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19 Nov 2018 at 01:31
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Bibliography on: Biofilm


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

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Citations The Papers (from PubMed®)

RevDate: 2018-11-18

Sampaio AA, Souza SE, Ricomini-Filho AP, et al (2018)

Candida albicans Increases Dentine Demineralization Provoked by Streptococcus mutans Biofilm.

Caries research, 53(3):322-331 pii:000494033 [Epub ahead of print].

Streptococcus mutans are considered the most cariogenic bacteria, but it has been suggested that Candida albicans could increase their cariogenicity. However, the effect of this dual-species microorganisms' combination on dentine caries has not been experimentally evaluated. Biofilms of C. albicans, S. mutans and C. albicans + S. mutans (n = 12/biofilm) were grown in ultra-filtered tryptone yeast extract broth culture medium for 96 h on root dentine slabs of known surface hardness and exposed 8 times per day for 3 min to 10% sucrose. The medium was changed 2 times per day (after the 8 cariogenic challenges and after the overnight period of famine), and aliquots were analyzed to determinate the pH (indicator of biofilm acidogenicity). After 96 h, the biofilms were collected to determine the wet weight, colony-forming units, and the amounts of extracellular polysaccharides (soluble and insoluble). Dentine demineralization was assessed by surface hardness loss (% SHL). The architecture of the biofilms was analyzed by confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Data were analyzed by ANOVA followed by Tukey's test (α = 0.05). The dual-species C. albicans + S. mutans biofilm provoked higher % SHL on dentine (p < 0.05) than the S. mutans and C. albicans biofilm. This was supported by the results of biofilm acidogenicity and the amounts of soluble (6.4 ± 2.14 vs. 4.0 ± 0.94 and 1.9 ± 0.97, respectively) and insoluble extracellular polysaccharides (24.9 ± 9.22 vs. 18.9 ± 5.92 and 0.7 ± 0.48, respectively) (p < 0.05). The C. albicans biofilm alone presented low cariogenicity. The images by CLSM and TEM, respectively, suggest that the C. albicans + S. mutans biofilm is more voluminous than the S. mutans biofilm, and S. mutans cells interact with C. albicans throughout polysaccharides from the biofilm matrix. These findings show that C. albicans enhances the cariogenic potential of the S. mutans biofilm, increasing dentine demineralization.

RevDate: 2018-11-17

Rizzi A, Roy S, Bellenger JP, et al (2018)

Iron homeostasis in Bacillus subtilis requires siderophore production and biofilm formation.

Applied and environmental microbiology pii:AEM.02439-18 [Epub ahead of print].

Iron (Fe) is the most important metal in biology. Despite its abundance, Fe is mostly present under ferric form in soils, strongly limiting its bioavailability. To overcome the challenge of Fe acquisition, many microorganisms produce siderophores to retrieve Fe from natural sources. Another ubiquitous feature of bacteria in natural environments is biofilm formation. Previous studies showed that external Fe strongly influenced biofilm formation in several bacteria, suggesting that this microenvironment could play a mechanistic role in micronutrient acquisition for bacteria.Here, we apply a complementary set of analytical methods and deletion mutants to evaluate the role of biofilm formation, siderophore production, and their interaction, on Fe homeostasis in Bacillus subtilis We observed that Fe homeostasis, i.e. active growth at constant intracellular Fe concentration, requires both siderophore production and biofilm formation. Also, we report that in B. subtilis both biofilm formation and siderophore production are required to achieve active Fe acquisition from the medium, and to sustain normal growth. Furthermore, we provide evidences that the formation of biofilm slightly enhances the kinetics of Fe complexation by catechol siderophores and markedly improves siderophore use efficiency. These results provide new perspectives on the mechanism underlying siderophore-based acquisition of Fe in biofilm-forming bacteria.IMPORTANCE Iron acquisition is of fundamental importance for microorganisms, since this metal is generally poorly bioavailable in natural conditions. In the environment, most bacteria are found tightly packed within multicellular communities also named biofilms. Here, using the soil Gram-positive bacterium Bacillus subtilis, we show that biofilm formation and siderophores production, i.e. small molecules specifically binding metals, are both essential to ensure Fe uptake from the medium and maintain cellular iron homeostasis. The biofilm matrix appears to play an important role favoring the efficient usage of siderophores. Put together, our results demonstrate a close link between biofilm formation and iron acquisition in B. subtilis, allowing a better comprehension of how bacteria can cope with metal limitation in environmental conditions.

RevDate: 2018-11-17

Wang Z, Bai H, Lu C, et al (2019)

Light controllable chitosan micelles with ROS generation and essential oil release for the treatment of bacterial biofilm.

Carbohydrate polymers, 205:533-539.

Bacterial biofilms are widely associated with persistent infections and food contamination. High resistance to conventional antimicrobial agents resulted in an urgent need for novel formulation to eliminate these bacterial communities. Herein we fabricated light controllable chitosan micelles loading with thymol (T-TCP) for elimination of biofilm. Due to the exterior chitosan, T-TCP micelles easily bind to negative biofilm through electrostatic interaction and efficiently deliver the essential oil payloads. Under irradiation, T-TCP micelles generated ROS, which triggered simultaneous thymol release and also resulted in additional ROS-inducing bactericidal effects, both effectively eradicating biofilms of Listeria monocytogenes and Staphylococcus aureus. This formulation provided a platform for other water-insoluble antimicrobials and might be used as a potent and controllable solution to biofilm fighting.

RevDate: 2018-11-17

Al Akeel R, Mateen A, R Syed (2018)

An Alanine-Rich Peptide Attenuates Quorum Sensing-Regulated Virulence and Biofilm Formation in Staphylococcus aureus.

Journal of AOAC International [Epub ahead of print].

Background: Alanine-rich proteins/peptides (ARP), with bioactivity of up to 20 amino acid residues, can be observed by the body easily during gastrointestinal digestion. Objective:Populus trichocarpa extract's capability to attenuate quorum sensing-regulated virulence and biofilm formation in Staphylococcus aureus is described. Methods: PT13, an ARP obtained from P. trichocarpa, was tested for its activity against S. aureus using the broth microdilution test; a crystal-violet biofilm assay was performed under a scanning electron microscope. The production of various virulence factors was estimated with PT13 treatment. Microarray gene expression profiling of PT13-treated S. aureus was conducted and compared with an untreated control. Exopolysaccharides (EPS) was estimated to observe the PT13 inhibition activity. Results: PT13 was antimicrobial toward S. aureus at different concentrations and showed a similar growth rate in the presence and absence of PT13 at concentrations ≤8 μg/mL. Biofilm production was interrupted even at low concentrations, and biofilm-related genes were down-regulated when exposed to PT13. The genes encoding cell adhesion and bacterial attachment protein were the major genes suppressed by PT13. In addition, hemolysins, clumping activity, and EPS production of S. aureus decreased after treatment in a concentration-dependent manner. Conclusions: A long-chain PT13 with effective actions that, even at low concentration levels, not only regulated the gene expression in the producer organism but also blocked the virulence gene expression in this Gram-positive human pathogen is described. Highlights: We identified a PT13 as a potential antivirulence agent that regulated production of bacterial virulence determinants (e.g., toxins, enzymes and biofilm), downwards and it may be a promising anti-virulence agent to be further developed as an anti-infective agent.

RevDate: 2018-11-16

Bigelow TA, Thomas CL, Wu H, et al (2018)

Impact of High-Intensity Ultrasound on Strength of Surgical Mesh when Treating Biofilm Infections.

IEEE transactions on ultrasonics, ferroelectrics, and frequency control [Epub ahead of print].

The use of cavitation-based ultrasound histotripsy to treat infections on surgical mesh has shown great potential. However, any impact of the therapy on the mesh must be assessed before the therapy can be applied in the clinic. The goal of this study was to determine if the cavitation-based therapy would reduce the strength of the mesh thus compromising the functionality of the mesh. First, S. aureus biofilms were grown on surgical mesh samples and exposed to high-intensity ultrasound pulses. For each exposure, the effectiveness of the therapy was confirmed by counting the number of colony forming units (CFUs) on the mesh. Most of the exposed meshes had no CFUs with an average reduction of 5.4-log10 relative to the sham exposures. To quantify the impact of the exposure on mesh strength, the force required to tear the mesh and the maximum mesh expansion before damage were quantified for control, sham, and exposed mesh samples. There was no statistical difference between the exposed and sham/control mesh samples in terms of ultimate tensile strength and corresponding mesh expansion. The only statistical difference was with respect to mesh orientation relative to the applied load. The tensile strength increased by 1.36 N while the expansion was reduced by 1.33 mm between the different mesh orientations.

RevDate: 2018-11-15

Shin NR, JS Choi (2018)

Manual dexterity and dental biofilm accumulation in independent older adults without hand disabilities: a cross-sectional study.

Photodiagnosis and photodynamic therapy pii:S1572-1000(18)30256-4 [Epub ahead of print].

BACKGROUND: This study investigated the relationship between manual dexterity and dental biofilm accumulation in independent older Koreans using Quantitative Light-Induced Fluorescence-Digital (QLF-D).

METHODS: This cross-sectional study included 44 participants recruited from senior welfare facilities in South Korea and aged ≥ 65 years. Participants were surveyed using face-to-face structured interviews; manual dexterity was assessed using the Box and Blocks Test. To evaluate dental biofilm accumulation, the 528 surfaces of six index teeth were imaged using QLF-D and then quantified into Simple Plaque Scores (SPS) and ΔR20 values. The t-test and one-way analysis of variance were used to analyze differences in SPS and ΔR20 according to general characteristics and manual dexterity.

RESULTS: Those who brushed their teeth ≤ 2 times per day had higher SPS and ΔR20 values on the lingual surface of tooth #24 than those who brushed ≥ 3 times per day (p < 0.05). The low manual dexterity group had higher SPS on lingual surfaces of teeth #12, #24, and #32, as well as higher ΔR20 values on the lingual surfaces of teeth #12, #24, #32, and #44 (p < 0.05) than the normal group.

CONCLUSIONS: The low manual dexterity group had more dental biofilm-particularly on the lingual surfaces of teeth-and more mature biofilm than the normal group. These findings indicate that reduced manual dexterity could be a predictor of poor oral hygiene in independent older adults without hand disabilities. Therefore, we suggest manual dexterity be assessed in advance of dental biofilm assessment and tooth brushing instruction.

RevDate: 2018-11-15

Albano M, Crulhas BP, Alves FCB, et al (2018)

Antibacterial and anti-biofilm activities of cinnamaldehyde against S. epidermidis.

Microbial pathogenesis pii:S0882-4010(18)31606-1 [Epub ahead of print].

The search for new antimicrobial drugs has been necessary due to the increased bacterial resistance to antibiotics currently in use, and natural products play an important role in this field. The aim of this study was to evaluate the in vitro effect of cinnamaldehyde on S. epidermidis strains, biofilm set-up prevention, as well as its effect on pre-established biofilms. The minimum inhibitory concentration (MIC) ranged from 300 to 500 μg/mL, and the minimum bactericidal concentration (MBC) from 400 to 600 μg/mL. The biofilm inhibitory concentration and biofilm eradication concentration values were four-fold (clinical isolate) and eight-fold (ATCC strain) greater than the concentration required to inhibit planktonic growth. Sub-inhibitory concentrations of cinnamaldehyde attenuated biofilm formation of S. epidermidis strains on polystyrene microtiter plates. The combination of cinnamaldehyde and linezolid was able to inhibit S. epidermidis with a bactericidal effect. Further investigation of the mechanism of action of cinnamaldehyde revealed its effect on the cell membrane permeability, and confocal laser scanning microscopy (CLSM) images illustrated the impact of cinnamaldehyde in the detachment and killing of existing biofilms. Thereby, our data confirmed the ability of cinnamaldehyde to reduce bacterial planktonic growth of S. epidermidis, inhibiting biofilm formation and eradicating pre-formed biofilm.

RevDate: 2018-11-15

Uğur S, Akçelik N, Yüksel FN, et al (2018)

Effects of dam and seqA genes on biofilm and pellicle formation in Salmonella.

Pathogens and global health [Epub ahead of print].

In this study, the effects of dam and seqA genes on the formation of pellicle and biofilm was determined using five different Salmonella serovars S. Group C1 (DMC2 encoded), S. Typhimurium (DMC4 encoded), S. Virchow (DMC11 encoded), S. Enteritidis (DMC22 encoded), and S. Montevideo (DMC89 encoded). dam and seqA mutants in Salmonella serovars were performed by the single step lambda red recombination method. The mutants obtained were examined according to the properties of biofilm on the polystyrene surfaces and the pellicle formation on the liquid medium. As a result of these investigations, it was determined that the biofilm formation properties on polystyrene surfaces decreased significantly (p < 0.05) in all tested dam and seqA mutants, while the pellicle formation properties were lost in the liquid medium. When pBAD24 vector, containing the dam and seqA genes cloned behind the inducible arabinose promoter, transduced into dam and seqA mutant strains, it was determined that the biofilm formation properties on the polystyrene surfaces reached to the natural strains' level in all mutant strains. Also, the pellicle formation ability was regained in the liquid media. All these data demonstrate that dam and seqA genes play an important role in the formation of biofilm and pellicle structures in Salmonella serovars.

RevDate: 2018-11-15

Palmieri V, Bugli F, Cacaci M, et al (2018)

Graphene oxide coatings prevent Candida albicans biofilm formation with a controlled release of curcumin-loaded nanocomposites.

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

AIM: Fabrication of graphene oxide (GO)-based medical devices coatings that limit adhesion of Candida albicans, a main issue of healthcare-associated infections.

METHODS: The GO composites noncovalently functionalized with curcumin (CU), a hydrophobic molecule with active antimicrobial action, polyethylene glycol (PEG) that hinders the absorption of biomolecules or a combination of CU and PEG (GO-CU-PEG) were drop-casted on surfaces and antifungal efficacy was assessed.

RESULTS: We demonstrate that GO-CU-PEG coatings can reduce fungal adhesion, proliferation and biofilm formation. Furthermore, in an aqueous environment, surfaces release curcumin-PEG nanocomposites that have a minimum inhibitory concentration of 9.25 μg/ml against C. albicans.

CONCLUSION: Prevention of early cell adhesion and creation of a proximal environment unfavorable for growth make these GO-supported biomaterials attractive for innovative medical device manufacturing.

RevDate: 2018-11-15

de Macêdo Andrade AC, Rosalen PL, Freires IA, et al (2018)

Antifungal activity, mode of action, docking prediction and anti-biofilm effects of (+)-β-pinene enantiomers against Candida spp.

Current topics in medicinal chemistry pii:CTMC-EPUB-94558 [Epub ahead of print].

AIMS: The objective of this study was to investigate the effectiveness of (+)-β-pinene inhibition onCandida spp. growth,aiming at elucidation of the mechanism of action; to determinefungal cell enzymebinding activity (through molecular docking simulations) and its effects on biofilm reduction.

METHODOLOGY: Candidastrains (n=26)from referencedand clinical origins, eithersusceptible or resistant to standard clinical antifungals, were tested for determination of Minimum Inhibitory Concentration (MIC); Minimum Fungicidal Concentration (MFC); and microbial death curves upon treatment with (+)-β-pinene; the effects of (+)-β-pinene on the cell wall (sorbitol assay), membrane ergosterol binding, and effects on biofilm wereevaluatedby microdilution techniques. We also evaluated the interactions between (+)-β-pinene and cell wall and membrane enzymes of interest.

RESULTS: The MIC values of (+)-β-pinene ranged from <56.25 to 1800 µmol/L. The MIC of (+)-β-pinene did not increase when ergosterol was added to the medium, however it did increase in the presence of sorbitol, leading to a doubled MIC for C. tropicalis and C. krusei. The results of the molecular docking simulationsindicatedbetter interactionwith delta-14-sterol reductase (-51 kcal/mol). (+)-β-pinene presents anti-biofilm activity againstmultiples species of Candida.

CONCLUSION: (+)-β-pinene has antifungal activityand most likely acts throughinterference with the cell wall; through molecular interaction with Delta-14-sterol reductase and, to a lesser extent, with the 1,3-β-glucan synthase.This molecules was also found to effectively reduceCandida biofilm adhesion.

RevDate: 2018-11-15

Inaba T, Hori T, Aizawa H, et al (2018)

Microbiomes and chemical components of feed water and membrane-attached biofilm in reverse osmosis system to treat membrane bioreactor effluents.

Scientific reports, 8(1):16805 pii:10.1038/s41598-018-35156-2.

Reverse osmosis (RO) system at a stage after membrane bioreactor (MBR) is used for the wastewater treatment and reclamation. One of the most serious problems in this system is membrane fouling caused by biofilm formation. Here, microbiomes and chemical components of the feed water and membrane-attached biofilm of RO system to treat MBR effluents were investigated by non-destructive confocal reflection microscopy, excitation-emission fluorescence spectroscopy and high-throughput sequencing of 16S rRNA genes. The microscopic visualization indicated that the biofilm contained large amounts of microbial cells (0.5 ± 0.3~3.9 ± 2.3 µm3/µm2) and the extracellular polysaccharides (3.3 ± 1.7~9.4 ± 5.1 µm3/µm2) and proteins (1.0 ± 0.2~1.3 ± 0.1 µm3/µm2). The spectroscopic analysis identified the humic and/or fulvic acid-like substances and protein-like substances as the main membrane foulants. High-throughput sequencing showed that Pseudomonas spp. and other heterotrophic bacteria dominated the feed water microbiomes. Meanwhile, the biofilm microbiomes were composed of diverse bacteria, among which operational taxonomic units related to the autotrophic Hydrogenophaga pseudoflava and Blastochloris viridis were abundant, accounting for up to 22.9 ± 4.1% and 3.1 ± 0.4% of the total, respectively. These results demonstrated that the minor autotrophic bacteria in the feed water played pivotal roles in the formation of polysaccharide- and protein-rich biofilm on RO membrane, thereby causing membrane fouling of RO system.

RevDate: 2018-11-15

Suzuki I, Shimizu T, H Senpuku (2018)

Role of SCFAs for Fimbrillin-Dependent Biofilm Formation of Actinomyces oris.

Microorganisms, 6(4): pii:microorganisms6040114.

Actinomyces oris expresses type 1 and 2 fimbriae on the cell surface. Type 2 fimbriae mediate co-aggregation and biofilm formation and are composed of the shaft fimbrillin FimA and the tip fimbrillin FimB. Short-chain fatty acids (SCFAs) are metabolic products of oral bacteria, but the effects of exogenous SCFAs on FimA-dependent biofilm formation are poorly understood. We performed two types of biofilm formation assays using A. oris MG1 or MG1.ΔfimA to observe the effects of SCFAs on FimA-dependent biofilm formation in 96-well and six-well microtiter plates and a flow cell system. SCFAs did not induce six- and 16-hour biofilm formation of A. oris MG1 and MG1.ΔfimA in saliva-coated 96-well and six-well microtiter plates in which metabolites produced during growth were not excluded. However, 6.25 mM butyric acid and 3.125 mM propionic acid induced FimA-dependent biofilm formation and cell death in a flow cell system in which metabolites produced during growth were excluded. Metabolites produced during growth may lead to disturbing effects of SCFAs on the biofilm formation. The pure effects of SCFAs on biofilm formation were induction of FimA-dependent biofilm formation, but the stress responses from dead cells may regulate its effects. Therefore, SCFA may play a key role in A. oris biofilm formation.

RevDate: 2018-11-14

Rathnaweera SS, Rusten B, Korczyk K, et al (2018)

Novel biofilm reactor for denitrification of municipal wastewater.

Water science and technology : a journal of the International Association on Water Pollution Research, 78(7):1566-1575.

A pilot-scale CFIC® (continuous flow intermittent cleaning) reactor was run in anoxic conditions to study denitrification of wastewater. The CFIC process has already proven its capabilities for biological oxygen demand removal with a small footprint, less energy consumption and low cost. The present study focused on the applicability for denitrification. Both pre-denitrification (pre-DN) and post-denitrification (post-DN) were tested. A mixture of primary treated wastewater and nitrified wastewater was used for pre-DN and nitrified wastewater with ethanol as a carbon source was used for post-DN. The pre-DN process was carbon limited and removal rates of only 0.16 to 0.74 g NOx-N/m²-d were obtained. With post-DN and an external carbon source, 0.68 to 2.2 g NO3-Neq/m²-d removal rates were obtained. The carrier bed functioned as a good filter for both the larger particles coming with influent water and the bio-solids produced in the reactor. Total suspended solids removal in the reactor varied from 20% to 78% (average 45%) during post-DN testing period and 9% to 70% (average 29%) for pre-DN. The results showed that the forward flow washing improves both the DN function and filtration ability of the reactor.

RevDate: 2018-11-14

Stabb EV (2018)

Should they stay or should they go? Nitric oxide and the clash of regulators governing Vibrio fischeri biofilm formation.

Molecular microbiology [Epub ahead of print].

A key regulatory decision for many bacteria is the switch between biofilm formation and motile dispersal, and this dynamic is well illustrated in the light-organ symbiosis between the bioluminescent bacterium Vibrio fischeri and the Hawaiian bobtail squid. Biofilm formation mediated by the syp gene cluster helps V. fischeri transition from a dispersed planktonic lifestyle to a robust aggregate on the surface of the nascent symbiotic organ. However, the bacteria must then swim to pores and down into the deeper crypt tissues that they ultimately colonize. A number of positive and negative regulators control syp expression and biofilm formation, but until recently the environmental inputs controlling this clash between opposing regulatory mechanisms have been unclear. Thompson et al. have now shown that Syp-mediated biofilms can be repressed by a well known host-derived molecule: nitric oxide. This regulation is accomplished by the NO sensor HnoX exerting control over the biofilm regulator HahK. The discoveries reported here by Thompson et al. cast new light on a critical early stage of symbiotic initiation in the V. fischeri-squid model symbiosis, and more broadly it adds to a growing understanding of the role(s) that NO and HnoX play in biofilm regulation by many bacteria. This article is protected by copyright. All rights reserved.

RevDate: 2018-11-14

Liu J, Yang L, Hou Y, et al (2018)

Transcriptomics Study on Staphylococcus aureus Biofilm Under Low Concentration of Ampicillin.

Frontiers in microbiology, 9:2413.

Staphylococcus aureus is one of the representative foodborne pathogens which forms biofilm. Antibiotics are widely applied in livestock husbandry to maintain animal health and productivity, thus contribute to the dissemination of antimicrobial resistant livestock and human pathogens, and pose a significant public health threat. Effect of antibiotic pressure on S. aureus biofilm formation, as well as the mechanism, remains unclear. In this study, the regulatory mechanism of low concentration of ampicillin on S. aureus biofilm formation was elucidated. The viability and biomass of biofilm with and without 1/4 MIC ampicillin treatment for 8 h were determined by XTT and crystal violet straining assays, respectively. Transcriptomics analysis on ampicillin-induced and non-ampicillin-induced biofilms were performed by RNA-sequencing, differentially expressed genes identification and annotation, GO functional and KEGG pathway enrichment. The viability and biomass of ampicillin-induced biofilm showed dramatical increase compared to the non-ampicillin-induced biofilm. A total of 530 differentially expressed genes (DEGs) with 167 and 363 genes showing up- and down-regulation, respectively, were obtained. Upon GO functional enrichment, 183, 252, and 21 specific GO terms in biological process, molecular function and cellular component were identified, respectively. Eight KEGG pathways including "Microbial metabolism in diverse environments", "S. aureus infection", and "Monobactam biosynthesis" were significantly enriched. In addition, "beta-lactam resistance" pathway was also highly enriched. In ampicillin-induced biofilm, the significant up-regulation of genes encoding multidrug resistance efflux pump AbcA, penicillin binding proteins PBP1, PBP1a/2, and PBP3, and antimicrobial resistance proteins VraF, VraG, Dlt, and Aur indicated the positive response of S. aureus to ampicillin. The up-regulation of genes encoding surface proteins ClfB, IsdA, and SasG and genes (cap5B and cap5C) which promote the adhesion of S. aureus in ampicillin induced biofilm might explain the enhanced biofilm viability and biomass.

RevDate: 2018-11-13

Kelly de Oliveira Lopes L, de Melo Costa D, Veiga Tipple AF, et al (2018)

Surgical instruments complex design as barrier for cleaning effectiveness, favouring biofilm formation.

The Journal of hospital infection pii:S0195-6701(18)30587-5 [Epub ahead of print].

AIM: Determine the cumulative effect of 20 cycles of contamination, cleaning (manual or manual followed by automated) and steam sterilisation on high-complex-design reusable surgical instruments (RSI) used for orthopaedic surgery.

METHOD: New flexible medullary reamers and depth gauges were contaminated by soaking in tryptone soya broth, containing 5% sheep blood and 109CFU/mL of Staphylococcus aureus (ATCC 25923), for 5 minutes. To mimic a worse-case scenario, RSI were dried seven hours and subjected to either a) rinsing in distilled water, b) manual cleaning or c) manual plus automated cleaning (gold standard), and steam sterilisation. The contamination, cleaning and sterilisation cycle was repeated 20 times. Adenosine Triphosphate (ATP) was measured after cleaning procedures, while microbial load and residual protein were measured following the 10th and 20th reprocessing, in triplicate. Scanning electron microscopy (SEM) was used to confirm soil and biofilm presence on the RSI after the 20th reprocessing.

FINDINGS: Manual and manual plus automated cleaning significantly reduced the amount of ATP and protein residues for all RSI. Viable bacteria were not detected following sterilisation. However, SEM detected soil after automated cleaning, and soil, including biofilms, after manual cleaning.

CONCLUSION: Soil and/or biofilms were evident on complex-design RSI following 20 cycles of contamination and reprocessing, even using the gold standard method of cleaning. Although the depth gauges could be disassembled, biological residues and biofilm accumulated in its lumen. The current design of these RSI prevents removal of all biological soil and this may have an adverse effect on patient outcome.

RevDate: 2018-11-13

He J, Bao Y, Li J, et al (2018)

Nanocomplexes of Carboxymethyl Chitosan/Amorphous Calcium Phosphate Reduce Oral Bacteria Adherence and Biofilm Formation on Human Enamel Surface.

Journal of dentistry pii:S0300-5712(18)30393-2 [Epub ahead of print].

OBJECTIVES: This study investigated the effect of CMC/ACP on oral bacteria adherence and biofilm formation on the enamel surface as well as the underlying mechanism to determine the anti-cariogenic potential of CMC/ACP.

METHODS: A mineral solution of CMC/ACP was characterised by transmission electron microscope. The bactericidal activity of CMC/ACP was evaluated with the plate count method. An in vitro biofilm model was established on saliva-coated enamel blocks; the effect of CMC/ACP on the adherence of Streptococcus mutans and Streptococcus gordonii to and biofilm formation on these blocks, as well as co-aggregation of Fusobacterium nucleatum was assessed by scanning electron microscopy, crystal violet staining, and confocal microscopy. Bacterial surface charge was estimated with the cytochrome c binding assay and by zeta potential measurement.

RESULTS: CMC/ACP nanocomplexes inhibited S. mutans and S. gordonii adherence to enamel blocks by 90% and 86% (P < 0.01), respectively, and biofilm formation by 45% and 44% (P < 0.01), respectively, after 24 h without bactericidal activity. CMC/ACP reduced F. nucleatum attachment to streptococcal biofilm by 75% (P < 0.01) while also altering cytochrome c binding to bacteria and reducing the zeta potential of the bacterial suspension.

CONCLUSIONS: CMC/ACP nanocomplexes inhibit cariogenic bacterial adherence, co-adhesion, and biofilm formation on the enamel surface, possibly by altering bacterial surface charge and enhancing the flocculation effect. As an agent that promotes remineralisation and has anti-cariogenic effects, CMC/ACP can be used to prevent and treat early caries and white spot lesions.

RevDate: 2018-11-13

Qayyum S, Sharma D, Bisht D, et al (2018)

Identification of factors involved in Enterococcus faecalis biofilm under quercetin stress.

Microbial pathogenesis pii:S0882-4010(18)31037-4 [Epub ahead of print].

Enterococcus faecalis is a gram positive enteric commensal bacteria or opportunistic pathogen and its infection involves biofilm formation. Quercetin, a plant origin polyphenol was found to inhibit E. faecalis biofilm. Crystal violet assay, SEM and CLSM microscopy confirmed biofilm inhibition by quercetin. Proteomics was used to elucidate the changes occurred in bacterial cell by quercetin treatment. 2D-Electrophorosis and MALDI-TOF analysis revealed that nineteen proteins were differentially expressed in quercetin treated sample. Glycolytic pathways, protein translation-elongation pathways and protein folding pathways were under differential expression after treatment. Real Time-PCR (RT-PCR) validated the proteomic data at genomic level except for the translation elongation factor G which showed opposite data to proteomics. Protein-protein interaction networks constructed using STRING 10.0 demonstrated strong connection of translation-elongation proteins with many important proteins. The results of the comparative analysis indicate that quercetin exerts its inhibitory effect by disturbing glycolytic, protein translation-elongation and protein folding pathways. This disturbs bacterial physiology and stops transition of planktonic cells to biofilm state.

RevDate: 2018-11-13

Singh P, Pandit S, Beshay M, et al (2018)

Anti-biofilm effects of gold and silver nanoparticles synthesized by the Rhodiola rosea rhizome extracts.

Artificial cells, nanomedicine, and biotechnology [Epub ahead of print].

Bacterial biofilm represents a major problem in medicine. They colonize and damage medical devices and implants and, in many cases, foster development of multidrug-resistant microorganisms. Biofilm development starts by bacterial attachment to the surface and the production of extracellular polymeric substances (EPS). The EPS forms a structural scaffold for dividing bacterial cells. The EPS layers also play a protective role, preventing the access of antibiotics to biofilm-associated microorganisms. The aim of this work was to investigate the production nanoparticles that could be used to inhibit biofilm formation. The applied production procedure from rhizome extracts of Rhodiola rosea is simple and environmentally friendly, as it requires no additional reducing, stabilizing and capping agents. The produced nanoparticles were stable and crystalline in nature with an average diameter of 13-17 nm for gold nanoparticles (AuNPs) and 15-30 nm for silver nanoparticles (AgNPs). Inductively coupled plasma mass spectrometry analysis revealed the concentration of synthesized nanoparticles as 3.3 and 5.3 mg/ml for AuNPs and AgNPs, respectively. Fourier-transform infrared spectroscopy detected the presence of flavonoids, terpenes and phenols on the nanoparticle surface, which could be responsible for reducing the Au and Ag salts to nanoparticles and further stabilizing them. Furthermore, we explored the AgNPs for inhibition of Pseudomonas aeruginosa and Escherichia coli biofilms. AgNPs exhibited minimum inhibitory concentrations of 50 and 100 µg/ml, against P. aeruginosa and E. coli, respectively. The respective minimum bactericidal concentrations were 100 and 200 µg/ml. These results suggest that using the rhizome extracts of the medicinal plant R. rosea represents a viable route for green production of nanoparticles with anti-biofilm effects.

RevDate: 2018-11-13

Tahir S, Chowdhury D, Legge M, et al (2018)

Transmission of Staphylococcus aureus from dry surface biofilm (DSB) via different types of gloves.

Infection control and hospital epidemiology pii:S0899823X18002854 [Epub ahead of print].

BACKGROUND: Pathogens can survive for extended periods when incorporated into biofilm on dry hospital surfaces (ie, dry-surface biofilm, DSB). Bacteria within biofilm are protected from desiccation and have increased tolerance to cleaning agents and disinfectants.

OBJECTIVE: We hypothesized that gloved hands of healthcare personnel (HCP) become contaminated with DSB bacteria and hence may transmit bacteria associated with healthcare-associated infections (HAIs).

METHOD: Staphylococcus aureus DSB was grown in vitro on coupons in a bioreactor over 12 days with periodic nutrition interspersed with long periods of dehydration. Each coupon had ~107 DSB bacterial cells. Transmission was tested with nitrile, latex, and surgical gloves by gripping DSB-covered coupons then pressing finger tips onto a sterile horse blood agar surface for up to 19 consecutive touches and counting the number of colony-forming units (CFU) transferred. Coupons were immersed in 5% neutral detergent to simulate cleaning, and the experiment was repeated.

RESULTS: Bacterial cells were readily transmitted by all 3 types of gloves commonly used by HCP. Surprisingly, sufficient S. aureus to cause infection were transferred from 1 DSB touch up to 19 consecutive touches. Also, 6 times more bacteria were transferred by nitrile and surgical gloves than to latex gloves (P <.001). Treating the DSB with 5% neutral detergent increased the transmission rate of DSB bacteria 10-fold.

CONCLUSION: Staphylococcus aureus incorporated into environmental DSB and covered by extracellular polymeric substances readily contaminates gloved hands and can be transferred to another surface. These results confirm the possibility that DSB contributes to HAI acquisition.

RevDate: 2018-11-13

Wu Y, Ma Y, Xu T, et al (2018)

Nicotine Enhances Staphylococcus epidermidis Biofilm Formation by Altering the Bacterial Autolysis, Extracellular DNA Releasing, and Polysaccharide Intercellular Adhesin Production.

Frontiers in microbiology, 9:2575.

Staphylococcus epidermidis is a common bacterial colonizer of human skin and mucous membranes, yet it has emerged as an important nosocomial pathogen largely due to its ability to form biofilms. Tobacco smoke has been demonstrated as a contributor to various infection diseases by improving the biofilm formation of multiple bacterial species; however, the association between tobacco smoke and S. epidermidis biofilm is still unclear. In this study, we tested the effect of nicotine, one of the most active components of tobacco, on S. epidermidis biofilm formation, and we studied the underlying mechanisms. Our results showed that nicotine promoted the biofilm formation of S. epidermidis 1457 strain (SE1457) and enhanced its initial attachment to a polyethylene surface as well as polysaccharide intercellular adhesin (PIA) production. In addition, an increased extracellular DNA release and a higher autolysis rate of SE1457 was detected after nicotine treatment, which was consistent with the increased ratio of dead cells in nicotine-treated SE1457 biofilm observed with confocal laser-scanning microscopy. Furthermore, the effect of nicotine on several autolysis-related and biofilm-related gene knockout mutants of SE1457 was tested. It showed that in ΔsaeRS, ΔlytSR, and ΔsceD, nicotine induced increase in biofilm formation was similar to that in SE1457; but in ΔarlRS, ΔatlE, and ΔicaC, the effect was obviously impaired. Consistently, the increase of the bacterial autolysis rate in ΔarlRS and ΔatlE induced by nicotine was not as significant as that in SE1457. Meanwhile, the growth inhibition of nicotine on SE1457 was observed, and it was much less on ΔarlRS and restored by the arlRS complementation. The arlRS transcription in SE1457 was inhibited by nicotine during cultivation as indicated by a promoter reporter assay using green fluoresent protein. Taken together, our study indicates that nicotine improves S. epidermidis biofilm formation by promoting its initial attachment and intercellular accumulation; the arlRS, atlE, and ica genes mediating bacterial autolysis and PIA production play an important role in this process.

RevDate: 2018-11-12

Zeng Y, Nikitkova A, Abdelsalam H, et al (2018)

Activity of quercetin and kaemferol against Streptococcus mutans biofilm.

Archives of oral biology, 98:9-16 pii:S0003-9969(18)30444-8 [Epub ahead of print].

OBJECTIVE: Nidus Vespae (NV) is the honeycomb of Polistes Olivaceous, P. Japonicus Saussure, and Parapolybiavaria Fabricius. Previously, we have shown the extract and chemical fractions from NV demonstrated remarkable capacities of inhibiting the acid production of oral bacteria at sub-minimum inhibitory concentration (MIC) concentrations. In searching the most potent anti-caries compounds in NV, we further separated the NV Chl/MeOH fraction and obtained two purified compounds: quercetin and kaemferol. The objective of this study was to assess the effectiveness of quercetin and kaemferol against S. mutans biofilm formation.

METHODS: The MIC, minimum biofilm inhibition concentration (MBIC50) and minimum biofilm reduction concentration (MBRC50) against Streptococcus mutans were examined for NV-derived of quercetin and kaemferol. The effectiveness of inhibiting S. mutans biofilm formation was further examined using in vitro biofilm model.

RESULTS: Both quercetin and kaemferol compounds demonstrated anti-biofilm activities when compared to the negative control. They are capable of reducing biofilm dry-weight, total protein, viable cells measured by colony forming unit (CFU), insoluble and soluble glucans formation. The in situ culture pH was less acidic when the biofilms were treated by quercetin and kaemferol. The quercetin and kaemferol demonstrated comparable capability of S. mutans killing in biofilms, compared to chlorhexidine.

CONCLUSIONS: The results of this study showed inhibitory activity of quercetin and kaemferol against S. mutans biofilms, suggesting that quercetin and kaemferol might be considered as alternative anti-caries agents in searching novel anti-caries therapeutics.

RevDate: 2018-11-12

Pilz M, Staats K, Tobudic S, et al (2018)

Zirconium Nitride Coating Reduced Staphylococcus epidermidis Biofilm Formation on Orthopaedic Implant Surfaces: An In Vitro Study.

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

BACKGROUND: One of the most commonly identified pathogens responsible for orthopaedic implant infection is Staphylococcus epidermidis, which can form biofilms on surfaces. Currently, orthopaedic implants made of various surface materials are available, each with features influencing osseointegration, biocompatibility, and adherence of bacteria to the surface, which is the first step in biofilm formation. The aim of this experimental study was to investigate the effect of a high tribologic-resistant 2.5-µm zirconium nitride top coat on an antiallergic multilayer ceramic-covered cobalt-chromium-molybdenum surface on the formation of S. epidermidis biofilm compared with other commonly used smooth and rough orthopaedic implant surface materials.

QUESTIONS/PURPOSES: (1) When evaluating the surfaces of a cobalt-chromium-molybdenum (CoCrMo) alloy with a zirconium (Zr) nitride coating, a CoCrMo alloy without a coating, titanium alloy, a titanium alloy with a corundum-blasted rough surface, and stainless steel with a corundum-blasted rough surface, does a Zr coating reduce the number of colony-forming units of S. epidermidis in an in vitro setting? (2) Is there quantitatively less biofilm surface area on Zr-coated surfaces than on the other surfaces tested in this in vitro model?

METHODS: To determine bacterial adhesion, five different experimental implant surface discs were incubated separately with one of 31 different S. epidermidis strains each and subsequently sonicated. Twenty test strains were obtained from orthopaedic patients undergoing emergency hip prosthesis surgeries or revision of implant infection and 10 further strains were obtained from the skin of healthy individuals. Additionally, one reference strain, S. epidermidis DSM 3269, was tested. After serial dilutions, the number of bacteria was counted and expressed as colony-forming units (CFUs)/mL. For biofilm detection, discs were stained with 0.1% Safranin-O for 15 minutes, photographed, and analyzed with computer imaging software.

RESULTS: The lowest bacterial count was found in the CoCrMo + Zr surface disc (6.6 x 10 CFU/mL ± 4.6 x 10 SD) followed by the CoCrMo surface (1.1 x 10 CFU/mL ± 1.9 x 10 SD), the titanium surface (1.36 x 10 CFU/mL ± 1.8 x 10 SD), the rough stainless steel surface (2.65 x 10 CFU/mL ± 3.8 x 10 SD), and the rough titanium surface (2.1 x 10 CFU/mL ± 3.0 x 10 SD). The mean CFU count was lower for CoCrMo + Zr discs compared with the rough stainless steel surface (mean difference: 2.0 x 10, p = 0.021), the rough titanium alloy surface (mean difference: 1.4 x 10, p = 0.002), and the smooth titanium surface (mean difference: 7.0 x 10, p = 0.016). The results of biofilm formation quantification show that the mean covered area of the surface of the CoCrMo + Zr discs was 19% (± 16 SD), which was lower than CoCrMo surfaces (35% ± 23 SD), titanium alloy surface (46% ± 20 SD), rough titanium alloy surface (66% ± 23 SD), and rough stainless steel surface (58% ± 18 SD).

CONCLUSIONS: These results demonstrate that a multilayer, ceramic-covered, CoCrMo surface with a 2.5-µm zirconium nitride top coat showed less S. epidermidis biofilm formation compared with other surface materials used for orthopaedic implants.

CLINICAL RELEVANCE: CoCrMo with a 2.5-µm zirconium nitride top coat seems to be a promising surface modification technology able to reduce bacterial attachment on the surface of an implant and, hence, may further prevent implant infection with S. epidermidis biofilm formation.

RevDate: 2018-11-12

Jin X, IH Riedel-Kruse (2018)

High-resolution Patterned Biofilm Deposition Using pDawn-Ag43.

Journal of visualized experiments : JoVE.

Spatial structure and patterning play an important role in bacterial biofilms. Here we demonstrate an accessible method for culturing E. coli biofilms into arbitrary spatial patterns at high spatial resolution. The technique uses a genetically encoded optogenetic construct-pDawn-Ag43-that couples biofilm formation in E. coli to optical stimulation by blue light. We detail the process for transforming E. coli with pDawn-Ag43, preparing the required optical set-up, and the protocol for culturing patterned biofilms using pDawn-Ag43 bacteria. Using this protocol, biofilms with a spatial resolution below 25 μm can be patterned on various surfaces and environments, including enclosed chambers, without requiring microfabrication, clean-room facilities, or surface pretreatment. The technique is convenient and appropriate for use in applications that investigate the effect of biofilm structure, providing tunable control over biofilm patterning. More broadly, it also has potential applications in biomaterials, education, and bio-art.

RevDate: 2018-11-12

Butini ME, Gonzalez Moreno M, Czuban M, et al (2018)

Real-Time Antimicrobial Susceptibility Assay of Planktonic and Biofilm Bacteria by Isothermal Microcalorimetry.

Advances in experimental medicine and biology [Epub ahead of print].

Most antimicrobials currently used in the clinical practice are tested as growth inhibitors against free-floating microorganisms in a liquid suspension, rather than against sessile cells constituting biofilms. Hence, reliable, fast, and reproducible methods for assessing biofilm susceptibility to antimicrobials are strongly needed. Isothermal microcalorimetry (IMC) is a nondestructive sensitive technique that allows for the real-time monitoring of microbial viability in the presence or absence of antimicrobial compounds. Therefore, the efficacy of specific antimicrobials, alone or in combination, may be promptly validated supporting the development of new drugs and avoiding the administration of ineffective therapies. Furthermore, the susceptibility of both planktonic and biofilm cells to antimicrobials can be conveniently assessed without the need for elaborated staining procedures and under nontoxic working conditions. Quantitative data regarding the antimicrobial effect against different strains might be collected by monitoring the microbial cell replication, and, more importantly, a dose-dependent activity can be efficiently detected by measuring the delay and decrease in the heat flow peak of the treated samples. A limitation of IMC for anti-biofilm susceptibility test is the inability to directly quantify the non-replicating cells in the biofilm or the total biomass. However, as IMC is a nondestructive method, the samples can be also analyzed by using different techniques, acquiring more information complementary to calorimetric data. IMC finds application also for the investigation of antibiotic eluting kinetics from different biomaterials, as well as for studying bacteriophages activity against planktonic and biofilm bacteria. Thus, the wide applicability of this ultra-sensitive and automated technique provides a further advance in the field of clinical microbiology and biomedical sciences.

RevDate: 2018-11-10

da Silva PM, Baldry M, Peng P, et al (2018)

Punica granatum sarcotesta lectin (PgTeL) impairs growth, structure, viability, aggregation, and biofilm formation ability of Staphylococcus aureus clinical isolates.

International journal of biological macromolecules pii:S0141-8130(18)35347-9 [Epub ahead of print].

In this work, we evaluated the ability of Punica granatum sarcotesta lectin (PgTeL) to impair the growth and viability of the Staphylococcus aureus clinical isolates 8325-4 (non-resistant) and LAC USA300 (MRSA strain). The effects of this lectin on aggregating, hemolytic activity, biofilm-forming ability, and expression of virulence genes (hla, rnaIII, and spa) were also investigated. PgTeL showed antibacterial activity against 8325-4 and LAC USA300 strains by interfering with both the growth (MIC50 of 6.25 and 12.5 μg/mL, respectively) and survival (MBC values of 25.0 and 50.0 μg/mL). Culture growth started only at the ninth (8325-4) and tenth (LAC USA300) hour in the presence of PgTeL at MIC50, while growth was detected since the first hour in the control. The lectin caused markedly altered cell morphology in both the strains. Although, at the MIC50, PgTeL caused structural alterations, most cells were still viable, while at the MBC it promoted cell injury and death. PgTeL showed anti-aggregation effect and exhibited antibiofilm activity against both the isolates. However, the lectin did not interfere with the hemolytic activity of LAC USA300 and with the expression of hla, rnaIII, and spa genes. In conclusion, PgTeL is a lectin with multiple inhibitory effects on S. aureus clinical isolates.

RevDate: 2018-11-09

Stenhagen ISR, Rukke HV, Dragland IS, et al (2018)

Effect of methacrylated chitosan incorporated in experimental composite and adhesive on mechanical properties and biofilm formation.

European journal of oral sciences [Epub ahead of print].

The lifespan of a resin-based restoration is limited, with the main reason for failure being secondary caries. Biofilm formation at the tooth-material interface is a necessary etiological agent for caries development. Dental materials with antimicrobial properties may reduce formation of biofilm and thus increase the longevity of restorations. This study aimed to investigate the effect of methacrylated chitosan (CH-MA), incorporated into the polymeric network of an experimental dental composite and adhesive, on biofilm growth of Streptococcus mutans and to assess the mechanical properties of the modified materials. The methacrylation of low-molecular-weight chitosan was achieved and biofilm studies confirmed the antibacterial effect of the modified polymer in solution. Methacrylated chitosan was incorporated into an experimental composite and adhesive, and the modified materials reduced the formation of S. mutans biofilm. The incorporation of CH-MA did not alter the bond strength of the adhesives. However, the amount of CH-MA in composite that is required to elicit an antibacterial response challenges the mechanical properties of the material. The hardness and flexural strength of the composite decreased with increasing amounts of CH-MA. However, flexural strength values still met the requirement in the ISO standard.

RevDate: 2018-11-09

Zayed MF, Ibrahim SRM, Habib EE, et al (2018)

Design, synthesis, antimicrobial and anti-biofilm evaluation, and molecular docking of new substituted fluoroquinazolinones.

Medicinal chemistry (Shariqah (United Arab Emirates)) pii:MC-EPUB-94379 [Epub ahead of print].

BACKGROUND: Quinazolines and quinazolinones derivatives are well known for their important range of therapeutic activities.

OBJECTIVE: Synthesis of some derivatives of substituted fluoroquinazolinones based on structure-based design and evaluation of their antibacterial, antifungal, and anti-biofilm activities.

METHOD: Compounds were chemically synthesized by conventional methods. Structures were established on the basis of spectral and elemental analyses. Antimicrobial potential was tested against various microorganisms using the agar disc-diffusion method. MIC and MBC as well as anti-biofilm activity for the highly active compounds were assessed. Moreover, the computational studies were performed using Auto dock free software package (version 4.0) to explain the predicted mode of binding.

RESULT: All derivatives (5-8), (10a-g), and (A-H) were biologically tested and showed significant antimicrobial activity comparable to the reference compounds. Compounds 10b, 10c, and 10d had a good MIC and MBC against Gram-positive bacteria, whereas 10b and 10d showed significant MIC and MBC against Gram-negative bacteria. However, compounds E and F exhibited good MIC and MBC against fungi. Compound 10c and 8 exhibited significant anti-biofilm activity towards S. aureus and M. luteus. Molecular docking study revealed a strong binding of these derivatives with their receptor-site and detected their predicted mode of binding.

CONCLUSION: The synthesized derivatives showed promising antibacterial, antifungal, and anti-biofilm activities. Modeling study explained their binding mode and showed strong binding affinity with their receptor-site. The highly active compounds 5 and 10c could be subjected to future optimization and investigation to be effective antimicrobial agents.

RevDate: 2018-11-09

Yan PF, Yuan S, Wang W, et al (2018)

Efficiency of sequential UV/H2O2 and biofilm process for the treatment of secondary effluent.

Environmental science and pollution research international pii:10.1007/s11356-018-3606-6 [Epub ahead of print].

In response to the shortage of water resources, multiple processes have been applied to turn wastewater secondary effluent (SE) into potable water. However, trace organic contaminants (TOrCs) and high concentrations of organic matter contained in SE pose a significant challenge to the reclamation. In this manuscript, combined UV-based and biofilm processes were used to treat the SE spiked with ibuprofen (IBU) and clofibric acid (CA). The efficiency of these sequential treatments was characterized in terms of changes in dissolved organic carbon (DOC), absorbance at 254 nm (A254), fluorescence excitation-emission matrix (FEEM), the concentration of IBU and CA, and molecular weight of SE. Parallel factor (PARAFAC) was applied as the analysis method for FEEM of the samples and two fluorescent components were successfully identified: humic-like substances (C1) and protein-like matter (C2). Large reductions in A254, C1, C2, IBU, and CA were observed during the UV-based processes, especially with the addition of H2O2. Nearly 50% of A254, 80% of the component C1 were decreased and almost complete removal of the component C2 and TOrCs was achieved by UV/2.0 mM H2O2 after 90-min treatment. During the oxidation processes, the formation of lower molecular weight (LMW) compounds was detected, and the biodegradability of the organic matters was greatly increased. Although no significant DOC reduction was obtained in UV-based processes, an obvious further DOC reduction (30~60%) was achieved by biofilm treatment following UV-based processes, especially after UV/H2O2 treatments. In the meantime, large amounts of LMW were removed in the biofilm treatment process. This manuscript provides an effective advanced treatment of SE for the removal of DOC and TOrCs, facilitating the wastewater reclamation.

RevDate: 2018-11-09

Husain FM, Ahmad I, Khan FI, et al (2018)

Seed Extract of Psoralea corylifolia and Its Constituent Bakuchiol Impairs AHL-Based Quorum Sensing and Biofilm Formation in Food- and Human-Related Pathogens.

Frontiers in cellular and infection microbiology, 8:351.

The emergence of multi-drug resistance in pathogenic bacteria in clinical settings as well as food-borne infections has become a serious health concern. The problem of drug resistance necessitates the need for alternative novel therapeutic strategies to combat this menace. One such approach is targeting the quorum-sensing (QS) controlled virulence and biofilm formation. In this study, we first screened different fractions of Psoralea corylifolia (seed) for their anti-QS property in the Chromobacterium violaceum 12472 strain. The methanol fraction was found to be the most active fraction and was selected for further bioassays. At sub-inhibitory concentrations, the P. corylifolia methanol fraction (PCMF) reduced QS-regulated virulence functions in C. violaceum CVO26 (violacein); Pseudomonas aeruginosa (elastase, protease, pyocyanin, chitinase, exopolysaccharides (EPS), and swarming motility), A. hydrophila (protease, EPS), and Serratia marcescens (prodigiosin). Biofilm formation in all the test pathogens was reduced significantly (p ≤ 0.005) in a concentration-dependent manner. The β-galactosidase assay showed that the PCMF at 1,000 μg/ml downregulated las-controlled transcription in PAO1. In vivo studies with C. elegans demonstrated increased survival of the nematodes after treatment with the PCMF. Bakuchiol, a phytoconstituent of the extract, demonstrated significant inhibition of QS-regulated violacein production in C. violaceum and impaired biofilm formation in the test pathogens. The molecular docking results suggested that bakuchiol efficiently binds to the active pockets of LasR and RhlR, and the complexes were stabilized by several hydrophobic interactions. Additionally, the molecular dynamics simulation of LasR, LasR-bakuchiol, RhlR, and RhlR-bakuchiol complexes for 50 ns revealed that the binding of bakuchiol to LasR and RhlR was fairly stable. The study highlights the anti-infective potential of the PCMF and bakuchiol instead of bactericidal or bacteriostatic action, as the extract targets QS-controlled virulence and the biofilm.

RevDate: 2018-11-08

Liao K, Bai Y, Huo Y, et al (2018)

Use of convertible flow cells to simulate the impacts of anthropogenic activities on river biofilm bacterial communities.

The Science of the total environment, 653:148-156 pii:S0048-9697(18)34262-1 [Epub ahead of print].

Bacterial attachment to surfaces and the development of biofilms are crucial processes during the self-purification of polluted rivers. Biofilm bacterial communities also are a potential indicator of the human impact on an aquatic system. Here, we used indoor reactors with 7.7 cm3 transparent convertible flow cells to observe the formation of biofilms in river water from different land-use areas (i.e., an undisturbed mountainous area, a wastewater-discharge urban area, and a pesticide-fertilizer applied agricultural area). We then compared the bacterial biomass, composition, and function among the formed biofilms and explored whether the biofilm bacterial communities formed in polluted river water (urban area) could shift to those formed in unpolluted water (mountainous area) after simulating water-body remediation. After 60 d of indoor biofilm cultivation, the biofilms formed with the three types of influent were markedly different. Anthropogenic activities (e.g., wastewater discharge and pesticide-fertilizer use) facilitated biofilm bacterial production and the metabolic rate and altered the composition and metabolic patterns of the biofilm bacterial communities. After switching from an urban water to mountainous water influent in the same reactor, the biofilm bacterial communities that initially formed in the polluted discharge did not shift to that formed in unpolluted water. This result indicated that even after water remediation, the composition of the river biofilm bacterial community would not recover to a community like that observed under non-polluted conditions. Our study highlights possible issues related to current pollution-remediation routines and emphasizes the importance of sustainable anthropogenic activities within river basins.

RevDate: 2018-11-08

Ebersole JL, Peyyala R, OA Gonzalez (2018)

Biofilm Induced Profiles of Immune Response Gene Expression by Oral Epithelial Cells.

Molecular oral microbiology [Epub ahead of print].

OBJECTIVE: This study examined the oral epithelial immunotranscriptome response patterns modulated by oral bacterial planktonic or biofilm challenge METHODS: We assessed gene expression patterns when epithelial cells were challenged with a multispecies biofilm composed of S. gordonii, F. nucleatum, and P. gingivalis representing a type of periodontopathic biofilm compared to challenge with the same species of planktonic bacteria RESULTS: Of the 579 human immunology genes, a substantial signal of the epithelial cells was observed to 181 genes. Biofilm challenged stimulated significant elevations compared to planktonic bacteria for IL32, IL8, CD44, B2M, TGFBI, NFKBIA, IL1B, CD59, IL1A, CCL20 representing the top 10 signals comprising 55% of the overall signal for the epithelial cell responses. Levels of PLAU, CD9, IFITM1, PLAUR, CD24, TNFSF10, and IL1RN were all elevated by each of the planktonic bacterial challenge versus the biofilm responses. While the biofilms upregulated 123/579 genes (>2-fold), fewer genes were increased by the planktonic species [36 (S. gordonii), 30 (F. nucleatum), 44 (P. gingivalis)] CONCLUSIONS: A wide array of immune genes were regulated by oral bacterial challenge of epithelial cells that would be linked to the local activity of innate and adaptive immune response components in the gingival tissues. Incorporating bacterial species into a structured biofilm dramatically altered the number and level of genes expressed. Additionally a specific set of genes were significantly decreased with the multispecies biofilms suggesting that some epithelial cell biologic pathways are down-regulated when in contact with this type of pathogenic biofilm. This article is protected by copyright. All rights reserved.

RevDate: 2018-11-08

Das T, Das MC, Das A, et al (2018)

Modulation of S. aureus and P. aeruginosa biofilm: an in vitro study with new coumarin derivatives.

World journal of microbiology & biotechnology, 34(11):170 pii:10.1007/s11274-018-2545-1.

Coumarin is an important heterocyclic molecular framework of bioactive molecules against broad spectrum pathological manifestations. In the present study 18 new coumarin derivatives (CDs) were synthesized and characterized for antibiofilm activity against two model bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. It was observed that all the CDs executed significant effect in moderating activities against both planktonic and biofilm forms of these selected bacteria. Hence, to interpret the underlying probable reason of such antibiofilm effect, in-silico binding study of CDs with biofilm and motility associated proteins of these organisms were performed. All CDs have shown their propensity for occupying the native substrate binding pocket of each protein with moderate to strong binding affinities. One of the CDs such as CAMN1 showed highest binding affinity with these proteins. Interestingly, the findings of in-silico studies coincides the experimental results of antibiofilm and motility affect of CDs against both S. aureus and P. aeruginosa. Moreover, in-silico studies suggested that the antibiofilm activity of test CDs may be due to the interference of biofilm and motility associated proteins of the selected model organisms (PilT from P. aeruginosa and TarK, TarO from S. aureus). The detailed synthesis, characterization, methodology and results of biological screening along with computational studies have been reported. This study could be of greater interest in the context of the development of new anti-bacterial agent in the future.

RevDate: 2018-11-08

Ali SS, Kenawy ER, Sonbol FI, et al (2018)

Pharmaceutical Potential of a Novel Chitosan Derivative Schiff Base with Special Reference to Antibacterial, Anti-Biofilm, Antioxidant, Anti-Inflammatory, Hemocompatibility and Cytotoxic Activities.

Pharmaceutical research, 36(1):5 pii:10.1007/s11095-018-2535-x.

PURPOSE: Chitosan and its derivatives possess several unique properties relevant in the field of pharmaceutics and medicinal chemistry. This study aimed to evaluate the pharmaceutical performance of an innovative chitosan derivative, methyl acrylate chitosan bearing p-nitrobenzaldehyde (MA*CS*pNBA) Schiff base.

METHODS: The antibacterial activity of MA*CS*pNBA was tested against multi-drug resistant (MDR) Gram-negative and Gram-positive bacteria using agar-well diffusion method. Anti-biofilm formation was analyzed using a microtitre plate. Antioxidant assays were performed to assess the scavenging activity of MA*CS*pNBA using DPPH, hydrogen peroxide, superoxide together with its reducing power activity. Anti-inflammatory activity was evaluated by albumin denaturation, membrane stabilization, and proteinase inhibition methods. MA*CS*pNBA was tested for its hemolytic efficiency on human erythrocytes. Cytotoxicity of MA*CS*pNBA was evaluated by MTT assay.

RESULTS: MA*CS*pNBA showed a significant performance as an antibacterial candidate against MDR bacteria, anti-biofilm, antioxidant and anti-inflammatory biomaterial, evidencing hemocompatibility and no cytotoxicity. It exhibited a significant negative correlation with biofilm formation by the MDR-PA-09 strain. Biological activities were found to be significantly concentration-dependent.

CONCLUSIONS: the newly chitosan derivative MA*CS*pNBA showed to be promising for pharmaceutical applications, expanding the treatment ways toward skin burn infections since it allied excellent antibacterial, anti-biofilm, antioxidant, anti-inflammatory, hemocompatibility and absence of cytotoxic activities.

RevDate: 2018-11-08

Bhandari V, Chakraborty S, Brahma U, et al (2018)

Identification of Anti-staphylococcal and Anti-biofilm Compounds by Repurposing the Medicines for Malaria Venture Pathogen Box.

Frontiers in cellular and infection microbiology, 8:365.

There has been an alarming increase in infections caused by antimicrobial-resistant pathogens. These infections are responsible for more than half a million deaths globally each year. Staphylococcus aureus is one of the deadliest bacterial pathogen responsible for nosocomial and community acquired infections. The open-access Pathogen Box (PBox) provides a potential platform to identify new treatment options against antibiotic-resistant bacteria by repurposing it. In this study, we have screened the PBox library comprised of ~400 compounds to identify novel anti-staphylococcal compounds. in vitro antimicrobial screening using S. aureus isolates, ATCC 29213 (methicillin-sensitive) and ATCC 700699 (methicillin-resistant) revealed 13 compounds which showed highly potent antibacterial activity against both planktonic and biofilm state. The 13 compounds were not found cytotoxic to mouse macrophage cell line, RAW264.7. Out of the 13 compounds, only MMV687251 and MMV676477 revealed structural similarity with vancomycin by comparing their atomic pair fingerprints using Tanimoto coefficient method. The structural similarities may indicate similar mode of action like vancomycin for the two compounds. Our result showed that PBox compounds offer a promising lead for the development of new anti-staphylococcal treatment options.

RevDate: 2018-11-08

Marak MB, B Dhanashree (2018)

Antifungal Susceptibility and Biofilm Production of Candida spp. Isolated from Clinical Samples.

International journal of microbiology, 2018:7495218.

Objective: The study aims to speciate clinical Candida isolates and detect their biofilm-forming ability and antifungal resistance.

Methods: All the Candida spp. isolated from different clinical samples like pus, urine, blood, and body fluid were included in the study. Biofilm production was tested by the microtiter plate method. Antifungal susceptibility was studied by the disk diffusion method. Patient's demographic details such as age, sex, and clinical information were collected. Presence of other risk factors such as diabetes mellitus, history of antibiotic use, and any urinary tract instrumentations was also recorded.

Results: Among 90 Candida species isolated, most predominant species was found to be C. albicans (45.5%) followed by C. tropicalis (28.88%), C. krusei (20%), C. glabrata (3.33%), and C. parapsilosis (2.22%). Candida spp. were isolated from urine (43%), BAL/sputum (18.88%), high vaginal swab (8.88%), suction tips (7.77%), blood and wound swabs (6.66%), pus (3.33%), bile aspirate (2.22%), and deep tissue (1.11%). A larger number of females were affected than males, and the age group of 51 to 60 years was more susceptible to candidiasis. A higher number of C. albicans isolates produced biofilm followed by C. parapsilosis, C. tropicalis, and C. krusei. However, C. glabrata showed no biofilm production in our study. All Candida isolates were 100% sensitive to amphotericin B. Voriconazole was the next effective drug with 81.11% susceptibility. 24.44% of strains were resistant to fluconazole.

Conclusion: Speciation of Candida isolates, detection of ability to form the biofilm, and monitoring of antifungal susceptibility testing are necessary for appropriate treatment.

RevDate: 2018-11-08

Li T, Sharp CE, Ataeian M, et al (2018)

Role of Extracellular Carbonic Anhydrase in Dissolved Inorganic Carbon Uptake in Alkaliphilic Phototrophic Biofilm.

Frontiers in microbiology, 9:2490.

Alkaline Soda Lakes are extremely productive ecosystems, due to their high dissolved inorganic carbon (DIC) concentrations. Here, we studied the dynamics of the carbonate system, in particular, the role of extracellular carbonic anhydrase (eCA) of an alkaliphilic phototrophic biofilm composed of bacteria enriched from soda lake benthic mats. By using measurements with microsensors and membrane inlet mass spectrometry, combined with mathematical modeling, we show how eCA controls DIC uptake. In our experiments, the activity of eCA varied four-fold, and was controlled by the bicarbonate concentration during growth: a higher bicarbonate concentration led to lower eCA activity. Inhibition of eCA decreased both the net and the gross photosynthetic productivities of the investigated biofilms. After eCA inhibition, the efflux of carbon dioxide (CO2) from the biofilms increased two- to four-fold. This could be explained by the conversion of CO2, leaking from cyanobacterial cells, by eCA, to bicarbonate. Bicarbonate is then taken up again by the cyanobacteria. In suspensions, eCA reduced the CO2 leakage to the bulk medium from 90 to 50%. In biofilms cultivated at low bicarbonate concentration (~0.13 mM), the oxygen production was reduced by a similar ratio upon eCA inhibition. The role of eCA in intact biofilms was much less significant compared to biomass suspensions, as CO2 loss to the medium is reduced due to mass transfer resistance.

RevDate: 2018-11-08

Chong PP, Chin VK, Wong WF, et al (2018)

Transcriptomic and Genomic Approaches for Unravelling Candida albicans Biofilm Formation and Drug Resistance-An Update.

Genes, 9(11): pii:genes9110540.

Candida albicans is an opportunistic fungal pathogen, which causes a plethora of superficial, as well as invasive, infections in humans. The ability of this fungus in switching from commensalism to active infection is attributed to its many virulence traits. Biofilm formation is a key process, which allows the fungus to adhere to and proliferate on medically implanted devices as well as host tissue and cause serious life-threatening infections. Biofilms are complex communities of filamentous and yeast cells surrounded by an extracellular matrix that confers an enhanced degree of resistance to antifungal drugs. Moreover, the extensive plasticity of the C. albicans genome has given this versatile fungus the added advantage of microevolution and adaptation to thrive within the unique environmental niches within the host. To combat these challenges in dealing with C. albicans infections, it is imperative that we target specifically the molecular pathways involved in biofilm formation as well as drug resistance. With the advent of the -omics era and whole genome sequencing platforms, novel pathways and genes involved in the pathogenesis of the fungus have been unraveled. Researchers have used a myriad of strategies including transcriptome analysis for C. albicans cells grown in different environments, whole genome sequencing of different strains, functional genomics approaches to identify critical regulatory genes, as well as comparative genomics analysis between C. albicans and its closely related, much less virulent relative, C. dubliniensis, in the quest to increase our understanding of the mechanisms underlying the success of C. albicans as a major fungal pathogen. This review attempts to summarize the most recent advancements in the field of biofilm and antifungal resistance research and offers suggestions for future directions in therapeutics development.

RevDate: 2018-11-08

Grillo-Puertas M, Delaporte-Quintana P, Pedraza RO, et al (2018)

Intracellular Polyphosphate Levels in Gluconacetobacter diazotrophicus Affect Tolerance to Abiotic Stressors and Biofilm Formation.

Microbes and environments [Epub ahead of print].

Gluconacetobacter diazotrophicus is a plant growth-promoting bacterium that is used as a bioinoculant. Phosphate (Pi) modulates intracellular polyphosphate (polyP) levels in Escherichia coli, affecting cellular fitness and biofilm formation capacity. It currently remains unclear whether environmental Pi modulates polyP levels in G. diazotrophicus to enhance fitness in view of its technological applications. In high Pi media, cells accumulated polyP and degraded it, thereby improving survival, tolerance to environmental stressors, biofilm formation capacity on abiotic and biotic surfaces, and competence as a growth promoter of strawberry plants. The present results support the importance of Pi and intracellular polyP as signals involved in the survival of G. diazotrophicus.

RevDate: 2018-11-08

Kot B, Sytykiewicz H, I Sprawka (2018)

Expression of the Biofilm-Associated Genes in Methicillin-Resistant Staphylococcus aureus in Biofilm and Planktonic Conditions.

International journal of molecular sciences, 19(11): pii:ijms19113487.

The role of genes that are essential for development of Staphylococcus aureus biofilm during infection is not fully known. mRNA from two methicillin-resistant S. aureus strains that formed weak and strong biofilm on polystyrene plates were isolated at five time points from cells grown in biofilm and planktonic culture. Quantitative real-time PCR analysis showed that the expression levels of investigated genes under biofilm conditions were significantly higher than under planktonic conditions. The expression levels of the gene encoding elastin binding protein (ebps) and laminin binding protein (eno) were significantly increased in biofilm at 3 h, both in strongly and weakly adhering strain. The peak expression of fib gene encoding fibrinogen binding protein was found at 6 and 8 h in the case of strongly and weakly adhering strain, respectively. The expression of icaA and icaD genes in both strains was significantly higher under biofilm conditions when comparing to planktonic cells during 12 h. The expression level of the genes encoding binding proteins and the glucosamine polymer polysaccharide intercellular adhesin (PIA) slowly decreased after 24 h. Finally, we found that the expression levels of genes encoding binding factors in weakly adhering strain were significantly lower than in strongly adhering strain.

RevDate: 2018-11-07

Pederson DB, Dong Y, Blue LB, et al (2018)

Water-soluble cranberry extract inhibits Vibrio cholerae biofilm formation possibly through modulating the second messenger 3', 5' - Cyclic diguanylate level.

PloS one, 13(11):e0207056 pii:PONE-D-18-16745.

Quorum sensing (QS) and nucleotide-based second messengers are vital signaling systems that regulate bacterial physiology in response to changing environments. Disrupting bacterial signal transduction is a promising direction to combat infectious diseases, and QS and the second messengers are undoubtedly potential targets. In Vibrio cholerae, both QS and the second messenger 3', 5'-cyclic diguanylate (c-di-GMP) play a central role in controlling motility, motile-to-sessile life transition, and virulence. In this study, we found that water-soluble extract from the North American cranberry could significantly inhibit V. cholerae biofilm formation during the development/maturation stage by reducing the biofilm matrix production and secretion. The anti-biofilm effect by water-soluble cranberry extract was possibly through modulating the intracellular c-di-GMP level and was independent of QS and the QS master regulator HapR. Our results suggest an opportunity to explore more functional foods to fight stubborn infections through interference with the bacterial signaling systems.

RevDate: 2018-11-07

Chew SC, Yam JKH, Matysik A, et al (2018)

Matrix Polysaccharides and SiaD Diguanylate Cyclase Alter Community Structure and Competitiveness of Pseudomonas aeruginosa during Dual-Species Biofilm Development with Staphylococcus aureus.

mBio, 9(6): pii:mBio.00585-18.

Mixed-species biofilms display a number of emergent properties, including enhanced antimicrobial tolerance and communal metabolism. These properties may depend on interspecies relationships and the structure of the biofilm. However, the contribution of specific matrix components to emergent properties of mixed-species biofilms remains poorly understood. Using a dual-species biofilm community formed by the opportunistic pathogens Pseudomonas aeruginosa and Staphylococcus aureus, we found that whilst neither Pel nor Psl polysaccharides, produced by P. aeruginosa, affect relative species abundance in mature P. aeruginosa and S. aureus biofilms, Psl production is associated with increased P. aeruginosa abundance and reduced S. aureus aggregation in the early stages of biofilm formation. Our data suggest that the competitive effect of Psl is not associated with its structural role in cross-linking the matrix and adhering to P. aeruginosa cells but is instead mediated through the activation of the diguanylate cyclase SiaD. This regulatory control was also found to be independent of the siderophore pyoverdine and Pseudomonas quinolone signal, which have previously been proposed to reduce S. aureus viability by inducing lactic acid fermentation-based growth. In contrast to the effect mediated by Psl, Pel reduced the effective crosslinking of the biofilm matrix and facilitated superdiffusivity in microcolony regions. These changes in matrix cross-linking enhance biofilm surface spreading and expansion of microcolonies in the later stages of biofilm development, improving overall dual-species biofilm growth and increasing biovolume severalfold. Thus, the biofilm matrix and regulators associated with matrix production play essential roles in mixed-species biofilm interactions.IMPORTANCE Bacteria in natural and engineered environments form biofilms that include many different species. Microorganisms rely on a number of different strategies to manage social interactions with other species and to access resources, build biofilm consortia, and optimize growth. For example, Pseudomonasaeruginosa and Staphylococcus aureus are biofilm-forming bacteria that coinfect the lungs of cystic fibrosis patients and diabetic and chronic wounds. P. aeruginosa is known to antagonize S. aureus growth. However, many of the factors responsible for mixed-species interactions and outcomes such as infections are poorly understood. Biofilm bacteria are encased in a self-produced extracellular matrix that facilitates interspecies behavior and biofilm development. In this study, we examined the poorly understood roles of the major matrix biopolymers and their regulators in mixed-species biofilm interactions and development.

RevDate: 2018-11-07

Melo MAS, Weir MD, Passos VF, et al (2018)

Human In Situ Study of the effect of Bis(2-Methacryloyloxyethyl) Dimethylammonium Bromide Immobilized in Dental Composite on Controlling Mature Cariogenic Biofilm.

International journal of molecular sciences, 19(11): pii:ijms19113443.

Cariogenic oral biofilms cause recurrent dental caries around composite restorations, resulting in unprosperous oral health and expensive restorative treatment. Quaternary ammonium monomers that can be copolymerized with dental resin systems have been explored for the modulation of dental plaque biofilm growth over dental composite surfaces. Here, for the first time, we investigated the effect of bis(2-methacryloyloxyethyl) dimethylammonium bromide (QADM) on human overlying mature oral biofilms grown intra-orally in human participants for 7⁻14 days. Seventeen volunteers wore palatal devices containing composite specimens containing 10% by mass of QADM or a control composite without QADM. After 7 and 14 days, the adherent biofilms were collected to determine bacterial counts via colony-forming unit (CFU) counts. Biofilm viability, chronological changes, and percentage coverage were also determined through live/dead staining. QADM composites caused a significant inhibition of Streptococcus mutans biofilm formation for up to seven days. No difference in the CFU values were found for the 14-day period. Our findings suggest that: (1) QADM composites were successful in inhibiting 1⁻3-day biofilms in the oral environment in vivo; (2) QADM significantly reduced the portion of the S. mutans group; and (3) stronger antibiofilm activity is required for the control of mature long-term cariogenic biofilms. Contact-killing strategies using dental materials aimed at preventing or at least reducing high numbers of cariogenic bacteria seem to be a promising approach in patients at high risk of the recurrence of dental caries around composites.

RevDate: 2018-11-06

Anonymous (2018)

Skin Integrity and Infection Prevention Las Vegas: the science of biofilm, a multifaceted challenge to healing.

Journal of wound care, 27(11):756-757.

At the 4th International Skin Integrity and Infection Prevention conference, hosted by the Journal of Wound Care and the University of Huddersfield, in Las Vegas, one of the main themes was the control and resolution of biofilm. A series of reports will describe the key points of four sponsored symposia at the event. The first of these concentrates on the role of biofilm in chronic wounds and new therapies to aid the healing of these wounds by disrupting biofilm.

RevDate: 2018-11-06

Anonymous (2018)

Skin Integrity and Infection Prevention Las Vegas: don't bust on biofilm, bet on dHACM.

Journal of wound care, 27(11):764-766.

The 4th International Skin Integrity and Infection Prevention conference, hosted by the Journal of Wound Care and the University of Huddersfield, was held earlier this year in Las Vegas. A key theme was the impact of biofilm on wound healing. In the second of our sponsored symposia reports, the manner in which delayed healing can be reversed through effective biofilm management, and the introduction of regulatory proteins found in dehydrated human amnion chorion membrane allograft were explained.

RevDate: 2018-11-06

Gu Y, Xu Y, Xu J, et al (2018)

Identification of novel bacteriophage vB_EcoP-EG1 with lytic activity against planktonic and biofilm forms of uropathogenic Escherichia coli.

Applied microbiology and biotechnology pii:10.1007/s00253-018-9471-x [Epub ahead of print].

Urinary tract infections are one of the most common infectious diseases worldwide. Uropathogenic Escherichia coli (UPEC) is a major cause of unary tract infection. Due to increasing prevalence of multidrug resistance, alternative methods to eradicate the UPECs are urgently needed. In this respect, phage therapy has been demonstrated to be a good candidate. Here, we described a novel bacteriophage named vB_EcoP-EG1, which can infect several strains of UPEC. Phage morphology and genome sequencing analysis show that vB_EcoP-EG1 belongs to the T7-like Podoviridae. vB_EcoP-EG1 possesses a genome (39,919 bp) containing 51 predicted genes and 149 bp terminal repeats. vB_EcoP-EG1 genome does not encode toxic proteins or proteins related to lysogeny. And no known virulent proteins were found in purified phage particles by mass spectrometry. vB_EcoP-EG1 appeared to be relatively specific and sensitive to clinical UPEC strains, which could infect 10 out of 21 clinical multidrug-resistant UPEC strains. In addition, vB_EcoP-EG1 suspension can eliminate biofilm formed by E. coli MG1655 and multidrug-resistant UPEC strain 390G7. Therefore, we concluded that vB_EcoP-EG1 has desirable characteristics for potential therapy, which may serve as an alternative to antibiotic therapy against urinary tract infections caused by multidrug-resistant UPEC.

RevDate: 2018-11-06

Bartolini M, Cogliati S, Vileta D, et al (2018)

Regulation of biofilm aging and dispersal in Bacillus subtilis by the alternative sigma factor SigB.

Journal of bacteriology pii:JB.00473-18 [Epub ahead of print].

Bacterial biofilms are important in natural settings, biotechnology and medicine. However, regulation of biofilm development and its persistence in different niches is complex and only partially understood. One key step during the biofilm life cycle is dispersal, when motile cells abandon the mature biofilm to spread out and colonize new niches. Here, we show that in the model bacterium Bacillus subtilis the general stress transcription factor SigB is essential for halting detrimental overgrowth of mature biofilm and for triggering dispersal when nutrients become limited. Specifically, SigB-deficient biofilms were larger than wild-type biofilms but exhibited accelerated cell death, significantly greater sensitivity to different stresses and reduced dispersal. Interestingly, the signal detected by SigB to limit biofilm growth was transduced through the RsbP-dependent metabolic arm of the SigB regulatory cascade, which in turn positively controlled expression of SinR, the master regulator of biofilm formation and cell motility. This novel SigB-SinR regulatory circuit might be important in controlling the fitness of biofilms (either beneficial or harmful) in diverse environments.Importance Biofilms are crucial for bacterial survival, adaptation and dissemination in natural, industrial and medical systems. Sessile cells embedded in the self-produced extracellular matrix of the biofilm benefit from a division of labor and are protected from environmental insults. However, as the biofilm ages, cells become stressed because of overcrowding, starvation and accumulation of waste products. How does the sessile biofilm community sense and respond to stressful conditions? Here, we show that in Bacillus subtilis, the transcription factors SigB and SinR control whether cells remain in or leave a biofilm when metabolic conditions become unfavorable. This novel SigB-SinR regulatory circuit might be important for controlling the fitness of biofilms (either beneficial or harmful) in diverse environments.

RevDate: 2018-11-05

Lesouhaitier O, Clamens T, Rosay T, et al (2018)

Host Peptidic Hormones Affecting Bacterial Biofilm Formation and Virulence.

Journal of innate immunity pii:000493926 [Epub ahead of print].

Bacterial biofilms constitute a critical problem in hospitals, especially in resuscitation units or for immunocompromised patients, since bacteria embedded in their own matrix are not only protected against antibiotics but also develop resistant variant strains. In the last decade, an original approach to prevent biofilm formation has consisted of studying the antibacterial potential of host communication molecules. Thus, some of these compounds have been identified for their ability to modify the biofilm formation of both Gram-negative and Gram-positive bacteria. In addition to their effect on biofilm production, a detailed study of the mechanism of action of these human hormones on bacterial physiology has allowed the identification of new bacterial pathways involved in biofilm formation. In this review, we focus on the impact of neuropeptidic hormones on bacteria, address some future therapeutic issues, and provide a new view of inter-kingdom communication.

RevDate: 2018-11-05

Ramalingam V, Raja S, Sundaramahalingam S, et al (2018)

Chemical fabrication of graphene oxide nanosheets attenuates biofilm formation of human clinical pathogens.

Bioorganic chemistry, 83:326-335 pii:S0045-2068(18)30975-1 [Epub ahead of print].

Graphene oxide (GO) has been recently attracted considerable interest for its potential applications in physical, chemical and biological properties. In the present study, the GO nanosheets were prepared by a chemical exfoliation technique using a modified Hummers method. Initially, the prepared GO nanosheets were confirmed by UV-vis spectroscopy and further characterized by FE-SEM, Edax, HR-TEM and SAED that demonstrated the formation of GO nanosheets with few layers flat sheet structure with hexagonal lattice crystalline nature. The FTIR spectra revealed the presence of various oxygen containing functional groups has been produced from graphite plane by exfoliation technique. The prepared GO nanosheets showed excellent antibiotic resistant activity against planktonic bacteria and more effective to damage the established biofilms and inhibits the biofilm formation of human clinical pathogens like E. coli and P. aeruginosa. Further, the GO nanosheets were found to be non-toxic to normal mammalian cells and there are no apparent morphological changes were observed in control and treated cells. In conclusion, GO nanosheets were effectively preventing the formation of biofilms and kills the represent bacteria that suggested the GO nanosheets could be used for the prevention and treatment of biofilm-related infections.

RevDate: 2018-11-05

Wang S, Qian K, Zhu Y, et al (2018)

Reactivation and pilot-scale application of long-term storage denitrification biofilm based on flow cytometry.

Water research, 148:368-377 pii:S0043-1354(18)30875-3 [Epub ahead of print].

The work provides a method on the basis of flow cytometry to evaluate the performance of denitrification biofilm during the preservation, reactivation and pilot-scale operation process. The viable cell ratio of denitrification biofilm significantly reduced and further led to the decrease of denitrification capacity after long-term preservation for 5 months. Protein component in tightly bound extracellular polymeric substances (TB-EPS) could serve to enhance microbial adhesion and promote denitrification biofilm formation. With the significant correlation of viable cell ratio and microbial characteristics, 4 °C was more appropriate for preserving denitrification biofilm and conducive to maintain the relatively high denitrification capacity. A maximum denitrification rate of 5.80 gNO3--N/m2·d was obtained in pilot-scale anoxic-oxic (AO) process and Dechloromonas became greater prevalence in denitrification suspended carriers. Furthermore, the enrichment of Pseudomonas, Parcubacteria, Acidovorax, Aquabacterium and Unclassified_Flavobacteriaceae enhanced biofilm formation and nutrient conservation. The significantly positive correlation between viable cell ratio and the ratio of nitrate reduction to COD consumption was discovered, and the indices of Chao, ACE, Shannon and Simpson of denitrification biofilm were positively correlated with viable cell ratio, meaning that flow cytometry analysis was reasonable and suitable to evaluate the performances of denitrification biofilm.

RevDate: 2018-11-05

Gao T, Ding M, Yang CH, et al (2018)

The Phosphotransferase System Gene ptsH Plays an Important Role in MnSOD Production, Biofilm Formation, Swarming motility, and Root Colonization in Bacillus cereus 905.

Research in microbiology pii:S0923-2508(18)30144-X [Epub ahead of print].

The rhizosphere bacterium Bacillus cereus 905 is capable of promoting plant growth through effective colonization on plant roots. The sodA2-encoding manganese-containing superoxide dismutase (MnSOD2) is important for survival of B. cereus 905 in the wheat rhizosphere. However, the genes involved in regulating sodA2 expression and the mechanisms of rhizosphere colonization of B. cereus 905 are not well elucidated. In this study, we found that the deletion of the ptsH gene, which encodes the histidine-phosphorylatable protein (HPr), a component of the phosphotransferase system (PTS), causes a decrease of about 60% in the MnSOD2 expression. Evidences indicate that the ptsH dramatically influences resistance to oxidative stress, glucose uptake, as well as biofilm formation and swarming motility of B. cereus 905. Root colonization assay demonstrated that ΔptsH is defective in colonizing wheat roots, while complementation of the sodA2 gene could partially restore the ability in utilization of arabinose, a non-PTS sugar, and root colonization caused by the loss of the ptsH gene. In toto, based on the current findings, we propose that PtsH contributes to root colonization of B. cereus 905 through multiple indistinct mechanisms, involving PTS and uptake of PTS-sugars, up-regulation of MnSOD2 production, and promotion of biofilm formation and swarming motility.

RevDate: 2018-11-05

Pousti M, Zarabadi MP, Abbaszadeh Amirdehi M, et al (2018)

Microfluidic bioanalytical flow cells for biofilm studies: a review.

The Analyst [Epub ahead of print].

Bacterial biofilms are among the oldest and most prevalent multicellular life forms on Earth and are increasingly relevant in research areas related to industrial fouling, medicine and biotechnology. The main hurdles to obtaining definitive experimental results include time-varying biofilm properties, structural and chemical heterogeneity, and especially their strong sensitivity to environmental cues. Therefore, in addition to judicious choice of measurement tools, a well-designed biofilm study requires strict control over experimental conditions, more so than most chemical studies. Due to excellent control over a host of physiochemical parameters, microfluidic flow cells have become indispensable in microbiological studies. Not surprisingly, the number of lab-on-chip studies focusing on biofilms and other microbiological systems with expanded analytical capabilities has expanded rapidly in the past decade. In this paper, we comprehensively review the current state of microfluidic bioanalytical research applied to bacterial biofilms and offer a perspective on new approaches that are expected to drive continued advances in this field.

RevDate: 2018-11-05

McCall AD, M Edgerton (2018)

Real-time Imaging and Quantification of Fungal Biofilm Development Using a Two-Phase Recirculating Flow System.

Journal of visualized experiments : JoVE.

In oropharyngeal candidiasis, members of the genus Candida must adhere to and grow on the oral mucosal surface while under the effects of salivary flow. While models for the growth under flow have been developed, many of these systems are expensive, or do not allow imaging while the cells are under flow. We have developed a novel apparatus that allows us to image the growth and development of Candida albicans cells under flow and in real-time. Here, we detail the protocol for the assembly and use of this flow apparatus, as well as the quantification of data that are generated. We are able to quantify the rates that the cells attach to and detach from the slide, as well as to determine a measure of the biomass on the slide over time. This system is both economical and versatile, working with many types of light microscopes, including inexpensive benchtop microscopes, and is capable of extended imaging times compared to other flow systems. Overall, this is a low-throughput system that can provide highly detailed real-time information on the biofilm growth of fungal species under flow.

RevDate: 2018-11-05

Antypas H, Choong FX, Libberton B, et al (2018)

Rapid diagnostic assay for detection of cellulose in urine as biomarker for biofilm-related urinary tract infections.

NPJ biofilms and microbiomes, 4:26 pii:69.

The ability of uropathogenic Escherichia coli (UPEC) to adopt a biofilm lifestyle in the urinary tract is suggested as one cause of recurrent urinary tract infections (UTIs). A clinical role of UPEC biofilm is further supported by the presence of bacterial aggregates in urine of UTI patients. Yet, no diagnostics exist to differentiate between the planktonic and biofilm lifestyle of bacteria. Here, we developed a rapid diagnostic assay for biofilm-related UTI, based on the detection of cellulose in urine. Cellulose, a component of biofilm extracellular matrix, is detected by a luminescent-conjugated oligothiophene, which emits a conformation-dependent fluorescence spectrum when bound to a target molecule. We first defined the cellulose-specific spectral signature in the extracellular matrix of UPEC biofilm colonies, and used these settings to detect cellulose in urine. To translate this optotracing assay for clinical use, we composed a workflow that enabled rapid isolation of urine sediment and screening for the presence of UPEC-derived cellulose in <45 min. Using multivariate analysis, we analyzed spectral information obtained between 464 and 508 nm by optotracing of urine from 182 UTI patients and 8 healthy volunteers. Cellulose was detected in 14.8% of UTI urine samples. Using cellulose as a biomarker for biofilm-related UTI, our data provide direct evidence that UPEC forms biofilm in the urinary tract. Clinical implementation of this rapid, non-invasive and user-friendly optotracing diagnostic assay will potentially aid clinicians in the design of effective antibiotic treatment.

RevDate: 2018-11-05

Perez-Soto N, Moule L, Crisan DN, et al (2018)

Correction: Engineering microbial physiology with synthetic polymers: cationic polymers induce biofilm formation in Vibrio cholerae and downregulate the expression of virulence genes.

Chemical science, 9(39):7715 pii:c8sc90189a.

[This corrects the article DOI: 10.1039/C7SC00615B.].

RevDate: 2018-11-05

Liaqat I, Mirza SA, Iqbal R, et al (2018)

Flagellar motility plays important role in Biofilm formation of Bacillus cereus and Yersinia enterocolitica.

Pakistan journal of pharmaceutical sciences, 31(5(Supplementary)):2047-2052.

Bacteria live either independently as planktonic cells or in organized surface associated colonies called as biofilms. Biofilms play an important role in increased pathogenesis of bacteria and it is assumed that motility is one of the contributing factors towards biofilm initiation. This study was planned to identify the role of flagella in biofilm formation by constructing flagellated (wild type) and physically disrupted variants (non-motile). Total 10 clinical bacterial strains were isolated and characterized. Morphological and biochemical study identified these strains as Enterobacter spp., Pseudomonas spp., Yersinia spp., Escherichia spp., Salmonella spp., Proteus spp., Staphylococcus spp., Streptococcus spp., Lactobacillus spp. and Bacillus spp. Among all strains, two strains including Yersinia spp and Bacillus spp. showed higher antibiotic resistance, hence studied at molecular and physiological level. Biofilm formation capacity of strains was analyzed using three methods including Congo red assay, Test tube assay and Liquid-interface coverslip assay. Afterwards, flagellar disintegration was induced by blending and centrifugation for 5, 10 and 15 minutes. 16S rRNA sequencing showed two strains as Bacillus cereus and Yersinia enterocolitica. Both strains produced significant biofilm by all three above mentioned methods. A motility test of these blended variants showed partial/diminished motility with increased blending time. The significant loss in biofilm formation after 15 minutes blending confirmed the important flagellar contribution to the initiation of biofilm formation. This biofilm defect observed in flagella paralysed/minus variants presumably may be due to defects in attachments to surface at early stages. This study indicated that flagellar motility is crucial initially for surface attachment and subsequently for biofilm formation.

RevDate: 2018-11-05

Kunkle T, Abdeen S, Salim N, et al (2018)

Hydroxybiphenylamide GroEL/ES inhibitors are potent antibacterials against planktonic and biofilm forms of Staphylococcus aureus.

Journal of medicinal chemistry [Epub ahead of print].

We recently reported the identification of a GroEL/ES inhibitor (1: N-(4-(benzo[ d]thiazol-2-ylthio)-3-chlorophenyl)-3,5-dibromo-2-hydroxybenzamide) that exhibited in vitro antibacterial effects against Staphylococcus aureus comparable to vancomycin, an antibiotic of last resort. To follow-up, we have synthesized 43 compound 1 analogs to determine the most effective functional groups of the scaffold for inhibiting GroEL/ES and killing bacteria. Our results identified that the benzothiazole and hydroxyl groups are important for inhibiting GroEL/ES-mediated folding functions, with the hydroxyl essential for antibacterial effects. Several analogs exhibited >50-fold selectivity indices between antibacterial efficacy and cytotoxicity to human liver and kidney cells in cell culture. We found that MRSA were not able to easily generate acute resistance to lead inhibitors in a gain-of-resistance assay, and that lead inhibitors were able to permeate through established S. aureus biofilms and maintain their bactericidal effects.

RevDate: 2018-11-04

Vilarrasa J, Delgado LM, Galofré M, et al (2018)

In vitro evaluation of a multispecies oral biofilm over antibacterial coated titanium surfaces.

Journal of materials science. Materials in medicine, 29(11):164 pii:10.1007/s10856-018-6168-8.

Peri-implantitis is an infectious disease that affects the supporting soft and hard tissues around dental implants and its prevalence is increasing considerably. The development of antibacterial strategies, such as titanium antibacterial-coated surfaces, may be a promising strategy to prevent the onset and progression of peri-implantitis. The aim of this study was to quantify the biofilm adhesion and bacterial cell viability over titanium disc with or without antibacterial surface treatment. Five bacterial strains were used to develop a multispecies oral biofilm. The selected species represent initial (Streptococcus oralis and Actinomyces viscosus), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late (Porphyromonas gingivalis) colonizers. Bacteria were sequentially inoculated over seven different types of titanium surfaces, combining different roughness level and antibacterial coatings: silver nanoparticles and TESPSA silanization. Biofilm formation, cellular viability and bacterial quantification over each surface were analyzed using scanning electron microscopy, confocal microscopy and real time PCR. Biofilm formation over titanium surfaces with different bacterial morphologies could be observed. TESPSA was able to significantly reduce the cellular viability when compared to all the surfaces (p < 0.05). Silver deposition on titanium surface did not show improved results in terms of biofilm adhesion and cellular viability when compared to its corresponding non-coated surface. The total amount of bacterial biofilm did not significantly differ between groups (p > 0.05). TESPSA was able to reduce biofilm adhesion and cellular viability. However, silver deposition on titanium surface seemed not to confer these antibacterial properties.

RevDate: 2018-11-04

Cao X, Zhang S, Wang H, et al (2018)

Azo dye as part of co-substrate in a biofilm electrode reactor-microbial fuel cell coupled system and an analysis of the relevant microorganisms.

Chemosphere, 216:742-748 pii:S0045-6535(18)32078-2 [Epub ahead of print].

In general, refractory organics were hardly used as co-substrate in bioelectrochemical system. This study established a coupled bioelectrochemical system composed of a biofilm electrode reactor and a microbial fuel cell for using the azo dye X-3B as part of co-substrate. The two units degraded the azo dye X-3B stepwise while using it as part of co-substrate. Our results indicated that the removal efficiency of X-3B increased 28.5% using the coupled system compared with a control system. Moreover, the addition of the co-substrate glucose, which was necessary for MFC electricity generation, was reduced on the premise of stable removal efficiency in the coupled system to prevent resource waste due to using X-3B as part of co-substrate. The intermediate products of X-3B degradation were further explored using gas chromatography-mass spectrometry and a X-3B degradation pathway was proposed at the same time. Microbial communities were analyzed, illustrating that the mechanism of X-3B degradation was dependent on bioelectrochemistry rather than on microbial degradation.

RevDate: 2018-11-04

Anupama R, Lulu S, Madhusmita R, et al (2018)

Insights into the interaction of key biofilm proteins in Pseudomonas aeruginosa PAO1 with TiO2 nanoparticle: An in silico analysis.

Journal of theoretical biology pii:S0022-5193(18)30539-3 [Epub ahead of print].

Pseudomonas aeruginosa is a pathogenic biofilm forming bacteria which exist in wide range of environments such as water, soil and human body. In an earlier study, we used a system biology approach based analysis of biofilm forming genes of P. aeruginosa and their possible role in TiO2 nanoparticle binding. The major protein of P. aeruginosa targeted by TiO2 was found to be KatA, a major catalase required for H2O2 resistance and acute virulence and the direct interacting protein partners of KatA were found to be DnaK, Hfq, RpoA and RpoS. To understand the protein-protein physical interaction characteristic of these key proteins involved in biofilm related processes, homology modeling, docking and molecular dynamic simulation were performed. For all these proteins, physical and chemical properties, amino acid composition, nest and cleft analysis were performed using online tools. The interactions between TiO2NPs-KatA and four protein-protein complexes such as KatA-DnaK, KatA-Hfq, KatA-RpoA and KatA-RpoS were studied. Our results indicate that all four key proteins and TiO2NPs can have stable complexation with KatA. The study has given enough clues to understand the interaction of TiO2NPs with P. aeruginosa biofilm in natural environment. Further investigations could lead to development of TiO2NPs based therapeutic and sanitary interventions to combat this pathogenic bacterium.

RevDate: 2018-11-04

Cruz CD, Shah S, P Tammela (2018)

Defining conditions for biofilm inhibition and eradication assays for Gram-positive clinical reference strains.

BMC microbiology, 18(1):173 pii:10.1186/s12866-018-1321-6.

BACKGROUND: Biofilms are formed by a complex bacterial community encapsulated by a polymeric matrix, with strong adherent properties and persistent phenotype. Biofilms are considered one of the most challenging areas of modern medicine. Existing antibiotics have been developed against free-floating bacterial cells, and thus, many treatments of biofilm-related infection fail. In this study, we compared the effects of different media on biofilm growth of clinical reference strains of Staphylococci and Enterococci, including multi-drug resistant representatives. Further, we optimized the resazurin-based assay for determining the minimal biofilm inhibitory concentration (MBIC) of standard antibiotics, and evaluated its use for the determination of minimal biofilm eradication concentration (MBEC).

RESULTS: We showed that tryptic soy broth supplemented with 1% glucose was an optimal media for maximum biofilm growth of all strains tested, with an extended incubation time for Enterococci. A range of parameters were tested for the resazurin assay, including concentration, temperature and time of incubation. Using quality parameters to analyze the assay's performance, the conditions for the resazurin assay were set as follows: 4 μg/mL and 8 μg/mL, with incubation at 25 °C for 20 min and 40 min for Staphylococci and Enterococci, respectively.

CONCLUSIONS: In summary, we defined conditions for optimal biofilm growth and for standardized resazurin assay for MBIC determination against six Gram-positive clinical reference strains. We also observed that MBEC determination by the resazurin-based assay is limited due to the poor detection limit of the assay. Complementary cell counting data is needed for precise determination of MBEC.

RevDate: 2018-11-03

Purswani J, Guisado IM, Coello-Cabezas J, et al (2018)

Social microbial inocula confer functional stability in a methyl tert-butyl ether extractive membrane biofilm bioreactor.

Environmental pollution (Barking, Essex : 1987), 244:855-860 pii:S0269-7491(18)33435-3 [Epub ahead of print].

Methyl tert-butyl ether (MTBE) degradation technologies based on two-phase partitioning systems such as extractive membrane biofilm reactors (EMBFR) permit separation of biological and contaminant compartments, thus allowing optimization of the biological section. In this study, we set-up an EMBFR with three MTBE-degrading and cooperating strains (termed social biofilm: Agrobacterium sp. MS2, Paenibacillus etheri SH7T and Rhodococcus ruber EE6). The removal efficiency of the social-biofilm EMBFR was 80%, and functional stability was observed in the reactor, i.e. more efficient than previous studies (single-strain inoculated EMBFR, <50% removal efficiency and unstable function). Metabolite tert-butyl alcohol was not observed, and the EC50 values were higher than those observed in single-strain EMBFRs. Comparative analysis of the MTBE enzymatic pathway and the social-biofilm was performed, where the mechanism of cooperation observed within the social-biofilm is likely due to enzymatic redundancy. Functional outcomes were equal to previous batch tests, hence 100% scalability was obtained. Overall, higher functional and stability outcomes are obtained with the use of the social-biofilm in an MTBE-EMBFR.

RevDate: 2018-11-03

Huang N, Pu X, Zhang J, et al (2018)

In Vitro Formation of Dickeya zeae MS1 Biofilm.

Current microbiology pii:10.1007/s00284-018-1593-y [Epub ahead of print].

Bacterial soft rot caused by Dickeya zeae MS1 (Erwinia chrysanthemi) is one of the most devastating banana diseases worldwide. However, knowledge of the development and ecological interactions of D. zeae MS1 biofilm is limited. Here, we visualized the development and architecture of D. zeae MS1 biofilm using confocal laser scanning microscopy, and we evaluated the ability of D. zeae MS1 to form biofilms under different environmental conditions (carbon sources, temperatures, pH levels and mineral elements) using a microtiter plate assay. We found that the development of D. zeae MS1 biofilm could be categorized into four phases and that mature biofilm consisted of a highly organized architecture of both bacterial cells and a self-produced matrix of extracellular polysaccharides. Furthermore, sucrose was the most suitable carbon source for supporting the growth of biofilm cells and that 32 °C and pH 7.0 were the most favorable of the temperatures and pH levels examined. Meanwhile, the addition of Ca2+, Fe2+, K+ and Na+ enhanced the formation of biofilm in minimal medium cultures, whereas 2.5 mM Cu2+ and Mn2+ was inhibitory. A better understanding of biofilm formation under different environmental parameters will improve our knowledge of the growth kinetics of D. zeae MS1 biofilm.

RevDate: 2018-11-03

Ramalingam K, BT Amaechi (2018)

Antimicrobial effect of herbal extract of Acacia arabica with triphala on the biofilm forming cariogenic microorganisms.

Journal of Ayurveda and integrative medicine pii:S0975-9476(17)30459-X [Epub ahead of print].

BACKGROUND: Dental caries is a biofilm-related infectious disease with a multifactorial etiology, over five billion inhabitants have affected worldwide due to this disease.

OBJECTIVE: Antimicrobial efficacy of a mixed herbal powder extract (MHPE) against cariogenic microorganisms was investigated.

MATERIALS AND METHODS: MIC, MBC, kinetics of killing, biofilm disruption and anticaries effect of MHPE were determined. For biofilm disruption, biofilms of Streptococcus mutans, Lactobacillus casei, Actinomyces viscosus and Candida albicans were treated with MHPE for 30 min and attached cells were quantified after staining. For live/dead staining biofilm assay, S. mutans biofilm treated with MHPE for 1min, 5min and 1 h was examined with confocal laser scanning system after live/dead staining. Efficacy was experimented by structural quality using Scanning Electron Microscope (SEM). Anticaries effect was determined by formation of caries-like lesion in continuous flow biofilm model.

RESULTS: MHPE exhibited inhibition zones ranging from 12.5 to 24.0 mm. The highest inhibition zone was recorded at concentration of 50 μg/ml. MIC for S. mutans was between 12.23 and 36.7 μg/ml, while the MBC values ranged from 36.7 to 110.65 μg/ml. Inhibitory concentration of MHPE was three fold higher than CHLX. Significant reduction of cell count (49-95%) was observed with increasing time and higher concentration. Percentage biofilm reduction compare with negative control was 96.9% (A. viscosus), 94% (C. albicans), 99.8% (L. casei) and 91.7% (S. mutans). For MHPE-treated biofilm, live/dead staining demonstrated significant (p < 0.05) higher in deceased red fluorescence areas in all kinetics points from 53.6% (1min) to 85% (1h). SEM confirmed the damage in the outer layers of S. mutans. MHPE has components with effective antibacterial activity against caries-inducing microorganisms.

CONCLUSION: The anti-adherence and anti-biofilm effect as well as the faster killing activity suggests that MHPE formula has effective antibacterial activity and could be a useful source of anti-cariogenic agents in near future.

RevDate: 2018-11-02

Carreiro AF, Delben JA, Guedes S, et al (2018)

Low-temperature plasma on peri-implant related biofilm and gingival tissue.

Journal of periodontology [Epub ahead of print].

BACKGROUND: Evaluate the effect of Low Temperature Plasma (LTP) on an anaerobic biofilm and on the biological response of an in vitro reconstituted gingival epithelium tissue.

METHODS: P. gingivalis W83 biofilm was cultured on titanium discs and reconstituted gingival tissue were submitted to similar treatment conditions.

TREATMENTS: LTP1 - plasma treatment for 1 min, LTP3 - plasma treatment for 3 min, CHX - 0.2% chlorhexidine for 1 min, GAS - gas only (no plasma) for 3 min, NEGATIVE - no treatment. TRITON group was included as a positive control for tissue analysis. Counting of viable colony forming units (CFU/mL) and confocal laser scanning microscopy were performed to evaluate LTP's antimicrobial effect. EpiGingival™ tissue was evaluated through cytotoxocity, viability, histology and imunnohistochemistry (Ki67, VEGF-A and TUNEL expression).

RESULTS: LTP1 and LTP3 significantly reduced CFU/mL in comparison to the negative control (ρ < 0.001), but it was not as effective as the positive control (CHX). Low cytotoxicity and high viability were observed in gingival epithelium of NEGATIVE, GAS, CHX and both LTP groups. The morphological analysis revealed minor cell damage in the plasma groups (score 1). LTP1, LTP3, GAS and NEGATIVE groups exhibited less than 5% of basal layer positive cells. LTP1, LTP3, GAS and CHX groups were not positive for TUNEL assay. LTP1 and LTP3 showed the most positivity for VEGF.

CONCLUSIONS: LTP treatment can be considered an effective method for reducing P. gingivalis biofilm on implant surfaces being safe for the gingival epithelium. Furthermore, plasma treatment may be associated with cell repair. This article is protected by copyright. All rights reserved.

RevDate: 2018-11-02

Vogt MS, Völpel SL, Albers SV, et al (2018)

Crystal structure of an Lrs14-like archaeal biofilm regulator from Sulfolobus acidocaldarius.

Acta crystallographica. Section D, Structural biology, 74(Pt 11):1105-1114.

The small winged helix-turn-helix (wHTH) proteins of the Lrs14 family are major transcriptional regulators and act as archaeal biofilm regulators (AbfRs) in the crenarchaeote Sulfolobus acidocaldarius. Here, the first crystal structure of an AbfR ortholog, AbfR2, the deletion of which is known to impair biofilm formation, is presented. Like most other wHTH orthologs, AbfR2 is dimeric in solution as well as in its 2.45 Å resolution crystal structure. Given the presence of three independent AbfR2 dimers in the asymmetric unit, the crystal structure shows a considerable degree of conformational variation within the dimer, the antiparallel orientations of which are stabilized by coiled-coil interaction between H4 helices. Conserved anchor interactions between helices H0 and H4 of AbfR2 further contribute to dimer stabilization. The combined structural and bioinformatic analysis reveals cluster-specific structural differences between different members of the Lrs14 protein family.

RevDate: 2018-11-02

Dinamarca MA, Eyzaguirre J, Baeza P, et al (2018)

A new functional biofilm biocatalyst for the simultaneous removal of dibenzothiophene and quinoline using Rhodococcus rhodochrous and curli amyloid overproducer mutants derived from Cobetia sp. strain MM1IDA2H-1.

Biotechnology reports (Amsterdam, Netherlands), 20:e00286 pii:e00286.

Biocatalyst systems based on biofilms were developed to remove nitrogen and sulfur-containing heterocyclic hydrocarbons using Cobetia sp. strain MM1IDA2H-1 and Rhodococcus rhodochrous. The curli overproducers mutants CM1 and CM4 were derived from Cobetia sp. strain and used to build monostrain biofilms to remove quinoline; and together with R. rhodochrous to simultaneously remove quinoline and dibenzothiophene using mixed biofilms. The quinoline removal using biofilms were 96% and 97% using CM1 or CM4 curli overproducers respectively, whereas bacterial suspensions assays yielded 19% and 24% with the same strains. At the other hand, the simultaneous removal of quinoline and dibenzothiophene using mixed biofilms were respectively 50% and 58% using strains R. rhodochrous with CM1 and 75% and 50% using R. rhodochrous with CM4. Results show that biofilms were more efficient than bacterial suspension assays and that in mixed biofilms the shared surface area by two or more bacteria could affect the final yield.

RevDate: 2018-11-02

Surgers L, Boyd A, Girard PM, et al (2018)

Biofilm formation by ESBL-producing strains of Escherichia coli and Klebsiella pneumoniae.

International journal of medical microbiology : IJMM pii:S1438-4221(17)30428-9 [Epub ahead of print].

OBJECTIVES: Biofilm production in extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae provides a favourable environment for the exchange of antibiotic-resistance genes and could facilitate widespread dissemination. We aimed to assess biofilm development in ESBL-producing E. coli and K. pneumoniae isolates and determine how development relates to microbiological characteristics and clinical outcomes.

METHODS: 147 ESBL-producing E. coli and 82 K. pneumoniae were genetically characterized. Biofilm formation was measured at 1.5, 4, 6, and 24 h during culture in blood heart infusion using a microbead immobilization assay (BioFilm Ring test®). Results were given as biofilm formation index (BFI) with lower values indicating increased presence of biofilm (range = 0-21).

RESULTS: In total, 57.1% of strains were strong producers of biofilm (BFI < 2), whereas 13.4% lacked biofilm production (BFI > 18). Standard biofilm production (BFI < 7) was common in E. coli isolates (61.9%). For E. coli, biofilm production was less frequently observed in ST131 clones (p = 0.03) but more frequently in strains harbouring toxin (p = 0.008) or adhesin (p = 0.008) virulence factor genes. Despite almost all K. pneumoniae having standard biofilm production (90.2%), there was a 2.4-times higher odds of observing biofilm in ST29/147/323 versus other ST-types (p = 0.13). Patients with standard biofilm producing isolates were not at increased risk of transfer to intensive-care (odds-ratio=2.80, 95%CI=0.59-13.21) or death within 12-months (odds-ratio=1.61, 95%CI=0.75-3.43).

CONCLUSION: In these ESBL-producing strains, biofilm production is linked to certain virulence factors in E. coli and is common in K. pneumoniae. Further exploration of whether biofilm production increases dissemination and risk of severe clinical outcomes is needed in larger collections of isolates.

RevDate: 2018-11-01

Khalid HF, Tehseen B, Sarwar Y, et al (2018)

Biosurfactant coated silver and iron oxide nanoparticles with enhanced anti-biofilm and anti-adhesive properties.

Journal of hazardous materials, 364:441-448 pii:S0304-3894(18)30958-0 [Epub ahead of print].

Pseudomonas aeruginosa and Staphylococcus aureus are among the hazardous biofilm forming bacteria ubiquitous in industrial/clinical wastes. Serious efforts are required to develop effective strategies to control surface-growing antibiotic resistant pathogenic bacterial communities which they are emerging as a global health issue. Blocking hazardous biofilms would be a useful aspect of biosurfactant coated nanoparticles (NPs). In this regard, we report a facile method for the synthesis of rhamnolipid (RL) coated silver (Ag) and iron oxide (Fe3O4) NPs and propose the mechanism of their synergistic antibacterial and anti-adhesive properties against biofilms formed by P. aeruginosa and S. aureus. These NPs demonstrated excellent anti-biofilm activity not only during the biofilms formation but also on the pre-formed biofilms. Mechanistically, RL coated silver (35 nm) and Fe3O4 NPs (48 nm) generate reactive oxygen species, which contribute to the antimicrobial activity. The presence of RLs shell on the nanoparticles significantly reduces the cell adhesion by modifying the surface hydrophobicity and hence enhancing the anti-biofilm property of NPs against both mentioned strains. These findings suggest that RL coated Ag and Fe3O4 NPs may be used as potent alternate to reduce the infection severity by inhibiting the biofilm formation and, therefore, they possess potential biomedical applications for antibacterial coatings and wound dressings.

RevDate: 2018-11-01

Ripolles-Avila C, Cervantes-Huaman BH, Hascoët AS, et al (2018)

Quantification of mature Listeria monocytogenes biofilm cells formed by an in vitro model: A comparison of different methods.

International journal of food microbiology, 289:209-214 pii:S0168-1605(18)30455-0 [Epub ahead of print].

The presence of biofilms in food industrial environments is one of the main causes associated with food product contamination by L. monocytogenes. Biofilm control in the food industry is very relevant to public health and finding reliable and realistic quantification methods is essential. The aim of this study is to compare five L. monocytogenes biofilm quantification methods - conventional plate count, TEMPO, DEM, VIDAS and qPCR - and to examine a biodetector to visually detect biofilms in industrial settings. Results show that depending on the biofilm matrix production, the recovery of cells that conform the biofilm can be low and therefore, if it is an indirect method, microbial counts can be underestimated. At a species level, the methods that did not present significant differences were plate count, TEMPO (P = 0.998), DEM and qPCR (P = 0.508), so correlation studies were performed which established high correlation for plate count and TEMPO, but not for DEM and qPCR. The VIDAS method was adjusted so that it could quantify the biofilms, but the standard curve only allowed counts from 7 Log CFU cm-2. Results also revealed that the different strains of L. monocytogenes possess different biofilm-forming abilities, although it was not possible to correlate the capacity to produce these structures with the distinct serotypes. Last, visually detecting biofilms on stainless steel coupons proved that in industrial environments nowadays they can be rapidly and qualitatively detected so that relevant decisions can immediately be taken.

RevDate: 2018-11-01

Nolan LM, Whitchurch CB, Barquist L, et al (2018)

A global genomic approach uncovers novel components for twitching motility-mediated biofilm expansion in Pseudomonas aeruginosa.

Microbial genomics [Epub ahead of print].

Pseudomonas aeruginosa is an extremely successful pathogen able to cause both acute and chronic infections in a range of hosts, utilizing a diverse arsenal of cell-associated and secreted virulence factors. A major cell-associated virulence factor, the Type IV pilus (T4P), is required for epithelial cell adherence and mediates a form of surface translocation termed twitching motility, which is necessary to establish a mature biofilm and actively expand these biofilms. P. aeruginosa twitching motility-mediated biofilm expansion is a coordinated, multicellular behaviour, allowing cells to rapidly colonize surfaces, including implanted medical devices. Although at least 44 proteins are known to be involved in the biogenesis, assembly and regulation of the T4P, with additional regulatory components and pathways implicated, it is unclear how these components and pathways interact to control these processes. In the current study, we used a global genomics-based random-mutagenesis technique, transposon directed insertion-site sequencing (TraDIS), coupled with a physical segregation approach, to identify all genes implicated in twitching motility-mediated biofilm expansion in P. aeruginosa. Our approach allowed identification of both known and novel genes, providing new insight into the complex molecular network that regulates this process in P. aeruginosa. Additionally, our data suggest that the flagellum-associated gene products have a differential effect on twitching motility, based on whether components are intra- or extracellular. Overall the success of our TraDIS approach supports the use of this global genomic technique for investigating virulence genes in bacterial pathogens.

RevDate: 2018-11-01

Gazizov A, Smolobochkin AV, Muravyeva EA, et al (2018)

Synthesis and Evaluation of Water-Soluble 1-Sulfonyl-2-Arylpyrrolidine Derivatives as Bacterial Biofilm Formation Inhibitors.

Chemistry & biodiversity [Epub ahead of print].

The approach to the novel 1-((2-aminoethyl)sulfonyl)-2-arylpyrrolidines via unique intramolecular cyclisation / aza-Michael reactions of N-(4,4-diethoxybutyl)ethenesulfonamide have been developed, which benefits from high yields of target compounds, mild reaction conditions, usage of inexpensive and low-toxic reagents, and allows for wide variability in both amine and aryl moieties. Biotesting with whole-cell luminescent bacterial biosensors responding to DNA damage showed that all tested compounds are not genotoxic. Tested compounds differently affect the formation of biofilms by Vibrio aquamarinus DSM 26054. Some of the tested compounds were found to suppress the bacterial biofilms growth and thus are promising candidates for further studies.

RevDate: 2018-11-01

Kim MK, Lee TG, Jung M, et al (2018)

In Vitro Synergism and Anti-biofilm Activity of Quercetin-Pivaloxymethyl Conjugate against Staphylococcus aureus and Enterococcus Species.

Chemical & pharmaceutical bulletin, 66(11):1019-1022.

Upon single treatment against Staphylococus aureus, quercetin-pivaloxymethyl conjugate (Q-POM) had antibacterial activities with minimum inhibitory concentrations (MICs) of 16-32 mg/L. Q-POM showed MIC of 32 mg/L against vancomycin-resistant Enterococcus faceium (VRE), which is remarkably lower than other antibiotics investigated (≥256 mg/L). Under sub-MIC concentrations, Q-POM potentiated the activity of ampicillin, cefepime, and vancomycin against S. aureus and Enterococcus (including highly resistant strains such as hetero-resistant vancomycin-intermediate S. aureus (hVISA), vancomycin-intermediate S. aureus (VISA), and VRE), by decreasing the MICs of these antibiotics by 4-128 folds. Q-POM was found to be partially synergistic with ampicillin and cefepime against S. aureus and Enterococcus, while it was strongly synergistic with vancomycin. Q-POM at 5 mg/L inhibited the formation of biofilms of S. aureus by 24-83% and VRE by 70%. Additionally, Q-POM inhibited the hemolytic activity of S. aureus in a dose-dependent manner. Cytotoxic activity was evaluated in human liver epithelial cells (HepG2), and the 50% cytotoxicity concentration (CC50) value of Q-POM was higher than 50 mg/L. These results indicate the potential use of Q-POM in treatment of methicillin-resistant Staphylococcus aureus (MRSA) and VRE infections.

RevDate: 2018-11-01

Yuyama KT, Wendt L, Surup F, et al (2018)

Cytochalasans Act as Inhibitors of Biofilm Formation of Staphylococcus Aureus.

Biomolecules, 8(4): pii:biom8040129.

During the course of our ongoing work to discover new inhibitors of biofilm formation of Staphylococcus aureus from fungal sources, we observed biofilm inhibition by cytochalasans isolated from cultures of the ascomycete Hypoxylon fragiforme for the first time. Two new compounds were purified by a bioassay-guided fractionation procedure; their structures were elucidated subsequently by nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HR-MS). This unexpected finding prompted us to test further cytochalasans from other fungi and from commercial sources for comparison. Out of 21 cytochalasans, 13 showed significant inhibition of Staphylococcus aureus biofilm formation at subtoxic levels. These findings indicate the potential of cytochalasans as biofilm inhibitors for the first time, also because the minimum inhibitory concentrations (MIC) are independent of the anti-biofilm activities. However, cytochalasans are known to be inhibitors of actin, making some of them very toxic for eukaryotic cells. Since the chemical structures of the tested compounds were rather diverse, the inclusion of additional derivatives, as well as the evaluation of their selectivity against mammalian cells vs. the bacterium, will be necessary as next step in order to develop structure-activity relationships and identify the optimal candidates for development of an anti-biofilm agent.

RevDate: 2018-11-01

Bernal-Mercado AT, Vazquez-Armenta FJ, Tapia-Rodriguez MR, et al (2018)

Comparison of Single and Combined Use of Catechin, Protocatechuic, and Vanillic Acids as Antioxidant and Antibacterial Agents against Uropathogenic Escherichia Coli at Planktonic and Biofilm Levels.

Molecules (Basel, Switzerland), 23(11): pii:molecules23112813.

The objective of this study was to evaluate the effect of combining catechin, protocatechuic, and vanillic acids against planktonic growing, adhesion, and biofilm eradication of uropathogenic Escherichia coli (UPEC), as well as antioxidant agents. The minimum inhibitory concentrations (MIC) of protocatechuic, vanillic acids and catechin against the growth of planktonic bacteria were 12.98, 11.80, and 13.78 mM, respectively. Mixing 1.62 mM protocatechuic acid + 0.74 mM vanillic acid + 0.05 mM catechin resulted in a synergistic effect acting as an MIC. Similarly, the minimum concentrations of phenolic compounds to prevent UPEC adhesion and biofilm formation (MBIC) were 11.03 and 7.13 mM of protocatechuic and vanillic acids, respectively, whereas no MBIC of catechin was found. However, combinations of 1.62 mM protocatechuic acid + 0.74 mM vanillic acid + 0.05 mM catechin showed a synergistic effect acting as MBIC. On the other hand, the minimum concentrations to eradicate biofilms (MBEC) were 25.95 and 23.78 mM, respectively. The combination of 3.20 mM protocatechuic acid, 2.97 mM vanillic acid, and 1.72 mM catechin eradicated pre-formed biofilms. The antioxidant capacity of the combination of phenolics was higher than the expected theoretical values, indicating synergism by the DPPH•, ABTS, and FRAP assays. Effective concentrations of catechin, protocatechuic, and vanillic acids were reduced from 8 to 1378 times when combined. In contrast, the antibiotic nitrofurantoin was not effective in eradicating biofilms from silicone surfaces. In conclusion, the mixture of phenolic compounds was more effective in preventing cell adhesion and eradicating pre-formed biofilms of uropathogenic E. coli than single compounds and nitrofurantoin, and showed antioxidant synergy.

RevDate: 2018-10-31

Zhao X, Yu Y, Zhang X, et al (2018)

Decreased biofilm formation ability of Acinetobacter baumannii after spaceflight on China's Shenzhou 11 spacecraft.

MicrobiologyOpen [Epub ahead of print].

China has prepared for construction of a space station by the early 2020s. The mission will require astronauts to stay on the space station for at least 180 days. Microbes isolated from the International Space Station (ISS) have shown profound resistance to clinical antibiotics and environmental stresses. Previous studies have demonstrated that the space environment could affect microbial survival, growth, virulence, biofilms, metabolism, as well as their antibiotic-resistant phenotypes. Furthermore, several studies have reported that astronauts experience a decline in their immunity during long-duration spaceflights. Monitoring microbiomes in the ISS or the spacecraft will be beneficial for the prevention of infection among the astronauts during spaceflight. The development of a manned space program worldwide not only provides an opportunity to investigate the impact of this extreme environment on opportunistic pathogenic microbes, but also offers a unique platform to detect mutations in pathogenic bacteria. Various microorganisms have been carried on a spacecraft for academic purposes. Acinetobacter baumannii is a common multidrug-resistant bacterium often prevalent in hospitals. Variations in the ability to cope with environmental hazards increase the chances of microbial survival. Our study aimed to compare phenotypic variations and analyze genomic and transcriptomic variations in A. baumannii among three different groups: SS1 (33 days on the Shenzhou 11 spacecraft), GS1 (ground control), and Aba (reference strain). Consequently, the biofilm formation ability of the SS1 strain decreased after 33 days of spaceflight. Furthermore, high-throughput sequencing revealed that some differentially expressed genes were downregulated in the SS1 strain compared with those in the GS1 strain. In conclusion, this present study provides insights into the environmental adaptation of A. baumannii and might be useful for understanding changes in the opportunistic pathogenic microbes on our spacecraft and on China's future ISS.

RevDate: 2018-10-31

Weisel JW, RI Litvinov (2018)

Keeping it clean: clot biofilm to wall out bacterial invasion.

Journal of thrombosis and haemostasis : JTH [Epub ahead of print].

RevDate: 2018-10-31

Hathroubi S, Zerebinski J, KM Ottemann (2018)

Helicobacter pylori Biofilm Involves a Multigene Stress-Biased Response, Including a Structural Role for Flagella.

mBio, 9(5): pii:mBio.01973-18.

Helicobacter pylori has an impressive ability to persist chronically in the human stomach. Similar characteristics are associated with biofilm formation in other bacteria. The H. pylori biofilm process, however, is poorly understood. To gain insight into this mode of growth, we carried out comparative transcriptomic analysis between H. pylori biofilm and planktonic cells, using the mouse-colonizing strain SS1. Optimal biofilm formation was obtained with a low concentration of serum and 3 days of growth, conditions that caused both biofilm and planktonic cells to be ∼80% coccoid. Transcriptome sequencing (RNA-seq) analysis found that 8.18% of genes were differentially expressed between biofilm and planktonic cell transcriptomes. Biofilm-downregulated genes included those involved in metabolism and translation, suggesting these cells have low metabolic activity. Biofilm-upregulated genes included those whose products were predicted to be at the cell envelope, involved in regulating a stress response, and surprisingly, genes related to formation of the flagellar apparatus. Scanning electron microscopy visualized flagella that appeared to be a component of the biofilm matrix, supported by the observation that an aflagellated mutant displayed a less robust biofilm with no apparent filaments. We observed flagella in the biofilm matrix of additional H. pylori strains, supporting that flagellar use is widespread. Our data thus support a model in which H. pylori biofilm involves a multigene stress-biased response and that flagella play an important role in H. pylori biofilm formation.IMPORTANCE Biofilms, communities of bacteria that are embedded in a hydrated matrix of extracellular polymeric substances, pose a substantial health risk and are key contributors to many chronic and recurrent infections. Chronicity and recalcitrant infections are also common features associated with the ulcer-causing human pathogen H. pylori However, relatively little is known about the role of biofilms in H. pylori pathogenesis, as well as the biofilm structure itself and the genes associated with this mode of growth. In the present study, we found that H. pylori biofilm cells highly expressed genes related to cell envelope and stress response, as well as those encoding the flagellar apparatus. Flagellar filaments were seen in high abundance in the biofilm. Flagella are known to play a role in initial biofilm formation, but typically are downregulated after that state. H. pylori instead appears to have coopted these structures for nonmotility roles, including a role building a robust biofilm.

RevDate: 2018-10-31

Ealand C, Rimal B, Chang J, et al (2018)

Erratum for Ealand et al., "Resuscitation-Promoting Factors Are Required for Mycobacterium smegmatis Biofilm Formation".

Applied and environmental microbiology, 84(22): pii:84/22/e02179-18.

RevDate: 2018-10-31

Carniello V, Peterson BW, van der Mei HC, et al (2018)

Physico-chemistry from initial bacterial adhesion to surface-programmed biofilm growth.

Advances in colloid and interface science pii:S0001-8686(18)30229-X [Epub ahead of print].

Biofilm formation is initiated by adhesion of individual bacteria to a surface. However, surface adhesion alone is not sufficient to form the complex community architecture of a biofilm. Surface-sensing creates bacterial awareness of their adhering state on the surface and is essential to initiate the phenotypic and genotypic changes that characterize the transition from initial bacterial adhesion to a biofilm. Physico-chemistry has been frequently applied to explain initial bacterial adhesion phenomena, including bacterial mass transport, role of substratum surface properties in initial adhesion and the transition from reversible to irreversible adhesion. However, also emergent biofilm properties, such as production of extracellular-polymeric-substances (EPS), can be surface-programmed. This review presents a four-step, comprehensive description of the role of physico-chemistry from initial bacterial adhesion to surface-programmed biofilm growth: (1) bacterial mass transport towards a surface, (2) reversible bacterial adhesion and (3) transition to irreversible adhesion and (4) cell wall deformation and associated emergent properties. Bacterial transport mostly occurs from sedimentation or convective-diffusion, while initial bacterial adhesion can be described by surface thermodynamic and Derjaguin-Landau-Verwey-Overbeek (DLVO)-analyses, considering bacteria as smooth, inert colloidal particles. DLVO-analyses however, require precise indication of the bacterial cell surface, which is impossible due to the presence of bacterial surface tethers, creating a multi-scale roughness that impedes proper definition of the interaction distance in DLVO-analyses. Application of surface thermodynamics is also difficult, because initial bacterial adhesion is only an equilibrium phenomenon for a short period of time, when bacteria are attached to a substratum surface through few surface tethers. Physico-chemical bond-strengthening occurs in several minutes leading to irreversible adhesion due to progressive removal of interfacial water, conformational changes in cell surface proteins, re-orientation of bacteria on a surface and the progressive involvement of more tethers in adhesion. After initial bond-strengthening, adhesion forces arising from a substratum surface cause nanoscopic deformation of the bacterial cell wall against the elasticity of the rigid peptidoglycan layer positioned in the cell wall and the intracellular pressure of the cytoplasm. Cell wall deformation not only increases the contact area with a substratum surface, presenting another physico-chemical bond-strengthening mechanism, but is also accompanied by membrane surface tension changes. Membrane-located sensor molecules subsequently react to control emergent phenotypic and genotypic properties in biofilms, most notably adhesion-associated ones like EPS production. Moreover, also bacterial efflux pump systems may be activated or mechano-sensitive channels may be opened upon adhesion-induced cell wall deformation. The physico-chemical properties of the substratum surface thus control the response of initially adhering bacteria and through excretion of autoinducer molecules extend the awareness of their adhering state to other biofilm inhabitants who subsequently respond with similar emergent properties. Herewith, physico-chemistry is not only involved in initial bacterial adhesion to surfaces but also in what we here propose to call "surface-programmed" biofilm growth. This conclusion is pivotal for the development of new strategies to control biofilm formation on substratum surfaces, that have hitherto been largely confined to the initial bacterial adhesion phenomena.

RevDate: 2018-10-30

Naderi J, Giles C, Saboohi S, et al (2018)

Surface coatings with covalently attached anidulafungin and micafungin prevent Candida albicans biofilm formation.

The Journal of antimicrobial chemotherapy pii:5146520 [Epub ahead of print].

Objectives: Fungal biofilms caused by Candida spp. are a major contributor to infections originating from infected biomaterial implants. Since echinocandin-class molecules interfere with the integrity of the fungal cell wall, it was hypothesized that surface-immobilized anidulafungin and micafungin could play a role in preventing fungal adhesion and biofilm formation on surfaces.

Methods: Anidulafungin and micafungin were covalently coupled to biomaterial surfaces and washed. Surface-sensitive instrumental analysis quantitatively and qualitatively confirmed their presence. Analysis after washing experiments provided evidence of their covalent immobilization. The in vitro antifungal properties of surfaces were confirmed using static biofilm assays and fluorescence microscopy kinetic studies.

Results: Antifungal surface coatings eliminated 106 cfu/cm2 inoculations of Candida albicans and prevented biofilm formation and hyphal development on coated surfaces. Surfaces were successively exposed to fresh inoculum and were effective for at least five challenges in eliminating adherent yeasts.

Conclusions: We have observed antifungal and anti-biofilm activity of surfaces bearing conjugated echinocandins, which operate through surface contact. The analytical and biological evidence suggests an antifungal mechanism for echinocandins that does not rely upon freely diffusing molecules.

RevDate: 2018-10-30

Shang L, Deng D, Buskermolen JK, et al (2018)

Multi-species oral biofilm promotes reconstructed human gingiva epithelial barrier function.

Scientific reports, 8(1):16061 pii:10.1038/s41598-018-34390-y.

Since the oral mucosa is continuously exposed to abundant microbes, one of its most important defense features is a highly proliferative, thick, stratified epithelium. The cellular mechanisms responsible for this are still unknown. The aim of this study was to determine whether multi-species oral biofilm contribute to the extensive stratification and primed antimicrobial defense in epithelium. Two in vitro models were used: 3D reconstructed human gingiva (RHG) and oral bacteria representative of multi-species commensal biofilm. The organotypic RHG consists of a reconstructed stratified gingiva epithelium on a gingiva fibroblast populated hydrogel (lamina propria). Biofilm was cultured from healthy human saliva, and consists of typical commensal genera Granulicatella and major oral microbiota genera Veillonella and Streptococcus. Biofilm was applied topically to RHG and host-microbiome interactions were studied over 7 days. Compared to unexposed RHG, biofilm exposed RHG showed increased epithelial thickness, more organized stratification and increased keratinocyte proliferation. Furthermore biofilm exposure increased production of RHG anti-microbial proteins Elafin, HBD2 and HBD3 but not HBD1, adrenomedullin or cathelicidin LL-37. Inflammatory and antimicrobial cytokine secretion (IL-6, CXCL8, CXCL1, CCL20) showed an immediate and sustained increase. In conclusion, exposure of RHG to commensal oral biofilm actively contributes to RHG epithelial barrier function.

RevDate: 2018-10-30

Tuohy JM, Mueller-Spitz SR, Albert CM, et al (2018)

MALDI-TOF MS Affords Discrimination of Deinococcus aquaticus Isolates Obtained From Diverse Biofilm Habitats.

Frontiers in microbiology, 9:2442.

Matrix-assisted Laser Desorption Ionization-Time of Flight Mass Spectroscopy (MALDI-TOF MS) has been used routinely over the past decade in clinical microbiology laboratories to rapidly characterize diverse microorganisms of medical importance both at the genus and species levels. Currently, there is keen interest in applying MALDI-TOF MS at taxonomic levels beyond species and to characterize environmental isolates. We constructed a model system consisting of 19 isolates of Deinococcus aquaticus obtained from biofilm communities indigenous to diverse substrates (concrete, leaf tissue, metal, and wood) in the Fox River - Lake Winnebago system of Wisconsin to: (1) develop rapid sample preparation methods that produce high quality, reproducible MALDI-TOF spectra and (2) compare the performance of MALDI-TOF MS-based profiling to common DNA-based approaches including 16S rRNA sequencing and genomic diversity by BOX-A1R fingerprinting. Our results suggest that MALDI-TOF MS can be used to rapidly and reproducibly characterize environmental isolates of D. aquaticus at the subpopulation level. MALDI-TOF MS provided higher taxonomic resolution than either 16S rRNA gene sequence analysis or BOX-A1R fingerprinting. Spectra contained features that appeared to permit characterization of isolates into two co-occurring subpopulations. However, reliable strain-level performance required rigorous and systematic standardization of culture conditions and sample preparation. Our work suggests that MALDI-TOF MS offers promise as a rapid, reproducible, and high-resolution approach to characterize environmental isolates of members of the genus Deinococcus. Future work will focus upon application of methods described here to additional members of this ecologically diverse and ubiquitous genus.

RevDate: 2018-10-29

Balato G, Roscetto E, Vollaro A, et al (2018)

Bacterial biofilm formation is variably inhibited by different formulations of antibiotic-loaded bone cement in vitro.

Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA pii:10.1007/s00167-018-5230-x [Epub ahead of print].

PURPOSE: The aim of the present study was to quantitatively assess biofilm growth on the surface of bone cements discs containing different antibiotics, including colistin and linezolid. Biofilms of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Staphylococcus epidermidis were grown on bone cement discs for 96 h.

METHODS: Biofilm amounts were measured by confocal laser microscopy using live/dead staining and dedicated software at different time intervals (48, 72, and 96 h).

RESULTS: Bone cement containing vancomycin was not effective at reducing MRSA biofilm formation 96 h following bacterial inoculation. At a comparable time interval, linezolid-, clindamycin-, and aminoglycoside-loaded cement was still active against this biofilm. At the 72- and 96-h observations, S. epidermidis biofilm was present only on tobramycin and gentamicin discs. P. aeruginosa biofilms were present on cement discs loaded with colistin at all time intervals starting from the 48-h observation, whereas no biofilms were detected on tobramycin or gentamicin discs.

CONCLUSION: Bone cements containing different antibiotics have variable and time-dependent windows of activity in inhibiting or reducing surface biofilm formation. The effectiveness of bone cement containing vancomycin against MRSA biofilm is questionable. The present study is clinically relevant, because it suggests that adding the right antibiotic to bone cement could be a promising approach to treat periprosthetic infections. Indeed, the antibiofilm activity of different antibiotic-loaded bone cements could be preoperatively assessed using the current methodology in two-stage exchange procedures.

RevDate: 2018-10-29

Korany AM, Hua Z, Green T, et al (2018)

Efficacy of Ozonated Water, Chlorine, Chlorine Dioxide, Quaternary Ammonium Compounds and Peroxyacetic Acid Against Listeria monocytogenes Biofilm on Polystyrene Surfaces.

Frontiers in microbiology, 9:2296.

Listeria monocytogenes contaminated processing equipment and the general packing environment have been implicated in deadly foodborne listeriosis outbreaks, highlighting the significance of proper sanitization and disinfection of food contact surfaces. This study aims to comprehensively evaluate antimicrobial efficacy of commercially available, economical sanitizers at practical concentrations against L. monocytogenes biofilm formed on polystyrene surfaces under different conditions. Ozonated water 1-min treatment at 1.0, 2.0, and 4.0 ppm resulted in ∼0.9, 3.4, and 4.1 log reduction of L. monocytogenes single strain biofilm grown on polystyrene surfaces, respectively. However, its efficacy was dramatically diminished in multi-strain L. monocytogenes biofilm and was further compromised by aged biofilm and in the presence of organic matter. Quaternary ammonium compounds (QAC) at 100/400 ppm, chlorine at 100/200 ppm, chlorine dioxide at 2.5/5.0 ppm and peroxyacetic acid (PAA) at 80/160 ppm resulted in 2.4/3.6, 2.0/3.1, 2.4/3.8, and 3.6/4.8 log reduction of L. monocytogenes single strain biofilm, respectively. Antimicrobial efficacies of all tested sanitizers against 7-day-old biofilm were much lower when compared to 2-day-old biofilm, with PAA being the least influenced by the age of the biofilm. Organic matter conditioning with diluted milk or apple juice dramatically impacted the antimicrobial efficacy of all sanitizers. PAA treatment of 1 min at 160-200 ppm resulted in a 3.2-3.5 log reduction against 7-day-old biofilm in the presence of organic matter, thus showing its effectiveness in eradicating L. monocytogenes biofilm on polystyrene surface. Collectively, data highlight the importance of timely and thoroughly cleaning food contact surfaces before disinfection and provides practical information and guidance for the food industry in selecting the most effective sanitizer in their sanitizing regimes to eliminate L. monocytogenes biofilm.

RevDate: 2018-10-28

Yan J, Moreau A, Khodaparast S, et al (2018)

Bacterial Biofilm Material Properties Enable Removal and Transfer by Capillary Peeling.

Advanced materials (Deerfield Beach, Fla.) [Epub ahead of print].

Biofilms, surface-attached communities of bacterial cells, are a concern in health and in industrial operations because of persistent infections, clogging of flows, and surface fouling. Extracellular matrices provide mechanical protection to biofilm-dwelling cells as well as protection from chemical insults, including antibiotics. Understanding how biofilm material properties arise from constituent matrix components and how these properties change in different environments is crucial for designing biofilm removal strategies. Here, using rheological characterization and surface analyses of Vibrio cholerae biofilms, it is discovered how extracellular polysaccharides, proteins, and cells function together to define biofilm mechanical and interfacial properties. Using insight gained from our measurements, a facile capillary peeling technology is developed to remove biofilms from surfaces or to transfer intact biofilms from one surface to another. It is shown that the findings are applicable to other biofilm-forming bacterial species and to multiple surfaces. Thus, the technology and the understanding that have been developed could potentially be employed to characterize and/or treat biofilm-related infections and industrial biofouling problems.

RevDate: 2018-10-28

Mahdinia E, Demirci A, A Berenjian (2018)

Effects of medium components in a glycerol-based medium on vitamin K (menaquinone-7) production by Bacillus subtilis natto in biofilm reactors.

Bioprocess and biosystems engineering pii:10.1007/s00449-018-2027-8 [Epub ahead of print].

Menaquinone-7 (MK-7) as the most important form of Vitamin K has been reported to have miraculous benefits such as preventing cardiovascular diseases and osteoporosis along with antitumor effects. Therefore, there have been numerous studies in the past decades to improve MK-7 production via microbial fermentation. Unfortunately, both solid and liquid state fermentation strategies that are utilized for MK-7 production, face fundamental operational and scale-up issues as well as intense heat and mass transfer problems during fermentation. In this regard, biofilm reactors seem to be a practical solution to overcome these issues and enhance the production in agitated liquid fermentation. Therefore, this study was undertaken to utilize biofilm reactors in investigating and optimizing different media components in a glycerol-based medium. Using response surface methodology, the effects of glycerol, yeast extract, and soytone were studied in the fermentation medium on MK-7 production in biofilm reactor. With a composition of 48.2 g/L of glycerol, 8.1 g/L of yeast extracts, 13.6 g/L of soytone and 0.06 g/L of K2HPO4, MK-7 concentrations could reach 14.7 ± 1.4 mg/L in biofilm reactors, which was 57% higher compared to the MK-7 concentration achieved in suspended-cell reactors under similar conditions, while glycerol was depleted by the end of the fifth day in biofilm reactors, but glycerol was never depleted in suspended-cell reactors. Evidently, biofilm reactors present a reliable strategy to address the operational issues that occur during MK-7 biosynthesis on an industrial scale production.

RevDate: 2018-10-28

Irankhah S, Abdi Ali A, Reza Soudi M, et al (2018)

Highly efficient phenol degradation in a batch moving bed biofilm reactor: benefiting from biofilm-enhancing bacteria.

World journal of microbiology & biotechnology, 34(11):164 pii:10.1007/s11274-018-2543-3.

In this study, the efficiency improvement of three moving bed biofilm reactors (MBBRs) was investigated by inoculation of activated sludge cells (R1), mixed culture of eight strong phenol-degrading bacteria consisted of Pseudomonas spp. and Acinetobacter spp. (R2) and the combination of both (R3). Biofilm formation ability of eight bacteria was assessed initially using different methods and media. Maximum degradation of phenol, COD, biomass growth and also changes in organic loading shock were used as parameters to measure the performance of reactors. According to the results, all eight strains were determined as enhanced biofilm forming bacteria (EBFB). Under optimum operating conditions, more than 90% of initial COD load of 2795 mg L-1 was reduced at 24 HRT in R3 while this reduction efficiency was observed in concentrations of 1290 mg L-1 and 1935 mg L-1, in R1 and R2, respectively. When encountering phenol loading shock-twice greater than optimum amount-R1, R2 and R3 managed to return to the steady-state condition within 32, 24 and 18 days, respectively. SEM microscopy and biomass growth measurements confirmed the contribution of more cells to biofilm formation in R3 followed by R2. Additionally, established biofilm in R3 was more resistant to phenol loading shock which can be attributed to the enhancer role of EBFB strains in this reactor. It has been demonstrated that the bacteria with both biofilm-forming and contaminant-degrading abilities are not only able to promote the immobilization of other favorable activated sludge cells in biofilm structure, but also cooperate in contaminant degradation which all consequently lead to improvement of treatment efficiency.

RevDate: 2018-10-27

Naumova EA, Weber L, Pankratz V, et al (2018)

Bacterial viability in oral biofilm after tooth brushing with amine fluoride or sodium fluoride.

Archives of oral biology, 97:91-96 pii:S0003-9969(18)30304-2 [Epub ahead of print].

OBJECTIVE: The aim of this study was to investigate the effects of sodium fluoride (NaF) and amine fluoride (AmF) on bacterial viability in the oral cavity.

MATERIAL AND METHODS: Healthy subjects brushed their teeth with either fluoride free toothpaste, NaF- or AmF-containing toothpaste. Biofilm smears from different locations were collected before and immediately and 30 and 120 min after tooth brushing. The smears were stained with live/dead bacterial staining, and the number of the respective bacteria was counted. The data were statistically analyzed by comparing the numbers of bacteria before and after the application of no fluoride, NaF and AmF.

RESULTS: The highest numbers of bacteria were found in the tongue biofilm, followed by the palatal and cheek biofilm. The lowest numbers were found in the mouth floor biofilm. After the application of AmF, no changes in the numbers of bacteria were found in the biofilms, except for the cheek, where they were reduced. After the application of NaF, the number of bacteria decreased significantly in all biofilms. After 120 min, bacterial regrowth was complete.

CONCLUSIONS: AmF has only little effect on the bacterial viability of oral biofilms. NaF application reduces the number of living bacteria in the oral biofilms. This effect lasts not longer than 120 min.

RevDate: 2018-10-27

Kharadi RR, Castiblanco LF, Waters CM, et al (2018)

Phosphodiesterase genes regulate amylovoran production, biofilm formation, and virulence in Erwinia amylovora.

Applied and environmental microbiology pii:AEM.02233-18 [Epub ahead of print].

Cyclic di-GMP (c-di-GMP) is a ubiquitous bacterial second messenger molecule that is an important virulence regulator in the plant pathogen Erwinia amylovora Intracellular levels of c-di-GMP are modulated by diguanylate cyclase (DGC) enzymes that synthesize c-di-GMP and phosphodiesterase (PDE) enzymes that degrade c-di-GMP. The regulatory role of the PDE enzymes in E. amylovora has not been determined. Using a combination of single, double, and triple deletion mutants, we determined the effect of each of the four putative PDE-encoding genes (pdeA, pdeB, pdeC, and edcA) in E. amylovora on cellular processes related to virulence. Our results indicate that pdeA and pdeC are the two most active phosphodiesterases in virulence regulation in E. amylovora Ea1189. The deletion of pdeC resulted in a measurably significant increase in the intracellular pool of c-di-GMP, and the highest intracellular concentrations of c-di-GMP were observed in the Ea1189ΔpdeAC and Ea1189ΔpdeABC mutants. The regulation of virulence traits due to the deletion of the pde genes showed two patterns. A stronger regulatory effect was observed on amylovoran production and biofilm formation, where both Ea1189ΔpdeA and Ea1189ΔpdeC exhibited a significant increase in these two phenotypes in vitro In contrast, the deletion of two or more pde genes was required to affect motility and virulence phenotypes. Our results indicate a functional redundancy among the pde genes in E. amylovora for certain traits and indicate that the intracellular degradation of c-di-GMP is mainly regulated by pdeA and pdeC, but also suggest a role for pdeB in regulating motility and virulence.IMPORTANCE Precise control of the expression of virulence genes is essential for successful infection of apple hosts by the fire blight pathogen Erwinia amylovora The presence and buildup of a signaling molecule called cyclic di-GMP enables the expression and function of some virulence determinants in E. amylovora such as amylovoran production and biofilm formation. However, other determinants, such as motility and the type III secretion system are expressed and functional when cyclic di-GMP is absent. In this manuscript, we report studies of enzymes called phosphodiesterases that function in the degradation of cyclic di-GMP. We show the importance of these enzymes in virulence gene regulation and the ability of E. amylovora to cause plant disease.

RevDate: 2018-10-26

Rago L, Zecchin S, Villa F, et al (2018)

Bioelectrochemical Nitrogen fixation (e-BNF): Electro-stimulation of enriched biofilm communities drives autotrophic nitrogen and carbon fixation.

Bioelectrochemistry (Amsterdam, Netherlands), 125:105-115 pii:S1567-5394(18)30363-3 [Epub ahead of print].

A new approach to microbial electrosynthesis is proposed, aimed at producing whole biomass from N2 and inorganic carbon, by electrostimulation of complex microbial communities. On a carbon-based conductor under constant polarization (-0.7 V vs SHE), an electroactive biofilm was enriched with autotrophic nitrogen fixing microorganims and led to biomass synthesis at higher amounts (up to 18 fold), as compared to controls kept at open circuit (OC). After 110 days, the electron transfer had increased by 30-fold, as compared to abiotic conditions. Metagenomics evidenced Nif genes associated with autotrophs (both Archaea and Bacteria) only in polarized biofilms, but not in OC. With this first proof of concept experiment, we propose to call this promising field 'bioelectrochemical nitrogen fixation' (e-BNF): a possible way to 'power' biological nitrogen fixation, organic carbon storage and soil fertility against desertification, and possibly a new tool to study the development of early prokaryotic life in extreme environments.

RevDate: 2018-10-26

Borges KRA, Pimentel IV, Lucena LCLDS, et al (2018)

Adhesion and biofilm formation of Candida parapsilosis isolated from vaginal secretions to copper intrauterine devices.

Revista do Instituto de Medicina Tropical de Sao Paulo, 60:e59 pii:S0036-46652018005000233.

INTRODUCTION: Candida parapsilosis is one of the main species that is able to adhere to forming biofilms on inert materials. Adhesion is the first step towards the colonization and invasion of host cells during the infectious process. Among the infections, vulvovaginal candidiasis is increasingly common. The objective was to evaluate the profile of adherence and biofilm formation of eight isolates of C. parapsilosis on the metal used in intrauterine devices (IUDs).

METHODS: Eight strains of C. parapsilosis presenting strong adhesion and biofilm formation properties were isolated from vaginal secretions in a previous study. To assay the adhesion and biofilm formation, copper fragments were made and cultivated in tubes containing 3 mL of phosphate-buffered saline and incubated for 6 and 24 h at 37 °C to evaluate biofilm formation. After incubation, the intensity of adherence and of biofilm formation on copper fragments were determined by performing a colony count.

RESULTS: All isolates were able to form biofilms and the isolate Cp62 showed many cells joined in a planktonic mode forming biofilms. The use of an IUD is one of the main factors that favors vulvovaginal candidiasis, and the presence of copper in this device increases the chance of recurrent vulvovaginal candidiasis (CVVR) due to the ease with which species of the genus Candida can adhere to inert surfaces.

CONCLUSION: This research showed that the clinical isolates studied adhered to IUD copper fragments and formed biofilms, further increasing their virulence.

RevDate: 2018-10-26

Midha A, Janek K, Niewienda A, et al (2018)

Corrigendum: The Intestinal Roundworm Ascaris suum Releases Antimicrobial Factors Which Interfere With Bacterial Growth and Biofilm Formation.

Frontiers in cellular and infection microbiology, 8:367.

[This corrects the article DOI: 10.3389/fcimb.2018.00271.].

RevDate: 2018-10-26

Farkash Y, Feldman M, Ginsburg I, et al (2018)

Green Tea Polyphenols and Padma Hepaten Inhibit Candida albicans Biofilm Formation.

Evidence-based complementary and alternative medicine : eCAM, 2018:1690747.

Candida albicans (C. albicans) is the most prevalent opportunistic human pathogenic fungus and can cause mucosal membrane infections and invade the blood. In the oral cavity, it can ferment dietary sugars, produce organic acids and therefore has a role in caries development. In this study, we examined whether the polyphenol rich extractions Polyphenon from green tea (PPFGT) and Padma Hepaten (PH) can inhibit the caries-inducing properties of C. albicans. Biofilms of C. albicans were grown in the presence of PPFGT and PH. Formation of biofilms was tested spectrophotometrically after crystal violet staining. Exopolysaccharides (EPS) secretion was quantified using confocal scanning laser microscopy (CSLM). Treated C. albicans morphology was demonstrated using scanning electron microscopy (SEM). Expression of virulence-related genes was tested using qRT-PCR. Development of biofilm was also tested on an orthodontic surface (Essix) to assess biofilm inhibition ability on such appliances. Both PPFGT and PH dose-dependently inhibited biofilm formation, with no inhibition on planktonic growth. The strongest inhibition was obtained using the combination of the substances. Crystal violet staining showed a significant reduction of 45% in biofilm formation using a concentration of 2.5mg/ml PPFGT and 0.16mg/ml PH. A concentration of 1.25 mg/ml PPFGT and 0.16 mg/ml PH inhibited candidal growth by 88% and EPS secretion by 74% according to CSLM. A reduction in biofilm formation and in the transition from yeast to hyphal morphotype was observed using SEM. A strong reduction was found in the expression of hwp1, eap1, and als3 virulence associated genes. These results demonstrate the inhibitory effect of natural PPFGT polyphenolic extraction on C. albicans biofilm formation and EPS secretion, alone and together with PH. In an era of increased drug resistance, the use of phytomedicine to constrain biofilm development, without killing host cells, may pave the way to a novel therapeutic concept, especially in children as orthodontic patients.

RevDate: 2018-10-26

Kim SK, Li XH, Hwang HJ, et al (2018)

Antibiofilm effect of biofilm-dispersing agents on clinical isolates of Pseudomonas aeruginosa with various biofilm structures.

Journal of microbiology (Seoul, Korea) pii:10.1007/s12275-018-8336-4 [Epub ahead of print].

Pseudomonas aeruginosa, an opportunistic human pathogen, causes many biofilm-mediated chronic infections. In this study, biofilm structures of various clinical strains of P. aeruginosa isolated from hospitalized patients were examined and their influence on the biofilm-dispersing effects of chemicals was investigated. The clinical isolates formed structurally distinct biofilms that could be classified into three different groups: 1) mushroom-like, 2) thin flat, and 3) thick flat structures. A dispersion of these differently structured biofilms was induced using two biofilm-dispersing agents, anthranilate and sodium nitroprusside (SNP). Although both SNP and anthranilate could disperse all types of biofilms, the thick flat biofilms were dispersed less efficiently than the biofilms of other structures. This suggests that biofilm-dispersing agents have higher potency on the biofilms of porous structures than on densely packed biofilms.

RevDate: 2018-10-26

Song Z, Zhang X, Ngo HH, et al (2019)

Zeolite powder based polyurethane sponges as biocarriers in moving bed biofilm reactor for improving nitrogen removal of municipal wastewater.

The Science of the total environment, 651(Pt 1):1078-1086.

This study aims to enhance nitrogen removal efficiency of a moving bed biofilm reactor (MBBR) by developing a new MBBR with zeolite powder-based polyurethane sponges as biocarriers (Z-MBBR). Results indicated the total nitrogen (TN) removal efficiency and simultaneous nitrification and denitrification (SND) performance in Z-MBBR were nearly 10% higher than those in the conventional MBBR with sponges as biocarriers (S-MBBR). About 84.2 ± 4.8% of TN was removed in Z-MBBR compared to 75.1 ± 6.8% in S-MBBR. Correspondingly, the SND performance in Z-MBBR and S-MBBR was 90.7 ± 4.1% and 81.7 ± 6.5%, respectively. The amount of biofilm attached to new biocarriers (0.470 ± 0.131 g/g carrier) was 1.3 times more than that of sponge carriers (0.355 ± 0.099 g/g carrier). Based on the microelectrode measurements and microbial community analysis, more denitrifying bacteria existed in the Z-MBBR system, and this can improve the SND performance. Consequently, this new Z-MBBR can be a promising option for a hybrid treatment system to better nitrogen removal from wastewater.

RevDate: 2018-10-25

Cao W, Zhang Y, Wang X, et al (2018)

Novel resin-based dental material with anti-biofilm activity and improved mechanical property by incorporating hydrophilic cationic copolymer functionalized nanodiamond.

Journal of materials science. Materials in medicine, 29(11):162 pii:10.1007/s10856-018-6172-z.

There is an increasing clinical need to design dental restorative materials that combine excellent mechanical property and anti-biofilm activity. In the current study, photocurable polycation functionalized nanodiamond (QND) was synthesized and proposed as novel filler for dental resins. By reason of increased repulsive force between nanoparticles and enhanced compatibility with resin matrix, QND dispersed uniformly in reinforced resins, which would help to transfer stress and deformation from the matrix to fillers more efficiently, resulting in a significant improvement in mechanical properties. Notably, the Vickers's hardness, flexural strength and flexural modulus of resins containing 1.0 wt% QND were 44.5, 36.1 and 41.3% higher than that of control, respectively. The antibacterial activity against Streptococcus mutans (S. mutans) showed that QND-incorporated resins produced anti-adhesive property due to their hydrophilic surfaces and could suppress bacterial growth as a result of the contact-killing effect of embedded nanocomposites. As the synergistic effect of anti-adhesive and bactericidal performance, resins loading 1.0~1.5 wt% QNDs displayed excellent anti-biofilm activity. Meanwhile, the results of macrophage cytotoxicity showed that the proliferation of RAW 264.7 cells remained 84.3%, even at a concentration of 1.0 wt% QNDs after 7-day incubation. Therefore, the QND-containing dental resin with the combination of high mechanical property, bacteria-repellent capability and antibacterial performance holds great potential as a restorative material based on this scheme.

RevDate: 2018-10-25

Parandhaman T, SK Das (2018)

Facile synthesis, biofilm disruption properties and biocompatibility study of a poly-cationic peptide functionalized graphene-silver nanocomposite.

Biomaterials science [Epub ahead of print].

Bacterial colonization and biofilm formation is a growing challenge in the biomedical field. Although nanotechnology has emerged as an alternative strategy to combat biofilm formation, the toxicity of nanomaterials is a major concern. In this study, we report a safe-by-design strategy for the synthesis of a poly-cationic peptide functionalized graphene-silver nanocomposite (designated as GAPP) and its enhanced biofilm inhibition and disruption properties to eliminate the biofilm development of Gram-negative bacteria. The graphene-silver (rGOAg) nanocomposite was synthesized by microwave reduction, and subsequently functionalized with an antimicrobial poly-cationic peptide through covalent bonding. The results demonstrated that GAPP effectively killed the planktonic cells and biofilms of Escherichia coli and Pseudomonas aeruginosa depending upon the concentration and duration of the interaction. The complete eradication of preformed biofilm was achieved when treated with 10 μg mL-1 of GAPP for 5 h. The GAPP exerted bactericidal and biofilm inhibition activity through a "contact-kill-release" mode of action, wherein the electrostatic interaction of GAPP with the bacterial cells induced physical disruption accompanied by ROS-mediated biochemical changes. The internalization of GAPP into the cytoplasm through the damaged membrane led to metabolic imbalance in the cells. The peptide functionalization further prevented the dissolution of Ag+ ions, thus minimizing the cytotoxicity of GAPP to adult zebrafish. More importantly, the poly-cationic peptide functionalization enhanced the bioavailability, biofilm inhibition and disruption activities of GAPP, while minimizing its toxicological impact. The results obtained thereby provide an effective strategy in the design of alternative antibacterial agents for fighting biofilms of Gram-negative bacteria.

RevDate: 2018-10-25

Yu L, Shang F, Chen X, et al (2018)

The anti-biofilm effect of silver-nanoparticle-decorated quercetin nanoparticles on a multi-drug resistant Escherichia coli strain isolated from a dairy cow with mastitis.

PeerJ, 6:e5711 pii:5711.

Background: Escherichia coli is an important opportunistic pathogen that could cause inflammation of the udder in dairy cows resulting in reduced milk production and changes in milk composition and quality, and even death of dairy cows. Therefore, mastitis is the main health issue which leads to major economic losses on dairy farms. Antibiotics are routinely used for the treatment of bovine mastitis. The ability to form biofilm increases the antibiotic resistance of E. coli. Nanoparticles (NPs), a nanosized, safe, and highly cost-effective antibacterial agent, are potential biomedical tools. Given their antibacterial activities, silver nanoparticles (Ag NPs) have a broad range of applications.

Methods: In this study, we performed antibacterial activity assays, biofilm formation assays, scanning electron microscopy (SEM) experiments, and real-time reverse transcription PCR (RT-PCR) experiments to investigate the antibacterial and anti-biofilm effect of quercetin, Ag NPs, and Silver-nanoparticle-decorated quercetin nanoparticles (QA NPs) in E. coli strain ECDCM1.

Results: In this study, QA NPs, a composite material combining Ag NPs and the plant-derived drug component quercetin, exhibited stronger antibacterial and anti-biofilm properties in a multi-drug resistant E. coli strain isolated from a dairy cow with mastitis, compared to Ag NPs and Qe.

Discussion: This study provides evidence that QA NPs possess high antibacterial and anti-biofilm activities. They proved to be more effective than Ag NPs and Qe against the biofilm formation of a multi-drug resistant E. coli isolated from cows with mastitis. This suggests that QA NPs might be used as a potential antimicrobial agent in the treatment of bovine mastitis caused by E. coli.

RevDate: 2018-10-25

Takesh T, Ho J, Firmalino MV, et al (2018)

Effects of a Novel Formulation on Oral Biofilm, pH Buffering, and Gingival Health in Patients with Dry Mouth.

International journal of dentistry, 2018:2748274.

Goal: To identify in patients with dry mouth the effects of a novel test agent (Oral Essentials Hydrating Formula Mouthwash, Beverly Hills, CA) versus a control agent (Biotène Dry Mouth Oral Rinse, GlaxoSmithKline Consumer Healthcare L.P., Moon Township, PA, USA) versus no treatment on dry mouth, plaque, salivary pH and buffering capacity, gingival health, and tooth sensitivity.

Materials and Methods: In this cross-over study, ten subjects with dry mouth used test and control dry mouth interventions, as well as no dry mouth intervention in randomized sequence. Plaque Index, Gingival Index, Sulcus Bleeding Index, Plaque staining, and photographs were recorded at baseline and end of each study arm. Salivary volume, pH, and buffering capacity were also recorded at these time points. Additionally, subjects completed a questionnaire for dry mouth and dentinal sensitivity at each visit.

Results: Reductions in plaque presence and clinical indices were similar after use of test or control products (p < 0.05). Saliva volume and pH buffering improved significantly after use of test and control products (p < 0.05).

Conclusions: The effects of a novel dry mouth intervention are similar to those of an existing OTC remedy and are significantly better than no intervention.


RJR Experience and Expertise


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


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


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


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


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


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


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


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

Order from Amazon

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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Woodinville, WA 98077


E-mail: RJR8222@gmail.com

Collection of publications by R J Robbins

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

Research Gate page for R J Robbins

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

Curriculum Vitae for R J Robbins

short personal version

Curriculum Vitae for R J Robbins

long standard version

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