemolyticus. TQ was shown to effectively inhibit V. parahaemolyticus. Subminimum inhibitory concentrations of TQ inhibited swimming and swarming motility, quorum sensing, biofilm formation, the ability of V. parahaemolyticus to adhere and invade the host cells, and the expression of virulence-associated genes of V. parahaemolyticus. These findings suggest that TQ can effectively inhibit the growth of V. parahaemolyticus and significantly reduce its pathogenicity. Considering its safety and various biological activities, TQ has the potential to be developed as a natural antibacterial substance to reduce the diseases associated with V. parahaemolyticus.

RevDate: 2019-05-08

Zhou R, Zhou R, Wang P, et al (2019)

Microplasma Bubbles: Reactive Vehicles for Biofilm Dispersal.

ACS applied materials & interfaces [Epub ahead of print].

Interactions between effects generated by cold atmospheric-pressure plasmas (CAPPs) and water have been widely investigated water purification, chemical and nanomaterial synthesis, and more recently, medicine and biotechnology. Reactive oxygen and nitrogen species (RONS) play critical roles in transferring the reactivity from gas plasmas to solutions to induce specific biochemical responses in living targets, e.g. pathogen inactivation and biofilm removal. While this approach works well in a single-organism system at lab scale, integration of plasma-enabled biofilm removal into complex real-life systems, e.g. large aquaculture tanks, is far from trivial. This is because it is difficult to deliver sufficient concentrations of the right kind of species to biofilm-covered surfaces while carefully maintaining a suitable physiochemical environment that is healthy for its inhabitants, e.g. fish. In this work, we show that underwater microplasma bubbles (generated by a microplasma-bubble reactor that forms a dielectric barrier discharge (DBD) at the gas-liquid interface with the aplied voltage of 4.0 kV) act as transport vehicles to efficiently deliver reactive plasma species to target biofilm sites on artificial and living surfaces while keeping healthy water conditions in a multi-species system. Thus-generated air microplasma bubbles and plasma activated water (PAW) both can effectively reduce existing pathogenic biofilm load, by ~83% and 60% respectively after 15 min-discharge at 40 W, and prevent any new biofilm from forming. Generation of underwater microplasma bubbles in a custom-made fish tank for less than a minute per day (20 seconds per-time, twice daily) can introduce sufficient quantities of RONS into PAW to reduce biofilm infected area by ~80-90% and imrpove the health status of Cichlasoma synspilum × Cichlasoma citrinellum blood parrot cichlid fish. Species generated include hydrogen peroxide, ozone, nitrite, nitrate and nitric oxide. Using mimicked chemical solutions, we show that plasma-induced nitric oxide acts as a critical bioactive species that triggers the release of cells from biofilm and their inactivation.

RevDate: 2019-05-08

Zhang C, Du C, Liao JY, et al (2019)

Synthesis of magnetite hybrid nanocomplexes to eliminate bacteria and enhance biofilm disruption.

Biomaterials science [Epub ahead of print].

Bacteria can increase drug resistance by forming bacterial biofilms. Once the biofilm is formed, it becomes difficult to remove or kill the related bacteria completely by antibiotics and other antibacterial agents because these antibacterial agents cannot easily break through the biofilm matrix barrier and reach the internal bacteria. Therefore, we synthesized magnetite hybrid nanocomplexes that can penetrate and disrupt bacterial biofilms. The obtained nanocomposites are composed of multinucleated iron oxides and Ag seeds. The outer iron oxides can help the internal Ag nanoparticles penetrate the bacterial biofilms, hence killing the internal bacteria and disrupting the biofilms. We took advantage of E. coli and P. aeruginosa bacteria to test the antibacterial properties of the magnetite hybrid nanocomplexes. When planktonic E. coli and P. aeruginosa bacteria were incubated with 100 μg mL-1 magnetite hybrid nanocomplexes for 30 min, almost all the bacteria were killed. When the obtained biofilms of E. coli and P. aeruginosa were treated with magnetite hybrid nanocomplexes (10 μg mL-1 and 100 μg mL-1), the survival of E. coli and P. aeruginosa biofilms with a magnetic field showed a big decrease compared with that without a magnetic field. Therefore, the as-synthesized nanocomposites have promising potential as antimicrobial agents for killing bacteria and disrupting biofilms in the presence of a magnetic field, and thus should be further studied for a wide range of antibacterial applications.

RevDate: 2019-05-08

Wei C, Ding T, Chang C, et al (2019)

Global Regulator PhoP is Necessary for Motility, Biofilm Formation, Exoenzyme Production and Virulence of Xanthomonas citri Subsp. citri on Citrus Plants.

Genes, 10(5): pii:genes10050340.

Citrus canker caused by Xanthomonas citri subsp. citri is one of the most important bacterial diseases of citrus, impacting both plant growth and fruit quality. Identifying and elucidating the roles of genes associated with pathogenesis has aided our understanding of the molecular basis of citrus-bacteria interactions. However, the complex virulence mechanisms of X. citri subsp. citri are still not well understood. In this study, we characterized the role of PhoP in X. citri subsp. citri using a phoP deletion mutant, ΔphoP. Compared with wild-type strain XHG3, ΔphoP showed reduced motility, biofilm formation, as well as decreased production of cellulase, amylase, and polygalacturonase. In addition, the virulence of ΔphoP on citrus leaves was significantly decreased. To further understand the virulence mechanisms of X. citri subsp. citri, high-throughput RNA sequencing technology (RNA-Seq) was used to compare the transcriptomes of the wild-type and mutant strains. Analysis revealed 1017 differentially-expressed genes (DEGs), of which 614 were up-regulated and 403 were down-regulated in ΔphoP. Gene ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that the DEGs were enriched in flagellar assembly, two-component systems, histidine metabolism, bacterial chemotaxis, ABC transporters, and bacterial secretion systems. Our results showed that PhoP activates the expression of a large set of virulence genes, including 22 type III secretion system genes and 15 type III secretion system effector genes, as well as several genes involved in chemotaxis, and flagellar and histidine biosynthesis. Two-step reverse-transcription polymerase chain reaction analysis targeting 17 genes was used to validate the RNA-seq data, and confirmed that the expression of all 17 genes, except for that of virB1, decreased significantly. Our results suggest that PhoP interacts with a global signaling network to co-ordinate the expression of multiple virulence factors involved in modification and adaption to the host environment during infection.

RevDate: 2019-05-07

Misba L, Abdulrahman H, AU Khan (2019)

Photodynamic efficacy of toluidine blue O against mono species and dual species bacterial biofilm.

Photodiagnosis and photodynamic therapy pii:S1572-1000(19)30067-5 [Epub ahead of print].

AIM: The purpose of this study was to investigate how Enterococcus faecalis and Streptococcus mutans behave in mono and dual species biofilm after photodynamic treatment.

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

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

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

CONCLUSION: We conclude that dual species biofilm shows resistance over monospecies biofilm and S.mutans in dual species inhibits the growth of E. faecalis.

RevDate: 2019-05-07

González MJ, Da Cunda P, Notejane M, et al (2019)

Fosfomycin tromethamine activity on biofilm and intracellular bacterial communities produced by uropathogenic Escherichia coli isolated from patients with urinary tract infection.

Pathogens and disease, 77(3):.

Fosfomycin tromethamine (FT), an old antibiotic revived as a new strategy to overcome antibiotic resistance, is an excellent option for the treatment of lower urinary tract infection (UTI). During UTI, Escherichia coli produces biofilms and could invade the bladder epithelial cells, developing intracellular bacterial communities (IBC). The present work aimed to evaluate the activity of FT on biofilms and IBC from clinical isolates of E. coli. A total of 38 E. coli clinical UTI isolates previously characterized as biofilm and IBC producers were studied. FT susceptibility was evaluated and its activity on 48 h biofilm was determined by microtiter plate-based biofilm assay comparing three different antibiotic concentrations. Two UPEC strains were selected to evaluate FT activity on IBC in vitro using T24 bladder cells. The survival percentage of intracellular bacteria after 24 h exposure to FT was calculated and compared to the percentage of intracellular bacteria without antibiotic. All the strains were susceptible to FT. FT produced a significant reduction of biofilms at the three concentrations tested, compared to the control. However, no statistically effect on IBC was observed after 24 h of fosfomycin exposure in cell culture. FT is a good option for bacterial biofilm reduction within UTI. However, it does not affect IBC.

RevDate: 2019-05-07

Gu H, Lee SW, Carnicelli J, et al (2019)

Antibiotic susceptibility of Escherichia coli cells during early-stage biofilm formation.

Journal of bacteriology pii:JB.00034-19 [Epub ahead of print].

Bacteria form complex multicellular structures on solid surfaces called biofilms, which allow them to survive in harsh environments. A hallmark characteristic of mature biofilms is the high-level antibiotic tolerance (up to 1,000 times) compared to planktonic cells. Here, we report our new findings that biofilm cells are not always more tolerant to antibiotics than planktonic cells in the same culture. Specifically, Escherichia coli RP437 exhibited a dynamic change in antibiotic susceptibility during its early-stage biofilm formation. This phenomenon was not strain specific. Upon initial attachment, surface-associated cells became more sensitive to antibiotics than planktonic cells. By controlling the cell adhesion and cluster size using patterned E. coli biofilms, cells involved in the interaction between cell clusters during microcolony formation were found to be more susceptible to ampicillin than cells within clusters, suggesting a role of cell-cell interactions in biofilm-associated antibiotic tolerance. After this stage, biofilm cells became less susceptible to ampicillin and ofloxacin than planktonic cells. However, when the cells were detached by sonication, both antibiotics were more effective in killing the detached biofilm cells than the planktonic cells. Collectively, these results indicate that biofilm formation involves active cellular activities in adaption to the attached life form and interactions between cell clusters to build the complex structure of a biofilm, which can render these cells more susceptible to antibiotics. These findings shed new lights on bacterial antibiotic susceptibility during biofilm formation and can guide the design of better antifouling surfaces, e.g., those with micron-scale topographic structures to interrupt cell-cell interactions.IMPORTANCE Mature biofilms are known for their high-level tolerance to antibiotics; however, antibiotic susceptibility of sessile cells during early-stage biofilm formation is not well understood. In this study, we aim to fill this knowledge gap by following bacterial antibiotic susceptibility during early-stage biofilm formation. We found that the attached cells have a dynamic change in antibiotic susceptibility, and during certain phases, they can be more sensitive to antibiotics compared to planktonic counterparts in the same culture. Using surface chemistry controlled patterned biofilm formation, cell-surface and cell-cell interactions were found to be important to biofilm-associated antibiotic tolerance. Collectively, these findings provide new insights into biofilm physiology and reveal how adaptation to the attached life form affects antibiotic susceptibility of bacterial cells.

RevDate: 2019-05-06

Johansen MP, Cresswell T, Davis J, et al (2019)

Biofilm-enhanced adsorption of strong and weak cations onto different microplastic sample types: Use of spectroscopy, microscopy and radiotracer methods.

Water research, 158:392-400 pii:S0043-1354(19)30337-9 [Epub ahead of print].

The adsorption of metals and other elements onto environmental plastics has been previously quantified and is known to be enhanced by surface-weathering and development of biofilms. However, further biofilm-adsorption characterisation is needed with respect to the fate of radionuclides. This study uses spectroscopy, microscopy and radiotracer methods to investigate the adsorption capacity of relatively strong and weak cations onto different microplastic sample types that were conditioned in freshwater, estuarine and marine conditions although marine data were limited. Fourier-transform infrared spectroscopy confirmed that surface oxidation chemistry changes induced by gamma irradiation were similar to those resulting from environmental exposures. Microscopy elemental mapping revealed patchy biofilm development, which contained Si, Al, and O, consistent with microbial-facilitated capture of clays. The plastics+biofilm of all sample types had measurable adsorption for Cs and Sr radiotracers, suggesting environmental plastics act broadly as a sink for the key pervasive environmental radionuclides of 137Cs and 90Sr associated with releases from nuclear activities. Adsorption onto high-density polyethylene plastic types was greater than that on polypropylene. However, in most cases, the adsorption rates of all types of plastic+biofilm were much lower than those of reference sediments and roughly consistent with their relative exchangeable surface areas.

RevDate: 2019-05-06

Xie Z, Meng K, Yang X, et al (2019)

Identification of a Quorum Sensing System Regulating Capsule Polysaccharide Production and Biofilm Formation in Streptococcus zooepidemicus.

Frontiers in cellular and infection microbiology, 9:121.

Streptococcus zooepidemicus is an important opportunistic pathogen of several species including humans. This organism is also well-known as the main producing strain in industrial production of hyaluronic acid (HA), which is the component of its capsule polysaccharide. How its virulence and capsule polysaccharide production is regulated remains poorly understood. Intercellular chemical signaling among bacteria provides communities of microbes the opportunity to coordinate gene expression to facilitate group behavior, such as pathogenicity, capsule polysaccharide production, etc. Yet no conserved cell-to-cell signaling system has been elucidated in S. zooepidemicus. Encoded within the genome of S. zooepidemicus is one Rgg regulator encoding gene (rgg) with low similarity to both rgg2 and rgg3 from Streptococcus pyogenes. A small ORF (named as shp) encoding a novel short hydrophobic peptide (SHP) was found in the vicinity of rgg. We found that the active form of pheromone is short and hydrophobic (LLLLKLA), corresponding to the C terminal 7 amino acids of the pre-peptide Shp, which shows divergent sequence to all peptide pheromones reported in streptococci. In response to active SHP, Rgg functions as a transcriptional activator to induce the expression of shp, forming a positive feedback circuit. Bacteria social behaviors, such as capsule polysaccharide production and biofilm formation, were significantly affected when the rgg-shp pathway was inactivated. These data provide the first demonstration that Rgg/Shp signaling pathway comprises an active quorum sensing system in S. zooepidemicus.

RevDate: 2019-05-06

Post SJ, Shapiro JA, WM Wuest (2019)

Connecting iron acquisition and biofilm formation in the ESKAPE pathogens as a strategy for combatting antibiotic resistance.

MedChemComm, 10(4):505-512 pii:c9md00032a.

The rise of antibiotic resistant bacteria has become a problem of global concern. Of particular interest are the ESKAPE pathogens, species with high rates of multi-drug resistant infections. Novel antibiotic mechanisms of action are necessary to compliment traditional therapeutics. Recent research has focused on targeting virulence factors as a method of combatting infection without creating selective pressure for resistance or damaging the host commensal microbiome. Some investigations into one such virulence behavior, iron acquisition, have displayed additional effects on another virulence behavior, biofilm formation. The use of exogenous iron-chelators, gallium as an iron mimic, and inhibition of siderophore-mediated iron acquisition are all strategies for disturbing iron-homeostasis that have implicated effects on biofilms. However, the exact nature of this connection remains ambiguous. Herein we summarize these findings and identify opportunities for further investigation.

RevDate: 2019-05-06

Igbinosa EO, A Beshiru (2019)

Antimicrobial Resistance, Virulence Determinants, and Biofilm Formation of Enterococcus Species From Ready-to-Eat Seafood.

Frontiers in microbiology, 10:728.

Enterococcus species form an important population of commensal bacteria and have been reported to possess numerous virulence factors considered significantly important in exacerbating diseases caused by them. The present study was designed to characterize antibiotic-resistant and virulent enterococci from ready-to-eat (RTE) seafood. A total of 720 RTE shrimp samples comprising sauced shrimp (n = 288), boiled shrimp (n = 216), and smoked shrimp (n = 216) obtained from open markets in Delta State, Nigeria, were assessed. Standard classical methods and polymerase chain reaction (PCR) were used in identifying the Enterococcus species. Potential virulence factors (β-hemolysis, gelatinase activity, S-layer, and biofilm formation) were assessed using standard procedures. The antibiotic susceptibility profile of the identified enterococci isolates was assayed using the Kirby-Bauer disc diffusion method. PCR was further used to screen selected antibiotic resistance and virulence genes. Prevalence of Enterococcus species from shrimp varieties is as follows: sauced, 26 (9.03%); boiled, 6 (2.78%); and smoked, 27 (12.50%), with an overall prevalence of 59 (8.19%) based on the occurrence of black hallow colonies after incubation. Enterococcus species detected include E. faecalis, 17 (28.8%); E. faecium, 29 (49.2%); E. gallinarum, 6 (10.2%); E. casseliflavus, 2 (3.4%); E. hirae, 3 (5.1%); and E. durans, 2 (3.4%). Biofilm occurrence among the shrimp varieties is as follows: 19/26 (73.1%) for sauced shrimps, 5/6 (83.3%) for boiled shrimps, and 16/27 (59.3%) for smoked shrimps. The phenotypic expression of the enterococci virulence revealed the following: S-layer, 59 (100%); gelatinase production, 19 (32.2%); and β-hemolysis, 21 (35.6%). An average of 3-11 virulence genes were detected in the Enterococcus species. The resistance profile of Enterococcus species is as follows: erythromycin, 29 (49.2%); vancomycin, 22 (37.3%); and tetracycline, 27 (45.8%). The frequency of occurrence of antibiotic resistance genes from the phenotypic resistant enterococci isolates to the macrolide, glycopeptide, and tetracycline antibiotics is as follows: ermA, 13/29 (44.8%); vanA, 14/22 (63.6%); tetA, 14/27 (51.9%); tetM, 15/27 (55.6%); ermB, 4/29 (13.8%); and vanB, 5/22 (22.7%). Findings from this study reveal the antibiotic resistance of enterococci strains of such species as E. durans, E. casseliflavus, E. gallinarum, and E. hirae. This study further revealed that RTE food products are reservoirs of potential virulent enterococci with antibiotic-resistant capabilities. This provides useful data for risk assessment and indicates that these foods may present a potential public health risk to consumers.

RevDate: 2019-05-06

Lee JH, Kim YG, Khadke SK, et al (2019)

Nepodin inhibits biofilm formation by Candida albicans and polymicrobial microorganisms via hyphal growth suppression.

ACS infectious diseases [Epub ahead of print].

Candida albicans is an opportunistic pathogenic yeast and is responsible for candidiasis. It readily colonizes host tissues and implant devices, and forms biofilms, which play an important role in pathogenesis and drug resistance. In this study, the antibiofilm, antihyphal, and antivirulence activities of nepodin isolated from Rumex japonicus roots, was investigated against a fluconazole-resistant C. albicans strain and polymicrobial microorganisms biofilm formation. Nepodin effectively inhibited C. albicans biofilm formation without affecting its planktonic cell growth. Also, Rumex root extract and nepodin both inhibited the hyphal growth and cell aggregation of C. albicans. Interestingly, nepodin also showed antibiofilm activities against Candida glabrata, Candida parapsilosis, Staphylococcus aureus and Acinetobacter baumannii strains and dual biofilms of C. albicans and S. aureus or A. baumannii, but not against Pseudomonas aeruginosa. Transcriptomic analysis performed by RNA-Seq and qRT-PCR showed nepodin repressed the expressions of several hypha/biofilm related genes (ECE1, HGT10, HWP1, and UME6) and increased the expressions of several transport genes (CDR4, CDR11, and TPO2), which supported phenotypic changes. Moreover, nepodin reduced C. albicans virulence in a nematode infection model and exhibited minimal cytotoxicity against the nematode and an animal cell line. These results demonstrate nepodin and Rumex root extract might be useful for controlling C. albicans infections and multispecies biofilms.

RevDate: 2019-05-05

Lynch C, O'Connor JA, O'Brien D, et al (2019)

First reported detection of biofilm formation by Campylobacter fetus during investigation of a case of prosthetic valve endocarditis.

Journal of clinical pathology pii:jclinpath-2018-205677 [Epub ahead of print].

AIMS: Campylobacter fetus subsp fetus (CFF) can cause intestinal illness, particularly in immunocompromised humans, with the potential to cause severe systemic infections. CFF is a zoonotic pathogen with a broad host range among farm animals and humans, inducing abortion in sheep and cows. The current paper describes a strain of CFF isolated from a patient with prosthetic valve endocarditis in Mercy University Hospital, Cork, Ireland, during 2017. Only five cases of C. fetus as a cause of prosthetic valve endocarditis have been reported in the literature, with no reports of biofilm formation within the species.

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

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

CONCLUSIONS: This clinically significant C. fetus isolate showed considerable biofilm-forming capability, which we suggest conferred a survivalist advantage, contributing to the genesis of infective prosthetic valve endocarditis.

RevDate: 2019-05-04

Peng L, Ngo HH, Song S, et al (2019)

Heterotrophic denitrifiers growing on soluble microbial products contribute to nitrous oxide production in anammox biofilm: Model evaluation.

Journal of environmental management, 242:309-314 pii:S0301-4797(19)30551-1 [Epub ahead of print].

In this work, a model framework was constructed to assess and predict nitrous oxide (N2O) production, substrate and microbe interactions in an anammox biofilm bioreactor. The anammox kinetics were extended by including kinetics of autotrophic soluble microbial products (SMP) formation, which consisted of utilization-associated products (UAP) and biomass-associated products (BAP). Heterotrophic bacteria growing on UAP, BAP and decay released substance (SS) were modelled to perform four-step sequential reductions from nitrate to dinitrogen gas. N2O was modelled as an intermidiate of heterotrophic denitrification via three pathways with UAP, BAP and SS as the electron donors. The developed model framework was evaluated using long-term operational data from an anammox biofilm reactor and satisfactorily reproduced effluent nitrogen and SMP as well as N2O emission factors under different operational conditions. The modeling results revealed that N2O was mainly produced with UAP as the electron donor while BAP and SS play minor roles. Heterotrophic denitrifiers growing on UAP would significantly contribute to N2O emission from anammox biofilm reactor even though heterotrophs only account for a relatively small fraction of active biomass in the anammox biofilm. Comprehensive simulations were conducted to investigate the effects of N loading rate and biofilm thickness, which indicated that maintaining a low N loading rate and a thick biofilm thickness were essential for high total nitrogen removal efficiency and low N2O emission.

RevDate: 2019-05-04

Babbar A, Barrantes I, Pieper DH, et al (2019)

Superantigen SpeA attenuates the biofilm forming capacity of Streptococcus pyogenes.

Journal of microbiology (Seoul, Korea) pii:10.1007/s12275-019-8648-z [Epub ahead of print].

Beta haemolytic Group A streptococcus (GAS) or Streptococcus pyogenes are strict human pathogens responsible for mild to severe fatal invasive infections. Even with enormous number of reports exploring the role of S. pyogenes exotoxins in its pathogenesis, inadequate knowledge on the biofilm process and the potential role of exotoxins in bacterial dissemination from matured biofilms has been a hindrance in development of effective and targeted treatments. Therefore, the present study was aimed in investigating the uncharted role of these exotoxins in biofilm process. Through our study the putative role of ciaRH in the SpeA dependent ablation of biofilm formation could be speculated and thus helping in bacterial dissemination. The seed-dispersal effect of SpeA was time and concentration dependent and seen to be consistent within various streptococcal species. Transcriptome analysis of SpeA treated S. pyogenes biofilms revealed the involvement of many transcriptional regulators (ciaRH) and response genes (luxS, shr, shp, SPy_0572), hinting towards specific mechanisms underlying the dispersal effect by SpeA. This finding opens up a discussion towards understanding a new mechanism involved in the pathogenesis of Streptococcus pyogenes and might help in understanding the bacterial infections in a better way.

RevDate: 2019-05-04

Taha MN, Saafan AE, Ahmedy A, et al (2019)

Two novel synthetic peptides inhibit quorum sensing-dependent biofilm formation and some virulence factors in Pseudomonas aeruginosa PAO1.

Journal of microbiology (Seoul, Korea) pii:10.1007/s12275-019-8548-2 [Epub ahead of print].

Quorum sensing (QS) regulates virulence factor expression in Pseudomonas aeruginosa. Inhibiting the QS-controlled virulence factors without inhibiting the growth of P. aeruginosa is a promising approach for overcoming the widespread resistance of P. aeruginosa. This study was proposed to investigate the effects of two novel synthetic peptides on the biofilm development and virulence factor production of P. aeruginosa. The tested strain was P. aeruginosa PAO1. The results indicated that both of the synthetic peptides (LIVRHK and LIVRRK) inhibited (P < 0.05) the formation of biofilms and the production of virulence factors, including pyocyanin, protease, and rhamnolipids, without inhibiting the growth of PAO1. Additionally, we detected transcriptional changes related to QS and found a significant reduction in the levels of gene expression of lasI, lasR, rhlI, and rhlR. This study demonstrates that LIVRRK and LIVRHK are novel synthetic peptides that can act as potent inhibitors of QS-regulated virulence factors in P. aeruginosa. Moreover, these synthetic peptides have potential applications in the treatment of biofilmrelated diseases. Both peptides may be able to control chronic infections and biofilm-associated problems of P. aeruginosa.

RevDate: 2019-05-04

Gu D, Zhang J, Hao Y, et al (2019)

Alternative sigma factor RpoX is a part of RpoE regulon and plays distinct roles in stress response, motility, biofilm formation and hemolytic activities in the marine pathogen Vibrio alginolyticus.

Applied and environmental microbiology pii:AEM.00234-19 [Epub ahead of print].

Vibrio alginolyticus is one of the most abundant microorganisms in marine environments and is also an opportunistic pathogen mediating high-mortality vibriosis in marine animals. Alternative sigma factors play essential roles in bacterial pathogens in the adaptation to environmental changes during infection and the adaptation to various niches, but little is known about them for V. alginolyticus Our previous investigation indicated that the transcript level of the gene rpoX significantly decreased in an RpoE mutant. Here, we found that rpoX was highly expressed in response to high-temperature and low-osmotic stress and was under the direct control of the alternative sigma factor RpoE and its own product RpoX. Moreover, the RNA-seq results showed that RpoE and RpoX had different regulons, although they coregulated 105 genes at high temperature (42°C), including genes associated with biofilm formation, motility, virulence, regulatory factors and stress response. RNA-seq and ChIP-seq as well as EMSA analyses revealed the distinct binding motifs of RpoE and RpoX proteins. Furthermore, qRT-PCR analysis also confirmed that RpoX can upregulate genes associated with flagella, biofilm formation and hemolytic activities at higher temperatures. rpoX abrogation does not appear to attenuate virulence towards model fish at normal temperature. Collectively, this study demonstrated the regulatory cascades of RpoE and an alternative sigma factor, RpoX, in response to heat and osmotic stresses and their distinct and overlapping roles in pathogenesis and stress responses in the marine bacterium V. alginolyticusIMPORTANCE The alternative sigma factor RpoE is essential for the virulence of Vibrio alginolyticus towards marine fish, coral and other animals in response to sea surface temperature increases. In this study, we characterized another alternative sigma factor, RpoX, which is induced at high temperatures and under low-osmotic conditions. The expression of rpoX is under the tight control of RpoE and RpoX. Although RpoE and RpoX coregulate 105 genes, they are programming different regulatory functions in stress responses and virulence in V. alginolyticus These findings illuminated the RpoE-RpoX-centered regulatory cascades and their distinct and overlapping regulatory roles in V. alginolyticus, which facilitates to unravel the mechanisms by which the bacterium causes diseases in various sea animals in response to temperature fluctuations as well as to develop appropriate strategies to tackle the infections by the bacterium.

RevDate: 2019-05-04

Bahamondez-Canas TF, Heersema LA, HDC Smyth (2019)

Current Status of In Vitro Models and Assays for Susceptibility Testing for Wound Biofilm Infections.

Biomedicines, 7(2): pii:biomedicines7020034.

Biofilm infections have gained recognition as an important therapeutic challenge in the last several decades due to their relationship with the chronicity of infectious diseases. Studies of novel therapeutic treatments targeting infections require the development and use of models to mimic the formation and characteristics of biofilms within host tissues. Due to the diversity of reported in vitro models and lack of consensus, this review aims to provide a summary of in vitro models currently used in research. In particular, we review the various reported in vitro models of Pseudomonas aeruginosa biofilms due to its high clinical impact in chronic wounds and in other chronic infections. We assess advances in in vitro models that incorporate relevant multispecies biofilms found in infected wounds, such as P. aeruginosa with Staphylococcus aureus, and additional elements such as mammalian cells, simulating fluids, and tissue explants in an attempt to better represent the physiological conditions found at an infection site. It is hoped this review will aid researchers in the field to make appropriate choices in their proposed studies with regards to in vitro models and methods.

RevDate: 2019-05-03

Guo J, Qin S, Wei Y, et al (2019)

Silver nanoparticles exert concentration-dependent influences on biofilm development and architecture.

Cell proliferation [Epub ahead of print].

OBJECTIVES: To investigate the impact of silver nanoparticles (AgNPs) on the biofilm growth and architecture.

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

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

CONCLUSIONS: AgNPs exert concentration-dependent influences on biofilm development and structure, which provides new insight into the role of concentration played in the interaction between antibacterial nanoparticles and biofilm, especially, an ignored sublethal concentration associated with potential unintended consequences.

RevDate: 2019-05-02

Alcaraz E, García C, Friedman L, et al (2019)

The rpf/DSF signalling system of Stenotrophomonas maltophilia positively regulates biofilm formation, production of virulence-associated factors and β-lactamase induction.

FEMS microbiology letters, 366(6):.

Stenotrophomonas maltophilia is a multidrug-resistant opportunistic pathogen. S. maltophilia quorum-sensing system is mediated by the diffusible signal factor (DSF), which synthesis depends on rpfF. It has been reported that rpfF disruption in S. maltophilia K279a leads to a loss of DSF synthesis, reduced levels of extracellular protease, swarming motility and virulence in the Galleria mellonella model. The aim of this work was to attain a deeper knowledge of the role of the rpf/DSF signalling system in S. maltophilia biofilm formation, phenotypic traits associated with biofilm development and virulence and antimicrobial susceptibility. To this end, comparative studies were conducted on S. maltophilia K279a and K279arpfF. The results presented here put in evidence the positive role of DSF in bacterial growth, biofilm formation, swimming and twitching motilities, DNAse, lipases and siderophores production as well as resistance to oxidative stress. Interestingly, DSF seems to be essential for the development of the spatially organised structure seen in mature biofilms. Therefore, DSF from S. maltophlia K279a positively regulates biofilm formation and virulence. Furthermore, DSF is necessary for the induction of L1 and L2 β-lactamase production in K279a. This is the first evidence of the role of the rpf/DSF signalling system in S. maltophilia β-lactam resistance.

RevDate: 2019-05-02

de Carvalho Leonel L, Carvalho ML, da Silva BM, et al (2019)

Photodynamic Antimicrobial Chemotherapy (PACT) using Methylene blue inhibits the viability of the biofilm produced by Candida albicans.

Photodiagnosis and photodynamic therapy pii:S1572-1000(19)30046-8 [Epub ahead of print].

BACKGROUND: Candida albicans is an opportunistic fungus, an etiological agent of human infections, presenting high rates of morbidity and mortality. The resistance of C. albicans to conventional therapies has been reported due to the extensive use of conventional antifungals. Photodynamic antimicrobial chemotherapy (PACT) is a technique that combines a visible light with a specific wavelength and a photosensitizer, producing ROS and permanent damages in the treated cells.

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

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

CONCLUSIONS: Taken together, these results indicate the potential PACT effects using MB to decrease the C. albicans development.

RevDate: 2019-05-01

Crenier C, Sanchez-Thirion K, Bec A, et al (2019)

Interactive Impacts of Silver and Phosphorus on Autotrophic Biofilm Elemental and Biochemical Quality for a Macroinvertebrate Consumer.

Frontiers in microbiology, 10:732.

Autotrophic biofilms are complex and fundamental biological compartments of many aquatic ecosystems. In particular, these biofilms represent a major resource for many invertebrate consumers and the first ecological barrier against toxic metals. To date, very few studies have investigated the indirect effects of stressors on upper trophic levels through alterations of the quality of biofilms for their consumers. In a laboratory study, we investigated the single and combined effects of phosphorus (P) availability and silver, a re-emerging contaminant, on the elemental [carbon (C):nitrogen (N):P ratios] and biochemical (fatty acid profiles) compositions of a diatom-dominated biofilm initially collected in a shallow lake. We hypothesized that (1) P and silver, through the replacement of diatoms by more tolerant primary producer species, reduce the biochemical quality of biofilms for their consumers while (2) P enhances biofilm elemental quality and (3) silver contamination of biofilm has negative effects on consumers life history traits. The quality of biofilms for consumers was assessed for a common crustacean species, Gammarus fossarum, by measuring organisms' survival and growth rates during a 42-days feeding experiment. Results mainly showed that species replacement induced by both stressors affected biofilm fatty acid compositions, and that P immobilization permitted to achieve low C:P biofilms, whatever the level of silver contamination. Gammarids growth and survival rates were not significantly impacted by the ingestion of silver-contaminated resource. On the contrary, we found a significant positive relationship between the biofilm P-content and gammarids growth. This study underlines the large indirect consequences stressors could play on the quality of microbial biomass for consumers, and, in turn, on the whole food web.

RevDate: 2019-05-01

Hold GL, E Allen-Vercoe (2019)

Gut microbial biofilm composition and organisation holds the key to CRC.

Nature reviews. Gastroenterology & hepatology pii:10.1038/s41575-019-0148-4 [Epub ahead of print].

RevDate: 2019-04-30

Nagay BE, Dini C, Cordeiro JM, et al (2019)

Visible-light-induced Photocatalytic and Antibacterial Activity of TiO2 Codoped with Nitrogen and Bismuth: New Perspective to Control Implant-biofilm-related Disease.

ACS applied materials & interfaces [Epub ahead of print].

Biofilm-associated disease is one of the main cause of implant failure. Currently, the development of implant surface treatment goes beyond the osseointegration process, and focuses on the creation of surfaces with antimicrobial action and with the possibility to be reactivated (i.e. light source activation). Titanium dioxide (TiO2), an excellent photocatalyst used for photocatalytic antibacterial applications, could be a great alternative, but its efficiency is limited to the ultraviolet (UV) range of the electromagnetic spectrum. Since UV radiation has carcinogenic potential, we created a functional TiO2 coating codoped with nitrogen and bismuth via the plasma electrolytic oxidation (PEO) of titanium to achieve an antibacterial effect under visible light with reactivation potential. A complex surface topography was demonstrated by scanning electron microscopy and 3D confocal laser scanning microscopy. Additionally, PEO-treated surfaces showed greater hydrophilicity and albumin adsorption compared to control, untreated titanium. Bismuth incorporation shifted the band gap of TiO2 to the visible region and facilitated the higher degradation of methyl orange (MO) in the dark, with a greater reduction in the concentration of MO after visible-light irradiation even after 72 h of aging. These results were consistent with the in vitro antibacterial effect, where samples with nitrogen and bismuth in their composition showed the greatest bacterial reduction after 24 h of dual-species biofilm formation (Streptococcus sanguinis and Actinomyces naeslundii) in darkness with a superior effect at 30 min of visible-light irradiation. In addition, such coating presents a reusable photocatalytic potential and good biocompatibility by presenting non-cytotoxicity effect on human gingival fibroblast cells. Therefore, nitrogen and bismuth incorporation in TiO2 via PEO can be considered a promising alternative for dental implants application with antibacterial properties in darkness, with a stronger effect after visible-light application.

RevDate: 2019-04-30

El-Khatib M, Tetreau G, JP Colletier (2019)

[Porins: a vital role and a social link within the bacterial biofilm of P. stuartii].

Medecine sciences : M/S, 35(4):291-295.

RevDate: 2019-04-30

Vinod Kumar K, Lall C, Raj RV, et al (2019)

Coaggregation and biofilm formation of Leptospira with Staphylococcus aureus.

Microbiology and immunology [Epub ahead of print].

It is not known how Leptospira react to wound or a cut infected with microbes, such as pathogenic Staphylococcus, or their common habitat on oral or nasal mucosal membranes. In the present study, Staphylococcus aureus MTCC-737 showed strong co-aggregation with leptospiral strains (>75%, visual score of + 4) in vitro. All tested strains of Leptospira were able to form biofilm with S. aureus. Scanning electron microscopy analysis revealed intertwined networks of attached cells of L. interrogans and S. aureus, thus providing evidence of a matrix-like structure. This phenomenon may have implications in Leptospira infection, which occurs via cuts and wounds of the skin.

RevDate: 2019-04-30

Vargas-Cruz N, Reitzel RA, Rosenblatt J, et al (2019)

Nitroglycerin-Citrate-Ethanol (NiCE) Catheter Lock Solution is Highly Effective for in vitro Eradication of Candida auris Biofilm.

Antimicrobial agents and chemotherapy pii:AAC.00299-19 [Epub ahead of print].

Candida auris poses emerging risks for causing severe central line associated bloodstream infections (CLABSIs). We tested in vitro, the ability of antifungal lock solutions to rapidly eradicate C. auris biofilms. Liposomal amphotericin B, amphotericin B deoxycholate, fluconazole, voriconazole, micafungin, caspofungin and anidulafungin failed to completely eradicate all ten tested C. auris biofilms. Conversely, nitroglycerin-citrate-ethanol (NiCE) catheter lock solution was able to completely eradicate all replicates for all C. auris biofilms tested.

RevDate: 2019-04-30

Perera M, Wijayarathna D, Wijesundera S, et al (2019)

Biofilm mediated synergistic degradation of hexadecane by a naturally formed community comprising Aspergillus flavus complex and Bacillus cereus group.

BMC microbiology, 19(1):84 pii:10.1186/s12866-019-1460-4.

BACKGROUND: The hydrophobic nature of hydrocarbons make them less bioavailable to microbes, generally leading to low efficiency in biodegradation. Current bioremediation strategies for hydrocarbon contamination, uses induced mixed microbial cultures. This in-vitro study demonstrates the utilization of naturally occurring communities in suitable habitats for achieving highly efficient, synergistic degradation of hydrocarbons in a simple community structure without additives.

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

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

CONCLUSIONS: This study demonstrates the utilization of naturally formed fungal-bacterial communities for enhanced biodegradation of hydrocarbons such as hexadecane and reports for the first time, synergistic degradation of hexadecane through biofilm formation, by a community comprising of Bacillus cereus group and Aspergillus flavus complex.

RevDate: 2019-04-29

Yonezawa H, Osaki T, Hojo F, et al (2019)

Effect of Helicobacter pylori biofilm formation on susceptibility to amoxicillin, metronidazole and clarithromycin.

Microbial pathogenesis pii:S0882-4010(19)30449-8 [Epub ahead of print].

The human gastric pathogen Helicobacter pylori forms biofilms in vitro and in vivo. We previously demonstrated that H. pylori biofilm formation in vitro decreased its susceptibility to clarithromycin (CAM). The aim of this study was to evaluate the effects of biofilm formation on amoxicillin (AMPC) and metronidazole (MNZ) susceptibility. In addition, we assessed the influence of biofilms of CAM resistant H. pylori on CAM susceptibility. It was shown that high levels of efflux pump gene transcripts were detected in biofilm cells of all H. pylori strains used in this study. H. pylori biofilm biomass was significantly decreased compared to initial biomass after treatment with the minimum inhibitory concentration (MIC) of AMPC. Similarly, the biofilm biomass of H. pylori decreased after treatment with MIC of MNZ, although the difference was not statistically significant. However, minimum bactericidal concentrations (MBCs) of AMPC or MNZ to biofilm cells were higher than those of planktonic cells. The biofilm biomasses of all of the CAM resistant strains were significantly decreased compared to initial biomass after treatment with 2x MIC of CAM. However, the viability of the CAM treated biofilm cells with 2x MIC of CAM was not significantly reduced compared to initial cell numbers with the exception of one strain. The viability of biofilm cells of all strains was higher than that of planktonic cells after treatment with various concentrations of CAM. These results indicate that biofilm cells were more resistant to these antibiotics than planktonic cells and that the assessment of the ability to form biofilms in H. pylori is important for eradication of this microorganism.

RevDate: 2019-04-29

Bernardi S, Continenza MA, Al-Ahmad A, et al (2019)

Streptococcus spp. and Fusobacterium nucleatum in tongue dorsum biofilm from halitosis patients: a fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) study.

The new microbiologica, 41(2): pii:496N089 [Epub ahead of print].

The present study involved a qualitative and quantitative evaluation of tongue dorsum biofilms sampled from halitosis patients and healthy volunteers. The aim of the study was to quantify the distribution of Streptococcus spp. and Fusobacterium nucleatum within the oral halitosis biofilm in order to highlight the role of these bacterial members in halitosis. Tongue plaque samples from four halitosis-diagnosed patients and four healthy volunteers were analyzed and compared. The visualization and quantification of the tongue dorsum biofilm was performed combining fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM). Eubacteria, Streptococcus spp. and Fusobacterium nucleatum were stained using specific fluorescent probes. For a comparison of the two tested biofilm groups the Wilcoxon rank-sum test was used. Morphological analysis by CLSM illustrated the distribution of the species which were tracked. Streptococcus spp. appeared to be enclosed within the samples and always associated to F. nucleatum. Furthermore, compared to the control group the biofilm within the halitosis group contained significantly higher proportions of F. nucleatum and Streptococcus spp., as revealed by the FISH and CLSM-analysis. The total microbial load and relative proportions of F. nucleatum and Streptococcus spp. can be considered as causative factors of halitosis and thus, as potential treatment targets.

RevDate: 2019-04-29

Danikowski KM, T Cheng (2019)

Colorimetric Analysis of Alkaline Phosphatase Activity in S. aureus Biofilm.

Journal of visualized experiments : JoVE.

Alkaline phosphatase (ALP) is a common enzyme expressed in both prokaryotic and eukaryotic cells. It catalyzes the hydrolysis of phosphate monoesters from many molecules at basic pH and plays an indispensable role in phosphate metabolism. In humans, eukaryotic ALP is one of the most frequently used enzymatic signals in diagnosing various diseases, such as cholestasis and rickets. In S. aureus, ALP is detected exclusively on the cell membrane; it is also expressed as a secretory form as well. Yet, little is known about its function in biofilm formation. The purpose of this manuscript is to develop a quick and reliable assay to measure ALP activity in S. aureus biofilm that does not require protein isolation. Using p-nitrophenyl phosphate (pNPP) as a substrate, we measured ALP activity in S. aureus biofilm formed in 96-well tissue culture plates. Activity was based on the formation of the soluble reaction product measured by 405 nm absorbance. The high throughput nature of the 96 well tissue culture plate method provides a sensitive and reproducible method for ALP activity assays. The same experimental set up can also be extended to measure other extracellular molecular markers related to biofilm formation.

RevDate: 2019-04-29

Benoit DSW, Sims KR, D Fraser (2019)

Nanoparticles for Oral Biofilm Treatments.

ACS nano [Epub ahead of print].

Pathogenic oral biofilms are universal, chronic, and costly. Despite advances in understanding the mechanisms of biofilm formation and persistence, novel and effective treatment options remain scarce. Nanoparticle-mediated eradication of the biofilm matrix and resident bacteria holds great potential. In particular, nanoparticles that target specific microbial and biofilm features utilizing nontoxic materials are well-suited for clinical translation. However, much work remains to characterize the local and systemic effects of therapeutic agents that are topically applied to chronic biofilms, such as those that cause dental caries. In this Perspective, we summarize the pathogenesis of oral biofilms, describe current and future nanoparticle-mediated treatment approaches, and highlight outstanding questions that are paramount to answer for effectively targeting and treating oral biofilms.

RevDate: 2019-04-29

Tuna T, Kuhlmann L, Bishti S, et al (2019)

Removal of simulated biofilm at different implant crown designs with interproximal oral hygiene aids. An in vitro study.

Clinical oral implants research [Epub ahead of print].

OBJECTIVES: To compare the removal of simulated biofilm at two different implant-supported restoration designs with various interproximal oral hygiene aids.

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

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

CONCLUSIONS: ACD allowed more removal of the artificial biofilm than CCD with Super floss, dental floss and interdental brush. Flossing and interproximal brushing were the most effective cleaning methods. A complete removal of the artificial biofilm could not be achieved in any group. This article is protected by copyright. All rights reserved.

RevDate: 2019-04-29

Bhatwalkar SB, Gound SS, Mondal R, et al (2019)

Anti-biofilm and Antibacterial Activity of Allium sativum Against Drug Resistant Shiga-Toxin Producing Escherichia coli (STEC) Isolates from Patient Samples and Food Sources.

Indian journal of microbiology, 59(2):171-179.

Escherichia coli (E. coli) colonizes human intestinal tract and is usually harmless to the host. However, several strains of E. coli have acquired virulent genes and could cause enteric diseases, urinary tract and even brain infections. Shiga toxin producing Escherichia coli (STEC) is an enterohaemorrhagic E. coli (EHEC) which can result in bloody diarrhoea and could potentially lead to deadly heamolytic uremic syndrome (HUS). STEC is one of the important food borne pathogens that causes food poisoning leading to diarrhoea and number of STEC outbreaks have occurred across the world. The use of standard antibiotics to treat STEC infection is not recommended as it increases the production of shiga toxin which could lead to HUS. Therefore, use of alternative approaches which include use of plant products to treat STEC infections have been gaining attention. The objective of this study was to evaluate the antibacterial and anti-biofilm activity of garlic (Allium sativum) against STEC strains isolated from various patient and food samples using in vitro assays. The microbiological isolation of STEC from various patient and food samples resulted in eight STEC isolates of which seven strains were multidrug resistant. Antibacterial assay results indicated that all the strains exhibited dose dependent sensitivity towards garlic with zone of inhibition diameters ranging from 7 to 24 mm with 15 µl of fresh garlic extract (FGE). Minimum inhibitory concentration (MIC) of FGE for isolates ranged from 30 to 140 µl/ml. Interestingly, the biofilm formation of all isolates in presence of 4% of FGE decreased by 35 to 59%. FTIR analysis indicated that treatment with 1% FGE results in compositional and content changes in the biofilm. In addition, the total carbohydrate content of biofilm was reduced by 40% upon 1% FGE treatment. The results of the present study report for the first time the antibacterial and anti-biofilm activity of garlic against STEC. The findings will enable development of novel garlic organosulfide based drugs for the prevention and treatment of STEC infections.

RevDate: 2019-04-28

Noverr MC, PL Fidel (Jr) (2019)

Questions remain regarding the presence of fungal species biofilm in women with vulvovaginal candidiasis.

RevDate: 2019-04-28

Daengngam C, Lethongkam S, Srisamran P, et al (2019)

Green fabrication of anti-bacterial biofilm layer on endotracheal tubing using silver nanoparticles embedded in polyelectrolyte multilayered film.

Materials science & engineering. C, Materials for biological applications, 101:53-63.

Endotracheal tubes (ETTs) are a common source of bacterial colonization, leading to ventilator-associated pneumonia (VAP). This research developed a biofilm-resistant ETT, following the principles of green chemistry. Using an aqueous layer-by-layer (LbL) technique, a thick polyelectrolyte multilayered film was deposited on a ventilation tube. The polyelectrolyte multilayered film accommodated silver nanoparticles (AgNPs) formed in situ by reducing Ag+ ions with Eucalyptus citriodora leaf extract. The multilayered film coating conformed to the curved surfaces of the ETT. Film thickness and silver content increased exponentially with the number of polyelectrolyte bilayer pairs, and a sufficiently high AgNPs content of 10-30%w/w was obtained at 75 to 125 bilayer films. Adhesion of the Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa was prevented by 99.9 and 99.99%, respectively, without cytotoxic effects against human lung epithelial cells (p < 0.05).

RevDate: 2019-04-27

Perez-Tanoira R, Aarnisalo A, Haapaniemi A, et al (2019)

Bacterial biofilm in salivary stones.

European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery pii:10.1007/s00405-019-05445-1 [Epub ahead of print].

PURPOSE: To assess the susceptibility of salivary stones to bacterial biofilm formation, which may be involved in the development of salivary gland infection, and to investigate a relation between microbiological aspects and patient characteristics.

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

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

CONCLUSIONS: Salivary stones are susceptible to bacterial biofilm formation, which could be related with the development and severity of the inflammation and the refractory nature of the disease. Sonication of salivary gland stones could be a useful method for finding the etiology of the chronic infection.

RevDate: 2019-04-27

Ostrov I, Sela N, Belausov E, et al (2019)

Adaptation of Bacillus species to dairy associated environment facilitates their biofilm forming ability.

Food microbiology, 82:316-324.

Biofilm-forming Bacillus species are often involved in contamination of dairy products and therefore present a major microbiological challenge in the field of food quality and safety. In this study, we sequenced and analyzed the genomes of milk- and non-milk-derived Bacillus strains, and evaluated their biofilm-formation potential in milk. Unlike non-dairy Bacillus isolates, the dairy-associated Bacillus strains were characterized by formation of robust submerged and air-liquid interface biofilm (pellicle) during growth in milk. Moreover, genome comparison analysis revealed notable differences in putative biofilm-associated determinants between the dairy and non-dairy Bacillus isolates, which correlated with biofilm phenotype. These results suggest that biofilm formation by Bacillus species might represent a presumable adaptation strategy to the dairy environment.

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ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

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In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

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Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

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In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

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

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