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Bibliography on: Biofilm

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ESP: PubMed Auto Bibliography 08 Mar 2021 at 01:31 Created: 


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

Created with PubMed® Query: biofilm[title] NOT 28392838[PMID] NOT 31293528[PMID] NOT 29372251[PMID] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)


RevDate: 2021-03-06

Calvo DC, Ontiveros-Valencia A, Krajmalnik-Brown R, et al (2021)

Carboxylates and alcohols production in an autotrophic hydrogen-based membrane biofilm reactor.

Biotechnology and bioengineering [Epub ahead of print].

Microbiological conversion of CO2 into biofuels and/or organic industrial feedstock is an excellent carbon-cycling strategy. In this study, autotrophic anaerobic bacteria in the membrane biofilm reactor (MBfR) transferred electrons from hydrogen gas (H2) to inorganic carbon (IC) and produced organic acids and alcohols. We systematically varied the H2 -delivery, the IC concentration, and the hydraulic retention time in the MBfR. The relative availability of H2 versus IC was the determining factor for enabling microbial chain elongation (MCE). When the H2 :IC mole ratio was high (> 2.0 mol H2 /mol C), MCE was an important process, generating medium chain carboxylates up to octanoate (C8, 9.1 ± 1.3 mM C and 28.1 ± 4.1 mmol C m-2 d-1). Conversely, products with two carbons were the only ones present when the H2 :IC ratio was low (< 2.0 mol H2 /mol C), so that H2 was the limiting factor. The biofilm microbial community was enriched in phylotypes most similar to the well-known acetogen Acetobacterium for all conditions tested, but phylotypes closely related with families capable of MCE (e.g., Bacteroidales, Rhodocyclaceae, Alcaligenaceae, Thermoanaerobacteriales, and Erysipelotrichaceae) became important when the H2 :IC ratio was high. Thus, proper management of IC availability and H2 supply allowed control over community structure and function, reflected by the chain length of the carboxylates and alcohols produced in the MBfR. This article is protected by copyright. All rights reserved.

RevDate: 2021-03-06

Matias RR, Sepúlveda AMG, Batista BN, et al (2021)

Degradation of Staphylococcus aureus Biofilm Using Hydrolytic Enzymes Produced by Amazonian Endophytic Fungi.

Applied biochemistry and biotechnology [Epub ahead of print].

Microbial biofilms can cause serious health problems, since, due to their persistent character, they often function as spreaders of contaminants. Hydrolytic enzymes have a number of industrial applications and have been indicated as an alternative to the traditional chemical methods that are used to eradicate microbial biofilms. In this study, we evaluated the ability of enzymatic extracts produced by endophytic fungi isolated from the Amazonian species Myrcia guianensis to remove Staphylococcus aureus biofilms. After culture in liquid medium, the fungal hydrolytic extracts showed amylase (3.77 U/mL), lipase (3.84 U/mL), protease (3.63 U/mL), and xylanase (2.91 U/mL) activity. A 24 h mature S. aureus ATCC6538 biofilm was exposed to each enzyme extract with standardized enzyme activities for 10, 30, and 60 min. The optical density at 630 nm was used to calculate the growth rate (GR%) and the residual biofilm rate (RBR%). The most promising solutions were used in combination, based on a 24 factorial design for 0, 10, 20, and 30 min of exposure. Lipase and protease solutions, when applied separately, were the most effective, and promoted the complete removal of S. aureus biofilms in t10 (lipase) and t30 and t60 (lipase and protease). Of the combined treatments using 1.0 U/mL protease and 0.4 U/mL lipase, total biofilm degradation was observed for all exposure times. Thus, the hydrolases produced by the Amazonian endophytic fungi evaluated here are highlighted as an interesting tool in the fight against microbial biofilms.

RevDate: 2021-03-06

Tang Y, Bai J, Yang Y, et al (2021)

Effect of Syringopicroside Extracted from Syringa oblata Lindl on the Biofilm Formation of Streptococcus suis.

Molecules (Basel, Switzerland), 26(5): pii:molecules26051295.

Syringopicroside is a natural drug with antibacterial activity, which is the main ingredient of Syringa oblata Lindl (S. oblata). In order to further develop the application of S. oblata and evaluate the ability of syringopicroside against Streptococcus suis (S. suis), this investigation first applied an ultrasonic-assisted method to extract syringopicroside, and then response surface methodology (RSM) was performed to get the optimum condition. Based on RSM analysis, a second-order polynomial equation about the syringopicroside yield and four variables, including ultrasonic power, time, temperature, and liquid-to-solid ratio, was purposed. Through RSM prediction and model verification experiments, the optimum conditions were determined, as follows: ultrasonic time was 63 min, temperature was 60 °C, a liquid-to-solid ratio was set to 63 mL/g, and ultrasonic power was 835 W. Under this condition, a high syringopicroside yield was obtained (3.07 ± 0.13 mg/g), which was not significantly different with a predicated value. After separation and purification by HPD 500 microporous resin, then mass spectrum was applied to identify the main ingredient in aqueous extract. A minimal inhibitory concentration (MIC) assay revealed the value against S. suis of syringopicroside was 2.56 µg/µL and syringopicroside with sub-inhibitory concentrations that could effectively inhibit biofilm formation of S. suis. Besides, scanning electron microscopy analysis indicated syringopicroside could destroy the multi-layered aggregation structure of S. suis. Finally, molecular docking analysis confirmed that syringopicroside was combined with Orfy protein of S. suis through hydrogen bonds, hydrophobic interaction, and π-π stacking.

RevDate: 2021-03-06

Hwang G, Blatz MB, Wolff MS, et al (2021)

Diagnosis of Biofilm-Associated Peri-Implant Disease Using a Fluorescence-Based Approach.

Dentistry journal, 9(3): pii:dj9030024.

Dental implants have become a routine component of daily dental practice and the demand for dental implants is expected to increase significantly in the future. Despite the high success rates of dental implants, failures do occur, resulting in discomfort, rampant destruction of the oral health, or painful and costly surgical replacement of a failed implant. Peri-implant diseases are inflammatory conditions affecting the soft/hard tissues surrounding a functional dental implant. Plenty of experimental evidence indicates that the accumulation of dental plaque at the soft tissue-implant interface and the subsequent local inflammatory response seems to be key in the pathogenesis of the peri-implant mucositis. Such peri-implant-soft tissue interface is less effective than natural teeth in resisting bacterial invasion, enhancing vulnerability to subsequent peri-implant disease. Furthermore, in certain individuals, it will progress to peri-implantitis, resulting in alveolar bone loss and implant failure. Although early diagnosis and accurate identification of risk factors are extremely important to effectively prevent peri-implant diseases, current systematic reviews revealed that a uniform classification and diagnostic methodology for peri-implantitis are lacking. Recent progress on fluorescence-based technology enabled rapid diagnosis of the disease and effective removal of plaques. Here, we briefly review biofilm-associated peri-implant diseases and propose a fluorescence-based approach for more accurate and objective diagnoses. A fluorescence-based diagnosis tool through headlights combined with special-filtered dental loupes may serve as a hands-free solution for both precise diagnosis and effective removal of plaque-biofilms.

RevDate: 2021-03-06

Rezk AI, Park J, Moon JY, et al (2021)

A Novel Design of Tri-Layer Membrane with Controlled Delivery of Paclitaxel and Anti-Biofilm Effect for Biliary Stent Applications.

Nanomaterials (Basel, Switzerland), 11(2): pii:nano11020486.

Here, we developed a novel biliary stent coating material that is composed of tri-layer membrane with dual function of sustained release of paclitaxel (PTX) anticancer drug and antibacterial effect. The advantages of using electrospinning technique were considered for the even distribution of PTX and controlled release profile from the nanofiber mat. Furthermore, film cast method was utilized to fabricate AgNPs-immobilized PU film to direct the release towards the tumor site and suppress the biofilm formation. The in vitro antibacterial test conducted against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria species showed excellent antibacterial effect. The in vitro drug release study confirmed the sustained release of PTX from the tri-layer membrane and the release profile fitted first order with correlation coefficient of R2 = 0.98. Furthermore, the release mechanism was studied using Korsmeyer-Peppas model, revealing that the release mechanism follows Fickian diffusion. Based on the results, this novel tri-layer membrane shows curative potential in clinical development.

RevDate: 2021-03-06

Sato K, Naya M, Hatano Y, et al (2021)

Biofilm Spreading by the Adhesin-Dependent Gliding Motility of Flavobacterium johnsoniae. 1. Internal Structure of the Biofilm.

International journal of molecular sciences, 22(4): pii:ijms22041894.

The Gram-negative bacterium Flavobacterium johnsoniae employs gliding motility to move rapidly over solid surfaces. Gliding involves the movement of the adhesin SprB along the cell surface. F. johnsoniae spreads on nutrient-poor 1% agar-PY2, forming a thin film-like colony. We used electron microscopy and time-lapse fluorescence microscopy to investigate the structure of colonies formed by wild-type (WT) F. johnsoniae and by the sprB mutant (ΔsprB). In both cases, the bacteria were buried in the extracellular polymeric matrix (EPM) covering the top of the colony. In the spreading WT colonies, the EPM included a thick fiber framework and vesicles, revealing the formation of a biofilm, which is probably required for the spreading movement. Specific paths that were followed by bacterial clusters were observed at the leading edge of colonies, and abundant vesicle secretion and subsequent matrix formation were suggested. EPM-free channels were formed in upward biofilm protrusions, probably for cell migration. In the nonspreading ΔsprB colonies, cells were tightly packed in layers and the intercellular space was occupied by less matrix, indicating immature biofilm. This result suggests that SprB is not necessary for biofilm formation. We conclude that F. johnsoniae cells use gliding motility to spread and maturate biofilms.

RevDate: 2021-03-06

Song S, TK Wood (2021)

The Primary Physiological Roles of Autoinducer 2 in Escherichia coli Are Chemotaxis and Biofilm Formation.

Microorganisms, 9(2): pii:microorganisms9020386.

Autoinducer 2 (AI-2) is a ubiquitous metabolite but, instead of acting as a "universal signal," relatively few phenotypes have been associated with it, and many scientists believe AI-2 is often a metabolic byproduct rather than a signal. Here, the aim is to present evidence that AI-2 influences both biofilm formation and motility (swarming and chemotaxis), using Escherichia coli as the model system, to establish AI-2 as a true signal with an important physiological role in this bacterium. In addition, AI-2 signaling is compared to the other primary signal of E. coli, indole, and it is shown that they have opposite effects on biofilm formation and virulence.

RevDate: 2021-03-06

Liu Z, Li L, Wang Q, et al (2021)

Transcriptome Analysis Reveals the Genes Involved in Bifidobacterium Longum FGSZY16M3 Biofilm Formation.

Microorganisms, 9(2): pii:microorganisms9020385.

Biofilm formation has evolved as an adaptive strategy for bacteria to cope with harsh environmental conditions. Currently, little is known about the molecular mechanisms of biofilm formation in bifidobacteria. A time series transcriptome sequencing analysis of both biofilm and planktonic cells of Bifidobacterium longum FGSZY16M3 was performed to identify candidate genes involved in biofilm formation. Protein-protein interaction network analysis of 1296 differentially expressed genes during biofilm formation yielded 15 clusters of highly interconnected nodes, indicating that genes related to the SOS response (dnaK, groS, guaB, ruvA, recA, radA, recN, recF, pstA, and sufD) associated with the early stage of biofilm formation. Genes involved in extracellular polymeric substances were upregulated (epsH, epsK, efp, frr, pheT, rfbA, rfbJ, rfbP, rpmF, secY and yidC) in the stage of biofilm maturation. To further investigate the genes related to biofilm formation, weighted gene co-expression network analysis (WGCNA) was performed with 2032 transcript genes, leading to the identification of nine WGCNA modules and 133 genes associated with response to stress, regulation of gene expression, quorum sensing, and two-component system. These results indicate that biofilm formation in B. longum is a multifactorial process, involving stress response, structural development, and regulatory processes.

RevDate: 2021-03-06

Tan X, Xie H, Zhang B, et al (2021)

A Novel Ivermectin-Derived Compound D4 and Its Antimicrobial/Biofilm Properties against MRSA.

Antibiotics (Basel, Switzerland), 10(2): pii:antibiotics10020208.

Methicillin-resistant Staphylococcus aureus (MRSA) and its biofilms infection is still a serious threat to global health. It is urgent to develop efficient drugs by repositioning or designing drugs to solve this problem. In this study, the antibacterial/biofilm activity and mechanisms of ivermectin (D) and its 4″-position amino substitution derivative (D4) against MRSA were investigated. The minimum inhibitory concentration (MIC) of D was 20 μg/mL, which is four times higher than D4 (MIC = 5 μg/mL). The mechanism research demonstrated that D4 was more potent than D at destroying bacterial cell wall, permeating cell membrane (6.25-36.0% vs 1.92-6.04%) and binding to MRSA genomic DNA. Moreover, after incubation with 10-40 μg/mL D4 for 24 h, the percentages of biofilm decreased by 21.2-92.9%, which was more effective than D (no significant change at 40 μg/mL). The antibiofilm effect is achieved by regulating the expression of related genes (RSH, relQ, rsbU, sigB, spA, and icaD). Additionally, though the higher hemolysis makes D4 a safety risk for intravenous injection, other administration options could be considered as well. Therefore, all the results have indicated that D4 may be a potential candidate compound for the treatment of MRSA and its biofilm infections.

RevDate: 2021-03-06

Castro J, Rosca AS, Muzny CA, et al (2021)

Atopobium vaginae and Prevotella bivia Are Able to Incorporate and Influence Gene Expression in a Pre-Formed Gardnerella vaginalis Biofilm.

Pathogens (Basel, Switzerland), 10(2): pii:pathogens10020247.

Bacterial vaginosis (BV) is associated with a highly structured polymicrobial biofilm on the vaginal epithelium where Gardnerella species presumably play a pivotal role. Gardnerella vaginalis, Atopobium vaginae, and Prevotella bivia are vaginal pathogens detected during the early stages of incident BV. Herein, we aimed to analyze the impact of A. vaginae and P. bivia on a pre-established G. vaginalis biofilm using a novel in vitro triple-species biofilm model. Total biofilm biomass was determined by the crystal violet method. We also discriminated the bacterial populations in the biofilm and in its planktonic fraction by using PNA FISH. We further analyzed the influence of A. vaginae and P. bivia on the expression of key virulence genes of G. vaginalis by quantitative PCR. In our tested conditions, A. vaginae and P. bivia were able to incorporate into pre-established G. vaginalis biofilms but did not induce an increase in total biofilm biomass, when compared with 48-h G. vaginalis biofilms. However, they were able to significantly influence the expression of HMPREF0424_0821, a gene suggested to be associated with biofilm maintenance in G. vaginalis. This study suggests that microbial relationships between co-infecting bacteria can deeply affect the G. vaginalis biofilm, a crucial marker of BV.

RevDate: 2021-03-06

Feldman M, Sionov RV, Mechoulam R, et al (2021)

Anti-Biofilm Activity of Cannabidiol against Candida albicans.

Microorganisms, 9(2): pii:microorganisms9020441.

Candida albicans is a common fungal pathogen in humans. Biofilm formation is an important virulence factor of C. albicans infections. We investigated the ability of the plant-derived cannabidiol (CBD) to inhibit the formation and removal of fungal biofilms. Further, we evaluated its mode of action. Our findings demonstrate that CBD exerts pronounced time-dependent inhibitory effects on biofilm formation as well as disruption of mature biofilm at a concentration range below minimal inhibitory and fungicidal concentrations. CBD acts at several levels. It modifies the architecture of fungal biofilm by reducing its thickness and exopolysaccharide (EPS) production accompanied by downregulation of genes involved in EPS synthesis. It alters the fungal morphology that correlated with upregulation of yeast-associated genes and downregulation of hyphae-specific genes. Importantly, it represses the expression of C. albicans virulence-associated genes. In addition, CBD increases ROS production, reduces the intracellular ATP levels, induces mitochondrial membrane hyperpolarization, modifies the cell wall, and increases the plasma membrane permeability. In conclusion, we propose that CBD exerts its activity towards C. albicans biofilm through a multi-target mode of action, which differs from common antimycotic agents, and thus can be explored for further development as an alternative treatment against fungal infections.

RevDate: 2021-03-06

Ma A, Neumann N, L Chui (2021)

Phenotypic and Genetic Determination of Biofilm Formation in Heat Resistant Escherichia coli Possessing the Locus of Heat Resistance.

Microorganisms, 9(2): pii:microorganisms9020403.

Despite the effectiveness of thermal inactivation processes, Escherichiacoli biofilms continue to be a persistent source of contamination in food processing environments. E. coli strains possessing the locus of heat resistance are a novel food safety threat and raises the question of whether these strains can also form biofilms. The objectives of this study were to determine biofilm formation in heat resistant E. coli isolates from clinical and environmental origins using an in-house, two-component apparatus and to characterize biofilm formation-associated genes in the isolates using whole genome sequencing. Optimal conditions for biofilm formation in each of the heat resistant isolates were determined by manipulating inoculum size, nutrient concentration, and temperature conditions. Biofilm formation in the heat resistant isolates was detected at temperatures of 24 °C and 37 °C but not at 4 °C. Furthermore, biofilm formation was observed in all environmental isolates but only one clinical isolate despite shared profiles in biofilm formation-associated genes encoded by the isolates from both sources. The circulation of heat resistant E. coli isolates with multi-stress tolerance capabilities in environments related to food processing signify that such strains may be a serious food safety and public health risk.

RevDate: 2021-03-06

Cuenca M, Sánchez MC, Diz P, et al (2021)

In Vitro Anti-Biofilm and Antibacterial Properties of Streptococcus downii sp. nov.

Microorganisms, 9(2): pii:microorganisms9020450.

The aim of this study was to evaluate the potential anti-biofilm and antibacterial activities of Streptococcus downii sp. nov. To test anti-biofilm properties, Streptococcus mutans, Actinomyces naeslundii, Veillonella parvula, Fusobacterium nucleatum, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans were grown in a biofilm model in the presence or not of S. downii sp. nov. for up to 120 h. For the potential antibacterial activity, 24 h-biofilms were exposed to S. downii sp. nov for 24 and 48 h. Biofilms structures and bacterial viability were studied by microscopy, and the effect in bacterial load by quantitative polymerase chain reaction. A generalized linear model was constructed, and results were considered as statistically significant at p < 0.05. The presence of S. downii sp. nov. during biofilm development did not affect the structure of the community, but an anti-biofilm effect against S. mutans was observed (p < 0.001, after 96 and 120 h). For antibacterial activity, after 24 h of exposure to S. downii sp. nov., counts of S. mutans (p = 0.019) and A. actinomycetemcomitans (p = 0.020) were significantly reduced in well-structured biofilms. Although moderate, anti-biofilm and antibacterial activities of S. downii sp. nov. against oral bacteria, including some periodontal pathogens, were demonstrated in an in vitro biofilm model.

RevDate: 2021-03-06

Velgosova O, Mudra E, M Vojtko (2021)

Preparing, Characterization and Anti-Biofilm Activity of Polymer Fibers Doped by Green Synthesized AgNPs.

Polymers, 13(4): pii:polym13040605.

The aim of the work was to prepare polymer matrix composite (PMC) microfibers doped by green synthesized silver nanoparticles (AgNPs). The incorporation of AgNP into the polymer matrix can provide toxic properties to the polymer. Polyvinyl alcohol (PVA) was used as a matrix. AgNPs were synthesized by the green method, where the leaf extract of Rosmarinus officinalis (R. officinalis) was used as a reduction and capping agent. PVA-AgNPs composites were prepared in two ways: the ex situ method (pre-prepared globular AgNPs with a mean diameter of 20 nm were added into polymer matrix) and the in situ method (AgNPs were synthesized in the process of polymer composite preparation; in situ synthesized nanoparticles were a mix of different shapes with a mean diameter of ~100 nm). FTIR (Infrared spectroscopy with Fourier Transformation), UV-vis (Ultraviolet-visible spectroscopy), TEM (Transmission Electron Microscope), EDX (Energy-dispersive X-ray spectroscopy), and SEM (Scanning Electron Microscope) techniques were used for the analysis of nanoparticles and prepared PMCs. Thin layers and microfibers of in situ and ex situ PMCs were prepared. The presence of AgNPs clusters was evident in both PMC thin layers. After electrospinning, the chains of nanoparticles were observed inside the fibers. The distribution of nanoparticles was improved by increasing the AgNPs volume fraction (from 5 vol.% to 20 vol.%). Toxic and antibiofilm activity of AgNPs colloid, pure PVA, and PVA-AgNPs composites against the one-cell green algae Parachlorella kessleri (P. kessleri) was analyzed. AgNPs colloid, as well as PVA-AgNPs composites, showed good toxic and antibiofilm activity, and pure PVA shows no toxic/antibiofilm activity.

RevDate: 2021-03-06

Bogiel T, Depka D, Rzepka M, et al (2021)

Prevalence of the Genes Associated with Biofilm and Toxins Synthesis amongst the Pseudomonas aeruginosa Clinical Strains.

Antibiotics (Basel, Switzerland), 10(3): pii:antibiotics10030241.

Pseudomonas aeruginosa is one of the most commonly isolated bacteria from clinical specimens, with an increasing isolation frequency in nosocomial outbreaks. The hypothesis tested was whether carbapenem-resistant P. aeruginosa strains display an altered carriage of the virulence factor genes, depending on the type of carbapenem resistance. The aim of the study was to investigate, by PCR, the frequency of 10 chosen virulence factors genes (phzM, phzS, exoT, exoY, exoU, toxA, exoS, algD, pilA and pilB) and the genotype distribution in 107 non-duplicated carbapenem-resistant P. aeruginosa isolates. P. aeruginosa genes involved in phenazine dyes and exoenzyme T synthesis were noted with the highest frequency (100%). Fimbriae-encoding genes were detected with the lowest incidence: 15.9% and 4.7% for pilin A and B, respectively. The differences observed between the exoS gene prevalence amongst the carbapenemase-positive and the carbapenemase-negative strains and the pilA gene prevalence amongst the strains of different origins were statistically significant. Virulence genes' prevalence and the genotype distribution vary amongst P. aeruginosa strains resistant to carbapenems, especially in terms of their carbapenemase synthesis ability and the strain origin.

RevDate: 2021-03-06

Ji J, H Yang (2021)

In Vitro Effects of Lactobacillus plantarum LN66 and Antibiotics Used Alone or in Combination on Helicobacter pylori Mature Biofilm.

Microorganisms, 9(2): pii:microorganisms9020424.

Helicobacter pylori is a gastrointestinal pathogen with high prevalence that harms human health. Studies have shown that H. pylori can form antibiotic-tolerant biofilms, which may interfere with the efficacy of clinical antibiotic therapy. Probiotics can antagonize planktonic and biofilm pathogen cells and thus may play an auxiliary role in H. pylori antibiotic therapy. However, the effects of different probiotic strains and antibiotic combinations on H. pylori biofilms need to be further investigated. We determined the cell viability of H. pylori mature biofilms after treatment with Lactobacillus plantarum LN66 cell-free supernatant (CFS), clarithromycin (CLR), and levofloxacin (LVX) alone or in combination by the XTT method. Biofilm cells were observed by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Subsequently, protein and polysaccharide concentrations in biofilm extracellular polymeric substances (EPSs) were quantitatively detected by the Bradford method and the phenol-sulfate method. The results showed that LN66 CFS had an eradication effect on mature H. pylori biofilm. When used in combination with CLR, LN66 CFS significantly attenuated the eradication effect of CLR on biofilms; in contrast, when used in combination with LVX, LN66 CFS enhanced the disrupting effect of LVX. We speculate that the different effects of CFS and antibiotic combinations on biofilms may be related to changes in the content of proteins and polysaccharides in EPS and that the combination of CFS and CLR might promote the secretion of EPS, while the combination of CFS and LVX might have the opposite effect. Accordingly, we suggest that supplementation with L. plantarum LN66 may provide additional help when therapy involving LVX is used for clinical H. pylori biofilm eradication, whereas it may impair CLR efficacy when therapy involving CLR is used.

RevDate: 2021-03-06

Heredia-Ponce Z, de Vicente A, Cazorla FM, et al (2021)

Beyond the Wall: Exopolysaccharides in the Biofilm Lifestyle of Pathogenic and Beneficial Plant-Associated Pseudomonas.

Microorganisms, 9(2): pii:microorganisms9020445.

The formation of biofilms results from a multicellular mode of growth, in which bacteria remain enwrapped by an extracellular matrix of their own production. Many different bacteria form biofilms, but among the most studied species are those that belong to the Pseudomonas genus due to the metabolic versatility, ubiquity, and ecological significance of members of this group of microorganisms. Within the Pseudomonas genus, biofilm studies have mainly focused on the opportunistic human pathogen Pseudomonas aeruginosa due to its clinical importance. The extracellular matrix of P. aeruginosa is mainly composed of exopolysaccharides, which have been shown to be important for the biofilm architecture and pathogenic features of this bacterium. Notably, some of the exopolysaccharides recurrently used by P. aeruginosa during biofilm formation, such as the alginate and polysaccharide synthesis loci (Psl) polysaccharides, are also used by pathogenic and beneficial plant-associated Pseudomonas during their interaction with plants. Interestingly, their functions are multifaceted and seem to be highly dependent on the bacterial lifestyle and genetic context of production. This paper reviews the functions and significance of the exopolysaccharides produced by plant-associated Pseudomonas, particularly the alginate, Psl, and cellulose polysaccharides, focusing on their equivalents produced in P. aeruginosa within the context of pathogenic and beneficial interactions.

RevDate: 2021-03-06

Sánchez MC, Alonso-Español A, Ribeiro-Vidal H, et al (2021)

Relevance of Biofilm Models in Periodontal Research: From Static to Dynamic Systems.

Microorganisms, 9(2): pii:microorganisms9020428.

Microbial biofilm modeling has improved in sophistication and scope, although only a limited number of standardized protocols are available. This review presents an example of a biofilm model, along with its evolution and application in studying periodontal and peri-implant diseases. In 2011, the ETEP (Etiology and Therapy of Periodontal and Peri-Implant Diseases) research group at the University Complutense of Madrid developed an in vitro biofilm static model using representative bacteria from the subgingival microbiota, demonstrating a pattern of bacterial colonization and maturation similar to in vivo subgingival biofilms. When the model and its methodology were standardized, the ETEP research group employed the validated in vitro biofilm model for testing in different applications. The evolution of this model is described in this manuscript, from the mere observation of biofilm growth and maturation on static models on hydroxyapatite or titanium discs, to the evaluation of the impact of dental implant surface composition and micro-structure using the dynamic biofilm model. This evolution was based on reproducing the ideal microenvironmental conditions for bacterial growth within a bioreactor and reaching the target surfaces using the fluid dynamics mimicking the salivary flow. The development of this relevant biofilm model has become a powerful tool to study the essential processes that regulate the formation and maturation of these important microbial communities, as well as their behavior when exposed to different antimicrobial compounds.

RevDate: 2021-03-06

Galdiero E, Salvatore MM, Maione A, et al (2021)

Impact of the Peptide WMR-K on Dual-Species Biofilm Candida albicans/Klebsiella pneumoniae and on the Untargeted Metabolomic Profile.

Pathogens (Basel, Switzerland), 10(2): pii:pathogens10020214.

In recent years, the scientific community has focused on the development of new antibiotics to address the difficulties linked to biofilm-forming microorganisms and drug-resistant infections. In this respect, synthetic antimicrobial peptides (AMPs) are particularly regarded for their therapeutic potential against a broad spectrum of pathogens. In this work, the antimicrobial and antibiofilm activities of the peptide WMR-K towards single and dual species cultures of Candida albicans and Klebsiella pneumoniae were investigated. We found minimum inhibitory concentration (MIC) values for WMR-K of 10 µM for K. pneumoniae and of 200 µM for C. albicans. Furthermore, sub-MIC concentrations of peptide showed an in vitro inhibition of biofilm formation of mono and polymicrobial systems and also a good biofilm eradication even if higher concentrations of it are needed. In order to provide additional evidence for the effect of the examined peptide, a study of changes in extracellular metabolites excreted and/or uptaken from the culture medium (metabolomic footprinting) in the poly-microbial association of C. albicans and K. pneumoniae in presence and absence of WMR-K was performed. Comparing to the untreated dual species biofilm culture, the metabolomic profile of the WMR-K treated culture appears significantly altered. The differentially expressed compounds are mainly related to the primary metabolic pathways, including amino acids, trehalose, pyruvic acid, glycerol and vitamin B6.

RevDate: 2021-03-05

Perera M, Chinthaka SDM, Wijayarathna CD, et al (2021)

Reduction of lag in crude oil degradation by Aspergillus when it is in synergy with Bacillus in biofilm mode.

Bioprocess and biosystems engineering [Epub ahead of print].

A major hindrance to the effective use of fungi in bioremediation is their inherent slow growth. Despite this, Aspergillus spp. may be used effectively. Our experiments demonstrate that bacteria, although inefficient in hydrocarbon degradation, may be effectively used in a consortium to overcome the lag in fungal utilization of petroleum hydrocarbons. Crude petroleum oil (160 mg; at 8 g/L) in minimal medium was inoculated with a previously isolated biofilm-forming consortium (Aspergillus sp. MM1 and Bacillus sp. MM1) as well as monocultures of each organism and incubated at 30 ℃ under static conditions. Residual oil was analyzed by GC-MS. Crude oil utilization of Aspergillus-Bacillus biofilm was 24 ± 1.4% in 3 days, increased to 66 ± 7% by day 5 and reached 99 ± 0.2% in 7 days. Aspergillus sp. MM1 monoculture degraded only 14 ± 6% in 5 days. However, at the end of 7 days, it was able to utilize 98 ± 2%. Bacillus sp. MM1 monoculture utilized 20 ± 4% in 7 days. This study indicates that there is a reduction of the fungal lag in bioremediation when it is in association with the bacterium. Although in monoculture, Bacillus sp. MM1 is inefficient in crude oil degradation, it synergistically enhances the initial rate of crude petroleum oil degradation of the fungus in the consortium. The rapid initial removal of as much crude oil as possible from contaminated sites is vital to minimize detrimental impacts on biodiversity.

RevDate: 2021-03-05

Furrer C, Bättig R, Votta I, et al (2021)

[Patient acceptance of «Guided Biofilm Therapy»].

Swiss dental journal, 131(3):229-234.

«Guided Biofilm Therapy» (GBT) represents a systematic, risk and demand-oriented prophylaxis and treatment concept. A significant difference to conventional methods is - above all - the reduced, tissue-friendly and targeted use of ultrasound and hand instruments. The biofilm is consistently shown with suitable color solutions, the oral hygiene instruction and professional tooth cleaning is optimized. The use of suitable powders guarantees a tissue-conserving and targeted removal of biofilm. While individual treatments, techniques and materials have already been well investigated and described, little data is available on patient acceptance. The aim of the present study was to gain an impression of the acceptance of this method in comparison to the conservative-classical recall care mainly based on hand and ultrasound devices in a survey of 100 consecutive patients from the clinic's internal recall system. The overall results were very positive. The powder jet device showed the best acceptance. The aspect fear before/during the recall session was also interesting: At a low level (10%), an additional reduction to 4% occurred, since hand instruments were probably used much less and only very specifically. mConclusion: The use of plaque elevators makes the work in the recall session more efficient, more effective and guarantees ma higher quality control, which is also highly appreciated by patients.

RevDate: 2021-03-05

Taylor A, Fuzi J, Sideris A, et al (2021)

Non-steroid, non-antibiotic anti-biofilm therapy for the treatment of chronic rhinosinusitis: a systematic review.

The Journal of laryngology and otology pii:S0022215121000542 [Epub ahead of print].

OBJECTIVE: Chronic rhinosinusitis patients with biofilms cultured from their sinonasal cavity have greater symptom burden and risk of recalcitrant disease. A number of non-antibiotic, 'anti-biofilm' treatments exist which show anti-biofilm properties in preclinical studies. There is little evidence evaluating their impact on clinical symptom scores in chronic rhinosinusitis.

METHOD: A systematic review was performed to assess the literature regarding the efficacy of non-steroid, non-antibiotic, anti-biofilm specific topical therapies in the treatment of chronic rhinosinusitis. The primary outcome assessed was change in validated patient reported outcome measures before and after anti-biofilm treatment.

RESULTS: Thirteen studies assessing the effect of anti-biofilm therapies in chronic rhinosinusitis through validated patient-reported outcome measures were included. Seven different anti-biofilm specific therapies for chronic rhinosinusitis were identified. None of the seven anti-biofilm therapies was identified as being confidently efficacious beyond placebo. Only one therapy (intranasal xylitol) showed a statistically significant reduction in symptom scores compared with placebo in more than one trial.

CONCLUSION: Robust evidence supporting the use of various anti-biofilm therapies in chronic rhinosinusitis is lacking. Further high quality, human, in vivo trials studying the effect of anti-biofilm therapies in chronic rhinosinusitis are needed to address the deficiencies of the current evidence base.

RevDate: 2021-03-05

de Sá MCA, da Silva WM, Rodrigues CCS, et al (2021)

Comparative Proteomic Analyses Between Biofilm-Forming and Non-biofilm-Forming Strains of Corynebacterium pseudotuberculosis Isolated From Goats.

Frontiers in veterinary science, 8:614011.

Caseous lymphadenitis (CLA) is a chronic disease that affects small ruminants and causes economic losses in the associated breeding system. The causative agent of CLA is Corynebacterium pseudotuberculosis, a Gram-positive bacterium that exhibits tropism for external and internal lymph nodes and induces abscess formation in the host. Bacterial communities often produce a biofilm matrix that serves various functions, including protection against hostile environmental conditions, antibiotics, and the host immune response. Although biofilm formation has been reported for C. pseudotuberculosis, not all strains demonstrate this property in culture. In this work, we report the first comparative proteomic analysis of one biofilm-forming (CAPJ4) and one biofilm-non-forming strain (CAP3W) of C. pseudotuberculosis isolated from goats. Bacterial whole cell protein extracts were obtained for mass spectrometry analyses. Using LC-MS/MS, our studies reveal three and four proteins exclusively found in the CAPJ4 and CAP3W proteome, respectively. In addition, label-free quantitative analysis identified 40 proteins showing at-least 2-fold higher values in CAPJ4 compared CAP3W proteome Notably, CAPJ4 differentially synthesized the penicillin-binding protein, which participates in the formation of peptidoglycans. CAPJ4 also exhibited upregulation of N-acetylmuramoyl-L-alanine amidase and galactose-1-phosphate uridylyltransferase, which are involved in biofilm formation and exopolysaccharide biosynthesis. Here, we demonstrate that biofilm formation in C. pseudotuberculosis is likely associated with specific proteins, some of which were previously shown to be associated with virulence and biofilm formation in other organisms. Our findings may drive studies related to the bacterial mechanisms involved in the biofilm formation, in addition to providing targets for the treatment of CLA.

RevDate: 2021-03-04

Nishitani Shibasaki PA, Cavalli V, Oliveira MC, et al (2021)

Influence Of Surface Treatment On The Physical Properties And Biofilm Formation Of Zirconia-Reinforced Lithium Silicate Ceramics: In Vitro Trial.

The International journal of prosthodontics [Epub ahead of print].

PURPOSE: To evaluate the performance of fully (Celtra Duo, Dentsply Sirona) and partially (VITA Suprinity, VITA) crystallized zirconia-reinforced lithium silicate and partially sintered lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) glass-ceramics submitted to polishing, glazing, or no surface treatment after aging.

MATERIALS AND METHODS: Specimens of each glass-ceramic were subjected to polishing with rubber cups (POL), glazing (GL), or control (C; no treatment) and afterwards aged with 18,000 thermal cycles (5°C to 55°C). The average roughness (Ra), 2D and 3D morphology, contact angle, multispecies biofilm formation (Streptococcus mutans and Candida albicans), and mechanical strength were evaluated by atomic force microscopy (AFM, n = 5), sessile-drop goniometry (n = 5), spectrophotometry (n = 5), and flexural strength test (n = 10), respectively. Data were analyzed using two-way analysis of variance and Tukey test (α = 5%).

RESULTS: POL promoted lower Ra than glazing, and Celtra Duo presented higher Ra than IPS e.max CAD (P < .05). Surfaces without polishing promoted higher Ra than the POL group (P < .001), greater contact angle (P < .001), and significant morphologic changes, regardless of the glass-ceramic. Irrespective of the treatment, the contact angle was higher in Celtra Duo, and regardless of the material, there was higher biofilm formation and lower flexural strength of unpolished compared to POL or GL ceramics.

CONCLUSION: Polishing with rubber cups promoted lower roughness and minor morphologic surface alterations, but biofilm formation and flexural strength were similar to the glazed surface. In general, Celtra Duo and VITA Suprinity showed similar behavior to IPS e.max CAD, which makes zirconia-reinforced lithium silicate glass-ceramics a good option for indirect restorations.

RevDate: 2021-03-04

Matthes de Freitas Pontes K, Fontenelle ISO, Nascimento CD, et al (2021)

Clinical study of the biofilm of implant-supported complete dentures in healthy patients.

Gerodontology [Epub ahead of print].

OBJECTIVE: The purpose of this study was to quantify the area covered by biofilm and identify bacteria and yeasts present in mandibular acrylic resin full-arch implant-supported fixed prostheses.

BACKGROUND: Biofilm control of implant-supported fixed prosthesis is hampered by their design, and it can cause oral and systemic problems, mainly in immunocompromised patients like the elder. Knowledge about microbiota reinforces the awareness about the need for periodic professional cleaning maintenance.

MATERIALS AND METHODS: Twenty prostheses were unscrewed, washed in 0.89% sodium chloride, stained with eosin 1% and photographed. The area covered by biofilm was digitally delimited and quantified. Biofilm samples were collected, diluted up to 1:107 , seeded in chromogenic agar media and incubated for 48 hours, at 37°C, for counting of colony-forming units (CFU/mL). DNA hybridization was performed to complement the identification and quantification of microorganisms. Data were analyzed using Mann-Whitney test, Spearman correlation and Fisher's exact test (α = .05).

RESULTS: An average of 62% of the gingival surface of the prostheses was covered by biofilm. Enterococcus spp. (5.82 ± 1.38 log10 CFU/mL) and Staphylococcus aureus (5.75 ± 2.02 log10 CFU/mL) showed higher prevalence in cultures. Patients with five implants had less biofilm compared to those with four implants (P = .031) but had higher Escherichia coli counts (P = .039). In DNA hybridization, Streptococcus pneumoniae, Veillonella parvula and Fusobacterium nucleatum presented higher quantification and were present in all the samples; patients over 65 years old contained more Candida tropicalis (P = .049); prostheses on five implants presented lower quantification for several species.

CONCLUSION: Biofilm was present on all prostheses, containing potentially pathogenic microorganisms. The number of implants may play a role in quantification of biofilm and in microorganism counts.

RevDate: 2021-03-04

Hazarika P, Chattopadhyay I, Umpo M, et al (2021)

Phylogeny, Biofilm Production, and Antimicrobial Properties of Fecal Microbial Communities of Adi Tribes of Arunachal Pradesh, India.

Applied biochemistry and biotechnology [Epub ahead of print].

The fecal flora consists of trillions of bacteria influencing human health and several host factors. Such population-based fecal flora studies are critical to uplift the health status of ethnic tribes from Arunachal Pradesh. This study aimed to analyze the ethnic tribe's biofilm producing antibiotic resistant bacteria and their phyllogenetic analysis in 15 stool samples collected from Adi tribes of Arunachal Pradesh. Of the analyzed samples, 42.85% were Escherichia, 20% lactic acid bacteria, 20% Salmonella, and 17.14% Enterococcus. Escherichia coli, lactic acid bacteria, and Enterococcus sp. emerged as strong biofilm producers; however, Salmonella declined to exhibit characters for a strong biofilm producer. Tetracycline resistance dominated in all the gut bacterial profiles. The 16SrRNA amplified PCR product was used for sequencing, and a phylogenetic tree was constructed exhibiting the relationship between the isolates. The test sequences were compared with the non-redundant Gene bank collection of the database with the Basic Local Alignment Search Tool.

RevDate: 2021-03-04

Gould FG, Carey MP, Plummer EL, et al (2021)

Bacterial biofilm formation on vaginal ring pessaries used for pelvic organ prolapse.

International urogynecology journal [Epub ahead of print].

INTRODUCTION AND HYPOTHESIS: The objective of this study was to characterize the bacterial biofilm on vaginal ring pessaries used to treat pelvic organ prolapse and investigate the relationship between biofilm phenotype and patient symptoms and clinical signs that are suggestive of inflammation.

METHODS: This was a cross-sectional observational study of 40 women wearing a ring-shaped pessary continuously for at least 12 weeks. Participants underwent a clinical examination, and the pessary was removed. Clinical signs were recorded. A swab from the pessary surface and a high vaginal swab were collected from each woman. Participants completed a questionnaire on symptoms. Pessary biofilm presence and phenotype were determined by scanning electron microscopy (SEM). Vaginal and pessary bacterial composition was determined by 16S rRNA gene sequencing. The relationship between biofilm phenotype and symptoms and clinical signs was assessed using logistic regression.

RESULTS: SEM confirmed biofilm formation on all 40 pessaries. Microbiota data were available for 25 pessary swabs. The pessary biofilm microbiota was composed of bacteria typically found in the vagina and was categorized into Lactobacillus-dominated (n = 10/25 pessaries, 40%) communities and Lactobacillus-deficient communities with high relative abundance of anaerobic/facultative anaerobes (n = 15/25 pessaries, 60%). While increasing age was associated with presence of a Lactobacillus-deficient pessary biofilm (odds ratio = 3.60, 95% CI [1.16-11.22], p = 0.04), no associations between biofilm microbiota composition and symptoms or clinical signs were observed.

CONCLUSIONS: Lactobacillus-deficient biofilms commonly form on pessaries following long-term use. However, the contribution of biofilm phenotype to symptoms and clinical signs remains to be determined.

RevDate: 2021-03-04

Nędzi-Góra M, Górska R, B Górski (2020)

Is the progression rate of periodontitis related to subgingival biofilm composition or gingival crevicular fluid IL-1β and MMP-8 concentrations?.

Central-European journal of immunology, 45(4):425-432.

Aim of the study: To analyze the composition of subgingival biofilm and to assess the concentration of IL-1 and MMP-8 in gingival crevicular fluid (GCF) from deep periodontal pockets in patients with severe periodontitis to determine whether the presence of specific microbial species or the severity of the host's immune response can be helpful in assessing the dynamics of disease.

Material and methods: The study included 30 individuals with periodontitis Grade B and 19 subjects with periodontitis Grade C. Quantitative and qualitative microbiological analysis of flora in pockets ≥ 7 mm was performed for the presence of selected periopathogens of the orange, red complex and Aggregatibacter actinomycetemcomitans using real-time PCR. The concentrations of IL-1 and MMP-8 in GCF were evaluated with the ELISA method.

Results: There were no differences in the composition of the subgingival biofilm depending on the diagnosis. The concentration of MMP-8 in GCF was significantly higher in periodontitis Grade C than in periodontitis Grade B (61 ng/µl and 37 ng/µl respectively, p = 0.039). The concentration of IL-1β was similar in both groups. No significant correlations were observed between the occurrence of individual periopathogens and concentrations of MMP-8 and IL-1β depending on the diagnosis.

Conclusions: Periodontitis grade may not be distinguished according to microbial analysis of subgingival biofilm or to concentration of IL-1β in GCF. On the other hand, higher concentrations of MMP-9 in GCF from deep pockets may be helpful in detecting subjects particularly prone to occurrence and rapid progress of periodontitis.

RevDate: 2021-03-04

Tomlinson KL, Lung TWF, Dach F, et al (2021)

Staphylococcus aureus induces an itaconate-dominated immunometabolic response that drives biofilm formation.

Nature communications, 12(1):1399.

Staphylococcus aureus is a prominent human pathogen that readily adapts to host immune defenses. Here, we show that, in contrast to Gram-negative pathogens, S. aureus induces a distinct airway immunometabolic response dominated by the release of the electrophilic metabolite, itaconate. The itaconate synthetic enzyme, IRG1, is activated by host mitochondrial stress, which is induced by staphylococcal glycolysis. Itaconate inhibits S. aureus glycolysis and selects for strains that re-direct carbon flux to fuel extracellular polysaccharide (EPS) synthesis and biofilm formation. Itaconate-adapted strains, as illustrated by S. aureus isolates from chronic airway infection, exhibit decreased glycolytic activity, high EPS production, and proficient biofilm formation even before itaconate stimulation. S. aureus thus adapts to the itaconate-dominated immunometabolic response by producing biofilms, which are associated with chronic infection of the human airway.

RevDate: 2021-03-04

Kaizerman-Kane D, Hadar M, Joseph R, et al (2021)

Design Guidelines for Cationic Pillar[n]arenes that Prevent Biofilm Formation by Gram-Positive Pathogens.

ACS infectious diseases [Epub ahead of print].

Bacterial biofilms are a major threat to human health, causing persistent infections that lead to millions of fatalities worldwide every year. Biofilms also cause billions of dollars of damage annually by interfering with industrial processes. Recently, cationic pillararenes were found to be potent inhibitors of biofilm formation in Gram-positive bacteria. To identify the structural features of pillararenes that result in antibiofilm activity, we evaluated the activity of 16 cationic pillar[5]arene derivatives including that of the first cationic water-soluble pillar[5]arene-based rotaxane. Twelve of the derivatives were potent inhibitors of biofilm formation by Gram-positive pathogens. Structure activity analyses of our pillararene derivatives indicated that positively charged head groups are critical for the observed antibiofilm activity. Although certain changes in the lipophilicity of the substituents on the positively charged head groups are tolerated, dramatic elevation in the hydrophobicity of the substituents or an increase in steric bulk on these positive charges abolishes the antibiofilm activity. An increase in the overall positive charge from 10 to 20 did not affect the activity significantly, but pillararenes with 5 positive charges and 5 long alkyl chains had reduced activity. Surprisingly, the cavity of the pillar[n]arene is not essential for the observed activity, although the macrocyclic structure of the pillar[n]arene core, which facilitates the clustering of the positive charges, appears important. Interestingly, the compounds found to be efficient inhibitors of biofilm formation were nonhemolytic at concentrations that are ∼100-fold of their MBIC50 (the minimal concentration of a compound at which at least 50% inhibition of biofilm formation was observed compared to untreated cells). The structure-activity relationship guidelines established here pave the way for a rational design of potent cationic pillar[n]arene-based antibiofilm agents.

RevDate: 2021-03-03

Kaźmierczak N, Grygorcewicz B, L Piechowicz (2021)

Biofilm Formation and Prevalence of Biofilm-Related Genes Among Clinical Strains of Multidrug-Resistant Staphylococcus aureus.

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

The biofilm-forming Staphylococcus aureus strains are responsible for causing a number of diseases. With the emergence of multidrug resistance they constitute a catastrophic threat to medicine. The ability of 65 clinical strains of multidrug-resistant S. aureus (MDRSA) to form biofilm in vitro was examined in this study and analyzed in relation to SCCmec, spa type, microbial surface components recognizing adhesive matrix molecules (MSCRAMMs), and ica genes. Results obtained from crystal violet and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays showed that all MDRSA strains tested form biofilm but, of 65 strains, only 18 strains (28%) were found to form a biofilm with high metabolic activity and a great amount of biomass. The high proportion of MDRSA isolates in our study made no significant difference for ica and MSCRAMMs genes according to biofilm-forming capacity, except for fib, icaA, and cna gene. In addition, this study demonstrated that strains carrying SCCmec type I showed a significantly decreased biofilm viability compared with the strains harboring SCCmec type II and type IV, but SCCmec type could not serve as a good predictor of biofilm formation. However, we found that significantly weaker metabolic activity was detected in the biofilm of isolates with spa type t011.

RevDate: 2021-03-03

Feng Y, Wang H, Lu HE, et al (2021)

Effects of ClpP protease on biofilm formation of Enterococcus faecalis.

Journal of applied oral science : revista FOB, 29:e20200733 pii:S1678-77572021000100408.

OBJECTIVES: Enterococcus faecalis (E. faecalis), one of the main pathogens responsible for refractory periapical periodontitis and nosocomial infections, exhibits markedly higher pathogenicity in biofilms. Studies have shown that caseinolytic protease P (ClpP) is involved in biofilm formation. However, to date, few studies have investigated the role of ClpP in the survival of E. faecalis, and in enhancing biofilm formation. Therefore, we investigated the role of ClpP in the formation of E. faecalis biofilms.

METHODOLOGY: In our study, we used homologous recombination to construct clpP deleted and clpP complement strains of E. faecalis ATCC 29212. A viable colony counting method was used to analyze the growth patterns of E. faecalis. Crystal violet staining (CV) and confocal scanning laser microscopy (CLSM) were used to characterize biofilm mass formation and scanning electron microscopy (SEM) was used to observe the biofilm microstructure. Data was statistically analyzed via Student's t-test or one-way analysis of variance (ANOVA).

RESULTS: The results exhibited altered growth patterns for the clpP deletion strains and depleted polysaccharide matrix, resulting in reduced biofilm formation capacity compared to the standard strains. Moreover, ClpP was observed to increase biofilm formation in E. faecalis.

CONCLUSION: Our study shows that ClpP can increase biofilm formation in E. faecalis and emphasizes the importance of ClpP as a potential target against E. faecalis.

RevDate: 2021-03-03

Shao X, Xie Y, Zhang Y, et al (2019)

Biofilm Formation Assay in Pseudomonas syringae.

Bio-protocol, 9(10):e3237 pii:3237.

Pseudomonas syringae is a model plant pathogen that infects more than 50 plant species worldwide, thus leading to significant yield loss. Pseudomonas biofilm always adheres to the surfaces of medical devices or host cells, thereby contributing to infection. Biofilm formation can be visualized on numerous matrixes, including coverslips, silicone tubes, polypropylene and polystyrene. Confocal laser scanning microscopy can be used to visualize and analyze biofilm structure. In this study, we modified and applied the current method of P. aeruginosa biofilm measurement to P. syringae, and developed a convenient protocol to visualize P. syringae biofilm formation using a borosilicate glass tube as the matrix coupled with crystal violet staining.

RevDate: 2021-03-03

Asaad AM, Ansari S, Ajlan SE, et al (2021)

Epidemiology of Biofilm Producing Acinetobacter baumannii Nosocomial Isolates from a Tertiary Care Hospital in Egypt: A Cross-Sectional Study.

Infection and drug resistance, 14:709-717 pii:261939.

Objective: This cross-sectional study aims to determine the prevalence and associated risk factors of biofilm-producing A. baumannii nosocomial isolates from a tertiary care hospital, as well as to investigate any possible association of biofilm formation with the distribution of biofilm-related genotypes and antibiotic resistance phenotypes.

Methods: A total of 94 non-duplicate A. baumannii nosocomial isolates were identified, their biofilm formation was quantitatively detected using the modified microtiter plate assay, and their susceptibilities to different antibiotics were determined using the breakpoint method. Isolates were then subjected to PCR assays targeting bap, ompA and blaPER-1 genes.

Results: The majority (70.1%) of isolates were biofilm producers. The most prevalent biofilm gene was ompA (63.8%), followed by bap (13.8%) and blaPER-1 (10.6%). The presence of multi- and extensive-drug resistance (MDR and XDR) was significantly associated with biofilm producers (p = 0.017 and 0.002, respectively). The length of hospital stay (aOR= 0.023), the presence of ompA gene (aOR = 0.286) or bap gene (aOR = 0.346), ampicillin/sulbactam resistance (aOR = 1), and the presence of MDR (aOR = -0.329) or XDR (aOR = -0.252) were considered significant risk factors associated with biofilm-producing isolates.

Conclusion: The high prevalence of biofilm-producing MDR and XDR nosocomial isolates in this study is worrisome and alarming. Characterization of risk factors could help control the continuous selection and transfer of this serious A. baumannii phenotype inside hospitals and improve the quality of patients' care.

RevDate: 2021-03-03

Yanuka-Golub K, Dubinsky V, Korenblum E, et al (2021)

Anode Surface Bioaugmentation Enhances Deterministic Biofilm Assembly in Microbial Fuel Cells.

mBio, 12(2):.

Microbial fuel cells (MFCs) generate energy while aiding the biodegradation of waste through the activity of an electroactive mixed biofilm. Metabolic cooperation is essential for MFCs' efficiency, especially during early colonization. Thus, examining specific ecological processes that drive the assembly of anode biofilms is highly important for shortening startup times and improving MFC performance, making this technology cost-effective and sustainable. Here, we use metagenomics to show that bioaugmentation of the anode surface with a taxonomically defined electroactive consortium, dominated by Desulfuromonas, resulted in an extremely rapid current density generation. Conversely, the untreated anode surface resulted in a highly stochastic and slower biofilm assembly. Remarkably, an efficient anode colonization process was obtained only if wastewater was added, leading to a nearly complete replacement of the bioaugmented community by Geobacter lovleyi Although different approaches to improve MFC startup have been investigated, we propose that only the combination of anode bioaugmentation with wastewater inoculation can reduce stochasticity. Such an approach provides the conditions that support the growth of specific newly arriving species that positively support the fast establishment of a highly functional anode biofilm.IMPORTANCE Mixed microbial communities play important roles in treating wastewater, in producing renewable energy, and in the bioremediation of pollutants in contaminated environments. While these processes are well known, especially the community structure and biodiversity, how to efficiently and robustly manage microbial community assembly remains unknown. Moreover, it has been shown that a high degree of temporal variation in microbial community composition and structure often occurs even under identical environmental conditions. This heterogeneity is directly related to stochastic processes involved in microbial community organization, similarly during the initial stages of biofilm formation on surfaces. In this study, we show that anode surface pretreatment alone is not sufficient for a substantial improvement in startup times in microbial fuel cells (MFCs), as previously thought. Rather, we have discovered that the combination of applying a well-known consortium directly on the anode surface together with wastewater (including the bacteria that they contain) is the optimized management scheme. This allowed a selected colonization process by the wastewater species, which improved the functionality relative to that of untreated systems.

RevDate: 2021-03-03

Hashimoto A, Miyamoto H, Kii S, et al (2021)

Time-dependent efficacy of combination of silver-containing hydroxyapatite coating and vancomycin on methicillin-resistant Staphylococcus aureus biofilm formation in vitro.

BMC research notes, 14(1):81.

OBJECTIVE: We developed a silver-containing hydroxyapatite (Ag-HA) coating to prevent periprosthetic joint infection (PJI). Methicillin-resistant Staphylococcus aureus (MRSA) is the main PJI-causing bacteria. Previously, we had reported the combined effect of Ag-HA coating and vancomycin (VCM) on MRSA biofilm formation 24 h after MRSA inoculation. In this study, we investigated the time-dependent efficacy of Ag-HA coating and VCM on MRSA biofilm formation on Ti discs in vitro by three-dimensional confocal laser scanning microscopic analysis.

RESULTS: For the Ti VCM and HA VCM groups, the total biofilm volumes per area at 96 h after MRSA inoculation were significantly larger than those at 48 h after MRSA inoculation, respectively (p < 0.001). In contrast, for the Ag-HA VCM group, the total biofilm volume per area at 96 h was significantly smaller than that at 48 h (p < 0.0001). Moreover, 96 h after MRSA inoculation, the total biofilm volume per area of the Ag-HA VCM groups was significantly smaller than those of the Ti VCM and HA VCM groups (p < 0.0001). Thus, the combination of Ag-HA and VCM might be useful for the prevention of MRSA-associated PJI.

RevDate: 2021-03-03

Zhang Y, Qiu Y, Xue X, et al (2021)

Transcriptional regulation of the virulence genes and the biofilm formation associated operons in Vibrio parahaemolyticus.

Gut pathogens, 13(1):15.

BACKGROUND: The membrane fusion protein (mfp) gene locus of Vibrio parahaemolyticus consists of two operons, cpsQ-mfpABC and mfpABC, which are both required for biofilm formation. ToxR and CalR are required for the full virulence of V. parahaemolyticus, and their mutual regulation has been demonstrated. Moreover, cell density-dependent expression of toxR was previously observed in V. parahaemolyticus, but details about the related mechanisms remained unclear. QsvR can work with the master quorum sensing (QS) regulators AphA and OpaR to regulate virulence expression and biofilm formation.

RESULTS: In the present work, we showed that QsvR bound to the promoter-proximal DNA regions of toxR and calR to repress their transcription as well as occupying the regulatory regions of cpsQ-mfpABC and mfpABC to activate their transcription. Thus, we reconstructed the QsvR-dependent promoter organization of toxR, calR, cpsQ-mfpABC, and mfpABC.

CONCLUSION: QsvR directly repressed toxR and calR transcription as well as directly activated cpsQ-mfpABC and mfpABC transcription. The data presented here promotes us to gain deeper knowledge of the regulatory network of the mfp locus in V. parahaemolyticus.

RevDate: 2021-03-03

Pharmaceuticals Editorial Office (2021)

Retraction: Qian, W., et al. Sanguinarine Inhibits Mono- and Dual-Species Biofilm Formation by Candida albicans and Staphylococcus aureus and Induces Mature Hypha Transition of C. albicans. Pharmacueticals 2020, 13, 13.

Pharmaceuticals (Basel, Switzerland), 14(3): pii:ph14030193.

The journal retracts the article [...].

RevDate: 2021-03-02

Cortês IT, Rosalen PL, Berto LA, et al (2021)

Effect of adrenaline and noradrenaline on biofilm formation and virulence factors of Streptococcus mutans UA159.

Archives of oral biology, 125:105091 pii:S0003-9969(21)00054-6 [Epub ahead of print].

OBJECTIVES: To evaluate in vitro the effects of adrenaline and noradrenaline on the biofilm formation on orthodontic brackets, acid production and expression of virulence genes of Streptococcus mutans UA159 (S. mutans).

DESIGN: S. mutans UA159 biofilm was formed on orthodontic brackets under exposure to adrenaline (100 μM), noradrenaline (50 μM) or PBS solution (control group) in triptone-yeast extract with 1 % sucrose. After 24 h, biofilm formation was quantified through Colony Forming Units / mL (CFU/mL) and RNA was extracted to perform gene expression analysis through real-time reverse transcriptase-PCR (RT-qPCR). Evaluation of acid production was carried out on planktonic cultures for 6 h. One-way ANOVA followed by Tukey's test was carried to determine statistical difference. The level of significance was set at 5 %.

RESULTS: Catecholamines stimulated biofilm formation of S. mutans in orthodontic brackets (p < 0,05) but did not interfere with acid production (pH reduction) or the expression of the tested genes related to biofilm formation (gtfB, gtfC, gbpA, gbpB, gbpC, gbpD and brpA), aciduric (relA) and acidogenic properties (ldh).

CONCLUSIONS: The present study was the first to demonstrate that catecholamines can stimulate S. mutans UA159 biofilm formation. These findings can contribute to clarify the role of stress on bacterial metabolism and contribute to the understanding of a possible role on caries development, mainly in orthodontic patients.

RevDate: 2021-03-02

Wang Y (2021)

Liposome as a Delivery System for the Treatment of Biofilm-Mediated Infections.

Journal of applied microbiology [Epub ahead of print].

Biofilm formation by pathogenic microorganisms has been a tremendous challenge for antimicrobial therapies due to various factors. The biofilm matrix sequesters bacterial cells from the exterior environment and therefore prevents antimicrobial agents from reaching the interior. In addition, biofilm surface extracellular polymeric substances can absorb antimicrobial agents and thus reduce their bioavailability. To conquer these protection mechanisms, liposomes have been developed into a drug delivery system for antimicrobial agents against biofilm-mediated infections. The unique characteristics of liposomes, including versatility for cargoes, target-specificity, non-immunogenicity, low toxicity, and biofilm matrix-/cell membrane-fusogenicity, remarkably improve the effectiveness of antimicrobial agents and minimize recurrence of infections. This review summarizes current development of liposomal carriers for biofilm therapeutics, presents evidence in their practical applications and discusses their potential limitations.

RevDate: 2021-03-02

Espíndola LCP, do Nascimento MVMR, do Souto RM, et al (2021)

Antimicrobial susceptibility and virulence of Enterococcus spp. isolated from periodontitis-associated subgingival biofilm.

Journal of periodontology [Epub ahead of print].

BACKGROUND: This study evaluated the prevalence, virulence and antimicrobial susceptibility of enterococci isolated from the subgingival microbiota of patients with different periodontal status.

METHODS: Subgingival biofilm was obtained from individuals with Periodontal health/PH (n = 139), Gingivitis/G (n = 103) and Periodontitis/P (n = 305) and cultivated on selective media. Isolated strains were identified by mass spectrometry. Antimicrobial sensitivity was determined by disk diffusion, virulence genes by PCR, and the subgingival microbiota by checkerboard. Differences among groups were assessed by Kruskal-Wallis, Mann-Whitney and Chi-square tests.

RESULTS: Enterococcus spp. were isolated from 7.4% of all samples; 53.7% were Enterococcus faecalis. They were more prevalent in P (9.8%) and G (7.8%) than PH (2.2%; p<0.05), but no differences among stages of disease severity were observed. High rates of low susceptibility/resistance (>64%) to at least one antimicrobial were observed. Predominant virulence factors included ace (64.3%), asa (39.3%) and esp (35.7%). Fusobacterium nucleatum was prevalent in the subgingival microbiota of enterococci+ individuals, whereas Dialister pneumosintes was found in low frequency in patients with bopD+ enterococci. Oral streptococci were prevalent (>70%) in patients carrying enterococci susceptible to doxycycline (p<0.05), usually bopD- and esp- (p<0.01).

CONCLUSION: E. faecalis is increased in periodontitis-associated biofilm. Oral enterococci carry virulence genes and express resistance to some antibiotics commonly used in dentistry, such as ciprofloxacin and erythromycin. Specific subgingival taxa are associated with oral enterococci, suggesting they may interact with species of the dysbiotic periodontitis biofilm, constituting a potential source of factors to tissue destruction, antibiotic resistance dissemination and poor response to periodontal therapy. This article is protected by copyright. All rights reserved.

RevDate: 2021-03-02

Zafari M, Adibi M, Chiani M, et al (2021)

Effects of cefazolin-containing niosome nanoparticles against methicillin-resistant Staphylococcus aureus biofilm formed on chronic wounds.

Biomedical materials (Bristol, England), 16(3):035001.

The ability of biofilm formation in methicillin-resistant Staphylococcus aureus (MRSA) causes significant mortality and morbidity in wound infections. Nanoparticles because of the drug concentration increment at the point of contact of nanoparticles and bacteria, and slower release of the drug at the desired location are considered as proper tools to overcome the therapeutic problem of antimicrobial-resistant infections. This study was aimed to evaluate the anti-biofilm activity of cefazolin-loaded nanoparticles against MRSA isolates. The 27 clinical isolates of MRSA were collected from patients with pressure sores and diabetic ulcers referred to Loghman Hospital in Tehran-Iran. MRSA isolates were detected by polymerase chain reaction (PCR) and biochemical tests. Cefazolin-loaded niosome was synthesized using the thin-film hydration method and were characterized by zeta potential measurement and transmission electron microscopy (TEM). The round-shaped cefazolin-loaded niosomes had a diameter of 100 nm and a -63 mV zeta potential. The cefazolin-containing niosomes removed 1, 3, and 5 d old biofilms at the concentration of 128 µg ml-1, 128 µg ml-1, and 256 µg ml-1, respectively. Histological results indicated that BALB/c mice receiving cefazolin-loaded niosomes were treated effectively faster than those treated by cefazolin or untreated group. In conclusion, the cefazolin-loaded niosome could be considered as a promising candidate for the treatment of biofilm-mediated infections of MRSA.

RevDate: 2021-03-02

Ledwoch K, Magoga M, Williams D, et al (2021)

Is a reduction in viability enough to determine biofilm susceptibility to a biocide?.

Infection control and hospital epidemiology pii:S0899823X21000428 [Epub ahead of print].

OBJECTIVE: The abundance and prevalence of dry-surface biofilms (DSBs) in hospitals constitute an emerging problem, yet studies rarely report the cleaning and disinfection efficacy against DSBs. Here, the combined impact of treatments on viability, transferability, and recovery of bacteria from DSBs has been investigated for the first time.

METHODS: Staphylococcus aureus DSBs were produced in alternating 48-hour wet-dry cycles for 12 days on AISI 430 stainless steel discs. The efficacy of 11 commercially available disinfectants, 4 detergents, and 2 contactless interventions were tested using a modified standardized product test. Reduction in viability, direct transferability, cross transmission (via glove intermediate), and DSB recovery after treatment were measured.

RESULTS: Of 11 disinfectants, 9 were effective in killing and removing bacteria from S. aureus DSBs with >4 log10 reduction. Only 2 disinfectants, sodium dichloroisocyanurate 1,000 ppm and peracetic acid 3,500 ppm, were able to lower both direct and cross transmission of bacteria (<2 compression contacts positive for bacterial growth). Of 11 disinfectants, 8 could not prevent DSB recovery for >2 days. Treatments not involving mechanical action (vaporized hydrogen peroxide and cold atmospheric plasma) were ineffective, producing <1 log10 reduction in viability, DSB regrowth within 1 day, and 100% transferability of DSB after treatment.

CONCLUSIONS: Reduction in bacterial viability alone does not determine product performance against biofilm and might give a false sense of security to consumers, manufacturers and regulators. The ability to prevent bacterial transfer and biofilm recovery after treatment requires a better understanding of the effectiveness of biocidal products.

RevDate: 2021-03-02

Zhao Y, Cai Y, Chen Z, et al (2021)

SpoT-mediated NapA upregulation promotes oxidative stress-induced Helicobacter pylori biofilm formation and confers multidrug resistance.

Antimicrobial agents and chemotherapy pii:AAC.00152-21 [Epub ahead of print].

Recently, there is increased incidence of drug-resistant Helicobacter pylori infection. Biofilm formation confers multidrug resistance to bacteria. Moreover, it has been found that the formation of biofilm on the surface of gastric mucosa is an important reason for the difficulty of eradication of H. pylori The mechanisms underlying H. pylori biofilm formation in vivo have not been elucidated. Reactive oxygen species (ROS) released by the host immune cells in response to H. pylori infection cannot effectively clear the pathogen. Moreover, the extracellular matrix of the biofilm protects the bacteria against ROS-mediated toxicity. This study hypothesized that ROS can promote H. pylori biofilm formation and treatment with low concentrations of hydrogen peroxide (H2O2) promoted this process in vitro The comparative transcriptome analysis of planktonic and biofilm-forming cells revealed that the expression of SpoT, a (p)ppGpp (guanosine 3'-diphosphate 5'-triphosphate and guanosine 3',5'-bispyrophosphate) synthetase/hydrolase, is upregulated in H2O2-induced biofilms and that knockout of spoT inhibited H. pylori biofilm formation. Additionally, this study examined the key target molecules involved in SpoT regulation using weighted gene co-expression network analysis. The analysis revealed that neutrophil-activating protein (NapA; HP0243) promoted H2O2-induced biofilm formation and conferred multidrug resistance. Furthermore, vitamin C exhibited anti-H. pylori biofilm activity and downregulated the expression of napA in vitro These findings provide novel insight into the clearance of H. pylori biofilms.

RevDate: 2021-03-02

Raval YS, Flurin L, Mohamed A, et al (2021)

in vitro Activity of Hydrogen Peroxide and Hypochlorous Acid Generated by Electrochemical Scaffolds Against Planktonic and Biofilm Bacteria.

Antimicrobial agents and chemotherapy pii:AAC.01966-20 [Epub ahead of print].

Hydrogen peroxide (H2O2) and hypochlorous acid (HOCl) are biocides used for cleaning and debriding chronic wound infections, which often harbor drug resistant bacteria. Here, we evaluated the in vitro activity of H2O2 and HOCl against 27 isolates of eight bacterial species involved in wound infections. Minimum inhibitory concentrations (MICs) and minimum biofilm bactericidal concentrations (MBBCs) were measured. When compared to their respective MICs, MBBCs of isolates exposed to H2O2 were 16- to 1,024-fold higher and those exposed to HOCl were 2- to 4-fold higher. We evaluated selection of resistance after exposure of Staphylococcus aureus and Pseudomonas aeruginosa biofilms to 10 iterations of electrochemically generated HOCl or H2O2 delivered using electrochemical scaffolds (e-scaffolds), observing no decrease in anti-biofilm effects with serial exposure to e-scaffold-generated H2O2 or HOCl. 24-hour exposure to H2O2-generating e-scaffolds consistently decreased colony forming units (CFUs) of S. aureus and P. aeruginosa biofilms by ∼5.0-log10 and ∼4.78-log10 through 10 iterations of exposure, respectively. 4-hour exposure to HOCl-generating e-scaffolds consistently decreased CFUs of S. aureus biofilms by ∼4.9-log10, and 1-hour exposure to HOCl-generating e-scaffolds consistently decreased CFUs of P. aeruginosa biofilms by ∼1.57-log10 These results suggest that HOCl has similar activity against planktonic and biofilm bacteria, whereas the activity of H2O2 is less against biofilm than planktonic bacteria, and that repeat exposure to either biocide, generated electrochemically under the experimental conditions studied, does not lessen antibiofilm effects.

RevDate: 2021-03-02

Ramires T, Kleinubing NR, Iglesias MA, et al (2021)

Genetic diversity, biofilm and virulence characteristics of Listeria monocytogenes in salmon sushi.

Food research international (Ottawa, Ont.), 140:109871.

Sushi is a ready-to-eat (RTE) food prepared from raw or cooked fish that is widely consumed worldwide. Listeria monocytogenes is the foodborne pathogen most commonly associated with RTE and fish products. The aim of the present study was to evaluate the presence of L. monocytogenes in salmon sushi commercialized in Pelotas city, Brazil, and to evaluate the genetic diversity, biofilm-forming ability in stainless steel, and virulence characteristics of the isolates. Four sampling events were carried out in seven specialized sushi establishments totaling 28 sushi pools. Listeria monocytogenes was detected in six samples (21.4%) from two establishments (28.6%). All isolates belonged to serotype 4b and carried the prfA, plcA, plcB, hlyA, mpl, actA, inlA, inlC, inlJ, and iap genes. The inlB gene was not detected in two isolates. The PFGE analysis grouped the isolates into four pulsotypes. All isolates had the ability to form biofilm on stainless steel and the average of biofilm formation counts varied between 6.4 and 7.2 log The isolates harbored the biofilm-related genes agrA, agrB, agrC, agrD, and prfA, with the exception of two isolates that did not harbor the agrD gene. The presence of L. monocytogenes in RTE sushi is a concern, demonstrating that sushi consumption may be a risk of human listeriosis. Furthermore, it was possible to identify the persistence of this pathogen for at least one month (pulsotypes III and IV), in two establishments (A and G), highlighting the need for improving the cleaning and sanitation procedures in establishments that commercialize RTE sushi.

RevDate: 2021-03-01

Egebro Birk S, Mazzoni C, Mobasharah Javed M, et al (2021)

Co-delivery of ciprofloxacin and colistin using microcontainers for bacterial biofilm treatment.

International journal of pharmaceutics pii:S0378-5173(21)00224-6 [Epub ahead of print].

In many infected patients, bacterial biofilms represent a mode of growth that significantly enhances the tolerance to antimicrobials, leaving the patients with difficult-to-cure infections. Therefore, there is a growing need for effective treatment strategies to combat biofilm infections. In this work, reservoir-based microdevices, also known as microcontainers (MCs), are co-loaded with two antibiotics: ciprofloxacin hydrochloride (CIP) and colistin sulfate (COL), targeting both metabolically active and dormant subpopulations of the biofilm. We assess the effect of the two drugs in a time-kill study of planktonic P. aeruginosa and find that co-loaded MCs are superior to monotherapy, resulting in complete killing of the entire population. Biofilm consortia of P. aeruginosa grown in flow chambers were not fully eradicated. However, antibiotics in MCs work significantly faster than simple perfusion of antibiotics (62.5±8.3 % versus 10.6±10.1 % after 5 h) in biofilm consortia, showing the potential of the MC-based treatment to minimize the use of antimicrobials in future therapies.

RevDate: 2021-03-01

Pérez-Rodríguez S, García-Aznar JM, J Gonzalo-Asensio (2021)

Microfluidic devices for studying bacterial taxis, drug testing and biofilm formation.

Microbial biotechnology [Epub ahead of print].

Some bacteria have coevolved to establish symbiotic or pathogenic relationships with plants, animals or humans. With human association, the bacteria can cause a variety of diseases. Thus, understanding bacterial phenotypes at the single-cell level is essential to develop beneficial applications. Traditional microbiological techniques have provided great knowledge about these organisms; however, they have also shown limitations, such as difficulties in culturing some bacteria, the heterogeneity of bacterial populations or difficulties in recreating some physical or biological conditions. Microfluidics is an emerging technique that complements current biological assays. Since microfluidics works with micrometric volumes, it allows fine-tuning control of the test conditions. Moreover, it allows the recruitment of three-dimensional (3D) conditions, in which several processes can be integrated and gradients can be generated, thus imitating physiological 3D environments. Here, we review some key microfluidic-based studies describing the effects of different microenvironmental conditions on bacterial response, biofilm formation and antimicrobial resistance. For this aim, we present different studies classified into six groups according to the design of the microfluidic device: (i) linear channels, (ii) mixing channels, (iii) multiple floors, (iv) porous devices, (v) topographic devices and (vi) droplet microfluidics. Hence, we highlight the potential and possibilities of using microfluidic-based technology to study bacterial phenotypes in comparison with traditional methodologies.

RevDate: 2021-03-01

Lahiri D, Nag M, Sarkar T, et al (2021)

Antibiofilm Activity of α-Amylase from Bacillus subtilis and Prediction of the Optimized Conditions for Biofilm Removal by Response Surface Methodology (RSM) and Artificial Neural Network (ANN).

Applied biochemistry and biotechnology [Epub ahead of print].

α-amylase is known to have antibiofilm activity against biofilms of both Gram positive and Gram-negative bacterial strains. Partially purified α-amylase from Bacillus subtilis was found to have inhibit biofilm formed by P. aeruginosa and S. aureus. The spectrophotometric and microscopic studies revealed that the antibiofilm efficacy of the working strain is greater than commercially purchased α-amylase. Response surface methodology (RSM) and artificial neural network (ANN) help to predict the optimum conditions [pH 8, treatment time 6 h and enzyme concentration (200 µg/mL)] for maximum biofilm eradication. This was confirmed by several in vitro experiments. Molecular docking interactions of α-amylase with the extracellular polymeric substances (EPS) of both P. aeruginosa and S. aureus indicate towards the existence of an efficient energy driven spontaneous process. Thus, this study highlights a combination of experimental and computational approach showing the naturally extracted α-amylase from B. subtilis having the potency of removing the biofilms of harmful bacterial strains involved in causing various nosocomial infections.

RevDate: 2021-03-01

Chen X, Iwatani S, Kitamoto T, et al (2021)

The Lack of SNARE Protein Homolog Syn8 Influences Biofilm Formation of Candida glabrata.

Frontiers in cell and developmental biology, 9:607188.

Biofilm formation of Candida species is considered to be a pathogenic factor of host infection. Since biofilm formation of Candida glabrata has not been as well studied as that of Candida albicans, we performed genetic screening of C. glabrata, and three candidate genes associated with biofilm formation were identified. Candida glabrata SYN8 (CAGL0H06325g) was selected as the most induced gene in biofilm cells for further research. Our results indicated that the syn8Δ mutant was defective not only in biofilm metabolic activity but also in biofilm morphological structure and biomass. Deletion of SYN8 seemed to have no effect on extracellular matrix production, but it led to a notable decrease in adhesion ability during biofilm formation, which may be linked to the repression of two adhesin genes, EPA10 and EPA22. Furthermore, hypersensitivity to hygromycin B and various ions in addition to the abnormal vacuolar morphology in the syn8Δ mutant suggested that active vacuolar function is required for biofilm formation of C. glabrata. These findings enhance our understanding of biofilm formation in this fungus and provide information for the development of future clinical treatments.

RevDate: 2021-03-01

Shang D, Han X, Du W, et al (2021)

Trp-Containing Antibacterial Peptides Impair Quorum Sensing and Biofilm Development in Multidrug-Resistant Pseudomonas aeruginosa and Exhibit Synergistic Effects With Antibiotics.

Frontiers in microbiology, 12:611009.

Pseudomonas aeruginosa uses quorum sensing (QS) to control virulence, biofilm formation and antibiotic efflux pump expression. The development of effective small molecules targeting the QS system and biofilm formation represents a novel attractive strategy. In this present study, the effects of a series of Trp-containing peptides on the QS-regulated virulence and biofilm development of multidrug-resistant P. aeruginosa, as well as their synergistic antibacterial activity with three classes of traditional chemical antibiotics were investigated. The results showed that Trp-containing peptides at low concentrations reduced the production of QS-regulated virulence factors by downregulating the gene expression of both the las and rhl systems in the strain MRPA0108. Biofilm formation was inhibited in a concentration-dependent manner, which was associated with extracellular polysaccharide production inhibition by downregulating pelA, algD, and pslA transcription. These changes correlated with alterations in the extracellular production of pseudomonal virulence factors and swarming motility. In addition, the combination of Trp-containing peptides at low concentration with the antibiotics ceftazidime and piperacillin provided synergistic effects. Notably, L11W and L12W showed the highest synergy with ceftazidime and piperacillin. A mechanistic study demonstrated that the Trp-containing peptides, especially L12W, significantly decreased β-lactamase activity and expression of efflux pump genes OprM, MexX, and MexA, resulting in a reduction in antibiotic efflux from MRPA0108 cells and thus increasing the antibacterial activity of these antibiotics against MRPA0108.

RevDate: 2021-03-01

Rudenko P, Sachivkina N, Vatnikov Y, et al (2021)

Role of microorganisms isolated from cows with mastitis in Moscow region in biofilm formation.

Veterinary world, 14(1):40-48.

Background and Aim: Mastitis is one of the most important diseases of cows and the most expensive pathology for the dairy industry. Therefore, this study was conducted to explore the role of microorganisms isolated from cows with mastitis in the formation of biofilms under the conditions of farm biogeocenosis in the Moscow region.

Materials and Methods: Periodic visits to 12 farms in the Moscow region were conducted to explore the microbial profile of the udder of cows with mastitis. During the visits, 103 milk samples from sick animals were collected and examined. Through microbiological analyses, 486 cultures of microorganisms were identified, which are assigned to 11 genera. Mastitis in cows is caused not only by a single pathogen but also by microbial associations, which included two to seven microbial isolates.

Results: It was observed that 309 isolates (63.6%) from the total number of isolated microorganisms could form a biofilm. The ability to form biofilms was most frequently observed in Staphylococcus aureus (18.8%), Escherichia coli (11.9%), and Staphylococcus uberis (11.7%) cultures from the total number of biofilm-forming microbial cultures. Low biofilm-forming ability among the isolated microorganisms was found in lactobacilli, wherein only 20 (22.5%) Lactobacillus strains had the ability to form biofilms. The isolated microorganisms exhibited different sensitivities to antimicrobial agents, which cause difficulty in selecting an antimicrobial agent that would act on all aspects of the parasitocenosis.

Conclusion: A high proportion of microorganisms isolated from cows with mastitis have the ability to form biofilms. The isolated microorganisms exhibited different and highly heterogeneous sensitivity to the action of antimicrobial drugs. This causes difficulty in using these tools for the effective control of mastitis in cows, which is frequently caused by pathogenic associations of microbial biofilms. Therefore, it is important to explore novel and more effective methods to combat this disease.

RevDate: 2021-03-01

Kim CM, Park G, Ko YJ, et al (2021)

Relationships between relative expression of RND efflux pump genes, H33342 efflux activity, biofilm-forming activity, and antimicrobial resistance in Acinetobacter baumannii clinical isolates.

Japanese journal of infectious diseases [Epub ahead of print].

Various mechanisms underlying antimicrobial resistance in Acinetobacter baumannii have been reported. There exists controversy regarding the relationships between efflux pump activity, biofilm formation, and antimicrobial resistance in A. baumannii. In this study, we investigated the relative expression of RND efflux pump genes, H33342 efflux activity, and biofilm-forming activity in 120 A. baumannii clinical isolates, examined their potential relationships with one another, and then statistically analyzed their effects on antibiotic resistance. High adeB expression and high H33342 efflux activity were correlated with low biofilm-forming activity. High adeB expression was significantly correlated with resistance to tigecycline and cefotaxime, but not with the multidrug resistance (MDR) phenotype. Importantly, only high adeJ expression was significantly correlated with the MDR phenotype, and was observed to be correlated with resistance to various antibiotics. However, we found no significant correlation between adeJ expression and biofilm-forming activity. Further, adeG expression was found to not be correlated with antibiotic resistance and biofilm-forming activity. The results of multivariate analysis showed that adeB overexpression and high H33342 efflux activity are related to biofilm-forming activity, and only adeJ overexpression is significantly associated with the MDR phenotype, highlighting the importance of adeJ overexpression.

RevDate: 2021-02-28

Learbuch KLG, Smidt H, PWJJ van der Wielen (2021)

Influence of pipe materials on the microbial community in unchlorinated drinking water and biofilm.

Water research, 194:116922 pii:S0043-1354(21)00120-2 [Epub ahead of print].

Biodegradable compounds can cause undesired microbial growth in drinking water systems and these compounds can originate from the water or pipe materials used in drinking water systems. The aim of our study was to determine the influence of different pipe materials on the microbial populations in water and biofilm under semi-stagnant conditions. The microbial communities in biofilm and water, which were in contact with seven different materials, were characterized by determining ATP concentrations, microbial composition gene copy numbers of some specific microbial groups. The ATP concentration in water and biofilm varied between the different materials with glass (negative control) < copper < PVCC < PE-Xc < PE-Xb < PE-100 < PVC-P. Gene copy numbers of Legionella spp., Mycobacterium spp., Pseudomonas spp., Aeromonas spp., fungi and Vermamoeba vermiformis were also higher for PVC-P and PE than for glass, copper and PVCC. The bacterial community composition in water and biofilm varied between materials as well. PERMANOVA and CAP analysis demonstrated that copper and PVC-P are different when compared to the other materials. Furthermore, bacterial community composition and ATP concentrations in water and biofilm were similar after eight and 16 weeks incubation, but differed from results obtained after one week. Finally, the ATP, the specific microbial groups and the bacterial community composition also differed between water and biofilm on each material. We conclude from our study that pipe material is an important factor that influences the biomass concentration, abundance of specific microorganisms and the bacterial community composition in distribution systems with unchlorinated drinking water.

RevDate: 2021-02-28

Duyar A, Ciftcioglu V, Cirik K, et al (2021)

Treatment of landfill leachate using single-stage anoxic moving bed biofilm reactor and aerobic membrane reactor.

The Science of the total environment, 776:145919 pii:S0048-9697(21)00986-4 [Epub ahead of print].

Landfill leachate (LFL) is one of the most serious environmental problems due to the high concentrations of toxic and hazardous matters. Although several physical, chemical, methods have been tested, biological processes and single or multiple-stage combinations of them have been receiving more attention due to their cost-effective and environmentally-friendly manner. The present work recommended coupling of conventional single-stage A/O with moving bed biofilm reactor and membrane bioreactor (AnoxMBBR/AeMBR) for LFL treatment. The system performance was evaluated for 233 d under varying nitrate concentrations (100-1000 mgNO3--N/L), sludge retention time (SRT) (30-90 d), and HRT (24-48 h) in AnoxMBBR, and constant SRT (infinite) and HRT (48 h) in the AeMBR. The best system performances were observed at 1000 mgNO3--N/L concentration, SRT of 90 d and HRT of 48 h, and the average removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and nitrate‑nitrogen (NO3-N) were 74.2%, 99.7%, and 89.1%, respectively. Besides, the AeMBR was achieved above 99% NH4+-N removal and not adversely affected by varying operation conditions of AnoxMBBR. A slight increase in selected phthalic acid ester (PAE) concentrations (diethyl phthalate (DEP), di (2-Ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP)) was detected in the AnoxMBR, and complete PAEs removal was attained in the AeMBR. Mg, Al, Si, Na, Fe was detected by SEM-EDX analyses in both biofilm of AnoxMBBR and the cake layers of AeMBR. Nitrobacter and Nitratireductor which showed a relatively high abundance played an important role in the removal of NH4+-N and COD in LFL. The results confirmed that the proposed sequence is efficient for COD removal, nitrogen removal, and PAEs being an acceptable treatment for landfill leachates.

RevDate: 2021-02-28

Jiang Y, Liu Y, Zhang X, et al (2021)

Biofilm application in the microbial biochemicals production process.

Biotechnology advances pii:S0734-9750(21)00030-6 [Epub ahead of print].

Biofilms can be naturally formed through the attachment of microorganisms on the supporting materials. However, natural biofilms formed in the environment may cause some detrimental effects, such as the equipment contamination and food safety issues et al. On the contrary, biofilms mediated microbial fermentation provides a promising approach for the efficient biochemicals production owing to the properties of self-immobilization, high resistance to toxic reactants and maintenance of long-term cells activity. While few reviews have specifically addressed the biological application of biofilms in the microbial fermentation process. Accordingly, this review will comprehensively summarize the biofilms formation mechanism and potential functions in the microbial fermentation process. Furthermore, the construction strategies for the formation of stable biofilms through synthetic biology technology or the modification of suitable supporting materials were also discussed. The application of biofilms mediated fermentation will provide an outlook for the biorefinery platform in the future.

RevDate: 2021-02-27

Qiao Y, Jia R, Luo Y, et al (2021)

The inhibitory effect of Ulva fasciata on culturability, motility, and biofilm formation of Vibrio parahaemolyticus ATCC17802.

International microbiology : the official journal of the Spanish Society for Microbiology [Epub ahead of print].

The outbreak of vibriosis from Vibrio parahaemolyticus (V. parahaemolyticus) is one of common pathogenic diseases found in the mariculture environment. In this study, the inhibitory effect of Ulva fasciata (U. fasciata) on the culturability, motility, and biofilm formation of V. parahaemolyticus ATCC17802 was examined by co-culturing system. Results showed that both of secretion and live tissue of U. fasciata could convert culturable V. parahaemolyticus ATCC17802 to non-culturable, both reaching more than 99% of inhibition rate after 3-day co-culture, and higher density (12 g L-1) of U. fasciata exhibited stronger inhibition. The twitching behavior of V. parahaemolyticus ATCC17802 was more easily affected by U. fasciata than the swimming behavior after 3-day co-culture, with the inhibitory rates varying at the ranges of 1.70-30.29% (twitching behavior) and 10.06-44.86% (swimming behavior) under the different environmental factors (salinity, NO3--N and PO43--P concentrations), but no significant correlation was found. The greatest inhibition effect on V. parahaemolyticus ATCC17802 biofilm formation occurred at 12 h, with inhibition rates at the range of 11.03-67.10 %, while there was still no significant correlation between inhibition rate and the three environmental factors. The different environmental factors might induce U. fasciata to excrete different levels of secondary metabolites, which caused the various inhibitory effect on the cultivability, motility, and biofilm formation of V. parahaemolyticus ATCC17802.

RevDate: 2021-02-27

Matsumoto A, Koga R, Kanaly RA, et al (2021)

Identification of a diguanylate cyclase that facilitates biofilm formation on electrodes by Shewanella oneidensis MR-1.

Applied and environmental microbiology pii:AEM.00201-21 [Epub ahead of print].

In many bacteria, cyclic diguanosine monophosphate (c-di-GMP), synthesized by diguanylate cyclase (DGC), serves as a second messenger involved in the regulation of biofilm formation. Although studies have suggested that c-di-GMP also regulates the formation of electrochemically active biofilms (EABFs) by Shewanella oneidensis MR-1, DGCs involved in this process remained to be identified. Here we report that the SO_1646 gene, hereafter named dgcS, is upregulated under medium-flow conditions in electrochemical flow cells (EFCs), and its product (DgcS) functions as a major DGC in MR-1. In vitro assays demonstrated that purified DgcS catalyzed the synthesis of c-di-GMP from GTP. Comparisons of intracellular c-di-GMP levels in the wild-type strain and a dgcS-deletion mutant (ΔdgcS) showed that production of c-di-GMP was markedly reduced in ΔdgcS when cells were grown in batch cultures and on electrodes in EFCs. Cultivation of ΔdgcS in EFCs also revealed that the loss of DgcS resulted in impaired biofilm formation and decreased current generation. These findings demonstrate that MR-1 uses DgcS to synthesize c-di-GMP under medium-flow conditions, thereby activating biofilm formation on electrodes.IMPORTANCEBioelectrochemical systems (BESs) have attracted wide attention owing to their utility in sustainable biotechnology processes, such as microbial fuel cells and electro-fermentation systems. In BESs, electrochemically active bacteria (EAB) form biofilms on electrode surfaces, thereby serving as effective catalysts for the interconversion between chemical and electric energy. It is therefore important to understand mechanisms for the formation of biofilm by EAB grown on electrodes. Here we show that a model EAB, S. oneidensis MR-1, expresses DgcS as a major DGC, thereby activating the formation of biofilms on electrodes via c-di-GMP-dependent signal transduction cascades. The findings presented herein provide the molecular basis for improving electrochemical interactions between EAB and electrodes in BESs. The results also offer molecular insights into how Shewanella regulates biofilm formation on solid surfaces in the natural environment.

RevDate: 2021-02-26

di Biase A, Kowalski MS, Devlin TR, et al (2021)

Modeling of the attached and suspended biomass fractions in a moving bed biofilm reactor.

Chemosphere, 275:129937 pii:S0045-6535(21)00406-9 [Epub ahead of print].

The performance, kinetics, and stoichiometry of three high-rate moving bed biofilm reactors (MBBRs) were evaluated. A constant surface area loading rate (SALR) and three different hydraulic retention times (HRTs) were utilized to create scenarios where the attached and suspended biomass fractions would differentiate, despite the main design parameter remaining constant. Performance was simulated using BioWin™ 6.0 software. The objective was to evaluate whether a calibrated/validated model could accurately predict experimental results. Initially, a sensitivity analysis was performed to determine influential parameters. The calibration/validation of influential parameters was then conducted via steady-state simulations for two base cases: 1) highest HRT; and 2) lowest HRT. Both sets of calibrated/validated parameters were substantiated using: 1) steady-state simulations at the other HRTs; and 2) dynamic simulations to evaluate the kinetic rates of attached and suspended biomass fractions at all HRTs. Results demonstrated that the model could be calibrated/validated for a single HRT, but could not accurately predict the performance, kinetics, or stoichiometry at other HRTs.

RevDate: 2021-02-26

Dong Y, Wang L, Yuan K, et al (2021)

Magnetic Microswarm Composed of Porous Nanocatalysts for Targeted Elimination of Biofilm Occlusion.

ACS nano [Epub ahead of print].

Biofilm is difficult to thoroughly cure with conventional antibiotics due to the high mechanical stability and antimicrobial barrier resulting from extracellular polymeric substances. Encouraged by the great potential of magnetic micro-/nanorobots in various fields and their enhanced action in swarm form, we designed a magnetic microswarm consisting of porous Fe3O4 mesoparticles (p-Fe3O4 MPs) and explored its application in biofilm disruption. Here, the p-Fe3O4 MPs microswarm (p-Fe3O4 swarm) was generated and actuated by a simple rotating magnetic field, which exhibited the capability of remote actuation, high cargo capacity, and strong localized convections. Notably, the p-Fe3O4 swarm could eliminate biofilms with high efficiency due to synergistic effects of chemical and physical processes: (i) generating bactericidal free radicals (•OH) for killing bacteria cells and degrading the biofilm by p-Fe3O4 MPs; (ii) physically disrupting the biofilm and promoting •OH penetration deep into biofilms by the swarm motion. As a demonstration of targeted treatment, the p-Fe3O4 swarm could be actuated to clear the biofilm along the geometrical route on a 2D surface and sweep away biofilm clogs in a 3D U-shaped tube. This designed microswarm platform holds great potential in treating biofilm occlusions particularly inside the tiny and tortuous cavities of medical and industrial settings.

RevDate: 2021-02-26

Berlec A, Janež N, Sterniša M, et al (2021)

Expression of NanoLuc Luciferase in Listeria innocua for Development of Biofilm Assay.

Frontiers in microbiology, 12:636421.

Studies of biofilm formation by bacteria are crucial for understanding bacterial resistance and for development of novel antibacterial strategies. We have developed a new bioluminescence biofilm assay for Listeria innocua, which is considered a non-pathogenic surrogate for Listeria monocytogenes. L. innocua was transformed with a plasmid for inducible expression of NanoLuc luciferase (Nluc). Concentration-dependent bioluminescence signals were obtained over a concentration range of more than three log units. This biofilm assay enables absolute quantification of bacterial cells, with the necessary validation. For biofilm detection and quantification, this "Nluc bioluminescence" method has sensitivity of 1.0 × 104 and 3.0 × 104 colony forming units (CFU)/mL, respectively, with a dynamic range of 1.0 × 104 to 5.0 × 107 CFU/mL. These are accompanied by good precision (coefficient of variation, <8%) and acceptable accuracy (relative error for most samples, <15%). This novel method was applied to assess temporal biofilm formation of L. innocua as a function of concentration of inoculant, in comparison with conventional plating and CFU counting, the crystal violet assay, and the resazurin fluorescence assay. Good correlation (r = 0.9684) of this Nluc bioluminescence assay was obtained with CFU counting. The limitations of this Nluc bioluminescence assay include genetic engineering of bacteria and relatively high cost, while the advantages include direct detection, absolute cell quantification, broad dynamic range, low time requirement, and high sensitivity. Nluc-based detection of L. innocua should therefore be considered as a viable alternative or a complement to existing methods.

RevDate: 2021-02-25

Xing F, Xi H, Yu Y, et al (2021)

Anode biofilm influence on the toxic response of microbial fuel cells under different operating conditions.

The Science of the total environment, 775:145048 pii:S0048-9697(21)00114-5 [Epub ahead of print].

The response of microorganisms in microbial fuel cells (MFCs) to toxic compounds under different operating conditions, such as flow rate and culture time, was investigated herein. While it has been reported that MFCs can detect some toxic substances, it is unclear if operating conditions affect MFCs toxicity response. In this study, the toxic response time of MFCs decreased when the flow rate increased from 0.5 mL/min to 2 mL/min and then increased with 5 mL/min. The inhibition rates at 0.5 mL/min, 2 mL/min, and 5 mL/min were 8.4% ± 1.6%, 45.1% ± 5.3%, and 4.9% ± 0.3%, respectively. With the increase of culture time from 7 days to 90 days, the toxic response time of MFCs gradually increased. The inhibition rates at culture times of 7 days, 45 days, and 90 days were 45.1% ± 5.3%, 32.6% ± 6.6%, and 23.2% ± 1.3%, respectively. Increasing the culture time will reduce the sensitivity of MFC. The results showed that MFCs can respond quickly at a flow rate of 2 mL/min after cultivation for 7 days. Under these conditions, the power density can reach 1137.0 ± 65.5 mW/m2, the relative content of Geobacter sp. is 57%, and the ORP of the multilayers changed from -159.2 ± 1.6 mV to -269.9 ± 1.7 mV within 200 μm biofilm thickness. These findings show that increasing the flow rate and shortening the culture time are conducive for the toxicity response of MFCs, which will increase the sensitivity of MFCs in practical applications.

RevDate: 2021-02-25

M W, I T (2021)

The hospital built environment - biofilm, biodiversity and bias.

RevDate: 2021-02-25

Silva NBS, de Andrade Marques L, D von Dolinger de Brito Röder (2021)

Diagnosis of biofilm infections: current methods used, challenges and perspectives for the future.

Journal of applied microbiology [Epub ahead of print].

The diagnosis of biofilms continues to be a challenge, and there is no standardized protocol for such a diagnosis in clinical practice. In addition, some proposed methodologies are expensive to require significant amounts of time and a high number of trained staff, making them impracticable for clinical practice. In recent years, mass spectrophotometry/MALDI-TOF has been applied it in biofilm studies. However, due to several problems and limitations of the technique, MALDI-TOF is far from being the gold standard for identifying biofilm formation. The omics analysis may prove to be a promising strategy for the diagnosis of biofilms in clinical laboratories since it allows the identification of pathogens in less time than needed for conventional techniques and in a more specific manner. However, omic tools are expensive and require qualified technical expertise and an analysis of the data obtained needs to be careful not to neglect sub-populations in the biofilm. More studies must therefore be developed for creating a protocol that guarantees rapid biofilm identification, ensuring greater chances of success in infection control. This review discusses the current methods of microbial biofilm detection and future perspectives for its diagnosis in clinical practice.

RevDate: 2021-02-25

Vincent-Bugnas S, Borsa L, Gruss A, et al (2021)

Prioritization of predisposing factors of gingival hyperplasia during orthodontic treatment: the role of amount of biofilm.

BMC oral health, 21(1):84.

BACKGROUND: The mechanism of gingival growth that may occur during fixed orthodontic treatment is not yet fully understood and the amount of dental plaque is often incriminated. The objective of this study was to evaluate the prevalence of gingival growth during multi-attachment orthodontic treatment and to prioritize its predicting factors, especially the quantity of biofilm.

METHODS: This comprehensive cross-sectional descriptive study was conducted on orthodontic patients aged 9 to 30 years, in good health, treated by a fixed appliance. Periodontal clinical parameters such as plaque index, gingival index, probing pocket depth, periodontal phenotype and gingival enhancement index were recorded. Likewise, the brushing habits and the date of the last scaling were noted. The orthodontic parameters studied were the duration of the treatment, the type of bracket, the alloys used for the arches and the type of ligatures. Descriptive statistics were carried out, and variables presenting p value < 0.25 were included in a multivariate analysis to calculate the Odds Ratio (OR) of gingival enlargement".

RESULTS: A total of 193 patients were included (16.38 ± 4.89 years). Gingival growth occurred for 49.7% of patients included. The predisposing factors for this pathology during fixed orthodontic treatment were conventional metal brackets (p = 0.021), mouth breathing (p = 0.040), male gender (p = 0.035), thick periodontal phenotype (p = 0.043), elastomeric ligations (p = 0.007), duration of treatment (p = 0.022) and presence of plaque (p = 0.004). After achievement of the logistic regression, only two factors remained related to gingival enlargement: metallic brackets (OR: 3.5, 95% CI: 1.1-10.55) and duration of treatment (OR: 2.03, 95% CI: 1.01-4.08). The amount of plaque would not be directly related to the development of gingival increase during orthodontic treatment.

CONCLUSIONS: Among the predisposing factors that underlie gingival growth during multi-attachment therapy, the amount of plaque is not found. The qualitative assessment of the plaque and its evolution during treatment could clarify the role of the biofilm in the occurrence of gingival overgrowth.

RevDate: 2021-02-24

Sriwiriyarat T, S Kuhakaew (2021)

Effects of cations on biofilm formation and characteristics in integrated fixed film activated sludge process at different carbon and nitrogen loadings.

Chemosphere, 275:130002 pii:S0045-6535(21)00471-9 [Epub ahead of print].

Both divalent cations including calcium and magnesium play important roles for microbial aggregates in binding to negatively charged functional groups on bacterial surfaces, in extracellular polymeric substances (EPS), and on inorganic materials in flocs and biofilms. Monovalent cations such as sodium and potassium deteriorate the floc structure and physical properties. The Integrated Fixed Activated Sludge (IFAS) process employs fixed film media in the aerobic zone; therefore, both monovalent and divalent cations are involved in the process performances. In this study, the effects of cations indicated as the monovalent to divalent cations (M/D) ratio on the biofilm formation and characteristics, and on the IFAS performances for carbon and ammonium removals were evaluated. The experiments were conducted in three IFAS systems feeding with the same wastewater but different M/D ratios and two carbon and nitrogen loadings. The findings revealed that high monovalent with low divalent cations at the M/D ratios higher than 2.0 produced excessive polysaccharides in EPS resulting in high viscosity of activated sludge flocs causing viscous bulking with high SVI values, decreasing the biofilm formation, and increasing the biofilm sloughing. Increasing of both monovalent and carbon loading increased more polysaccharides in the EPS leading to the failures of IFAS system. Nitrification failed at higher M/D ratios because of less nitrifiers in flocs and biofilm. The M/D ratio less than 2.0 is suggested to minimize the excessive EPS production in the IFAS system, especially at high organic loading.

RevDate: 2021-02-24

Khan MF, CD Murphy (2021)

3-Hydroxytyrosol regulates biofilm growth in Cunninghamella elegans.

Fungal biology, 125(3):211-217.

In contrast to yeast biofilms, those of filamentous fungi are relatively poorly understood, in particular with respect to their regulation. Cunninghamella elegans is a filamentous fungus that is of biotechnological interest as it catabolises drugs and other xenobiotics in an analogous manner to animals; furthermore, it can grow as a biofilm enabling repeated batch biotransformations. Precisely how the fungus switches from planktonic to biofilm growth is unknown and the aim of this study was to shed light on the possible mechanism of biofilm regulation. In dimorphic yeasts, alcohols such as tyrosol and 2-phenylethanol are known to control the yeast-to-hypha switch, and a similar molecule might be involved in regulating biofilm in C. elegans. Gas chromatography-mass spectrometry analysis of crude ethyl acetate extracts from supernatants of 72 h planktonic and biofilm cultures revealed 3-hydroxytyrosol as a prominent metabolite. Further quantification revealed that the amounts of the compound in planktonic cultures were substantially higher (>10-fold) than in biofilm cultures. In the presence of exogenous 3-hydroxytyrosol the growth of aerial mycelium was inhibited, and there was selective inhibition of biofilm when it was added to culture medium. There was no biotransformation of the compound when it was added to 72 h-old cultures, in contrast to the related compounds tyrosol and 2-phenylethanol, which were oxidised to a number of products. Therefore, we propose that 3-hydroxytyrosol is a new signalling molecule in fungi, which regulates biofilm growth.

RevDate: 2021-02-23

Tkachenko AG, Kashevarova NM, Sidorov RY, et al (2021)

A synthetic diterpene analogue inhibits mycobacterial persistence and biofilm formation by targeting (p)ppGpp synthetases.

Cell chemical biology pii:S2451-9456(21)00044-1 [Epub ahead of print].

Bacterial persistence coupled with biofilm formation is directly associated with failure of antibiotic treatment of tuberculosis. We have now identified 4-(4,7-DiMethyl-1,2,3,4-tetrahydroNaphthalene-1-yl)Pentanoic acid (DMNP), a synthetic diterpene analogue, as a lead compound that was capable of suppressing persistence and eradicating biofilms in Mycobacterium smegmatis. By using two reciprocal experimental approaches - ΔrelMsm and ΔrelZ gene knockout mutations versus relMsm and relZ overexpression technique - we showed that both RelMsm and RelZ (p)ppGpp synthetases are plausible candidates for serving as targets for DMNP. In vitro, DMNP inhibited (p)ppGpp-synthesizing activity of purified RelMsm in a concentration-dependent manner. These findings, supplemented by molecular docking simulation, suggest that DMNP targets the structural sites shared by RelMsm, RelZ, and presumably by a few others as yet unidentified (p)ppGpp producers, thereby inhibiting persister cell formation and eradicating biofilms. Therefore, DMNP may serve as a promising lead for development of antimycobacterial drugs.

RevDate: 2021-02-23

Püning C, Su Y, Lu X, et al (2021)

Molecular Mechanisms of Campylobacter Biofilm Formation and Quorum Sensing.

Current topics in microbiology and immunology, 431:293-319.

Even though Campylobacter spp. are known to be fastidious organisms, they can survive within the natural environment. One mechanism to withstand unfavourable conditions is the formation of biofilms, a multicellular structure composed of different bacterial and other microbial species which are embedded in an extracellular matrix. High oxygen levels, low substrate concentrations and the presence of external DNA stimulate the biofilm formation by C. jejuni. These external factors trigger internal adaptation processes, e.g. via regulating the expression of genes encoding proteins required for surface structure formation, as well as motility, stress response and antimicrobial resistance. Known genes impacting biofilm formation will be summarized in this review. The formation of biofilms as well as the expression of virulence genes is often regulated in a cell density depending manner by quorum sensing, which is mediated via small signalling molecules termed autoinducers. Even though quorum sensing mechanisms of other bacteria are well understood, knowledge on the role of these mechanisms in C. jejuni biofilm formation is still scarce. The LuxS enzyme involved in generation of autoinducer-2 is present in C. jejuni, but autoinducer receptors have not been identified so far. Phenotypes of C. jejuni strains lacking a functional luxS like reduced growth, motility, oxygen stress tolerance, biofilm formation, adhesion, invasion and colonization are also summarized within this chapter. However, these phenotypes are highly variable in distinct C. jejuni strains and depend on the culture conditions applied.

RevDate: 2021-02-23

Harada AMM, MS Nascimento (2021)

Effect of dry sanitizing methods on Bacillus cereus biofilm.

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

Bacillus cereus is a relevant foodborne pathogen and biofilm producer which can contaminate and persist in the processing environment of both high and low water activity foods. Because of this, it is crucial to understand better the resistance of this pathogen biofilm to different sanitation methods. The aim of this study was to evaluate the efficacy of dry sanitizing treatments against B. cereus biofilm formed on stainless steel (SS) and polypropylene (PP). Biofilm formation was held through the static method at 25 °C. After 4 days of incubation, coupons were exposed for up to 30 min to UV-C light, dry heat, gaseous ozone, 70% ethanol, and a commercial sanitizer. Sodium hypochlorite (200 mg/l) was also tested in two different pH values (7 and 11) for comparison purposes. In general, the surface material did not influence (p > 0.05) the performance of the treatments. From 10 min of exposure, 70% ethanol and the commercial product caused the lowest reductions on both surfaces. In addition, dry heat exhibited a poor performance on PP, with reductions < 1 log CFU/cm2. UV-C light on SS and PP and ozone on PP achieved reductions around 2 log CFU/cm2 after 30 min. The same level of reduction was obtained after 5 or 10 min using sodium hypochlorite (200 mg/l). Therefore, the results showed that dry sanitizing methods are not as effective as sodium hypochlorite against B. cereus biofilms. Further studies to evaluate the efficacy of the combination of dry methods are necessary.

RevDate: 2021-02-23

Villa-García LD, Márquez-Preciado R, Ortiz-Magdaleno M, et al (2021)

Antimicrobial effect of gold nanoparticles in the formation of the Staphylococcus aureus biofilm on a polyethylene surface.

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

The main of this study was to evaluate the inhibitory effect on the in vitro formation of the Staphylococcus aureus biofilm formed on a polyethylene (PE) surface with a nanostructured Gold (Au) coating for medical devices. An experimental in vitro study was carried out using PE discs with an Au nanoparticle coating (AuNPs) on one side (experimental group) and without coating on the other (control group); the discs were mounted in the CDC biofilm reactor adding broth of yeast-dextrose-peptone (YPD) sterile culture inoculated with S. aureus in a cell suspension (5 × 108 cells/ml). The specimens were evaluated at different times (6, 12, 24, 48, 72 h) and stained with the Live/Dead Bacterial Viability Kit (Invitrogen) for observation, analysis, and quantification with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The results showed that as evaluation time passed an increasing of S. aureus biofilm formation was observed in the control group, in the experimental group, a statistically significant biofilm inhibition was observed with respect to the AuNPs uncoated specimens (p ≤ 0.05) and showed a ratio of almost 4:1 viable/nonviable in the biofilm of the uncoated surfaces, with a difference > 5 Log10 in the CFU counts. The PE with AuNP coating showed an inhibitory effect on the biofilm formation of S. aureus.

RevDate: 2021-02-23

Kniha K, Heussen N, Modabber A, et al (2021)

The effect of zirconia and titanium surfaces on biofilm formation and on host-derived immunological parameters.

International journal of oral and maxillofacial surgery pii:S0901-5027(21)00040-0 [Epub ahead of print].

The aim of this study was to analyse the effect of zirconia and titanium surfaces on biofilm formation and host-derived parameters. Studies comparing zirconia and titanium surfaces were selected up to September 1, 2019. The outcome measures were surface roughness, contact angle, bacterial count, bacterial adherence, biofilm thickness, bacterial distribution, and specifically investigated biofilm and specific host-derived immunological parameters. Random-effects meta-analyses of in vitro and in vivo studies were conducted. A total of 39 studies were included for data extraction. In the systematic review data, 10 studies stated that zirconia accumulated less initial oral biofilm parameters, 16 investigations showed negligible inter-material differences, and only one study showed that zirconia attracted the most biofilm. However, in the meta-analysis, the bacterial coverage was found to be significantly superior for zirconia surfaces (P< 0.00001); the other outcome measures did not show any statistically significant differences between zirconia and titanium for the remaining parameters and the studies presented a substantial degree of heterogeneity. Overall, on the basis of the meta-analysis, the current data situation does not allow a clear preference for the use of zirconia or titanium.

RevDate: 2021-02-23

Li P, Gao Z, Tan Z, et al (2021)

New developments in anti-biofilm intervention towards effective management of orthopedic device related infections (ODRI's).

Biofouling [Epub ahead of print].

Orthopedic device related infections (ODRI's) represent a difficult to treat situation owing to their biofilm based nature. Biofilm infections once established are difficult to eradicate even with an aggressive treatment regimen due to their recalcitrance towards antibiotics and immune attack. The involvement of antibiotic resistant pathogens as the etiological agent further worsens the overall clinical picture, pressing on the need to look into alternative treatment strategies. The present review highlightes the microbiological challenges associated with treatment of ODRI's due to biofilm formation on the implant surface. Further, it details the newer anti-infective modalities that work either by preventing biofilm formation and/or through effective disruption of the mature biofilms formed on the medical implant. The study, therefore aims to provide a comprehensive insight into the newer anti-biofilm interventions (non-antibiotic approaches) and a better understanding of their mechanism of action essential for improved management of orthopedic implant infections.

RevDate: 2021-02-22

Scarabotti F, Rago L, Bühler K, et al (2021)

The electrode potential determines the yield coefficients of early-stage Geobacter sulfurreducens biofilm anodes.

Bioelectrochemistry (Amsterdam, Netherlands), 140:107752 pii:S1567-5394(21)00015-3 [Epub ahead of print].

Geobacter sulfurreducens is the model for electroactive microorganisms (EAM). EAM can use solid state terminal electron acceptors (TEA) including anodes via extracellular electron transfer (EET). Yield coefficients relate the produced cell number or biomass to the oxidized substrate or the reduced TEA. These data are not yet sufficiently available for EAM growing at anodes. Thus, this study provides information about kinetics as well as yield coefficients of early-stage G. sulfurreducens biofilms using anodes as TEA at the potentials of -200 mV, 0 mV and +200 mV (vs. Ag/AgCl sat. KCl). The selected microorganism was therefore cultivated in single and double chamber batch reactors on graphite or AuPd anodes. Interestingly, whereas the lag time and maximum current density within 12 days of growth differed, the anode potential does not influence the coulombic efficiency and the formal potential of the EET, which remains constant for all the experiments at ~ -300 to -350 mV. We demonstrated for the first time that the anode potential has a strong influence on single cell yield coefficients which ranged from 2.69 × 1012 cells mole--1 at -200 mV and 1.48 × 1012 cells mole--1 at 0 mV to 2.58 × 1011 cells mole--1 at +200 mV in single chamber reactors and from 1.15 × 1012 cells mole--1 at -200 mV to 8.98× 1011 cells mole--1 at 0 mV in double chamber reactors. This data can be useful for optimization and scaling-up of primary microbial electrochemical technologies.

RevDate: 2021-02-22

Pu Y, Pan J, Yao Y, et al (2021)

Ecotoxicological effects of erythromycin on a multispecies biofilm model, revealed by metagenomic and metabolomic approaches.

Environmental pollution (Barking, Essex : 1987), 276:116737 pii:S0269-7491(21)00317-1 [Epub ahead of print].

The presence of antibiotics such as erythromycin, even in trace amounts, has long been acknowledged for negatively impacting ecosystems in freshwater environments. Although many studies have focused on the impact of antibiotic pollution at a macroecological level, the impact of erythromycin on microecosystems, such as freshwater biofilms, is still not fully understood. This knowledge gap may be attributed to the lack of robust multispecies biofilm models for fundamental investigations. Here, we used a lab-cultured multispecies biofilm model to elucidate the holistic response of a microbial community to erythromycin exposure using metagenomic and metabolomic approaches. Metagenomic analyses revealed that biofilm microbial diversity did not alter following erythromycin exposure. Notably, certain predicted metabolic pathways such as cell-cell communication pathways, amino acid metabolism, and peptidoglycan biosynthesis, mainly by the phyla Actinobacteria, Alpha/Beta-proteobacteria, Bacteroidetes, and Verrucomicrobia, were found to be involved in the maintenance of homeostasis-like balance in the freshwater biofilm. Further untargeted metabolomics data highlighted changes in lipid metabolism and linoleic acid metabolism and their related molecules as a direct consequence of erythromycin exposure. Overall, the study presented a unique picture of how multispecies biofilms respond to single environmental stress exposures. Moreover, the study demonstrated the feasibility of using lab simulated multispecies biofilms for investigating their interaction and reactivity of specific bioactive compounds or pollutants at a fundamental level.

RevDate: 2021-02-22

Mea HJ, Yong PVC, EH Wong (2021)

An overview of Acinetobacter baumannii pathogenesis: Motility, adherence and biofilm formation.

Microbiological research, 247:126722 pii:S0944-5013(21)00028-8 [Epub ahead of print].

The Gram-negative opportunistic pathogen Acinetobacter baumannii has gain notoriety in recent decades, primarily due to its propensity to cause nosocomial infections in critically ill patients. Its global spread, multi-drug resistance features and plethora of virulence factors make it a serious threat to public health worldwide. Though much effort has been expended in uncovering its successes, it continues to confound researchers due to its highly adaptive nature, mutating to meet the needs of a given environment. Its persistence in the clinical setting allows it to be in close proximity to a potential host, where contact can be made facilitating infection and colonization. In this article, we aim to provide a current overview of the bacterial virulence factors, specifically focusing on factors involved in the initial stages of infection, highlighting the role of adaptation facilitated by two-component systems and biofilm formation. Finally, the study of host-pathogen interactions using available animal models, their suitability, notable findings and some perspectives moving forward are also discussed.

RevDate: 2021-02-22

Tao R, Zheng X, Guo X, et al (2021)

Pilot-scale enrichment of anammox biofilm using secondary effluent as source water.

Water science and technology : a journal of the International Association on Water Pollution Research, 83(4):894-905.

Enough biomass of anaerobic ammonium oxidation (anammox) bacteria is essential for maintaining a stable partial nitrification/anammox (PN/A) wastewater treatment system. Present enrichment procedures are mainly labor-intensive and inconvenient for up-scaling. A simplified procedure was developed for enrichment of anammox biofilm by using secondary effluent as source water with no supplement of mineral medium and unstrict control of influent dissolved oxygen (DO). Anammox biofilm was successfully enriched in two pilot-scale reactors (XQ-cul and BT-cul) within 250 and 120 days, respectively. The specific anammox activity increased rapidly during the last 2 months in both reactors and achieved 2.54 g N2-N/(m2·d) in XQ-cul and 1.61 g N2-N/(m2·d) in BT-cul. Similar microbial diversity and community structure were obtained in the two reactors despite different secondary effluent being applied from two wastewater treatment plants. Anaerobic ammonium oxidizing bacteria genera abundance reached up to 37.4% and 43.1% in XQ-cul and BT-cul biofilm, respectively. Candidatus Brocadia and Ca. Kuenenia dominated the enriched biofilm. A negligible adverse effect of residual organics and influent DO was observed by using secondary effluent as source water. This anammox biofilm enrichment procedure could facilitate the inoculation and/or bio-augmentation of large-scale mainstream PN/A reactors.

RevDate: 2021-02-22

Zhang Y, Ge H, Lin W, et al (2021)

Effect of different disinfection treatments on the adhesion and separation of biofilm on stainless steel surface.

Water science and technology : a journal of the International Association on Water Pollution Research, 83(4):877-885.

Attachment and separation of sulfate-reducing bacteria (SRB) biofilm on stainless steel (SS) in simulated cooling water with and without different sterilization treatments was investigated by calculation of surface energy, theoretical work of adhesion and analysis of Scanning Electron Microscope/Energy Dispersive Spectrometer. Two types of biocides, glutaraldehyde and Polyhexamethylene guanidine (PHMG), and electromagnetic treatment were used in this paper. The results show that PHMG had the best bactericidal performance, followed by glutaraldehyde, and electromagnetic treatment was the lowest one. The theoretical work of adhesion was used to quantitatively evaluate the adhesion of biofilm on the surface of the metal. Theoretical work of adhesion between biofilm and SS in simulated cooling water increased with time. The theoretical adhesion work and adhesive capacity of biofilm to SS surface increased after treating with glutaraldehyde while decreasing after treating with PHMG and electromagnetic field. As the theoretical adhesion work decreased, the biofilm was gradually removed from the stainless steel surface. On the contrary, the biofilm adhered more firmly. The results of SEM were also consistent with the calculation results of theoretical adhesion work. The results obtained indicated that electromagnetic treatment had the lowest effect in sterilization but the best in biofilm separation.

RevDate: 2021-02-22

Su C, Ye Y, Qiu H, et al (2021)

Solvent-Free Fabrication of Self-Regenerating Antibacterial Surfaces Resisting Biofilm Formation.

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

Biofilm formation on indwelling medical devices is a major cause of hospital-acquired infections. Monofunctional antibacterial surfaces have been developed to resist the formation of biofilms by killing bacteria on contact, but the adsorption of killed bacterial cells and debris gradually undermines the function of these surfaces. Here, we report a facile approach to produce an antibacterial surface that can regenerate its function after contamination. The self-regenerating surface was achieved by sequential deposition of alternating antibacterial and biodegradable layers of coating using a solvent-free initiated chemical vapor deposition method. As the top antibacterial layer gradually loses its killing ability due to the accumulation of debris, the underlying biodegradable layer degrades, shedding off the top surface layers and exposing another fresh antibacterial surface. Urinary catheters coated with monofunctional and self-regenerating antibacterial coatings both showed more than 99% bacterial killing ability at the initial antibacterial test, but the monofunctional surface lost its killing ability after continued exposure to concentrated bacterial solution, whereas the self-regenerating surfaces regained strong bacterial killing ability after prolonged exposure. Employing poly(methacrylic anhydride) and its copolymers with varied composition as the degrading layer, the degradation kinetics can be well-tailored and the self-regeneration duration spanned from minutes to days. The designed self-regenerating antibacterial surfaces could provide an effective approach to resist biofilm formation and extend the service life of indwelling medical devices.

RevDate: 2021-02-22

Quan K, Jiang G, Liu J, et al (2021)

Influence of interaction between surface-modified magnetic nanoparticles with infectious biofilm components in artificial channel digging and biofilm eradication by antibiotics in vitro and in vivo.

Nanoscale [Epub ahead of print].

Magnetic targeting of antimicrobial-loaded magnetic nanoparticles to micrometer-sized infectious biofilms is challenging. Bacterial biofilms possess water channels that facilitate transport of nutrient and metabolic waste products, but are insufficient to allow deep penetration of antimicrobials and bacterial killing. Artificial channel digging in infectious biofilms involves magnetically propelling nanoparticles through a biofilm to dig additional channels to enhance antimicrobial penetration. This does not require precise targeting. However, it is not known whether interaction of magnetic nanoparticles with biofilm components impacts the efficacy of antibiotics after artificial channel digging. Here, we functionalized magnetic-iron-oxide-nanoparticles (MIONPs) with polydopamine (PDA) to modify their interaction with staphylococcal pathogens and extracellular-polymeric-substances (EPS) and relate the interaction with in vitro biofilm eradication by gentamicin after magnetic channel digging. PDA-modified MIONPs had less negative zeta potentials than unmodified MIONPs due to the presence of amino groups and accordingly more interaction with negatively charged staphylococcal cell surfaces than unmodified MIONPs. Neither unmodified nor PDA-modified MIONPs interacted with EPS. Concurrently, use of non-interacting unmodified MIONPs for artificial channel digging in in vitro grown staphylococcal biofilms enhanced the efficacy of gentamicin more than the use of interacting, PDA-modified MIONPs. In vivo experiments in mice using a sub-cutaneous infection model confirmed that non-interacting, unmodified MIONPs enhanced eradication by gentamicin of Staphylococcus aureus Xen36 biofilms about 10 fold. Combined with the high biocompatibility of magnetic nanoparticles, these results form an important step in understanding the mechanism of artificial channel digging in infectious biofilms for enhancing antibiotic efficacy in hard-to-treat infectious biofilms in patients.

RevDate: 2021-02-22

de Arruda CNF, Salles MM, Oliveira VC, et al (2021)

Using denture cleansers to control biofilm from dentures and brushes: A randomized crossover clinical trial.

The International journal of prosthodontics [Epub ahead of print].

PURPOSE: To evaluate the effects of 0.2% sodium hypochlorite, Efferdent (Prestige Consumer Healthcare), and 6.25% Ricinus communis on biofilm removal and antimicrobial action on dentures and brushes using nonimmersion or immersion protocols for the brushes.

MATERIALS AND METHODS: A total of 45 denture wearers were randomly assigned to a denture immersion protocol for 7 days: 0.85% saline solution for 20 minutes (control); 0.2% sodium hypochlorite for 20 minutes (SH); Efferdent for 3 minutes; or 6.25% Ricinus communis for 20 minutes (RC). The participants were also randomized to immersion (n = 23) or no immersion (n = 22) of their brushes with their dentures in the same solutions. For biofilm evaluation, the dentures were stained and photographed, and the area of the biofilm was measured using Image Tool 3.0 (University of Texas Health Science Center). To evaluate microbial load on dentures and brushes, the biofilm was collected, and the Candida spp and Streptococcus mutans colonies were counted.

RESULTS: The SH, Efferdent, and RC groups showed reduced biofilm and Candida spp on dentures regardless of the immersion protocol for the brushes. However, no difference was found in the Candida spp counts collected from the brushes immersed compared to the brushes not immersed in the solutions. The SH and Efferdent groups showed reduced S mutans on both dentures and brushes, except for in the nonimmersion subgroups.

CONCLUSION: All solutions reduced denture biofilm and microbial load. However, immersion of brushes in the solutions did not contribute to reducing the microbial load.

RevDate: 2021-02-22

Silva BG, Oliveira JMS, Damianovic MHRZ, et al (2021)

Foam aerated biofilm reactor (FABR): a novel counter-diffusional process for COD and nitrogen removal from low COD/N effluents.

Environmental technology [Epub ahead of print].

Counter-diffusional biofilms are efficient in the removal of nitrogen from low strength wastewaters. Although counter-diffusion is usually stablished using expensive gas-permeable membranes, a polyurethane sheet is used to separate the aerobic and anoxic environments in the novel foam aerated biofilm reactor (FABR). Foam sheets with thicknesses of 10, 5 and 2 mm and synthetic wastewater with COD/N ratios of 5 and 2.5 were evaluated. The 2 mm thick foam reactor did not show good biomass adherence and, therefore, did not show N removal efficiency. The 5 and 10 mm reactors, in both COD/N ratios, showed similar total nitrogen and COD removal performance, up to 60% and 80%, respectively. The denitrification efficiency was close to100% throughout the experimental period. Nitrification efficiency decreased with microbial growth, which was recovered after removal of excessive biomass. Lower values of polyurethane foam thickness and COD/N ratio did not provide a higher nitrification rate, as expected. The increase in resistance to mass transfer was associated with the growth of biomass attached to the foam rather than to its thickness and resulted in specialization of the microbial communities as revealed by 16S amplicon sequencing. FABR reveals as a promising alternative for simultaneous removal of nitrogen and COD from low COD/N ratio wastewaters.

RevDate: 2021-02-22

Shastry RP, Ghate SD, Sukesh Kumar B, et al (2021)

Vanillin derivative inhibits quorum sensing and biofilm formation in Pseudomonas aeruginosa: a study in a Caenorhabditis elegans infection model.

Natural product research [Epub ahead of print].

Vanillin and its derivative, (4-((E)-(4-hydroxy-2-methylphenylimino) methyl)-2-methoxyphenol (MMP) were showed clear inhibition of violacein and pyocyanin at sub-MICs indicating a possible quorum quenching effect of both the compounds. MMP was able to inhibit the biofilm formation in Pseudomonas aeruginosa PAO1 at 125 μg/mL (p < 0.05), while vanillin at 250 μg/mL (p < 0.05) indicating that they act against quorum sensing regulated biofilm formation. The inhibition of biofilm was confirmed by visualization through fluorescence microscopy followed by docking analysis of molecules against quorum sensing activator proteins. Caenorhabditis elegans survival assay revealed that vanillin and MMP were able to increase survival of C. elegans from P. aeruginosa PAO1 infection. The study showed that the potent features of the MMP and vanillin in inhibiting the quorum sensing regulated virulence and biofilm, which was proved in C. elegans infection model as well as molecular docking studies.

RevDate: 2021-02-22

Kuiper JWP, Hogervorst JMA, Herpers BL, et al (2021)

The novel endolysin XZ.700 effectively treats MRSA biofilms in two biofilm models without showing toxicity on human bone cells in vitro.

Biofouling [Epub ahead of print].

In this in vitro study the effect of XZ.700, a new endolysin, on methicillin resistant Staphylococcus aureus (MRSA) biofilms grown on titanium was evaluated. Biofilms of S. aureus USA300 were grown statically and under flow, and treatment with XZ.700 was compared with povidone-iodine (PVP-I) and gentamicin. To evaluate the cytotoxic effects of XZ.700 and derived biofilm lysates, human osteocyte-like cells were exposed to biofilm supernatants, and metabolism and proliferation were quantified. XZ.700 showed a significant, concentration dependent reduction in biofilm viability, compared with carrier controls. Metabolism and proliferation of human osteocyte-like cells were not affected by XZ.700 or lysates, unlike PVP-I and gentamicin lysates which significantly inhibited proliferation. Using time-lapse microscopy, rapid biofilm killing and removal was observed for XZ.700. In comparison, PVP-I and gentamicin showed slower biofilm killing, with no apparent biofilm removal. In conclusion, XZ.700 reduced MRSA biofilms, especially under flow condition, without toxicity for surrounding bone cells.

RevDate: 2021-02-22

Ruiz A, Herráez M, Costa-Gutierrez SB, et al (2021)

The architecture of a mixed fungal-bacterial biofilm is modulated by quorum sensing signals.

Environmental microbiology [Epub ahead of print].

Interkingdom communication is of particular relevance in polymicrobial biofilms. In this work, the ability of the fungus Ophiostoma piceae to form biofilms individually and in consortium with the bacterium Pseudomonas putida, as well as the effect of fungal and bacterial signal molecules on the architecture of the biofilms was evaluated. P. putida KT2440 is able to form biofilms through the secretion of exopolysaccharides and two large extracellular adhesion proteins, LapA and LapF. It has two intercellular signalling systems, one mediated by dodecanoic acid and an orphan LuxR receptor that could participate in the response to AHL-type quorum sensing molecules (QSMs). Furthermore, the dimorphic fungus O. piceae uses farnesol as QSM to control its yeast to hyphae morphological transition. Results show for the first time the ability of this fungus to form biofilms alone and in mixed cultures with the bacterium. Biofilms were induced by bacterial and fungal QSMs. The essential role of LapA-LapF proteins in the architecture of biofilms was corroborated, LapA was induced by farnesol and dodecanol, while LapF by 3-oxo-C6-HSL and 3-oxo-C12-HSL. Our results indicate that fungal signals can induce a transient rise in the levels of the secondary messenger c-di-GMP, which control biofilm formation and architecture. This article is protected by copyright. All rights reserved.

RevDate: 2021-02-22

Rather MA, Gupta K, Bardhan P, et al (2021)

Microbial biofilm: A matter of grave concern for human health and food industry.

Journal of basic microbiology [Epub ahead of print].

Pathogenic microorganisms have adapted different strategies during the course of time to invade host defense mechanisms and overcome the effect of potent antibiotics. The formation of biofilm on both biotic and abiotic surfaces by microorganisms is one such strategy to resist and survive even in presence of antibiotics and other adverse environmental conditions. Biofilm is a safe home of microorganisms embedded within self-produced extracellular polymeric substances comprising of polysaccharides, extracellular proteins, nucleic acid, and water. It is because of this adaptation strategy that pathogenic microorganisms are taking a heavy toll on the health and life of organisms. In this review, we discuss the colonization of pathogenic microorganisms on tissues and medically implanted devices in human beings. We also focus on food spoilage, disease outbreaks, biofilm-associated deaths, burden on economy, and other major concerns of biofilm-forming pathogenic microorganisms in food industries like dairy, poultry, ready-to-eat food, meat, and aquaculture.

RevDate: 2021-02-22

Loss M, Thompson KG, Agostinho-Hunt A, et al (2020)

Noninflammatory comedones have greater diversity in microbiome and are more prone to biofilm formation than inflammatory lesions of acne vulgaris.

International journal of dermatology [Epub ahead of print].

BACKGROUND: The ability of Cutibacterium acnes strains to form biofilms has been correlated with their virulence.

OBJECTIVE: This study examined biofilm and skin microbiota in acne patients in order to understand their role in the development of acne lesions.

METHODS: Thin sections of punch biopsy specimens of (i) uninflamed comedones, (ii) inflammatory lesions, and (iii) uninvolved adjacent skin of acne patients were examined. Epiflourescence and confocal laser scanning microscopy were used for biofilm detection, and pyrosequencing with taxonomic classification of 16s rRNA gene amplicons was used for microbiota analysis.

RESULTS: Of the 39 skin specimens from patients with mild-moderate acne (n = 13) that were studied, nine (23%) contained biofilm. Among these specimens, biofilm was most frequently detected in comedones (55.6%) and less frequently in inflammatory papules (22.2%) and uninvolved skin (22.2%). Comedones demonstrated the highest mean alpha diversity of all the lesion subtypes. The relative abundance of Staphylococcus was significantly higher in comedones (11.400% ± 12.242%) compared to uninvolved skin (0.073% ± 0.185%, P = 0.024).

CONCLUSIONS: The microenvironment of the comedone differs from that of inflammatory lesions and unaffected skin. The increased frequency of biofilm in comedones may account for the lack of host inflammatory response to these lesions.

RevDate: 2021-02-21

Chen CL, Dudek A, Liang YH, et al (2021)

d-mannose-sensitive pilus of Acinetobacter baumannii is linked to biofilm formation and adherence onto respiratory tract epithelial cells.

Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi pii:S1684-1182(21)00021-9 [Epub ahead of print].

BACKGROUND/PURPOSE: Acinetobacter baumannii is an important nosocomial pathogen. To better understand the role of CsuA/BABCDE pilus of A. baumannii in virulence, bacterial biofilm formation, adherence and carbohydrate-mediated inhibition were conducted.

METHODS: CsuA/BABCDE pilus-producing (abbreviated Csu pilus) operon of A. baumannii ATCC17978 was cloned for analysis of biofilm formation on an abiotic plastic plate, bacterial adherence to respiratory epithelial human A549 cells and carbohydrate-mediated inhibition. The carbohydrates used for inhibition of biofilm formation and adherence to A549 cells included monosaccharides, pyranosides, and mannose-polymers.

RESULTS: The Csu pilus of A. baumannii ATCC17978 was cloned and expressed into a non-pilus-producing Escherichia coli JM109, and was knocked out as well. The recombinant Csu (rCsu) pilus on E. coli JM109/rCsu pilus-producing clone observed by both electro-microscopy and atomic force microscopy showed abundant, while Csu-knockout A. baumannii ATCC17978 mutant appeared less or no pilus production. The E. coli JM109/rCsu pilus-producing clone significantly increased biofilm formation and adherence to A549 cells; however, the Csu-knockout mutant dramatically lost biofilm-making ability but, in contrast, increased adherence. Moreover, both of biofilm formation and adherence could be significantly inhibited by d-mannose and methyl-α-d-mannopyranoside in Csu pilus-producing E. coli JM109, whereas in A. baumannii ATCC17978, high concentration of carbohydrates was required for the inhibition, suggesting that Csu pilus is sensitive to d-mannose.

CONCLUSION: This is the first study confirming that Csu pilus of A. baumannii belongs to mannose-sensitive type 1 pilus family and contributes to biofilm formation and bacterial adherence to human epithelial cells.

RevDate: 2021-02-20

Miao L, Gao Y, Adyel TM, et al (2021)

Effects of biofilm colonization on the sinking of microplastics in three freshwater environments.

Journal of hazardous materials, 413:125370 pii:S0304-3894(21)00333-2 [Epub ahead of print].

Microplastics (MPs) have frequently been detected in freshwater environments, and there is growing concern about their ecological effects, especially the influence of the "plastisphere" on the freshwater ecosystems. The colonization of microbes on MPs would significantly alter their transport behavior, i.e., buoyancy, in fresh water. In this research, we studied the effects of biofilm colonization on the sinking and floating of three MPs, i.e., polyethylene terephthalate (PET), polypropylene (PP), and polyvinyl chloride (PVC), after 44 days of incubation in three freshwater systems (the Niushoushan River, the Qinhuai River, and East Lake) in China. The results showed that the biofilms attached to the three MPs contained different biomass and chlorophyll-a levels were related to water environmental conditions and physicochemical properties of MPs, based on redundancy analysis. Generally, PET and PVC sinking, with density higher than water, tended to increase after biofilm formation. Thereafter, the settling velocity of biofouled PET and PVC squares became faster than that of the virgin ones. In summary, our study suggested that biofouling does affect the sinking of MPs in fresh water and consequently influences the transport behavior and the distribution characteristics of MPs in freshwater environments, and this issue deserves more scientific attention.

RevDate: 2021-02-20

Shatila F, Yaşa İ, HT Yalçın (2021)

Biofilm Formation by Salmonella enterica Strains.

Current microbiology [Epub ahead of print].

Biofilm formation by five different Salmonella enterica strains was assessed qualitatively and quantitatively under different incubation conditions. The strains exhibited different adherence abilities to test tubes. The isolates revealed Red Dry and Rough (RDAR) and Brown Dry and Rough (BDAR) morphotypes when cultured on Congo Red Agar (CRA). The pellicles formed by the tested strains ranged from strong to fragile when incubated in LB without NaCl at 27 °C. Smooth and White (SAW) morphotype on CRA and very weak pellicles were observed when the bacterial strains were incubated at 37 °C. The effect of temperature and media on biofilm formation by the tested strains was significant. Among the five Salmonella isolates, S. enteritidis TM 6 and S. enteritidis TM 68 formed strong biofilms when incubated in LB without NaCl at 27 °C for 24 h and consequently selected to be analysed under scanning electron microscope (SEM). Scanning electron micrographs revealed that S. enteritidis TM 6 formed more complex colonies when compared to those formed by S. enteritidis TM 68. As far as we know, this is the first study that provides quantitative and qualitative data for 5 Salmonella enterica isolates in different media mimicking four different nutritional conditions at two different temperatures after 24 and 48 h. The strains included two serovars S. bredeney and S. anatum, which are rarely accounted for. Additionally, the studies that described S. enteritidis biofilms under SEM are extremely limited, which makes it among the first comprehensive studies that screened for S. enteritidis biofilms.

RevDate: 2021-02-20

Zuo XS, Liu Y, Cai X, et al (2021)

Association of different Candida species with catheter-related candidemia, and the potential antifungal treatments against their adhesion properties and biofilm-forming capabilities.

Journal of clinical laboratory analysis [Epub ahead of print].

BACKGROUND: To compare the adhesion properties and biofilm-forming capabilities of 27 Candida isolates obtained from catheter-related candidemia patients and to evaluate the inhibitory effects of antifungal agents on different Candida species.

MATERIAL AND METHODS: Seven C. albicans, six C. parapsilosis, five C. guilliermondii, five C. tropicalis, and four C. glabrata clinical isolates were investigated. We quantified the adherence of these Candida species by flow cytometric method and evaluated the formation of biofilms by XTT reduction and crystal violet methods. Actions of micafungin (MF), fluconazole (FZ), and N-acetylcysteine (NAC) on the adhesion and biofilm formation of different Candida species were determined.

RESULTS: Non-albicans Candida species were demonstrated to have stronger adhesion abilities compared with C. albicans. The biofilm-forming capabilities of different Candida species were varied considerably, and the degree of biofilm formation might be affected by different assay approaches. Interestingly, C. parapsilosis displayed the highest biofilm formation abilities, while C. glabrata exhibited the lowest total biomass and metabolic activity. Furthermore, the inhibitory activities of MF, FZ, and NAC on fungal adhesion and biofilm formation were evaluated, and the results indicated that MF could reduce the adhesion ability and biofilm metabolism more significantly (p < 0.05), and its antifungal activity was elevated in a dose-dependent manner.

CONCLUSION: Non-albicans Candida species, especially C. guilliermondii, C. tropicalis, and C. parapsilosis, exhibited higher adhesion ability in catheter-related candidemia patients. However, these Candida species had varied biofilm-forming capabilities. MF tended to have stronger inhibitory effects against both adhesion and biofilm formation of different Candida species.

RevDate: 2021-02-19

Loera-Muro A, Guerrero-Barrera A, Tremblay D N Y, et al (2021)

Bacterial biofilm-derived antigens: a new strategy for vaccine development against infectious diseases.

Expert review of vaccines [Epub ahead of print].

INTRODUCTION: Microorganisms can develop into a social organization known as biofilms and these communities can be found in virtually all types of environment on earth. In biofilms, cells grow as multicellular communities held together by a self-produced extracellular matrix. Living within a biofilm allows for the emergence of specific properties for these cells that their planktonic counterparts do not have. Furthermore, biofilms are the cause of several infectious diseases and are frequently inhabited by multi-species. These interactions between microbial species are often critical for the biofilm process. Despite the importance of biofilms in disease, vaccine antigens are typically prepared from bacteria grown as planktonic cells under laboratory conditions. Vaccines based on planktonic bacteria may not provide optimal protection against biofilm-driven infections.

AREAS COVERED: In this review, we will present an overview of biofilm formation, what controls this mode of growth, and recent vaccine development targeting biofilms.

EXPERT OPINION: Previous and on-going research provides evidence that vaccine formulation with antigens derived from biofilms is a promising approach to prevent infectious diseases and can enhance the protective efficacy of existing vaccines. Therefore, research focusing on the identification of biofilm-derived antigens merits further investigations.

RevDate: 2021-02-19

Rajapakse S, Giardino MA, Kulasekara HD, et al (2020)

An Ayurvedic Herbal Extract Inhibits Streptococcus mutans Biofilm Formation and Disrupts Preformed Biofilms in vitro.

Journal of traditional medicine & clinical naturopathy, 9(4):.

Objective: Sudantha® (SUD), a natural proprietary mixture of herbal extracts that has been incorporated into toothpaste, has been shown in two separate placebo controlled human clinical studies to promote gingival health; and reduce gingival bleeding and plaque formation. However, the herbal based anti-gingivitis mechanisms of Sudantha are not fully understood. The objective of this study was to determine the effect of Sudantha on dental plaque biofilms by investigating its effect on mono-culture biofilms of a primary colonizer, Streptococcus mutans, in vitro.

Results: This study found that SUD contributes to the maintenance of oral health through the inhibition of S. mutans biofilm formation. In addition, SUD disrupted preformed S. mutans biofilms after exposure to SUD for 4 hours. Together, this pilot data suggests the inhibition of S. mutans biofilm formation and disruption represents one potential mechanism by which the herbal extract is able to reduce the oral bacterial biofilm resulting in its effective against gingivitis and its potential use in countering biofilm associated oral disease.

RevDate: 2021-02-19

Rostamifar S, Azad A, Bazrafkan A, et al (2021)

New Strategy of Reducing Biofilm Forming Bacteria in Oral Cavity by Bismuth Nanoparticles.

BioMed research international, 2021:6695692.

Objective: Enterococcus faecalis and Streptococcus salivarius are the most important species in dental decay and producing biofilm. Treatment with chlorhexidine 2% mouthwash for 7 days is the best way to eliminate these bacteria. However, due to the ability of these bacteria to survive in harsh environments, increasing emergence of bacterial resistance against available antibiotics, and favorable properties of nanoparticles including broad spectrum antimicrobial activity and lower toxicity, we decided to evaluate reducing biofilm forming bacteria in oral cavity by bismuth nanoparticles.

Materials and Methods: This was a cross-sectional study of 40 samples isolated from the patients visiting dental clinics in Shiraz in 2019. Samples, which showed growth, were cultured on blood agar plates and incubated for the PCR procedure. Nanoparticle powder was dissolved in high-purity water, and the final concentration of bismuth nanoparticles (BiNPs) was measured with a spectrophotometer. Minimum inhibitory concentration (MIC) of BiNPs against E. faecalis and S. salivarius was determined by the microbroth dilution method according to methods for antimicrobial susceptibility tests. Also, bactericidal assays were conducted in a Mueller-Hinton broth medium and reported as the concentration of BiNPs that reduced the viable bacterial count by 99.9%. Statistical analysis was carried out using SPSS 21 and one-way analysis of variance, and P values less than 0.05 were considered significant.

Results: MICs of BiNP suspension against Streptococcus salivarius and Enterococcus faecalis were 2.5 and 5 μg/ml, respectively. Minimum bactericidal concentrations (MBC) of BiNP suspension against Streptococcus salivarius and Enterococcus faecalis were 5 and 10 μg/ml, respectively. Antibacterial activity of BiNPs was compared with chlorhexidine 2%. MICs of BiNPs against Streptococcus salivarius and Enterococcus faecalis were one-twentieth less than those of chlorhexidine. MBC of BiNPs against both pathogens was one-tenth less than those of chlorhexidine.

Conclusion: BiNPs were more effective than chlorhexidine, and MIC and MBC of bismuth nanoparticles are lower than those of chlorhexidine.

RevDate: 2021-02-19

Harrell JE, Hahn MM, D'Souza SJ, et al (2020)

Salmonella Biofilm Formation, Chronic Infection, and Immunity Within the Intestine and Hepatobiliary Tract.

Frontiers in cellular and infection microbiology, 10:624622.

Within the species of Salmonella enterica, there is significant diversity represented among the numerous subspecies and serovars. Collectively, these account for microbes with variable host ranges, from common plant and animal colonizers to extremely pathogenic and human-specific serovars. Despite these differences, many Salmonella species find commonality in the ability to form biofilms and the ability to cause acute, latent, or chronic disease. The exact outcome of infection depends on many factors such as the growth state of Salmonella, the environmental conditions encountered at the time of infection, as well as the infected host and immune response elicited. Here, we review the numerous biofilm lifestyles of Salmonella (on biotic and abiotic surfaces) and how the production of extracellular polymeric substances not only enhances long-term persistence outside the host but also is an essential function in chronic human infections. Furthermore, careful consideration is made for the events during initial infection that allow for gut transcytosis which, in conjunction with host immune functions, often determine the progression of disease. Both typhoidal and non-typhoidal salmonellae can cause chronic and/or secondary infections, thus the adaptive immune responses to both types of bacteria are discussed with particular attention to the differences between Salmonella Typhi, Salmonella Typhimurium, and invasive non-typhoidal Salmonella that can result in differential immune responses. Finally, while strides have been made in our understanding of immunity to Salmonella in the lymphoid organs, fewer definitive studies exist for intestinal and hepatobiliary immunity. By examining our current knowledge and what remains to be determined, we provide insight into new directions in the field of Salmonella immunity, particularly as it relates to chronic infection.

RevDate: 2021-02-18

Nishiuchi Y (2021)

Ultrastructure of the Mycobacterium avium subsp. hominissuis Biofilm.

Microbes and environments, 36(1):.

Mycobacterium avium subsp. hominissuis (MAH) is one of the most common nontuberculous mycobacterial pathogens responsible for chronic lung disease in humans. It is widely distributed in biofilms in natural and living environments. It is considered to be transmitted from the environment. Despite its importance in public health, the ultrastructure of the MAH biofilm remains largely unknown. The ultrastructure of a MAH-containing multispecies biofilm that formed naturally in a bathtub inlet was herein reported along with those of monoculture biofilms developed from microcolonies and pellicles formed in the laboratory. Scanning electron microscopy revealed an essentially multilayered bathtub biofilm that was packed with cocci and short and long rods connected by an extracellular matrix (ECM). Scattered mycobacterium-like rod-shaped cells were observed around biofilm chunks. The MAH monoculture biofilms that developed from microcolonies in vitro exhibited an assembly of flat layers covered with thin film-like ECM membranes. Numerous small bacterial cells (0.76±0.19‍ ‍μm in length) were observed, but not embedded in ECM. A glycopeptidolipid-deficient strain did not develop the layered ECM membrane architecture, suggesting its essential role in the development of biofilms. The pellicle biofilm also consisted of flat layered cells covered with an ECM membrane and small cells. MAH alone generated a flat layered biofilm covered with an ECM membrane. This unique structure may be suitable for resistance to water flow and disinfectants and the exclusion of fast-growing competitors, and small cells in biofilms may contribute to the formation and transmission of bioaerosols.

RevDate: 2021-02-18

Dier-Pereira AP, Trevizani Thihara IR, Duarte FC, et al (2021)

Methicillin-Resistant Staphylococcus haemolyticus Displaying Reduced Susceptibility to Vancomycin and High Biofilm-Forming Ability.

Infectious disorders drug targets pii:IDDT-EPUB-114308 [Epub ahead of print].

BACKGROUND: Staphylococcus haemolyticus is one of the most frequently coagulase-negative staphylococci isolated from healthcare-associated infections, mainly those related to implanted medical devices.

OBJECTIVES: This study aimed to determine the antimicrobial susceptibility profile and biofilm forming capacity of S. haemolyticus isolated from bloodstream infections.

METHODS: A total of 40 S. haemolyticus isolates were characterized according to their genetic relatedness by repetitive element sequence based-PCR (REP-PCR), antimicrobial susceptibility profile, SCCmec typing, ability to form biofilm on abiotic surface and occurrence of putative genes related to biofilm formation.

RESULTS: One S. haemolyticus was susceptible to all antimicrobials. The other isolates (n=39) were resistant to cefoxitin; and among them 34 (87.2%) harbored the mecA gene into the SCCmec type I (5.9%), type III (29.4%), type IV (5.9%) and type V (20.6%); and 38.2% isolates were designated as NT. Apart from cefoxitin, 94.9% of the isolates were resistant to at least four antimicrobial classes, and 32.5% displayed minimal inhibitory concentration (MIC) values higher than 4.0 µg/mL for vancomycin. All isolates formed biofilm on polystyrene surface and were classified as strong biofilm-producers, except for one isolate. All isolates were negative for icaA gene, and the prevalence of the other genes was as follows: atl, 100%; fbp, 92.5%; aap, 90.0%; and bap, 20.0%.

CONCLUSION: This study reports a high prevalence of methicillin-resistant S. haemolyticus displaying decreased susceptibility to vancomycin with the ability to form strong biofilms on abiotic surface. The results support the importance of controlling the adequate use of antimicrobials for the treatment of staphylococcal infections.

RevDate: 2021-02-17

Moghaddam-Taaheri P, Leissa JA, Eppler HB, et al (2021)

Histatin 5 variant reduces Candida albicans biofilm viability and inhibits biofilm formation.

Fungal genetics and biology : FG & B pii:S1087-1845(21)00013-X [Epub ahead of print].

Candida albicans is a commensal organism and opportunistic pathogen that can form biofilms that colonize surfaces such as implants, catheters, and dentures. Compared to planktonic C. albicans cells, cells in biofilms exhibit increased resistance to treatment. Histatin 5 (Hst-5) is an antimicrobial peptide that is natively secreted by human salivary glands and has strong antifungal activity against C. albicans. However, C. albicans produce secreted aspartic proteases (Saps) that can cleave and inactivate Hst-5, limiting its antifungal properties. We previously showed that residue substitutions K11R and K17R within Hst-5 improve its antifungal activity and prevent proteolytic degradation by Saps when treating planktonic C. albicans. We investigated the use of the K11R-K17R peptide as an alternative therapeutic against C. albicans biofilms by assessing its ability to reduce viability of pre-formed biofilms and to inhibit the formation of biofilms and showed that K11R-K17R had improved activity compared to Hst-5. Based on these results, we incorporated K11R-K17R and Hst-5 into polyelectrolyte multilayer (PEM) surface coatings and demonstrated that films functionalized with K11R-K17R reduced the formation of C. albicans biofilms. Our results demonstrate the therapeutic potential of the K11R-K17R Hst-5 variant in preventing and treating biofilms.

RevDate: 2021-02-17

Arjes HA, Willis L, Gui H, et al (2021)

Three-dimensional biofilm colony growth supports a mutualism involving matrix and nutrient sharing.

eLife, 10: pii:64145 [Epub ahead of print].

Life in a three-dimensional biofilm is typical for many bacteria, yet little is known about how strains interact in this context. Here, we created essential-gene CRISPRi knockdown libraries in biofilm-forming Bacillus subtilis and measured competitive fitness during colony co-culture with wild type. Partial knockdown of some translation-related genes reduced growth rates and led to out-competition. Media composition led some knockdowns to compete differentially as biofilm versus non-biofilm colonies. Cells depleted for the alanine racemase AlrA died in monoculture but survived in a biofilm-colony co-culture via nutrient sharing. Rescue was enhanced in biofilm-colony co-culture with a matrix-deficient parent, due to a mutualism involving nutrient and matrix sharing. We identified several examples of mutualism involving matrix sharing that occurred in three-dimensional biofilm colonies but not when cultured in two dimensions. Thus, growth in a three-dimensional colony can promote genetic diversity through sharing of secreted factors and may drive evolution of mutualistic behavior.

RevDate: 2021-02-17

Kowalski CH, Morelli KA, Stajich JE, et al (2021)

A Heterogeneously Expressed Gene Family Modulates the Biofilm Architecture and Hypoxic Growth of Aspergillus fumigatus.

mBio, 12(1):.

The genus Aspergillus encompasses human pathogens such as Aspergillus fumigatus and industrial powerhouses such as Aspergillus niger In both cases, Aspergillus biofilms have consequences for infection outcomes and yields of economically important products. However, the molecular components influencing filamentous fungal biofilm development, structure, and function remain ill defined. Macroscopic colony morphology is an indicator of underlying biofilm architecture and fungal physiology. A hypoxia-locked colony morphotype of A. fumigatus has abundant colony furrows that coincide with a reduction in vertically oriented hyphae within biofilms and increased low oxygen growth and virulence. Investigation of this morphotype has led to the identification of the causative gene, biofilm architecture factor A (bafA), a small cryptic open reading frame within a subtelomeric gene cluster. BafA is sufficient to induce the hypoxia-locked colony morphology and biofilm architecture in A. fumigatus Analysis across a large population of A. fumigatus isolates identified a larger family of baf genes, all of which have the capacity to modulate hyphal architecture, biofilm development, and hypoxic growth. Furthermore, introduction of A. fumigatusbafA into A. niger is sufficient to generate the hypoxia-locked colony morphology, biofilm architecture, and increased hypoxic growth. Together, these data indicate the potential broad impacts of this previously uncharacterized family of small genes to modulate biofilm architecture and function in clinical and industrial settings.IMPORTANCE The manipulation of microbial biofilms in industrial and clinical applications remains a difficult task. The problem is particularly acute with regard to filamentous fungal biofilms for which molecular mechanisms of biofilm formation, maintenance, and function are only just being elucidated. Here, we describe a family of small genes heterogeneously expressed across Aspergillus fumigatus strains that are capable of modifying colony biofilm morphology and microscopic hyphal architecture. Specifically, these genes are implicated in the formation of a hypoxia-locked colony morphotype that is associated with increased virulence of A. fumigatus Synthetic introduction of these gene family members, here referred to as biofilm architecture factors, in both A. fumigatus and A. niger additionally modulates low oxygen growth and surface adherence. Thus, these genes are candidates for genetic manipulation of biofilm development in aspergilli.


ESP Quick Facts

ESP Origins

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

ESP Support

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

ESP Rationale

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

ESP Goal

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

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.


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

Electronic Scholarly Publishing
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E-mail: RJR8222 @

Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )