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Bibliography on: Biofilm

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ESP: PubMed Auto Bibliography 21 Sep 2018 at 01:32 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 pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2018-09-20

Beshiru A, Igbinosa IH, EO Igbinosa (2018)

Biofilm formation and potential virulence factors of Salmonella strains isolated from ready-to-eat shrimps.

PloS one, 13(9):e0204345 pii:PONE-D-18-11307.

Salmonella species is an important foodborne pathogen with the non-typhoidal serovars such as Enteritidis and Typhimurium as the most predominant strains. This study examines the biofilm formation, phenotypic virulence factors and cell surface characteristics of Salmonella strains from ready-to-eat shrimps. The ready-to-eat shrimps were obtained from open markets between November 2016 and October 2017 in Edo and Delta States, Nigeria. The occurrence of Salmonella strains in this study was 210/1440 (14.58%) of the ready-to-eat shrimp's samples. The identified strains comprise of Salmonella Enteritidis 11, Salmonella Typhimurium 14 and other Salmonella spp. 20. The 45 identified Salmonella strains revealed the following virulence properties: swimming and swarming motility 45(100%); S-layer 39(86.67%); haemolytic activity 40(88.89%); lipase activity 43(95.56%); protease activity 43(95.56%); gelatinase production 43(95.56%); and DNA degrading activity 41(91.11%). The variation in the formation of biofilm-based on the diversity of Salmonella species was observed with higher percentage of Salmonella Typhimurium strains as strong biofilms producers under different environmental conditions. For surface hydrophobicity using bacterial adherence to hydrocarbons, 25(55.56%) were hydrophilic while 20(44.44%) were moderately hydrophobic from the 45 Salmonella isolates. Using salting aggregation test for surface hydrophobicity, all selected isolates 45(100%) was hydrophilic. Autoaggregation index for the 12 selected Salmonella isolates ranged from 15.2-47.2%, while the autoaggragation index for the 12 selected test bacteria ranged from 26.2-71.3%. Coaggragation between the 12 selected test bacteria and 12 Salmonella isolates ranged from 12.5-81.0%. The occurrence of pathogenic species of Salmonella from ready-to-eat shrimps could be detrimental to the consumers. Findings on the physiological conditions of biofilms formed by the foodborne pathogenic Salmonella and the cell surface characteristics therein are crucial for the advancement of methods for controlling Salmonella from ready-to-eat foods.

RevDate: 2018-09-20

Martins DP, Leetanasaksakul K, Barros MT, et al (2018)

Molecular Communications Pulse-based Jamming Model for Bacterial Biofilm Suppression.

IEEE transactions on nanobioscience [Epub ahead of print].

Studies have recently shown that the bacteria survivability within biofilms is responsible for the emergence of superbugs. The combat of bacterial infections, without enhancing its resistance to antibiotics, includes the use of nanoparticles to quench the quorum sensing of these biofilm-forming bacteria. Several sequential and parallel multi-stage communication processes are involved in the formation of biofilms. In this paper, we use proteomic data from a wet lab experiment to identify the communication channels that are vital to these processes.We also identified the main proteins from each channel and propose the use of jamming signals from synthetically engineered bacteria to suppress the production of those proteins. This biocompatible technique is based on synthetic biology and enables the inhibition of biofilm formation. We analyse the communications performance of the jamming process, by evaluating the path loss for a number of conditions that include different engineered bacterial population sizes, distances between the populations and molecular signal power. Our results show that sufficient molecular pulsebased jamming signals are able to prevent the biofilm formation by creating lossy communications channels (almost -3 dB for certain scenarios). From these results, we define the main design parameters to develop a fully operational bacteria-based jamming system.

RevDate: 2018-09-20

Schmidt JC, Astasov-Frauenhoffer M, Waltimo T, et al (2018)

Influence of the amplitude of different side-to-side toothbrushes on noncontact biofilm removal.

Clinical oral investigations pii:10.1007/s00784-018-2633-5 [Epub ahead of print].

OBJECTIVES: To investigate the impact of the lateral deflection of toothbrush bristles (amplitude) of three side-to-side toothbrushes for noncontact biofilm removal in an artificial interdental space model.

MATERIALS AND METHODS: A three-species biofilm (Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus sanguinis) was formed in vitro on protein-coated titanium disks. A flow chamber system was combined with a static biofilm growth model. The amplitudes of three commercial side-to-side toothbrushes were evaluated by means of a dose response analysis. The amplitudes were decreased in steps (100%, 85%, 70%, 55%, and 40%). Subsequently, the biofilm-coated substrates were exposed to the toothbrushes. The biofilms were analyzed with confocal laser scanning microscope images and measured using volumetric analyses.

RESULTS: The predictability of interdental biofilm reduction differed among the toothbrushes. A lower variety in the results of repeated experiments occurred in toothbrush C compared to toothbrushes A and B. Toothbrush C obtained highest percentage of biofilm reduction by 85% of amplitude power setting (median biofilm reduction 76%). Decreasing the amplitude from 85 to 40% resulted in reduced biofilm reduction (p = 0.029). In contrast, no significance could be observed for the differences of the tested amplitudes within toothbrushes A and B (p > 0.05). Between the toothbrushes, a significant difference in interdental biofilm reduction was found between C-A (p = 0.029) and C-B (p = 0.029) with amplitude of 85%.

CONCLUSIONS: The amplitude of one of the investigated side-to-side toothbrushes affected the biofilm reduction predictably in an interdental space model.

CLINICAL RELEVANCE: Within certain toothbrushes, a specific amplitude power setting may demonstrate beneficial effects on noncontact biofilm removal.

RevDate: 2018-09-20

Chan WT, Domenech M, Moreno-Córdoba I, et al (2018)

The Streptococcus pneumoniaeyefM-yoeB and relBE Toxin-Antitoxin Operons Participate in Oxidative Stress and Biofilm Formation.

Toxins, 10(9): pii:toxins10090378.

Type II (proteic) toxin-antitoxin systems (TAs) are widely distributed among bacteria and archaea. They are generally organized as operons integrated by two genes, the first encoding the antitoxin that binds to its cognate toxin to generate a harmless protein⁻protein complex. Under stress conditions, the unstable antitoxin is degraded by host proteases, releasing the toxin to achieve its toxic effect. In the Gram-positive pathogen Streptococcus pneumoniae we have characterized four TAs: pezAT, relBE, yefM-yoeB, and phD-doc, although the latter is missing in strain R6. We have assessed the role of the two yefM-yoeB and relBE systems encoded by S. pneumoniae R6 by construction of isogenic strains lacking one or two of the operons, and by complementation assays. We have analyzed the phenotypes of the wild type and mutants in terms of cell growth, response to environmental stress, and ability to generate biofilms. Compared to the wild-type, the mutants exhibited lower resistance to oxidative stress. Further, strains deleted in yefM-yoeB and the double mutant lacking yefM-yoeB and relBE exhibited a significant reduction in their ability for biofilm formation. Complementation assays showed that defective phenotypes were restored to wild type levels. We conclude that these two loci may play a relevant role in these aspects of the S. pneumoniae lifestyle and contribute to the bacterial colonization of new niches.

RevDate: 2018-09-19

Azmy M, Nawar N, Mohiedden M, et al (2016)


Journal of the Egyptian Society of Parasitology, 46(3):475-484.

Biofilm formation on indwelling urinary catheters is a leading cause of Urinary tract infection (UTI). Presence of biofilm is associated with increased bacterial resistance to antimicrobial therapy and resultant treatment failure. The study detected a reliable method for diagnosis of biofilm formation by comparing scanning electron microscopy (SEM) and tissue culture plate method (TCP). The work was conducted on 20 urinary catheters from patients ranging from 1.5 to 85 years with catheters that remained in situ for a period of 3 to 20 days. Samples of catheters for culture and SEM and samples of urine were taken at the same time. The correlation between renal conditions and biofilm formation was not significant (p=0.336). No significant correlation (p =0.836, 0.163 respectively) was found between predisposing conditions (DM, renal insufficiency, diarrhea and impaired immunity) and development of Catheter associated urinary tract infection (CAUTI)and biofilm formation. Biofilm formation increased with duration of catheter in situ, but no significant.correlation was found (p=0.095). This could be due to small number of specimens. 9/20(45%) urine samples, 12/20(60%) catheter samples were positive by culture and 14/20(70%) catheters showed biofilm on SEM. 4/12(33.33%) organisms isolated from catheter culture produced biofilm by TCP method. 9 isolates were recovered from 9 positive urine cultures. The microorganisms isolated were non Candida albicans (3/9), E. coli (2/9), C. albicans (2/9) and Acenitobacter (2/9). 14 isolates were recovered from 12 culture- positive catheters. The organisms isolated were E.- coli (3/14), non-Candida albicans (3/14), C. albicans (2/14), C tropicalis (2/14), Acenitobacter (2/14), Klebsiella (1/14) and Enterococcus (1/14). Reduction in microbial diversity with antimicrobial use was noticed but the correlation was insignificant (p=0.317). The correlation between urine culture results as well as catheter culture results and biofilm formation by SEM were both significant (p = 0.008 & 0.000 respectively). The correlation between urine culture and TCP assay was insignificant (p =0.237). Using SEM as the gold standard method for the detection of biofilm, the sensitivity, specificity; total accuracy, PPV & NPV of urine culture and catheter culture were, 64.30%, 100%, 75%, 100%, 54% & 85.70%, 100%, 90%, 100%, 75% respectively.

RevDate: 2018-09-19

Abouelhassan Y, Zhang Y, Jin S, et al (2018)

Transcript Profiling of MRSA Biofilms Treated with a Halogenated Phenazine Eradicating Agent: A Platform for Defining Cellular Targets and Pathways Critical to Biofilm Survival.

Angewandte Chemie (International ed. in English) [Epub ahead of print].

Bacterial biofilms are surface-attached communities of non-replicating bacteria innately tolerant to antibiotics. Biofilms display differential gene expression profiles and physiologies compared to their planktonic counterparts; however, the biology of biofilms remains largely unknown. Here, we used a halogenated phenazine (HP) biofilm eradicator in transcript profiling experiments (RNA-seq) to define cellular targets and pathways critical to biofilm viability. A WoPPER analysis with time course validation (RT-qPCR) revealed that HP-14 induces rapid iron starvation in MRSA biofilms, as evident by the activation of iron-acquisition gene clusters (isd, sir/sbn, hts/sfa, ferrichrome ABC transporters) in 1 hour. Serine proteases and oligopeptide transporters were also found to be up-regulated while glycolysis, arginine deiminase and urease gene clusters were down-regulated. A KEGG analysis revealed that HP-14 impacts metabolic and ABC transporter functional pathways. These findings suggest that MRSA biofilm viability relies on iron homeostasis and establishes a framework to employ next-generation therapeutics to eradicate biofilms.

RevDate: 2018-09-19

Rupf S, Laczny CC, Galata V, et al (2018)

Comparison of initial oral microbiomes of young adults with and without cavitated dentin caries lesions using an in situ biofilm model.

Scientific reports, 8(1):14010 pii:10.1038/s41598-018-32361-x.

Dental caries is caused by acids released from bacterial biofilms. However, the in vivo formation of initial biofilms in relation to caries remains largely unexplored. The aim of this study was to compare the oral microbiome during the initial phase of bacterial colonization for individuals with (CC) and without (NC) cavitated dentin caries lesions. Bovine enamel slabs on acrylic splints were worn by the volunteers (CC: 14, NC: 13) for in situ biofilm formation (2 h, 4 h, 8 h, 1 ml saliva as reference). Sequencing of the V1/V2 regions of the 16S rRNA gene was performed (MiSeq). The relative abundances of individual operational taxonomic units (OTUs) were compared between samples from the CC group and the NC group. Random forests models were furthermore trained to separate the groups. While the overall heterogeneity did not differ substantially between CC and NC individuals, several individual OTUs were found to have significantly different relative abundances. For the 8 h samples, most of the significant OTUs showed higher relative abundances in the CC group, while the majority of significant OTUs in the saliva samples were more abundant in the NC group. Furthermore, using OTU signatures enabled a separation between both groups, with area-under-the-curve (AUC) values of ~0.8. In summary, the results suggest that initial oral biofilms provide the potential to differentiate between CC and NC individuals.

RevDate: 2018-09-19

Brockman KL, Azzari PN, Branstool MT, et al (2018)

Epigenetic Regulation Alters Biofilm Architecture and Composition in Multiple Clinical Isolates of Nontypeable Haemophilus influenzae.

mBio, 9(5): pii:mBio.01682-18.

Biofilms play a critical role in the colonization, persistence, and pathogenesis of many human pathogens. Multiple mucosa-associated pathogens have evolved a mechanism of rapid adaptation, termed the phasevarion, which facilitates a coordinated regulation of numerous genes throughout the bacterial genome. This epigenetic regulation occurs via phase variation of a DNA methyltransferase, Mod. The phasevarion of nontypeable Haemophilus influenzae (NTHI) significantly affects the severity of experimental otitis media and regulates several disease-related processes. However, the role of the NTHI phasevarion in biofilm formation is unclear. The present study shows that the phasevarions of multiple NTHI clinical isolates regulate in vitro biofilm formation under disease-specific microenvironmental conditions. The impact of phasevarion regulation was greatest under alkaline conditions that mimic those known to occur in the middle ear during disease. Under alkaline conditions, NTHI strains that express the ModA2 methyltransferase formed biofilms with significantly greater biomass and less distinct architecture than those formed by a ModA2-deficient population. The biofilms formed by NTHI strains that express ModA2 also contained less extracellular DNA (eDNA) and significantly less extracellular HU, a DNABII DNA-binding protein critical for biofilm structural stability. Stable biofilm structure is critical for bacterial pathogenesis and persistence in multiple experimental models of disease. These results identify a role for the phasevarion in regulation of biofilm formation, a process integral to the chronic nature of many infections. Understanding the role of the phasevarion in biofilm formation is critical to the development of prevention and treatment strategies for these chronic diseases.IMPORTANCE Upper respiratory tract infections are the number one reason for a child to visit the emergency department, and otitis media (middle ear infection) ranks third overall. Biofilms contribute significantly to the chronic nature of bacterial respiratory tract infections, including otitis media, and make these diseases particularly difficult to treat. Several mucosa-associated human pathogens utilize a mechanism of rapid adaptation termed the phasevarion, or phasevariable regulon, to resist environmental and host immune pressures. In this study, we assessed the role of the phasevarion in regulation of biofilm formation by nontypeable Haemophilus influenzae (NTHI), which causes numerous respiratory tract diseases. We found that the NTHI phasevarion regulates biofilm structure and critical biofilm matrix components under disease-specific conditions. The findings of this work could be significant in the design of improved strategies against NTHI infections, as well as diseases due to other pathogens that utilize a phasevarion.

RevDate: 2018-09-18

Capote-Bonato F, Sakita KM, de Oliveira AG, et al (2018)

In vitro interaction of Candida tropicalis biofilm formed on catheter with human cells.

Microbial pathogenesis pii:S0882-4010(18)30774-5 [Epub ahead of print].

Candida tropicalis has emerged as one of the major Candida non-C. albicans species, in terms of epidemiology and virulence. Despite its virulence, C. tropicalis pathogenic mechanism has yet not been fully defined. The current study aimed to demonstrate the interaction of mature C. tropicalis ATCC 750 biofilm formed on catheter with different human cell lines. In vitro mature (72 h) C. tropicalis biofilms were produced on small catheter fragments (SCF) and were mainly composed by blastoconidia. Then, migration of yeast cells from mature biofilm to human cell surfaces (HeLa and HUVEC) was investigated. After contact with both cell lines, the surface of SCF, containing mature C. tropicalis biofilm, exhibited predominantly the filamentous form. Meanwhile, fresh biofilm formed on human cell surfaces also revealed mainly of blastoconidia involved by extracellular matrix. Total biomass and metabolic activity from the remaining biofilm on SCF surface, after direct contact with human cells, exhibited a significant reduction. Mature C. tropicalis biofilm modified its extracellular matrix components, after contact with human cells. Thus, we described for the first time an easy and simple in vitro model with catheter, which could be a powerful tool for future studies that desires to elucidate the mechanisms involved in C. tropicalis biofilm.

RevDate: 2018-09-18

Chen XF, Yu CP, Li S, et al (2018)

Integration Host Factor is Essential for Biofilm formation, Extracellular enzyme, Zeamine Production and Virulence in Dickeya zeae.

Molecular plant-microbe interactions : MPMI [Epub ahead of print].

Dickeya zeae is a globally important pathogenic bacterium that infects a number of crops, including rice, maize, potato, and banana. Bacterial foot rot of rice caused by D. zeae is one of the most important bacterial diseases of rice in China and some Southeast Asian countries. To investigate the functions of integration host factor (IHF) in D. zeae, we generated knockout mutants of ihfA and ihfB. Phenotypic assays showed that both the ΔihfA and ΔihfB strains had greatly reduced mobility, biofilm formation, extracellular protease and pectinase activities, and toxin production compared with the wild-type strain. In addition, the mutants did not inhibit the germination of rice seeds, failed to cause soft rot in potatoes and a hypersensitive response in tobacco, and were avirulent in rice. Quantitative reverse-transcription polymerase chain reaction analysis demonstrated that IHF positively regulates the expression of zmsA, hrpN/Y, pelA/B/C, pehX, celZ, prtG, fliC, and DGC. Electrophoretic mobility shift assays further confirmed that IhfA binds to the promoter region of the diguanylate cyclase gene and alters the levels of a second bacterial messenger, c-di-GMP, to regulate the pathogenicity or other physiological functions of D. zeae. In summary, IHF is an important integrated regulator of pathogenicity in D. zeae.

RevDate: 2018-09-18

Maharjan G, Khadka P, Siddhi Shilpakar G, et al (2018)

Catheter-Associated Urinary Tract Infection and Obstinate Biofilm Producers.

The Canadian journal of infectious diseases & medical microbiology = Journal canadien des maladies infectieuses et de la microbiologie medicale, 2018:7624857.

Background: Biofilms, or colonies of uropathogen growing on the surface of indwelling medical devices, can inflict obstinate or recurring infection, thought-provoking antimicrobial therapy.

Methods: This prospective analysis included 105 urine samples from catheterized patients receiving intensive care. Ensuing phenotypic identification, antibiotic sensitivity test was performed by modified Kirby-Bauer disc diffusion method following CLSI guidelines; MDR isolates were identified according to the combined guidelines of the European Centre for Disease Prevention and Control (ECDC) and the Centers for Disease Control and Prevention (CDC). Biofilm-forming uropathogens were detected by the tissue culture plate (TCA) method.

Results: The predominant uropathogen in catheter-associated UTIs (CAUTIs) was Escherichia coli 57%, followed by Klebsiella pneumonia 15%, Pseudomonas aeruginosa 12%, Staphylococcus aureus 8%, Enterobacter spp. 3%, Enterococcus faecalis, Acinetobacter spp., and Proteus mirabilis 1.5%, of which 46% isolates were biofilm producers. Prime biofilm producers were Escherichia coli 33%, followed by Klebsiella pneumoniae 30%, Pseudomonas aeruginosa 20%, Staphylococcus aureus 10%, Acinetobacter, and Enterobacter 3.33%. Multidrug resistance associated with biofilm producers were greater than biofilm nonproducers. The Gram-negative biofilm producers found 96.15%, 80.76%, 73.07%, 53.84%, 53.84%, 46.15%, 19.23%, and 11.5% resistant to amoxyclave, ceftazidime, tetracycline, gentamicin, meropenem, nitrofurantoin, amikacin, imipenem, and fosfomycin, respectively. Gram-positive biofilm producers, however, were found 100% resistant to tetracycline, cloxacillin, and amoxyclave: 66.67% resistant to ampicillin while 33.33% resistant to gentamicin, ciprofloxacin, and nitrofurantoin.

Conclusion: High antimicrobial resistance was observed in biofilm producers than non-biofilm producers. Of recommended antimicrobial therapies for CAUTIs, ampicillin and amoxicillin-clavulanate were the least active antibiotics, whereas piperacillin/tazobactam and imipenem were found as the most effectual for gram-negative biofilm producer. Likewise, amoxicillin-clavulanate and tetracycline were the least active antibiotics, whereas vancomycin, fosfomycin, piperacillin-tazobactam, and meropenem were found as the most effective antibiotic for Gram-positive biofilm producer. In the limelight, the activity fosfomycin was commendable against both Gram-positive and Gram-negative biofilm producers.

RevDate: 2018-09-18

Ramalingam K, V Lee (2018)

Biotic and abiotic substrates for enhancing Acinetobacter baumannii biofilm formation: New approach using extracellular matrix and slanted coverslip technique.

The Journal of general and applied microbiology [Epub ahead of print].

Acinetobacter baumannii has been well recognized as a problematic human pathogen and several reports has shown the incidence of multidrug and pandrug-resistant A. baumannii strains in infirmary infections. A. baumannii grows only on an air-liquid interface and does not form a contiguous biofilm. Extracellular matrices (ECM) and slanted glass coverslips are (SGC) used as biofilm substrates and biofilms have been investigated by SEM, confocal and crystal violet staining. ECM has shown enhanced biofilm formation under dynamic conditions rather than static conditions. SGC biofilm yield assay has shown higher levels of continuous layers and packed thicker biofilm formation with glass coverslip inserts, up to 1.7 to 3 times higher biofilm formation, than when compared with no glass coverslip inserts. A media immersed ECM study revealed that biofilm grown on extracellular matrixes formed thread-like pili structures, and that these structures had contact with the ECM and also showed excellent cell-to-cell interaction. In summary, A. baumannii showed higher biofilm formation capacities with ECM, while the prominent results were directly related with the biofilm formation capacity of A. baumannii. For the initial step of biofilm formation, adherence is an important factor and, consequently, strains with a comparatively high capability to adhere to extracellular matrices and slanted glass coverslips provide a new method of enhanced biofilm growth for in vitro assays. ECM can be used as a substrate for immersed biofilm formation studies and the SGC method for air-liquid interface exposed biofilm formation studies, and these substrates can provide better biofilm growth and easy handling for in vitro adherence and biofilm assays.

RevDate: 2018-09-18

Mukherjee S, Moustafa DA, Stergioula V, et al (2018)

The PqsE and RhlR proteins are an autoinducer synthase-receptor pair that control virulence and biofilm development in Pseudomonas aeruginosa.

Proceedings of the National Academy of Sciences of the United States of America pii:1814023115 [Epub ahead of print].

Pseudomonas aeruginosa is a leading cause of life-threatening nosocomial infections. Many virulence factors produced by P. aeruginosa are controlled by the cell-to-cell communication process called quorum sensing (QS). QS depends on the synthesis, release, and groupwide response to extracellular signaling molecules called autoinducers. P. aeruginosa possesses two canonical LuxI/R-type QS systems, LasI/R and RhlI/R, that produce and detect 3OC12-homoserine lactone and C4-homoserine lactone, respectively. Previously, we discovered that RhlR regulates both RhlI-dependent and RhlI-independent regulons, and we proposed that an alternative ligand functions together with RhlR to control the target genes in the absence of RhlI. Here, we report the identification of an enzyme, PqsE, which is the alternative-ligand synthase. Using biofilm analyses, reporter assays, site-directed mutagenesis, protein biochemistry, and animal infection studies, we show that the PqsE-produced alternative ligand is the key autoinducer that promotes virulence gene expression. Thus, PqsE can be targeted for therapeutic intervention. Furthermore, this work shows that PqsE and RhlR function as a QS-autoinducer synthase-receptor pair that drives group behaviors in P. aeruginosa.

RevDate: 2018-09-18

Jiang Z, Zhang D, Zhou L, et al (2018)

Enhanced catalytic capability of electroactive biofilm modified with different kinds of carbon nanotubes.

Analytica chimica acta, 1035:51-59.

In this study two methods including coating carbon nanotubes (CNTs) layers on the electrode surface and adding CNTs-suspension during electrochemically active biofilms (EABs) growth were used, respectively, to develop CNTs hybrid EABs for enhancing electricity generation capability of EABs. EABs growth on the CNTs with functional groups of hydroxyl (CNTs-OH) or carboxyl (CNTs-COOH) and pristine CNTs without functionalization (P-CNTs) modified electrode was investigated. The maximum current densities of EABs growth on the P-CNTs, CNTs-OH and CNTs-COOH coated electrode were respective 1300 ± 117, 1082 ± 54 and 1124 ± 78 μA cm-2, which were much higher than unmodified electrode (663 μA cm-2). Meanwhile, EABs growth in doping CNTs-COOH or CNTs-OH suspensions system also produced twice higher current density than that on unmodified electrode. These results indicated that the current production of EABs can be significantly enhanced by coating P-CNTs, CNTs-OH, CNTs-COOH layers on the electrode surface or doping CNTs-OH and CNTs-COOH suspension into EABs. Furthermore, morphology analysis of as-obtained EABs had also been studied. It was found that there was no significant difference of the morphological characteristic for EABs growth on different types CNTs coated electrode surface. By comparison, a nano-hybrid porous structure of CNTs and EABs was observed when CNTs-COOH or CNTs-OH suspension was added into the medium during EABs growth, which will be responsible for high current generation.

RevDate: 2018-09-17

Vaigankar DC, Dubey SK, Mujawar SY, et al (2018)

Tellurite biotransformation and detoxification by Shewanella baltica with simultaneous synthesis of tellurium nanorods exhibiting photo-catalytic and anti-biofilm activity.

Ecotoxicology and environmental safety, 165:516-526 pii:S0147-6513(18)30849-2 [Epub ahead of print].

Tellurite reducing bacterial strain was isolated from Zuari estuary, Goa India which could tolerate 5.5 mM potassium tellurite with a minimum inhibitory concentration of 6 mM. This strain was designated as GUSDZ9 and was identified as Shewanella baltica (accession number: MF350629) based on 16S rRNA gene sequencing and BLAST analysis. The Diethyl-dithiocarbamate based colorimetric analysis clearly demonstrated a complete reduction of 2 mM tellurite to elemental tellurium during the late stationary phase. Te Nanoparticles (TeNPs) biosynthesis which initiated at early log phase (i.e. 4 h) was evidently monitored through colour change and a peak due to surface plasmon resonance at 210 nm using UV-Vis spectroscopic analysis. X-ray crystallographic studies and transmission electron microscopy revealed unique nano-rods with a diameter ranging from 8 to 75 nm. Energy dispersive X-ray analysis further confirmed the presence of pure tellurium. The biogenic TeNPs at 10 and 5 µg/mL evidently demonstrated 90% degradation of methylene blue dye and anti-biofilm activity against potential Gram-positive and Gram-negative human pathogens respectively. The alkaline comet assay revealed time and dose-dependent genotoxicity at concentrations higher than 15 µg/mL of TeNPs. This study clearly demonstrated the potential of Shewanella baltica strain GUSDZ9 in bioremediation of toxic tellurite through bio-reduction into elemental tellurium and involvement of biogenic TeNPs in the photo-catalytic reduction of methylene blue and anti-biofilm activity. This is the first report of its kind on the synthesis of biogenic TeNPs from Shewanella baltica demonstrating photo-catalytic, anti-biofilm activity as well as genotoxicity.

RevDate: 2018-09-17

Hongman H, Yifang W, Gongliang Z, et al (2018)

Effects of Sulfide Flavors on AHL-Mediated Quorum Sensing and Biofilm Formation of Hafnia alvei.

Journal of food science [Epub ahead of print].

In this study, 10 different sulfide flavor compounds commonly used as food additives were screened for antiquorum-sensing activity. Among these, diallyl disulfide (DADS) and methyl 2-methyl-3-furyl disulfide (MMFDS) were found to exert the strongest inhibition against violacein production in Chromobacterium violaceum 026, the tested biosensor strain. DADS and MMFDS also inhibited the growth of Hafnia alvei H4, yielding MIC values of 48 and 41.6 mM, respectively. In addition, DADS and MMFDS also inhibited the ability of H. alvei H4 to produce acyl-homoserine lactone as demonstrated by the reduced level of C6-HSL in the supernatant of DADS-treated culture. At concentrations corresponding to 1/4 MIC, DADS, and MMFDS inhibited the swarming ability of H. alvei H4 by 73.50% and 76.43%, respectively, while having virtually no effect on cell growth. The same concentrations of DADS and MMFDS also completely inhibited the formation of biofilm. These antiquorum sensing effects of DADS and MMFDS involved changes in the expression of the quorum-sensing genes luxI and luxR. Quantitative RT-PCR analysis showed that the mRNA levels of both genes were significantly reduced by DADS and MMDFS at concentrations below their MICs. However, further test using a mutant strain of H. alvei lacking luxR (ΔluxR) revealed significant reduction in luxI mRNA level upon treatment of the strain with DADS or MMDFS, but no change in luxR mRNA level occurred when a luxI-lacking mutant (ΔluxI) was treated with these compounds. The result therefore suggested that the antiquorum-sensing effect of DADS and MMFDS against H. alvei H4 might operate mainly through the inhibition of luxI expression in the cells.

PRACTICAL APPLICATION: The sulfide flavors compounds used in this paper are commonly used in food processing in China and are listed in the national standard of Chinese food additives GB2760-2014. The application of sulfide flavors in food processing can enhance aroma and prevent food spoilage.

RevDate: 2018-09-17

Raskov H, Kragh KN, Bjarnsholt T, et al (2018)

Bacterial biofilm formation inside colonic crypts may accelerate colorectal carcinogenesis.

Clinical and translational medicine, 7(1):30 pii:10.1186/s40169-018-0209-2.

BACKGROUND: Research in the field of relation between microbes and colorectal carcinogenesis has gained increasing interest in past years. Recently, link between microbial biofilm and carcinogenesis in colon was demonstrated by several authors indicating that biofilm not only is a key player in carcinogenesis, but also may contribute to the understanding of side-specific colon cancer-right sided colon cancer versus left sided. In this article, we briefly highlight the major findings of the research of biofilm and carcinogenesis and demonstrate our findings of colonic cancer tissue and colonic polyp examined for biofilm.

CASE PRESENTATION: Colonic cancer tissue from a patient with a right-sided colon cancer, and an adenoma tubular polyp were examined for biofilm formation by flourescens in situ hybridization. In cancer tissue we found biofilm formation on the surface epithelium but surprisingly also deep into the crypts. No biofilms were found in tubular polyp tissue.

CONCLUSIONS: To our knowledge, this is the first-time biofilm formation deep into colonic crypts are demonstrated in a patient with right-sided colon cancer. This may indicate that bacterial biofilm may have a key role in carcinogenesis.

RevDate: 2018-09-17

Roselló J, Giménez S, Ibáñez MD, et al (2018)

Bomba Rice Conservation with a Natural Biofilm.

ACS omega, 3(3):2518-2526.

The chemical composition of commercial Syzygium aromaticum, Cinnamomum verum, and Laurus nobilis essential oils as well as their antifungal activity against four pathogenic fungi isolated from Mediterranean rice grains has been investigated. Eighty nine compounds accounting for between 98.5 and 99.4% of the total essential oil were identified. The phenylpropanoids eugenol (89.37 ± 0.29%) and eugenol (56.34 ± 0.41%), followed by eugenol acetate (19.48 ± 0.13%) were, respectively, the main compounds in clove and cinnamon essential oils, whereas large amounts of the oxygenated monoterpenes 1,8-cineole (58.07 ± 0.83%) and α-terpinyl acetate (13.05 ± 0.44%) were found in bay leaf essential oil. Clove and cinnamon oils showed the best antifungal activity results against all tested fungi. Against Alternaria alternata, clove essential oil displayed the best antifungal effect, whereas against Curvularia hawaiiensis, cinnamon essential oil was more active. Both essential oils showed a similar antifungal effect towards Fusarium proliferatum and Fusarium oxysporum. In vitro studies in inoculated rice grains showed that clove and cinnamon totally inhibited pathogenic fungal development after 30 days of incubation. In vivo studies showed that eugenol used with a polysaccharide such as agar-agar formed a fine coat which wraps the inoculated rice grains, creating a natural biofilm and reducing the development of all pathogenic fungi (80-95%) for 30 days.

RevDate: 2018-09-17

Aumeeruddy-Elalfi Z, Ismaël IS, Hosenally M, et al (2018)

Essential oils from tropical medicinal herbs and food plants inhibit biofilm formation in vitro and are non-cytotoxic to human cells.

3 Biotech, 8(9):395.

The biofilm inhibition and eradication potential of essential oils (EOs) extracted from six tropical medicinal herbs and food plants [Psiadia arguta (PA), Psiadia terebinthina (PT), Citrus grandis (CGp), Citrus hystrix (CH), Citrus reticulata (CR), and Cinnamomum zeylanicum (CZ)] were assessed. The mechanism of inhibition was studied via quenching of efflux pump. Cytotoxicity was evaluated using Artemia salina assay and cell lines [human cervix carcinoma (HeLa), human lung fibroblast (MRC-5), and murine melanoma (B16F10)]. EOs of CH, CR, PA, and PT were found to be prospective antibiofilm agents (IC50 of 0.29, 0.59, 0.22, and 0.11 mg/mL against Staphylococcus epidermidis; 0.39, 0.54, 0.09, and 0.13 mg/mL against Escherichia coli; and 0.54, 0.90, 0.44 and 0.51 mg/mL against Candida albicans for CH, CR, PA, and PT, respectively). The simultaneous actions of the EOs and efflux pump inhibitor impacted on the resistance of the biofilms. LC50 of the EOs ranged from 223 to 583 µg/mL against A. salina. The non-cytotoxic concentration of the EOs varied from 200 to 300 µg/mL (HeLa and MRC-5), and 150-200 µg/mL (B16F10). EOs from these tropical medicinal herbs and food plants are useful sources of new antimicrobials with low cytotoxicity which could open new horizons in the drug development process.

RevDate: 2018-09-17

Astasov-Frauenhoffer M, Glauser S, Fischer J, et al (2018)

Biofilm formation on restorative materials and resin composite cements.

Dental materials : official publication of the Academy of Dental Materials pii:S0109-5641(18)30256-2 [Epub ahead of print].

OBJECTIVES: Monolithic zirconia, polymer-infiltrated ceramic and acrylate polymer cemented with resin composite cement have recently been identified as prosthetic treatment options for zirconia implants. The aim of the present study is to determine in vitro, to what extent bacteria adhere to these materials.

METHODS: Disks made of zirconia (Vita YZ [YZ]), polymer-infiltrated ceramic (Vita Enamic [VE]), acrylate polymer (Vita CAD-Temp [CT]), self-adhesive cement (RelyX Unicem 2 Automix [RUN]) and of two different adhesive cements (RelyX Ulimate [RUL] and Vita Adiva F-Cem [VAF]) were produced. The biofilm formation of three bacterial species (Streptococcus sanguinis, Fusobacterium nucleatum, Porphyromonas gingivalis) on each material was assessed over 72h using a flow chamber system. The biofilms were quantified by crystal violet staining (optical density 595nm) and visualized using SEM. The inorganic composition of the different materials was analyzed and the wettability of the specimens was measured.

RESULTS: For the restorative materials lowest biofilm formation was found on CT: OD 0.5±0.1, followed by VE: OD 0.8±0.1 and YZ: OD 1.4±0.3. The biofilm formation on resin composite cements was significantly lower on VAF: OD 0.6±0.1 than for RUL: OD 0.9±0.1 and RUN: OD 1.0±0.1. A high wettability of the specimens with saliva/serum mixture tended to result in a higher biofilm formation. Correlations were obtained between the organic/inorganic composition of the materials and the polar/dispersive part of the surface free energy.

SIGNIFICANCE: Three-species biofilm formation on restorative and cement materials strongly relies on the materials composition. If the restorative material CT and cement VAF also prevent excessive biofilm formation in a clinical situation should be further investigated.

RevDate: 2018-09-16

Benedek T, Szentgyörgyi F, Szabó I, et al (2018)

Aerobic and oxygen-limited enrichment of BTEX-degrading biofilm bacteria: dominance of Malikia versus Acidovorax species.

Environmental science and pollution research international pii:10.1007/s11356-018-3096-6 [Epub ahead of print].

Due to their high resistance against environmental challenges, bacterial biofilms are ubiquitous and are frequently associated with undesired phenomena in environmental industry (e. g. biofouling). However, because of the high phylogenetic and functional diversity, bacterial biofilms are important sources of biotechnologically relevant microorganisms, e.g. those showing bioremediation potential. In our previous work, the high phylogenetic and metabolic diversity of a clogging biofilm, developed in a simple aromatic hydrocarbon (BTEX)-contaminated groundwater well was uncovered. The determination of relationships between different groups of biofilm bacteria and certain metabolic traits has been omitted so far. Therefore, by setting up new biofilm-based enrichment microcosms, the research goal of the present study was to identify the aerobic/hypoxic BTEX-degrading and/or prolific biofilm-forming bacteria. The initial bacterial community composition as well as temporal dynamics due to the selective enrichment has been determined. The obtained results indicated that the concentration of dissolved oxygen may be a strong selective force on the evolution and final structure of microbial communities, developed in hydrocarbon-contaminated environments. Accordingly, members of the genus Malikia proved to be the most dominant community members of the aerobic BTEX-degrading enrichments. Acidovorax spp. dominated the oxygen-limited/hypoxic setup. During the study, a strain collection of 23 different bacterial species was obtained. Non-pathogenic members of this strain collection, with outstanding biodegradation (e.g. Pseudomonas, Variovorax isolates) and biofilm-forming potential (e.g. Rhizobium), may potentially be applied in the development of biofilm-based semipermeable reactive biobarriers.

RevDate: 2018-09-15

Han F, Ye W, Wei D, et al (2018)

Simultaneous nitrification-denitrification and membrane fouling alleviation in a submerged biofilm membrane bioreactor with coupling of sponge and biodegradable PBS carrier.

Bioresource technology, 270:156-165 pii:S0960-8524(18)31279-3 [Epub ahead of print].

Simultaneous nitrification-denitrification (SND) was achieved in submerged biofilm membrane bioreactor (SBF-MBR) treating low carbon/nitrogen (C/N) ratio wastewater. A novel bio-carrier coupling of sponge and biodegradable poly(butanediol succinate) (PBS) was applied as external carbon source and biofilm carrier. Result represented that NH4+-N and total nitrogen removal efficiencies were high of 99.1% and 94.3% in the SBF-MBR. Protein (PN) contents from SND-biofilm were reduced by 10.5% and 44.3% in TB-EPS and LB-EPS, while polysaccharides (PS) were reduced by 45.8% and 34.8%, respectively. 3D-EEM spectra indicated that protein-like, humic acid-like and fulvic acid-like substances were the main components in EPS and their peak intensities were reduced. Additionally, membrane fouling of SBF-MBR was improved after the achievement of biofilm. Microbial community analysis showed that Simplicispira, Thauera, Desulfovibrio, Dechlorobacter and Acinetobacter were dominant genus, which indicated co-existence of nitrifying bacteria, heterotrophic denitrifiers and aerobic denitrifiers in the SBF-MBR.

RevDate: 2018-09-15

Zhang X, Prévoteau A, Louro RO, et al (2018)

Periodic polarization of electroactive biofilms increases current density and charge carriers concentration while modifying biofilm structure.

Biosensors & bioelectronics, 121:183-191 pii:S0956-5663(18)30645-6 [Epub ahead of print].

Anodic electroactive biofilms (EABs) need to overcome low current densities for applications such as microbial fuel cells or biosensors. EABs can store charge in self-produced redox proteins when temporarily left in open circuit, and discharge them once the electrode is appropriately repolarized, thus behaving as pseudocapacitors. Here we investigated the effect of such periodic polarization on the intrinsic nature of the EABs during their entire growth (i.e. starting from inoculation and for 10 days) on glassy carbon electrodes. An optimal periodic polarization (half-period of 10 s) greatly increased the maximum steady-state current density delivered by the Geobacter-dominated EABs (up to 1.10 ± 0.02 mA cm-2, n = 3 electrodes) when compared to continuously polarized EABs (0.41 ± 0.04 mA cm-2); and increased the amount of electric charges produced per hour by 69 ± 17% even taking into account the half-periods of open circuit. This enhancement was highly correlated with a substantial increase in charge carriers concentration (10.6 ± 0.5 mMe- vs. 2.9 ± 0.6 mMe-), allowing higher charge storage capacity and higher electron mobility across the EABs. Our results suggest that appropriate periodic polarizations may upregulate the expression of heme-containing redox proteins associated with the matrix, such as c-type cytochromes. The EABs grown under periodic polarization presented mushroom-like structures on their top layers, while EABs grown under continuous polarization were flat.

RevDate: 2018-09-15

Keeney K, Trmcic A, Zhu Z, et al (2018)

Stress Survival Islet 1 Contributes to Serotype-specific Differences in Biofilm Formation in Listeria monocytogenes.

Letters in applied microbiology [Epub ahead of print].

Listeria monocytogenes has a significant impact on the food industry by forming biofilms on food-processing equipment. Tandem analysis of whole-genome sequencing data with biofilm data from 166 environmental and food-related L. monocytogenes isolates has revealed serotypic and genetic factors that strongly correlate with adherence and biofilm formation, such as lineage, plasmid harborage, a three codon-deletion in inlA and the presence of the Stress Survival Islet 1 (SSI-1). Strains from serotype 1/2b, the majority of which contained SSI-1, formed the strongest biofilms, while serotype 4b strains, the majority of which did not contain SSI-1, formed the weakest biofilms. When serotype 1/2a was separated by its SSI-1 genotype, SSI-1 positive 1/2a strains demonstrated significantly higher capacity for biofilm formation after 3 days of growth at 30°C (p<0.0001). Together, these findings indicate that SSI-1 may contribute to serotype-associated differences in the biofilm-forming capacity in L. monocytogenes. This article is protected by copyright. All rights reserved.

RevDate: 2018-09-15

Mahdinia E, Demirci A, A Berenjian (2018)

Implementation of fed-batch strategies for vitamin K (menaquinone-7) production by Bacillus subtilis natto in biofilm reactors.

Applied microbiology and biotechnology pii:10.1007/s00253-018-9340-7 [Epub ahead of print].

Recent studies show the essential health benefits associated with vitamin K, especially menaquinone-7 (MK-7). These benefits include reducing risks of cardiovascular diseases, osteoporosis, and even cancer. However, MK-7 production on an industrial level is only possible through bacterial fermentation and also current static fermentation strategies are not potent enough with difficulties to scale up. Biofilm reactors, however, may be a practical alternative. Biofilm reactors provide a controlled environment for the microorganisms to form mature and robust biofilms that enable them to produce value-added products with enhanced efficiencies. In this study, fed-batch addition of glucose and glycerol were investigated to the base media in biofilm reactors, as carbon source addition seemed crucial in batch fermentations. Results indicated that fed-batch strategies can be significantly effective in glucose-based medium, increasing the end-product concentrations to 28.7 ± 0.3 mg/L of MK-7 which was 2.3 fold higher than the level produced in suspended-cell bioreactors and renders the biofilm reactors as a potential replacement for static fermentation strategies. Moreover, morphological changes of B. subtilis were tracked during the 12-day long fermentation runs and finally, SEM investigations confirmed significant biofilm and extracellular matrices formed on the plastic composite support (PCS) in the biofilm reactors. In conclusion, biofilm reactors especially with fed-batch fermentation regimes seem to be an effective tool for MK-7 production at industrial scales.

RevDate: 2018-09-15

Latif M, EE May (2018)

A Multiscale Agent-Based Model for the Investigation of E. coli K12 Metabolic Response During Biofilm Formation.

Bulletin of mathematical biology pii:10.1007/s11538-018-0494-3 [Epub ahead of print].

Bacterial biofilm formation is an organized collective response to biochemical cues that enables bacterial colonies to persist and withstand environmental insults. We developed a multiscale agent-based model that characterizes the intracellular, extracellular, and cellular scale interactions that modulate Escherichia coli MG1655 biofilm formation. Each bacterium's intracellular response and cellular state were represented as an outcome of interactions with the environment and neighboring bacteria. In the intracellular model, environment-driven gene expression and metabolism were captured using statistical regression and Michaelis-Menten kinetics, respectively. In the cellular model, growth, death, and type IV pili- and flagella-dependent movement were based on the bacteria's intracellular state. We implemented the extracellular model as a three-dimensional diffusion model used to describe glucose, oxygen, and autoinducer 2 gradients within the biofilm and bulk fluid. We validated the model by comparing simulation results to empirical quantitative biofilm profiles, gene expression, and metabolic concentrations. Using the model, we characterized and compared the temporal metabolic and gene expression profiles of sessile versus planktonic bacterial populations during biofilm formation and investigated correlations between gene expression and biofilm-associated metabolites and cellular scale phenotypes. Based on our in silico studies, planktonic bacteria had higher metabolite concentrations in the glycolysis and citric acid cycle pathways, with higher gene expression levels in flagella and lipopolysaccharide-associated genes. Conversely, sessile bacteria had higher metabolite concentrations in the autoinducer 2 pathway, with type IV pili, autoinducer 2 export, and cellular respiration genes upregulated in comparison with planktonic bacteria. Having demonstrated results consistent with in vitro static culture biofilm systems, our model enables examination of molecular phenomena within biofilms that are experimentally inaccessible and provides a framework for future exploration of how hypothesized molecular mechanisms impact bulk community behavior.

RevDate: 2018-09-15

Xue D, Tian F, Yang F, et al (2018)

Phosphodiesterase EdpX1 promotes virulence, exopolysaccharide production and biofilm formation in Xanthomonas oryzae pv. oryzae.

Applied and environmental microbiology pii:AEM.01717-18 [Epub ahead of print].

In Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice, there are over twenty genes encoding GGDEF, EAL or HD-GYP domains, which are potentially involved in the metabolism of second messenger c-di-GMP. In this study, we focused on characterization of an EAL-domain protein EdpX1. Deletion of edpX1 resulted in a two-fold increase of the intracellular c-di-GMP levels, which was restored to the wild-type levels in the complemented strain ΔedpX1(pB-edpX1), demonstrating EdpX1 is an active phosphodiesterase (PDE) in Xoo. In addition, colorimetric assays further confirmed the PDE activity of EdpX1 by showing that mutation of E153A at the EAL motif strongly reduced its activity. Virulence assays on the leaves of susceptible rice showed that ΔedpX1 was severely impaired in causing disease symptoms. In trans expression of wild-type edpX1, but not edpX1E153A, was able to complement the weakened virulence phenotype. These results indicated that an active EAL domain is required for EdpX1 to regulate the virulence of Xoo. We then demonstrated that ΔedpX1 was defective in secreting exopolysaccharide (EPS) and forming biofilm. Expression of edpX1 in ΔedpX1, but not edpX1E153A restored the defective phenotypes to near wild-type level. In addition, we observed that EdpX1-GFP exhibited multiple subcellular localization foci, and this pattern was dependent on its transmembrane (TM) region, which did not seem to directly contribute to the regulatory function of EdpX1. Thus, we concluded that EdpX1 exhibits PDE activity to control c-di-GMP level, and its EAL domain is necessary and sufficient for its regulation on virulence in Xoo.IMPORTANCE Bacteria utilize c-di-GMP as a second messenger to regulate various biological functions. The synthesis and degradation of c-di-GMP are catalyzed by GGDEF domains and EAL or HD-GYP domains, respectively. Multiple genes encoding these domains are often found in one bacterial strain. For example, in the genome of Xoo PXO99A, 26 genes encoding proteins containing these domains were identified. Therefore, to fully appreciate the complexity and specificity of c-di-GMP signaling in Xoo, the enzymatic activities and regulatory functions of each GGDEF, EAL and HD-GYP domain proteins need to be elucidated. In this study, we showed the EAL-domain protein EdpX1 is a major PDE to regulate diverse virulence phenotypes through the c-di-GMP signaling pathway.

RevDate: 2018-09-15

Kamaruzzaman NF, Tan LP, Mat Yazid KA, et al (2018)

Targeting the Bacterial Protective Armour; Challenges and Novel Strategies in the Treatment of Microbial Biofilm.

Materials (Basel, Switzerland), 11(9): pii:ma11091705.

Infectious disease caused by pathogenic bacteria continues to be the primary challenge to humanity. Antimicrobial resistance and microbial biofilm formation in part, lead to treatment failures. The formation of biofilms by nosocomial pathogens such as Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Klebsiella pneumoniae (K. pneumoniae) on medical devices and on the surfaces of infected sites bring additional hurdles to existing therapies. In this review, we discuss the challenges encountered by conventional treatment strategies in the clinic. We also provide updates on current on-going research related to the development of novel anti-biofilm technologies. We intend for this review to provide understanding to readers on the current problem in health-care settings and propose new ideas for new intervention strategies to reduce the burden related to microbial infections.

RevDate: 2018-09-14

Lan M, Li M, Liu J, et al (2018)

Coal chemical reverse osmosis concentrate treatment by membrane-aerated biofilm reactor system.

Bioresource technology, 270:120-128 pii:S0960-8524(18)31248-3 [Epub ahead of print].

Coal chemical reverse osmosis concentrate (ROC), which is characterized by high salinity and high organics, remains as a serious environmental problem. In this study, a lab-scale three-stage membrane-aerated biofilm reactor (MABR) system was designed to treat such a ROC. The effects of influent salinity and operating parameters (pH, DO and HRT) on the treatment efficiency were discussed. The removal efficiencies of COD, NH4-N and TN under the optimal operating parameters reached to 81.01%, 92.31% and 70.72%, respectively. Simultaneous nitrification and denitrification (SND) as well as shortcut nitrogen removal were achieved. The salinity less than 3% did not induce significant decrease in treatment efficiency and microbial communities. Moreover, the dominant phyla in biofilms were Proteobacteria and Bacteroidetes. This work demonstrated MABR had great potential in ROC treatment.

RevDate: 2018-09-14

Yu Z, Deslouches B, Walton WG, et al (2018)

Enhanced biofilm prevention activity of a SPLUNC1-derived antimicrobial peptide against Staphylococcus aureus.

PloS one, 13(9):e0203621 pii:PONE-D-18-11092.

SPLUNC1 is a multifunctional protein of the airway with antimicrobial properties. We previously reported that it displayed antibiofilm activities against P. aeruginosa. The goal of this study was to determine whether (1) the antibiofilm property is broad (including S. aureus, another prevalent organism in cystic fibrosis); (2) the α4 region is responsible for such activity; and (3), if so, this motif could be structurally optimized as an antimicrobial peptide with enhanced activities. We used S. aureus biofilm-prevention assays to determine bacterial biomass in the presence of SPLUNC1 and SPLUNC1Δα4 recombinant proteins, or SPLUNC1-derived peptides (α4 and α4M1), using the well-established crystal-violet biofilm detection assay. The SPLUNC1Δα4 showed markedly reduced biofilm prevention compared to the parent protein. Surprisingly, the 30-residue long α4 motif alone demonstrated minimal biofilm prevention activities. However, structural optimization of the α4 motif resulted in a modified peptide (α4M1) with significantly enhanced antibiofilm properties against methicillin-sensitive (MSSA) and-resistant (MRSA) S. aureus, including six different clinical strains of MRSA and the well-known USA300. Hemolytic activity was undetectable at up to 100μM for the peptides. The data warrant further investigation of α4-derived AMPs to explore the potential application of antimicrobial peptides to combat bacterial biofilm-related infections.

RevDate: 2018-09-14

Cools F, Torfs E, Vanhoutte B, et al (2018)

Streptococcus pneumoniae galU gene mutation has a direct effect on biofilm growth, adherence and phagocytosis in vitro and pathogenicity in vivo.

Pathogens and disease, 76(7): pii:5078866.

Streptococcus pneumoniae, the most common cause of bacterial pneumonia, has developed a wide range of virulence factors to evade the immune system of which the polysaccharide capsule is the most important one. Formation of this capsule is dependent on the cps gene locus, but also involves other genes-like galU. The pyrophosphorylase encoded by galU plays a role in the UDP-glucose metabolism of prokaryotes and is required for the biosynthesis of capsular polysaccharides. In this paper, the effect of a galU mutation leading to a dysfunctional UDP-glucose pyrophosphorylase (UDPG:PP) on in vitro biofilm biomass, adherence to lung epithelial cells and macrophage phagocytosis is studied. Last, in vivo virulence using a Galleria mellonella model has been studied. We show that the mutation improves streptococcal adherence to epithelial cells and macrophage phagocytosis in vitro, while there is no definitive correlation on biofilm formation between parent and mutant strains. Moreover, in vivo virulence is attenuated for all mutated strains. Together, these results demonstrate that a galU mutation in S. pneumoniae influences host cell interactions in vitro and in vivo and can strongly influence the outcome of a streptococcal infection. As such, UDPG:PP is worth investigating further as a potential drug target.

RevDate: 2018-09-14

Bisson C, Lec PH, Blique M, et al (2018)

Presence of trichomonads in subgingival biofilm of patients with periodontitis: preliminary results.

Parasitology research pii:10.1007/s00436-018-6077-2 [Epub ahead of print].

This study aims to evaluate the prevalence of trichomonads in the subgingival biofilm of patients with periodontitis. Secondarily, the trichomonad presence was related to patient characteristics and periodontal clinical parameters, in order to highlight the factor favoring the development of these protozoans. Subgingival biofilm samples were collected from at least two diseased and one healthy site in 50 patients suffering from periodontitis. Trichomonads were identified using phase contrast microscopy. All patient characteristics and periodontal clinical parameter data were then statistically analyzed. From the 50 patients examined, 195 sites were sampled, including 145 diseased ones. Trichomonads were only observed on 16 of the 145 diseased sites (11%) and none in the other 50 healthy sites. Based on these results, 20% (n = 10) of patients were positive for the presence of trichomonads from at least one of the diseased sites collected. Tooth mobility, substantial supra-gingival dental deposits, and severe clinical attachment loss were statistically associated with trichomonad presence. If the subgingival biofilm of male patients over the age of 50 seemed to be more frequently contaminated with trichomonads, this data was not statistically supported. This preliminary study indicates for the first time that in periodontitis-involved patients, trichomonads are observed in the subgingival biofilm collected from diseased sites with severe bone loss, but not from healthy teeth. Further investigations are needed to fully explore the role of this microorganism in the etiology of periodontal disease.

RevDate: 2018-09-14

Wilson C, Lukowicz R, Merchant S, et al (2017)

Quantitative and Qualitative Assessment Methods for Biofilm Growth: A Mini-review.

Research & reviews. Journal of engineering and technology, 6(4):.

Biofilms are microbial communities attached to a surface and embedded in an extracellular polymeric substance which provides for the protection, stability and nutrients of the various bacterial species indwelling. These communities can build up in a variety of different environments from industrial equipment to medical devices resulting in damage, loss of productivity and disease. They also have great potential for economic and societal benefits as bioremediation agents and renewable energy sources. The great potential benefits and threats of biofilms has encouraged researchers across disciplines to study biofilm characteristics and antibiofilm strategies resulting in chemists, physicists, material scientists, and engineers, to develop beneficial biofilm applications and prevention methods. The ultimate outcome is a wealth of knowledge and innovative technology. However, without extensive formal training in microbes and biofilm research, these scientists find a daunting array of established techniques for growing, quantifying and characterizing biofilms while trying to design experiments and develop innovative laboratory protocols. This mini-review focuses on enriching interdisciplinary efforts and understanding by overviewing a variety of quantitative and qualitative biofilm characterization methods to assist the novice researcher in assay selection. This review consists of four parts. Part 1 is a brief overview of biofilms and the unique properties that demand a highly interdisciplinary approach. Part 2 describes the classical quantification techniques including colony forming unit (CFU) counting and crystal violet staining, but also introduces some modern methods including ATP bioluminescence and quartz crystal microbalance. Part 3 focuses on the characterization of biofilm morphology and chemistry including scanning electron microscopy and spectroscopic methods. Finally, Part 4 illustrates the use of software, including ImageJ and predictive modeling platforms, for biofilm analysis. Each section highlights the most common methods, including literature references, to help novice biofilm researchers make choices which commensurate with their study goals, budget and available equipment.

RevDate: 2018-09-14

Santos AL, DB Johnson (2018)

Design and Application of a Low pH Upflow Biofilm Sulfidogenic Bioreactor for Recovering Transition Metals From Synthetic Waste Water at a Brazilian Copper Mine.

Frontiers in microbiology, 9:2051.

A sulfidogenic bioreactor, operated at low pH (4-5), was set up and used to remove transition metals (copper, nickel, cobalt, and zinc) from a synthetic mine water, based on the chemistry of a moderately acidic (pH 5) drainage stream at an operating copper mine in Brazil. The module was constructed as an upflow biofilm reactor, with microorganisms immobilized on porous glass beads, and was operated continuously for 462 days, during which time the 2 L bioreactor processed >2,000 L of synthetic mine water. The initial treatment involved removing copper (the most abundant metal present) off-line in a stream of H2S-containing gas generated by the bioreactor, which caused the synthetic mine water pH to fall to 2.1. The copper-free water was then amended with glycerol (the principal electron donor), yeast extract and basal salts, and pumped directly into the bioreactor where the other three transition metals were precipitated (also as sulfides), concurrent with increased solution pH. Although some acetate was generated, most of the glycerol fed to the bioreactor was oxidized to carbon dioxide, and was coupled to the reduction of sulfate to hydrogen sulfide. No archaea or eukaryotes were detected in the bioreactor microbial community, which was dominated by acidophilic sulfate-reducing Firmicutes (Peptococcaceae strain CEB3 and Desulfosporosinus acididurans); facultatively anaerobic non-sulfidogens (Acidithiobacillus ferrooxidans and Actinobacterium strain AR3) were also found in small relative abundance. This work demonstrated how a single low pH sulfidogenic bioreactor can be used to remediate a metal-rich mine water, and to facilitate the recovery (and therefore recycling) of target metals. The system was robust, and was operated empirically by means of pH control. Comparison of costs of the main consumables (glycerol and yeast extract) and the values of the metals recovered showed a major excess of the latter, supporting the view that sulfidogenic biotechnology can have significant economic as well as environmental advantages over current approaches used to remediate mine waters which produce secondary toxic wastes and fail to recover valuable metals.

RevDate: 2018-09-14

Camarillo-Márquez O, Córdova-Alcántara IM, Hernández-Rodríguez CH, et al (2018)

Antagonistic Interaction of Staphylococcus aureus Toward Candida glabrata During in vitro Biofilm Formation Is Caused by an Apoptotic Mechanism.

Frontiers in microbiology, 9:2031.

Background: Infections caused by Candida species and Staphylococcus aureus are associated with biofilm formation. C. albicans-S. aureus interactions are synergistic due to the significant increase in mixed biofilms and improved resistance to vancomycin of S. aureus. C. glabrata and S. aureus both are nosocomial pathogens that cause opportunistic infections in similar host niches. However, there is scarce information concerning the interaction between these last microorganisms. Results: The relationship between C. glabrata and S. aureus was evaluated by estimating the viability of both microorganisms in co-culture of planktonic cells and in single and mixed biofilms. An antagonistic behavior of S. aureus and their cell-free bacterial supernatant (CFBS) toward C. glabrata, both in planktonic form and in biofilms, was demonstrated. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal laser scanning microscopy (CLSM) images showed yeast cells surrounded by bacteria, alterations in intracytoplasmic membranes, and non-viable blastoconidia with intact cell walls. Concomitantly, S. aureus cells remained viable and unaltered. The antagonistic activity of S. aureus toward C. glabrata was not due to cell-to-cell contact but the presence of CFBS, which causes a significant decrement in yeast viability and the formation of numerous lipid droplets (LDs), reactive oxygen species (ROS) accumulation, as well as nuclear alterations, and DNA fragmentation indicating the induction of an apoptotic mechanism. Conclusion: Our results demonstrate that the S. aureus CFBS causes cell death in C. glabrata by an apoptotic mechanism.

RevDate: 2018-09-14

Guillonneau R, Baraquet C, Bazire A, et al (2018)

Multispecies Biofilm Development of Marine Bacteria Implies Complex Relationships Through Competition and Synergy and Modification of Matrix Components.

Frontiers in microbiology, 9:1960.

Microbial communities composition is largely shaped by interspecies competition or cooperation in most environments. Ecosystems are made of various dynamic microhabitats where microbial communities interact with each other establishing metabolically interdependent relationships. Very limited information is available on multispecies biofilms and their microhabitats related to natural environments. The objective of this study is to understand how marine bacteria isolated from biofilms in the Mediterranean Sea interact and compete with each other when cultivated in multispecies biofilms. Four strains (Persicivirga mediterranea TC4, Polaribacter sp. TC5, Shewanella sp. TC10 and TC11) with different phenotypical traits and abilities to form a biofilm have been selected from a previous study. Here, the results show that these strains displayed a different capacity to form a biofilm in static versus dynamic conditions where one strain, TC11, was highly susceptible to the flux. These bacteria appeared to be specialized in the secretion of one or two exopolymers. Only TC5 seemed to secrete inhibitory molecule(s) in its supernatant, with a significant effect on TC10. Most of the strains negatively impacted each other, except TC4 and TC10, which presented a synergetic effect in the two and three species biofilms. Interestingly, these two strains produced a newly secreted compound when grown in dual-species versus mono-species biofilms. TC5, which induced a strong inhibition on two of its partners in dual-species biofilms, outfitted the other bacteria in a four-species biofilm. Therefore, understanding how bacteria respond to interspecific interactions should help comprehending the dynamics of bacterial populations in their ecological niches.

RevDate: 2018-09-13

Salinas B, Guembe M, Cussó L, et al (2018)

Assessment of the anti-biofilm effect of micafungin in an animal model of catheter-related candidemia.

Medical mycology pii:5095973 [Epub ahead of print].

In cases where catheter-related candidemia (CRC) must be managed without catheter withdrawal, antifungal lock therapy using highly active anti-biofilm (HAAB) agents is combined with systemic treatment. However, the activity of HAAB agents has never been studied in in vivo models using bioluminescence. We assessed the efficacy of micafungin using a bioluminescent Candida albicans SKCA23-ACTgLuc strain in an animal model of CRC. We divided 33 female Wistar rats into five groups: sham (A), infected nontreated (B), treated with lock therapy (0.16 mg/ml) (C), systemically treated only (1 mg/kg) (D), and systemically treated+lock (E). Catheters were colonized 24 h before insertion into the femoral vein (day 0). Treatment started on day 1 and lasted 7 days, followed by 7 days of surveillance. Bioluminescence assays were carried out on days 1, 3, 5, and 14, together with daily monitoring of clinical variables. Postmortem microbiological cultures from the catheter and several tissue samples were also obtained. Overall, 28 rats (84.8%) completed the study. Group B animals showed significant weight loss at days 2, 4, and 5 compared with groups C and D (P < .05). In group B, no animals survived after day 7, 75% had CRC, and bioluminescence remained constant 5 days after catheter implantation. Positive catheter culture rates in groups C, D, and E were, respectively, 83.3%, 62.5%, and 25.0% (P = .15). Micafungin proved to be a HAAB agent when administered both systemically and in lock therapy in an animal model of CRC, although the bioluminescence signal persists after treatment. This persistence should be further analyzed.

RevDate: 2018-09-13

Zhang JM, Liu J, Wang K, et al (2018)

Observations of Bacterial Biofilm on Ureteral Stent and Studies on the Distribution of Pathogenic Bacteria and Drug Resistance.

Urologia internationalis pii:000490621 [Epub ahead of print].

OBJECTIVE: This study aims to observe the morphological characteristics of bacterial biofilm on the surface of ureteral stents and analyze distribution characteristics of pathogens on the bacterial biofilm and drug resistance.

METHODS: Ureteral stents were sampled from 129 patients. A scanning electron microscope was used to observe the morphological characteristics of bacterial biofilms, and the Congo red medium was applied to screen bacterial biofilm strains on the renal pelvis section, ureter section, and bladder section respectively. Urine culture was performed, and the drug sensitive test analysis was carried out for the pathogenic bacteria detected.

RESULTS: Bacterial biofilms can be observed on the surface of ureteral stents, and these bacteria are embraced by large amounts of fiber membranes. A total of 107 patients were found to be positive for biofilms with a positive rate of 82.9%. The positive rates of the bladder section, ureter section, renal pelvis section, and urine culture were 85.0, 42.9, 67.3, and 24.3% respectively. Pathogenic bacteria mainly concentrated on Escherichia coli, and the drug resistance rate of the bacterial biofilm strains on the ureteral stent was relatively higher.

CONCLUSION: The bacterial biofilm on the ureteral stent is an important factor that induces catheter-associated urinary tract infections.

RevDate: 2018-09-13

Ye Y, Huang Y, Xia A, et al (2018)

Optimizing culture conditions for heterotrophic-assisted photoautotrophic biofilm growth of Chlorella vulgaris to simultaneously improve microalgae biomass and lipid productivity.

Bioresource technology, 270:80-87 pii:S0960-8524(18)31220-3 [Epub ahead of print].

In order to solve the technical bottleneck that the biomass yield and lipid accumulation cannot be increased simultaneously during microalgae growth, a heterotrophic-assisted photoautotrophic biofilm (HAPB) growth mode of Chlorella vulgaris was constructed. The light penetration capability of the microalgae biofilm formed through heterotrophic-assisted photoautotrophic growth was 64% stronger than that formed by photoautotrophic growth. Due to the different demands of autotrophic and heterotrophic growth of microalgae, the nutrient environment and growth conditions were optimized to fully utilize the advantages and potentials of the HAPB culture model. An optimized molar ratio of total inorganic carbon (CO2) to total organic carbon (glucose) (20:1) and a molar ratio of total carbon to total nitrogen (72:1) were obtained. The maximum specific growth rate of Chlorella vulgaris increased by 78% compared to that before optimization. Meanwhile, the lipid content and yield increased by 120% and 147%, respectively, up to 47.53% and 41.95 g m-2.

RevDate: 2018-09-13

Zhao B, Ran XC, Tian M, et al (2018)

Assessing the performance of a sequencing batch biofilm reactor bioaugmented with P. stutzeri strain XL-2 treating ammonium-rich wastewater.

Bioresource technology, 270:70-79 pii:S0960-8524(18)31252-5 [Epub ahead of print].

Pseudomonas stutzeri XL-2, with the capability of heterotrophic nitrification-aerobic denitrification and biofilm-forming, was applied in a sequencing batch biofilm reactor (SBBR) for bioaugmented treatment of ammonium-rich wastewater. The bioaugmented system SBBR 1 showed a rapid development of biofilm and relatively shorter time for biofilm hanging compared with the control system SBBR 2 without strain XL-2 inoculation. At different NH4+-N loads of 100, 200 and 300 mg/L, the effluent TN removal ratios ranged in 88.7-97.0%, 85.1-93.5% and 87.8-92.5% respectively in SBBR 1, while only ranged in 77.4-85.4%, 77.1-84.3% and 79.8-85.0% in SBBR 2. Less accumulation of NO2--N and NO3--N resulted in the better performance on TN removal in SBBR 1. Microbial community structure analysis revealed that strain XL-2 successfully proliferated in SBBR 1 and contributed to the less accumulation of NO2--N and NO3--N as well as biofilm formation.

RevDate: 2018-09-13

Han F, Wei D, Ngo HH, et al (2018)

Performance, microbial community and fluorescent characteristic of microbial products in a solid-phase denitrification biofilm reactor for WWTP effluent treatment.

Journal of environmental management, 227:375-385 pii:S0301-4797(18)30993-9 [Epub ahead of print].

Microbial products, i.e. extracellular polymeric substance (EPS) and soluble microbial product (SMP), have a significant correlation with microbial activity of biologically based systems. In present study, the spectral characteristics of two kinds of microbial products were comprehensively evaluated in a solid-phase denitrification biofilm reactor for WWTP effluent treatment by using poly (butylene succinate) (PBS) as carbon source. After the achievement of PBS-biofilm, nitrate and total nitrogen removal efficiencies were high of 97.39 ± 1.24% and 96.38 ± 1.1%, respectively. The contents of protein and polysaccharide were changed different degrees in both LB-EPS and TB-EPS. Excitation-emission matrix (EEM) implied that protein-like substances played a significant role in the formation of PBS-biofilm. High-throughput sequencing result implied that the proportion of denitrifying bacteria, including Simplicispira, Dechloromonas, Diaphorobacter, Desulfovibrio, increased to 9.2%, 7.4%, 4.8% and 3.6% in PBS-biofilm system, respectively. According to EEM-PARAFAC, two components were identified from SMP samples, including protein-like substances for component 1 and humic-like and fulvic acid-like substances for component 2, respectively. Moreover, the fluorescent scores of two components expressed significant different trends to reaction time. Gas chromatography-mass spectrometer (GC-MS) implied that some new organic matters were produced in the effluent of SP-DBR due to biopolymer degradation and denitrification processes. The results could provide a new insight about the formation and stability of solid-phase denitrification PBS-biofilm via the point of microbial products.

RevDate: 2018-09-13

Ead JK, Snyder RJ, Wise J, et al (2018)

Is PASH Syndrome a Biofilm Disease?: A Case Series and Review of the Literature.

Wounds : a compendium of clinical research and practice, 30(8):216-223.

INTRODUCTION: When occurring together, pyoderma gangrenosum, severe acne, and hidradenitis suppurativa have been described as PASH syndrome. Due to the chronic autoinflammatory state existing in affected patients, PASH syndrome has been attributed to the dysregulation of wound healing.

CASE REPORTS: Two cases are presented that demonstrate the paradigmatic clinical features of PASH syndrome and its potential link as an expanding spectrum of bacterial biofilm disorder.

CONCLUSIONS: As reported herein, based on biofilm's clinical presentation and resistance to proper wound healing, it could serve as the common denominator and may redirect clinicians' treatment pathways in the near future.

RevDate: 2018-09-13

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

All-in-one NIR-activated nanoplatforms for enhanced bacterial biofilm eradication.

Nanoscale [Epub ahead of print].

The chronic infection of humans by antibiotic-resistant bacteria and their related biofilm have, so far, not been properly addressed. In the present work, we developed a novel antibacterial nanoplatform showing the most efficient antibiotic-resistant bacteria inhibition and biofilm eradication. This particular formulation contains tobramycin-conjugated graphene oxide, for efficiently capturing bacteria through electrostatic interactions and eliminating bacteria as a "nano-knife", and copper sulphide nanoparticles for enhancing the photothermal and photodynamic properties. This novel formulation can selectively eliminate bacteria over NIH 3T3 cells, and the biofilm eradication capacity was up to 70%. Importantly, the nanoplatforms can inhibit bacterial growth and promote the repair of antibiotic-resistant bacteria-infected wounds on rats without non-specific damage to normal tissue. This work provides an effective, simple, and rapid method for the design and fabrication of near-infrared light-induced nanoplatforms that offer possibilities to treat biofilm-related infections.

RevDate: 2018-09-13

Mubarak Z, Humaira A, Gani BA, et al (2018)

Preliminary study on the inhibitory effect of seaweed Gracilaria verrucosa extract on biofilm formation of Candida albicans cultured from the saliva of a smoker.

F1000Research, 7:684.

Background:Candida albicans is an opportunistic fungus that infects the oral cavity. Increases in colony numbers of C. albicans can be caused by multiple factors, such as smoking, a weakened immune system, taking antibiotics and with immune-compromised individuals. Smoking can increase the virulence factor of C. albicans and make it stronger. One of the virulence factors of C. albicans is the biofilm it forms. The C. albicans biofilm makes it more tolerant to extracts of the seaweed Gracilariaverrucosa, which has antifungal activity. The objective of the study was to examine the ability of the G.verrucosa extracts to inhibit the formation of biofilm by C. albicans obtained from the saliva of smoker. Methods: A total of six concentrations of G. verrucosa (6.25, 12.5, 25, 50, 75 and 100%) were tested in this study. The positive control was fluconazole 0.31 µg/ml C. albicans was taken from the saliva of one smoker in Faculty of Dentistry, Syiah Kuala University. The total amount of biofilm was assessed using an ELISA reader. The data were subjected to Kruskal-Wallis test at a significance limit of p<0.05. Results: The seaweed extract has three bio-active compounds: steroids, terpenoid, and tannins. The results showed that the inhibitory activity of seaweed on C. albicans biofilm formation increases as its concentration increases. The highest effectiveness was recorded at a seaweed concentration of 100% at 48 h of exposure. Conclusions: The optimal inhibition of the C. albicans biofilm formation was recorded at the concentration of 100% G. verrucosa after 48 hours of exposure.

RevDate: 2018-09-13

Yang L, Zheng C, Chen Y, et al (2018)

FLO Genes Family and Transcription Factor MIG1 Regulate Saccharomyces cerevisiae Biofilm Formation During Immobilized Fermentation.

Frontiers in microbiology, 9:1860.

Saccharomyces cerevisiae immobilization is commonly used for efficient ethanol fuel production in industry due to the relatively higher ethanol stress resistance of S. cerevisiae in biofilms relative to planktonic cells. The mechanisms of biofilm formation and stress resistance, however, remain ambiguous. By analyzing biofilm and planktonic cell transcriptomes, this study observed that MIG1 (encoding a transcription factor) expression in cells increases during the biofilm formation process. To identify the role of MIG1 in yeast biofilm formation and the ethanol resistance of these cells, MIG1 was deleted and complemented in S. cerevisiae 1308. Results showed the MIG1 deletion mutant strain demonstrated weaker biofilm formation ability both on fibers and plastic than the wild-type and these could be restored by expressing MIG1 in deletion mutant. To verify the ability of MIG1 to regulate the expression of FLO genes, which encode adhesions responsible for yeast biofilm formation, FLO gene transcription levels were measured via qRT-PCR. Relative to wild-type S. cerevisiae, the adhesion genes FLO1, 5, and 9 which also demonstrate increased expression in the transcriptome of yeast cells during biofilm formation, but not FLO11, were down-regulated in the MIG1 mutant strain. Additionally, the MIG1 mutant lost a majority of its flocculation ability, which depended on cell-cell adhesions and its slightly invasive growth ability, dependent on cell-substrate adhesion. Deleting FLO1, 5, and 9 decreased biofilm formation on plastics, suggesting these FLO genes contribute to the biofilm formation process alongside FLO11. Moreover, the ethanol tolerance of yeast decreased in the MIG1 deletion mutant as well as the FLO11 deletion mutant, resulting in reduced biofilm formation during fermentation. It remains possible that in the later period of fermentation, when ethanol has accumulated, an over-expression of the FLO1, 5, and 9 genes regulated by MIG1 would enhanced cell-cell adhesions and thus protect cells in the outer layer of biofilms from ethanol, a function primarily dependent on cell-cell adhesions. This work offers a possible explanation for how biofilm formation is regulated during the immobilized fermentation process, and can enhance environmental tolerance in industrial production.

RevDate: 2018-09-13

Wang Y, Wang Y, Sun L, et al (2018)

Streptococcus suis biofilm: regulation, drug-resistance mechanisms, and disinfection strategies.

Applied microbiology and biotechnology pii:10.1007/s00253-018-9356-z [Epub ahead of print].

Streptococcus suis (S. suis) is a major swine pathogen and an important zoonotic agent. Like most pathogens, the ability of S. suis to form biofilms plays a significant role in its virulence and drug resistance. A better understanding of the mechanisms involved in biofilm formation by S. suis as well as of the methods to efficiently remove and kill biofilm-embedded bacteria can be of high interest for the prevention and treatment of S. suis infections. The aim of this literature review is to update our current knowledge of S. suis biofilm formation, regulatory mechanisms, drug-resistance mechanisms, and disinfection strategies.

RevDate: 2018-09-13

Khider M, Willassen NP, H Hansen (2018)

The alternative sigma factor RpoQ regulates colony morphology, biofilm formation and motility in the fish pathogen Aliivibrio salmonicida.

BMC microbiology, 18(1):116 pii:10.1186/s12866-018-1258-9.

BACKGROUND: Quorum sensing (QS) is a cell-to cell communication system that bacteria use to synchronize activities as a group. LitR, the master regulator of QS in Aliivibrio salmonicida, was recently shown to regulate activities such as motility, rugosity and biofilm formation in a temperature dependent manner. LitR was also found to be a positive regulator of rpoQ. RpoQ is an alternative sigma factor belonging to the sigma -70 family. Alternative sigma factors direct gene transcription in response to environmental signals. In this work we have studied the role of RpoQ in biofilm formation, colony morphology and motility of A. salmonicida LFI1238.

RESULTS: The rpoQ gene in A. salmonicida LFI1238 was deleted using allelic exchange. We found that RpoQ is a strong repressor of rugose colony morphology and biofilm formation, and that it controls motility of the bacteria. We also show that overexpression of rpoQ in a ΔlitR mutant of A. salmonicida disrupts the biofilm produced by the ΔlitR mutant and decreases its motility, whereas rpoQ overexpression in the wild-type completely eliminates the motility.

CONCLUSION: The present work demonstrates that the RpoQ sigma factor is a novel regulatory component involved in modulating motility, colony morphology and biofilm formation in the fish pathogen A. salmonicida. The findings also confirm that RpoQ functions downstream of the QS master regulator LitR. However further studies are needed to elucidate how LitR and RpoQ work together in controlling phenotypes related to QS in A. salmonicida.

RevDate: 2018-09-13

Zhang X, Chen T, Zhang J, et al (2018)

Performance of the nitrogen removal, bioactivity and microbial community responded to elevated norfloxacin antibiotic in an Anammox biofilm system.

Chemosphere, 210:1185-1192.

Antibiotic pollution in nitrogen contained wastewater is an urgent issue. In this study, the nitrogen removal, biofilm property and microbial community of Anammox system were investigated with elevated norfloxacin (NOR) feeding. Batch experiments were carried out to detect the specific anammox activity (SAA) in each phase. Anammox system could resist NOR in 0.001-50 mg L-1, in which the nitrogen removal was firstly limited to 0.220 from the initial 0.345 by NOR suppression and then regained to 0.354 kg m-3 d-1 after acclimatization. SAA decreased to 7.56 from the initial 10.84 and then climbed up to 11.01 mg g-1 SS, while the relative abundance of Candidatus Kuenenia decreased to 11.33% and then picked up to 25.28% from the initial 20.74%. The suppression threshold on Anammox was calculated as 50-100 mg L-1 NOR, the NRR, SAA and Candidatus Kuenenia abundance all recovered to almost the initial level when NOR feeding was terminated.

RevDate: 2018-09-12

Morris J, Kelly N, Elliott L, et al (2018)

Evaluation of Bacteriophage Anti-Biofilm Activity for Potential Control of Orthopedic Implant-Related Infections Caused by Staphylococcus Aureus.

Surgical infections [Epub ahead of print].

BACKGROUND: Despite significant advancements in surgical protocols and biomaterials for orthopedics, peri-prosthetic joint infection (PJI) remains a leading cause of implant failure. Staphylococcus aureus nasal colonization is an established risk factor for PJI, with methicillin-sensitive S. aureus a leading cause of orthopedic implant-related infections. The purpose of these in vitro studies was to investigate the antibacterial activity of a tailored bacteriophage cocktail against planktonic and biofilm-associated S. aureus.

METHODS: The S. aureus strains (n = 30) were screened for their susceptibility to a library of S. aureus-specific bacteriophage (n = 31). Five bacteriophage preparations that demonstrated bactericidal activity against >90% of S. aureus strains tested were combined as a StaPhage cocktail and assessed for their antibacterial activity toward planktonic and biofilm-associated S. aureus, with biofilms established on three-dimensional-printed porous titanium scaffolds.

RESULTS: StaPhage treatment immediately after bacterial inoculation inhibited growth of S. aureus by >98% in eight hour cultures when multiplicity of infection of phages to bacteria was greater than 1:1 (p < 0.01). Viable bacterial numbers within biofilms on titanium surfaces were significantly reduced (6.8 log10 to 6.2 log10 colony forming units [CFU]; p < 0.01) after exposure to the StaPhage cocktail, in vitro. No significant reduction was observed in biofilms exposed to 100 times the minimal inhibitory concentration of cefazolin (log10 6.81 CFU).

CONCLUSIONS: Combined, these data demonstrate the in vitro efficacy of S. aureus-specific bacteriophage cocktails against S. aureus growing on porous titanium and warrant further in vivo studies in a clinically relevant animal model to evaluate the potential application of bacteriophage in the management of PJI caused by S. aureus.

RevDate: 2018-09-12

Gula G, Dorotkiewicz-Jach A, Korzekwa K, et al (2018)

Complex Signaling Networks Controlling Dynamic Molecular Changes in Pseudomonas aeruginosa Biofilm.

Current medicinal chemistry pii:CMC-EPUB-92990 [Epub ahead of print].

The environment exerts strong influence on microbes. Adaptation of microbes to changing conditions is a dynamic process regulated by complex networks. Pseudomonas aeruginosa is a life-threating, versatile opportunistic and multi drug resistant pathogen that provides a model to investigate adaptation mechanisms to environmental changes. The ability of P. aeruginosa to form biofilms and to modify virulence in response to environmental changes are coordinated by various mechanisms including two-component systems (TCS), and secondary messengers involved in quorum sensing (QS) and c-di-GMP networks (diguanylate cyclase systems, DGC). In this review, we focus on the role of c-di-GMP during biofilm formation. We describe TCS and QS signal cascades regulated by c-di-GMP in response to changes in the external environment. We present a complex signaling network dynamically changing during the transition of P. aeruginosa from the free-living to sessile mode of growth.

RevDate: 2018-09-12

Silva AF, Borges A, Freitas CF, et al (2018)

Antimicrobial Photodynamic Inactivation Mediated by Rose Bengal and Erythrosine Is Effective in the Control of Food-Related Bacteria in Planktonic and Biofilm States.

Molecules (Basel, Switzerland), 23(9): pii:molecules23092288.

The thermal and chemical-based methods applied for microbial control in the food industry are not always environmentally friendly and may change the nutritional and organoleptic characteristics of the final products. Moreover, the efficacy of sanitizing agents may be reduced when microbial cells are enclosed in biofilms. The objective of this study was to investigate the effect of photodynamic inactivation, using two xanthene dyes (rose bengal and erythrosine) as photosensitizing agents and green LED as a light source, against Staphylococcus aureus, Listeria innocua, Enterococcus hirae and Escherichia coli in both planktonic and biofilm states. Both photosensitizing agents were able to control planktonic cells of all bacteria tested. The treatments altered the physicochemical properties of cells surface and also induced potassium leakage, indicating damage of cell membranes. Although higher concentrations of the photosensitizing agents (ranging from 0.01 to 50.0 μmol/L) were needed to be applied, the culturability of biofilm cells was reduced to undetectable levels. This finding was confirmed by the live/dead staining, where propidium iodide-labeled bacteria numbers reached up to 100%. The overall results demonstrated that photoinactivation by rose bengal and erythrosine may be a powerful candidate for the control of planktonic cells and biofilms in the food sector.

RevDate: 2018-09-11

Perez-Soto N, Creese O, Fernández-Trillo F, et al (2018)

Aggregation of Vibrio cholerae by cationic polymers enhances quorum sensing but over-rides biofilm dissipation in response to autoinduction.

ACS chemical biology [Epub ahead of print].

Vibrio cholerae is a Gram-negative bacterium found in aquatic environments and a human pathogen of global significance. Its transition between host-associated and environmental life styles involves the tight regulation of niche-specific phenotypes such as motility, biofilm formation and virulence. V. cholerae's transition from the host to environmental dispersal usually involves suppression of virulence and dispersion of biofilm communities. In contrast to this naturally occurring transition, bacterial aggregation by cationic polymers triggers a unique response, which is to suppress virulence gene expression while also triggering biofilm formation by V. cholerae, an artificial combination of traits that is potentially very useful to bind and neutralize the pathogen from contaminated water. Here, we set out to uncover the mechanistic basis of this polymer-triggered bacterial behavior. We found that bacteria-polymer aggregates undergo rapid autoinduction and achieve quorum sensing at bacterial densities far below those required for autoinduction in the absence of polymers. We demonstrate this induction of quorum sensing is due both to a rapid formation of autoinducer gradients and local enhancement of autoinducer concentrations within bacterial clusters, as well as the stimulation of CAI-1 and AI-2 production by aggregated bacteria. We further found that polymers cause an induction of the biofilm specific regulator VpsR and the biofilm structural protein RbmA, bypassing the usual suppression of biofilm during autoinduction. Overall, this study highlights that synthetic materials can be used to cross-wire natural bacterial responses to achieve a combination of phenotypes with potentially useful applications.

RevDate: 2018-09-11

Kwon HY, Kim JY, Lee JY, et al (2018)

CDy14: a novel biofilm probe targeting exopolysaccharide Psl.

Chemical communications (Cambridge, England) [Epub ahead of print].

Detection of biofilm bacteria would be an ideal method for the physicians to diagnose chronic bacterial infections directly, but there are few imaging probes available so far. Here, we report the development of a novel biofilm detecting fluorescent probe, CDy14, through an unbiased screening of a fluorescence library and elucidated its binding partner Psl, an exopolysaccharide of the biofilm.

RevDate: 2018-09-11

Sabba F, Terada A, Wells G, et al (2018)

Nitrous oxide emissions from biofilm processes for wastewater treatment.

Applied microbiology and biotechnology pii:10.1007/s00253-018-9332-7 [Epub ahead of print].

This paper discusses the microbial basis and the latest research on nitrous oxide (N2O) emissions from biofilms processes for wastewater treatment. Conditions that generally promote N2O formation in biofilms include (1) low DO values, or spatial DO transitions from high to low within the biofilm; (2) DO fluctuations within biofilm due to varying bulk DO concentrations or varying substrate concentrations; (3) conditions with high reaction rates, which lead to greater formation of intermediates, e.g., hydroxylamine (NH2OH) and nitrite (NO2-), that promote N2O formation; and (4) electron donor limitation for denitrification. Formation of N2O directly results from the activities of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and heterotrophic denitrifying bacteria. More research is needed on the roles of AOA, comammox, and specialized denitrifying microorganisms. In nitrifying biofilms, higher bulk ammonia (NH3) concentrations, higher nitrite (NO2-) concentrations, lower dissolved oxygen (DO), and greater biofilm thicknesses result in higher N2O emissions. In denitrifying biofilms, N2O accumulates at low levels as an intermediate and at higher levels at the oxic/anoxic transition regions of the biofilms and where COD becomes limiting. N2O formed in the outer regions can be consumed in the inner regions if COD penetrates sufficiently. In membrane-aerated biofilms, where nitrification takes place in the inner, aerobic biofilm region, the exterior anoxic biofilm can serve as a N2O sink. Reactors that include variable aeration or air scouring, such as denitrifying filters, trickling filters, or rotating biological contactors (RBCs), can form peaks of N2O emissions during or following a scouring or aeration event. N2O emissions from biofilm processes depend on the microbial composition, biofilm thickness, substrate concentrations and variability, and reactor type and operation. Given the complexity and difficulty in quantifying many of these factors, it may be difficult to accurately predict emissions for full-scale treatment plants. However, a better understanding of the mechanisms and the impacts of process configurations can help minimize N2O emission from biofilm processes for wastewater treatment.

RevDate: 2018-09-11

Díaz-García J, Marcos-Zambrano LJ, Muñoz P, et al (2018)

Does the composition of polystyrene trays affect Candida spp. biofilm formation?.

Medical mycology pii:5091889 [Epub ahead of print].

The biofilm formation ability of Candida species seems to have a role in the prognosis of patients with candidemia. Biofilm formation is usually tested using 96 well flat bottom polystyrene microtiter plates, although the type of plastic used is not commonly reported. This study compares biofilm formation by Candida spp. on six types of plates from three brands (three non-tissue-treated and three tissue-treated). Thirty isolates of each of the following species were selected: C. albicans, C. parapsilosis, C. glabrata, C. tropicalis, as well as 15 isolates of C. krusei (n = 135 isolates) from patients with candidemia. Biofilm production was evaluated by measuring biomass production and metabolic activity. Our results show higher biomass production and metabolic activity of biofilms formed on non-tissue-treated plates in comparison to those formed on tissue-treated plates (P < .001). We only found significant differences in metabolic activity of biofilms formed on non-tissue-treated plates (P < .003). All comparisons including biofilm formation and metabolic activity among plates of the same brand yielded higher biofilm formation on non-treated plates compared to treated plates (P < .001). Significant difference in biomass production by C. parapsilosis was only seen when comparing between the various tissue-treated plastics (P < .03). In contrast, comparisons of different non-tissue-treated tray brands yielded significant metabolic activity differences for all species except for C. parapsilosis (P < .05). Biofilm formation and metabolic activity is significantly affected by the plastic composition of non-tissue-treated trays leading to increased biofilm formation.

RevDate: 2018-09-11

Subhadra B, Kim DH, Woo K, et al (2018)

Control of Biofilm Formation in Healthcare: Recent Advances Exploiting Quorum-Sensing Interference Strategies and Multidrug Efflux Pump Inhibitors.

Materials (Basel, Switzerland), 11(9): pii:ma11091676.

Biofilm formation in healthcare is an issue of considerable concern, as it results in increased morbidity and mortality, imposing a significant financial burden on the healthcare system. Biofilms are highly resistant to conventional antimicrobial therapies and lead to persistent infections. Hence, there is a high demand for novel strategies other than conventional antibiotic therapies to control biofilm-based infections. There are two approaches which have been employed so far to control biofilm formation in healthcare settings: one is the development of biofilm inhibitors based on the understanding of the molecular mechanism of biofilm formation, and the other is to modify the biomaterials which are used in medical devices to prevent biofilm formation. This review will focus on the recent advances in anti-biofilm approaches by interrupting the quorum-sensing cellular communication system and the multidrug efflux pumps which play an important role in biofilm formation. Research efforts directed towards these promising strategies could eventually lead to the development of better anti-biofilm therapies than the conventional treatments.

RevDate: 2018-09-11

Zhang H, Du R, Cao S, et al (2018)

Mechanisms and characteristics of biofilm formation via novel DEAMOX system based on sequencing biofilm batch reactor.

Journal of bioscience and bioengineering pii:S1389-1723(18)30324-4 [Epub ahead of print].

A denitrifying ammonium oxidation (DEAMOX) process has been regarded as an innovative process to simultaneously treat ammonia and nitrate containing wastewaters, whereas very limited research has focused on its application in biofilm system. In this research, a novel DEAMOX process was established with fixed sponge carriers in a sequencing biofilm batch reactor (SBBR). To investigate biofilm formation process and characteristics can encourage further research on DEAMOX system optimization, deteriorated performance recovery strategies and application with actual wastewater. Total nitrogen removal efficiency was maintained at 93.0 % after 240 days of operation. With biofilm growth, the protein-like extracellular polymeric substances (EPS) and tightly-bound EPS (TB-EPS) of biofilms increased from 65.6 to 46.1, to 179.6 and 142.0 mg gVSS-1, respectively, revealing that protein-like substances and TB-EPS promote biofilm formation. The mechanism of biofilm formation was discussed by analyzing the morphological development and functional bacterial activities of biofilms. Furthermore, high anammox activity was obtained in biofilms with specific NH4+N removal rates over 4.29 mgN gVSS-1h-1, which were significantly higher than in suspended sludge (2.56 mgN gVSS-1h-1). Quantitative polymerase chain reaction results showed that the abundance of anammox bacteria in biofilms increased from 1.87 % to 11.48 % with biofilm growth. These results imply that mature biofilms formed on carriers and the anammox bacteria were sufficient enriched in DEAMOX-SBBR system.

RevDate: 2018-09-11

Morohoshi T, Xie X, T Ikeda (2018)

N-Acylhomoserine lactone-mediated quorum sensing regulates biofilm structure in Methylobacterium populi P-1M, an isolate from a pink-pigmented household biofilm.

Bioscience, biotechnology, and biochemistry [Epub ahead of print].

Numerous gram-negative bacteria have quorum-sensing systems and produce AHL as a quorum-sensing signal molecule. In this study, we demonstrated that Methylobacterium populi P-1M, an isolate from a pink-pigmented household biofilm, produced two AHLs, C14:1-HSL as a predominant product and 3OHC14-HSL as a minor product. The complete genome sequence of M. populi P-1M revealed the presence of genes that are predicted to encode an AHL synthase (mpoI) and AHL receptor (mpoR). M. populi P-1M formed a pellicle-like biofilm, which had a flat surface and was easily removable. In contrast, biofilms formed by mpoI and/or mpoR deletion mutants had a wavy surface structure and strongly adhered to the glass tube. When C14:1-HSL was added to the mpoI mutant culture, the biofilm structure resembled that of the wild-type strain. These results demonstrated that the structure and adhesion strength of M. populi P-1M biofilms are determined in part by AHL-mediated quorum sensing.

ABBREVIATIONS: AHL: N-acyl-l-homoserine lactone; C14:1-HSL: N-tetradecenoyl-l-homoserine lactone; 3OHC14-HSL: N-(3-hydroxytetradecanoyl)-l-homoserine lactone; SAM: S-adenosyl-l-methionine; ACP: acyl-acyl carrier protein; EPS: extracellular polysaccharide; DMSO: dimethyl sulfoxide.

RevDate: 2018-09-11

Zhou G, Wang YS, Peng H, et al (2018)

Role of Ttca of Citrobacter Werkmanii in Bacterial Growth, Biocides Resistance, Biofilm Formation and Swimming Motility.

International journal of molecular sciences, 19(9): pii:ijms19092644.

To screen, identify and study the genes involved in isothiazolone resistance and biofilm formation in Citrobacter werkmanii strain BF-6. A Tn5 transposon library of approximately 900 mutants of C. werkmanii strain BF-6 was generated and screened to isolate 1,2-benzisothiazolin-3-one (BIT) resistant strains. In addition, the tRNA 2-thiocytidine (32) synthetase gene (ttcA) was deleted through homologous recombination and the resulting phenotypic changes of the ΔttcA mutant were studied. A total of 3 genes were successfully identified, among which ΔttcA mutant exhibited a reduction in growth rate and swimming motility. On the other hand, an increase in biofilms formation in ΔttcA were observed but not with a significant resistance enhancement to BIT. This work, for the first time, highlights the role of ttcA gene of C. werkmanii strain BF-6 in BIT resistance and biofilm formation.

RevDate: 2018-09-11

Zhu CT, Mei YY, Zhu LL, et al (2018)

Recombinant Escherichia coli BL21-pET28a-egfp Cultivated with Nanomaterials in a Modified Microchannel for Biofilm Formation.

International journal of molecular sciences, 19(9): pii:ijms19092590.

The application of whole cells as catalytic biofilms in microchannels has attracted increasing scientific interest. However, the excessive biomass formation and structure of biofilms in a reactor limits their use. A microchannel reactor with surface modification was used to colonize recombinant Escherichia coil BL21-pET28a-egfp rapidly and accelerated growth of biofilms in the microchannel. The segmented flow system of 'air/culture medium containing nanomaterials' was firstly used to modulate the biofilms formation of recombinant E. coil; the inhibitory effects of nanomaterials on biofilm formation were investigated. The results indicated that the segmental flow mode has a significant impact on the structure and development of biofilms. Using the channels modified by silane reagent, the culture time of biofilms (30 h) was reduced by 6 h compared to unmodified channels. With the addition of graphene sheets (10 mg/L) in Luria-Bertani (LB) medium, the graphene sheets possessed a minimum inhibition rate of 3.23% against recombinant E. coil. The biofilms cultivated by the LB medium with added graphene sheets were stably formed in 20 h; the formation time was 33.33% shorter than that by LB medium without graphene. The developed method provides an efficient and simple approach for rapid preparation of catalytic biofilms in microchannel reactors.

RevDate: 2018-09-11

Phukhamsakda C, Macabeo APG, Yuyama KT, et al (2018)

Biofilm Inhibitory Abscisic Acid Derivatives from the Plant-Associated Dothideomycete Fungus, Roussoella sp.

Molecules (Basel, Switzerland), 23(9): pii:molecules23092190.

Roussoella species are well recorded from both monocotyledons and dicotyledons. As part of a research program to discover biologically active compounds from plant-associated Dothideomycetes in Thailand, the strain Roussoella sp. (MFLUCC 17-2059), which represents an undescribed species, was isolated from Clematis subumbellata Kurz, fermented in yeast-malt medium and explored for its secondary metabolite production. Bioassay-guided fractionation of the crude extract yielded the new abscisic acid derivative, roussoellenic acid (1), along with pestabacillin B (2), a related congener, and the cyclodipeptide, cyclo(S-Pro-S-Ile) (3). The structure of 1 was determined by 2D NMR spectroscopy and HR-ESIMS data analysis. Compounds 1 and 2 showed inhibitory activity on biofilm formation by Staphylococcus aureus. The biofilm formation of S. aureus was reduced to 34% at 16 µg/mL by roussoellenic acid (1), while pestabacillin B (2) only showed 36% inhibition at 256 µg/mL. In addition, compound 1 also had weak cytotoxic effects on L929 murine fibroblasts and human KB3-1 cancer cells.

RevDate: 2018-09-10

Yin B, Zhu L, Zhang Y, et al (2018)

The Characterization of Biofilm Formation and Detection of Biofilm-Related Genes in Salmonella Isolated from Beef Processing Plants.

Foodborne pathogens and disease [Epub ahead of print].

The biofilm formation behavior of Salmonella isolated from beef processing plants was investigated under varying temperatures (4°C, 10°C, 25°C, 37°C, and 42°C) and pH (4.5, 5.0, 5.5, 6.0, 7.0, and 8.0). The relationships between the presence of biofilm-related genes and the biofilm formation capacity were evaluated. A total of 77 Salmonella strains in 8 different serotypes were assessed: Salmonella Agona (n = 43), Salmonella Senftenberg (n = 13), Salmonella Meleagridis (n = 8), Salmonella Derby (n = 7), Salmonella Kottbus (n = 2), Salmonella Calabar (n = 2), Salmonella Kingston (n = 1), and Salmonella Typhimurium (n = 1). The results showed that all tested Salmonella strains produced biofilm at 25°C and 37°C after 3 d, and Salmonella Kingston and Salmonella Senftenberg had higher biofilm production than other strains under test conditions. Serotype, incubation temperature, pH, and their interactions had significant effects on biofilm formation for Salmonella. The strongest biofilm formation capacity of Salmonella (serovar Agona, Senftenberg, Kottbus, Calabar, Kingston, and Typhimurium) occurred at 25°C and at pH 7.0. Biofilm formation was significantly inhibited for all Salmonella strains incubated at 4°C. The detection rates of genes rpoS, fliC, wcaA, and invA were 100%, and the rates of genes csgB, csgD, csrA, sirA, adrA, gly, fimH, sdiA, ompR, sipB, sipC, luxS, and pfs exceeded 75% among all biofilm producer strains. The detection rate of igaA was significantly different between different biofilm producers. Based on the findings in this study, useful information on biofilm formation of Salmonella isolated from beef processing plants in China is provided, which could help clear the technological hurdle in delaying biofilm production to deal with risks from Salmonella biofilms in the beef industry.

RevDate: 2018-09-09

Vijayakumar K, T Ramanathan (2018)

Antiquorum sensing and biofilm potential of 5- Hydroxymethylfurfural against Gram positive pathogens.

Microbial pathogenesis pii:S0882-4010(18)30335-8 [Epub ahead of print].

The present investigates the antiquorum sensing and biofilm inhibitory potential of 5 - hydroxymethylfurfural against Chromobacterium violaceum, Streptococcus pyogenes, Streptococcus mutans, Staphylococcus aureus and Staphylococcus epidermidis. 5HMF inhibits the quorum sensing mediated violacein pigment production by 87% at 100 μg/ml concentration. A 100 μg/ml concentration of the compound inhibits S. mutans and S. epidermidis biofilm formation by 86% and 79% whereas for S. pyogenes and S. aureus 125 μg/ml concentration inhibits biofilm formation by 83% and 82%. The Confocal images clearly indicate that 5HMF as a promising antibiofilm agent.

RevDate: 2018-09-09

Zou M, D Liu (2018)

A systematic characterization of the distribution, biofilm-forming potential and the resistance of the biofilms to the CIP processes of the bacteria in a milk powder processing factory.

Food research international (Ottawa, Ont.), 113:316-326.

Owing to the resistance to conventional cleaning and sanitizing agents, biofilms formed on surfaces of dairy processing equipment pose a hazard to the dairy industry. The objective of this study was to evaluate the diversity of the microflora attached to various surfaces of the processing lines of a milk powder processing factory based on 16S rRNA gene sequence analysis. The production of biofilms by the bacterial strains was evaluated on polystyrene (PS) and stainless-steel (SS) surfaces by crystal violet staining method. Especially, effects of temperatures (e.g., 37 °C and 55 °C) and growth mediums (e.g., nutrient broth, NB; tryptic soy broth, TSB) on the production of biofilms by these strains on PS surfaces were explored. Besides, the tolerance of the biofilms of the strains to CIP processes (1.5% v/v HNO3 solution or 2.0% w/v NaOH solution at 80 °C) were analyzed. Forty-five isolates from eleven interior surfaces of the facilities were identified and the distribution of strains had high species diversity, which indicated that multiple spoilage and pathogenic microorganisms remained in milk powder processing lines after CIP processes. Bacteria showed higher biofilm-forming abilities on SS compared to PS surfaces under the same condition. Moreover, effects of the incubation temperature and growth medium on biofilm formation varied between genera, species, and strains. One strain of each species with biofilm-forming abilities on SS surfaces was selected to check the resistance of their biofilms formed on SS coupons to the CIP processes. Biofilms of all of the nine strains were highly or moderately alkali and acid resistant, posing a threat to the milk powder production. These results suggested that organisms within the biofilm might withstand temperature and pH changes better than planktonic organisms. More research is needed to investigate different species isolated from different facilities of the processing lines and to improve the key controlling points in the CIP processes.

RevDate: 2018-09-08

Quendera AP, Barreto AS, T Semedo-Lemsaddek (2018)

Antimicrobial activity of essential oils against foodborne multidrug-resistant enterococci and aeromonads in planktonic and biofilm state.

Food science and technology international = Ciencia y tecnologia de los alimentos internacional [Epub ahead of print].

The selection and use of natural compounds with antimicrobial activity against foodborne pathogens is of major importance. The present study evaluated the antimicrobial activity of commercial essential oils against multidrug-resistant Enterococcus spp. and Aeromonas spp. Cymbopogon flexuosus and Thymus vulgaris essential oils presented the highest inhibitory zones against both bacterial groups (p < 0.05). Subsequent determination of the minimum inhibitory concentrations showed values between 0.47 and 1.9 mg/ml for Aeromonas spp. and from 1.9 to 15 mg/ml for Enterococcus spp. The antimicrobial effect of C. flexuosus and T. vulgaris essential oils was also assessed against biofilms. Bacteria in biofilm state were subjected to 30 min or 1 h of exposure to each essential oil and eradication ability estimated by colony counting. Both essential oils exhibited antimicrobial activity against preformed Aeromonas biofilms, but were unable to successfully eradicate biofilms produced by enterococci, in the conditions under investigation. Nonetheless, the presumptive use of essential oils in the food industry should be considered in further investigations.

RevDate: 2018-09-07

Ionescu AC, Brambilla E, Azzola F, et al (2018)

Laser microtextured titanium implant surfaces reduce in vitro and in situ oral biofilm formation.

PloS one, 13(9):e0202262 pii:PONE-D-18-06541.

INTRODUCTION: Micro- or nano-topography can both provide antimicrobial properties and improve osseointegration of dental implant titanium surfaces. Laser treatment is one of the best surface microtexturing techniques. The aim of this study was to evaluate in vitro and in situ biofilm formation on a laser-treated titanium surface, comparing it with two conventional surfaces, machined and grit-blasted.

METHODS: For the in vitro experiment, an oral microcosm biofilm model was developed on the surface of titanium disks and reference human enamel using a bioreactor for 48 h. For the in situ experiment, titanium implants with laser-treated, machined and grit-blasted surfaces were mounted on intraoral trays and worn by ten volunteers for 48 h. Biofilm formation was quantitatively evaluated, and surfaces were analyzed using confocal laser scanning microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy.

RESULTS–IN VITRO STUDY: Biofilm structures with a prevalence of viable cells covered most of the machined, grit-blasted and human enamel surfaces, whereas less dense biofilm structures with non-confluent microcolonies were observed on the laser-treated titanium. Laser-treated titanium showed the lowest biofilm formation, where microorganisms colonized the edges of the laser-created pits, with very few or no biofilm formation observed inside the pits.

RESULTS–IN SITU STUDY: The biofilm formation pattern observed was similar to that in the in vitro experiment. Confocal laser scanning microscopy showed complete coverage of the implant threads, with mostly viable cells in grit-blasted and machined specimens. Unexpectedly, laser-treated specimens showed few dead microbial cells colonizing the bottom of the threads, while an intense colonization was found on the threading sides.

CONCLUSION: This data suggests that laser-created microtopography can reduce biofilm formation, with a maximum effect when the surface is blasted orthogonally by the laser beam. In this sense the orientation of the laser beam seems to be relevant for the biological interaction with biofilms.

RevDate: 2018-09-07

Kim M, Jeon J, J Kim (2018)

Streptococcus mutans extracellular DNA levels depend on the number of bacteria in a biofilm.

Scientific reports, 8(1):13313 pii:10.1038/s41598-018-31275-y.

Streptococcus mutans is a component of oral plaque biofilm that accumulates on the surface of teeth. The biofilm consists of extracellular components including extracellular DNA (eDNA). This study was conducted to investigate the factors that may affect the eDNA levels of S. mutans in biofilms. For the study, S. mutans UA159 biofilms were formed for 52 h on hydroxyapatite (HA) discs in 0% (w/v) sucrose +0% glucose, 0.5% sucrose, 1% sucrose, 0.5% glucose, 1% glucose, or 0.5% sucrose +0.5% glucose. Acidogenicity of S. mutans in the biofilms was measured after biofilm formation (22 h) up to 52 h. eDNA was collected after 52 h biofilm formation and measured using DNA binding fluorescent dye, SYBR Green I. Biofilms cultured in 0.5% sucrose or glucose had more eDNA and colony forming units (CFUs) and less exopolysaccharides (EPSs) than the biofilms cultured in 1% sucrose or glucose at 52 h, respectively. The biofilms formed in 0% sucrose +0% glucose maintained pH around 7, while the biofilms grown in 0.5% sucrose had more acidogenicity than those grown in 1% sucrose, and the same pattern was shown in glucose. In conclusion, the results of this study show that the number of S. mutans in biofilms affects the concentrations of eDNA as well as the acidogenicity of S. mutans in the biofilms. In addition, the thickness of EPS is irrelevant to eDNA aggregation within biofilms.

RevDate: 2018-09-07

Abtahi SM, Petermann M, Juppeau Flambard A, et al (2018)

Micropollutants removal in tertiary moving bed biofilm reactors (MBBRs): Contribution of the biofilm and suspended biomass.

The Science of the total environment, 643:1464-1480.

The performance of tertiary moving bed biofilm reactors (MBBRs) was evaluated in terms of micropollutants (MPs) removal from secondary-treated municipal wastewater. After stepwise establishment of a mature biofilm, monitored by scanning electron and confocal microscopies, abiotic and biotic removals of MPs were deeply studied. Since no MPs reduction was observed by the both photodegradation and volatilization, abiotic removal of MPs was ascribed to the sorption onto the biomass. Target MPs i.e. Naproxen, Diclofenac, 17β-Estradiol and 4n-Nonylphenol, arranged in the ascending order of hydrophobicity, abiotically declined up to 2.8%, 4%, 9.5% and 15%, respectively. MPs sorption onto the suspended biomass was found around two times more than the biofilm, in line with MPs' higher sorption kinetic constants (ksor) found for the suspended biomass. When comparing abiotic and biotic aspects, we found that biotic removal outperformed its counterpart for all compounds as Diclofenac, Naproxen, 17β-Estradiol and 4n-Nonylphenol were biodegraded by 72.8, 80.6, 84.7 and 84.4%, respectively. The effect of the changes in organic loading rates (OLRs) was investigated on the pseudo-first order degradation constants (kbiol), revealing the dominant biodegradation mechanism of co-metabolism for the removal of Diclofenac, Naproxen, and 4n-Nonylphenol, while 17β-Estradiol obeyed the biodegradation mechanism of competitive inhibition. Biotic removals and kbiol values of all MPs were also seen higher in the biofilm as compared to the suspended biomass. To draw a conclusion, a quite high removal of recalcitrant MPs is achievable in tertiary MBBRs, making them a promising technology that supports both pathways of co-metabolism and competitive inhibition, next to the abiotic attenuation of MPs.

RevDate: 2018-09-06

Fteita D, Könönen E, Gürsoy M, et al (2018)

Quorum sensing molecules regulate epithelial cytokine response and biofilm-related virulence of three Prevotella species.

Anaerobe pii:S1075-9964(18)30156-2 [Epub ahead of print].

Quorum sensing (QS) signaling regulates the motility, adhesion, and biofilm formation of bacteria, and at the same time activates immune response in eukaryotic organisms. We recently demonstrated that the QS molecule, dihydroxy-2, 3-pentanedione (DPD), and its analogs significantly inhibit estradiol-regulated virulence of Prevotella aurantiaca, one of the four species in the Prevotella intermedia group. Here, we examined the combined effects of estradiol and QS signaling on 1) cytokine response of human gingival keratinocytes (HMK) against whole cell extract (WCE) of P. intermedia, Prevotella nigrescens, and Prevotella pallens, and 2) biofilm formation of these three Prevotella species. All experiments were performed in the presence or absence of estradiol, and with different QS molecules: DPD and its analogs (ethyl-DPD, butyl-DPD, and isobutyl-DPD). Concentrations of interleukin (IL)-1β, -6, and -8 were determined by the Luminex multiplex immunoassay, biofilm mass was quantitatively evaluated by measuring protein concentration via the Bradford method, and the microtopography of biofilms was assessed by scanning electron microscopy (SEM) imaging. Concentrations of IL-6 and IL-8 were elevated when HMK cells were incubated with estradiol and WCE of P. intermedia and P. nigrescens, but decreased when incubated with estradiol and WCE of P. pallens. Butyl-DPD neutralized the estradiol- and WCE-induced regulation of HMK interleukin expression and, at the same time, inhibited the biofilm formation of P. intermedia and P. nigrescens. SEM micrographs revealed a decrease in biofilm mass after application of butyl-DPD, which was most detectable among the P. intermedia ATCC 25611 and P. nigrescens ATCC 33563 and AHN 8293 strains. In conclusion, butyl-DPD analog is able to neutralize the WCE-induced epithelial cytokine response and, at the same time, to inhibit the biofilm formation of P. intermedia and P. nigrescens.

RevDate: 2018-09-06

Esfahanizadeh N, Mirmalek SP, Bahador A, et al (2018)

Formation of biofilm on various implant abutment materials.

General dentistry, 66(5):39-44.

The characteristics of prosthetic implant components, such as the type, material, and surface roughness of abutments, can affect biofilm formation. Since an ideal abutment surface for the reduction of bacterial adhesion has yet to be found, this in vitro study aimed to quantify biofilm formation on laser-treated titanium, zirconia, and titanium surfaces. Sterile titanium, zirconia, and laser-treated titanium discs were placed in sterile 48-well plates. Biofilm formation was induced by adding sterilized, unstimulated human saliva and suspensions of Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), and Prevotella intermedia (Pi) to the wells. Viable bacteria in the biofilm were quantified with real-time polymerase chain reaction in conjunction with propidium monoazide. The disc material, the type of bacteria, and their interactions had significant effects on the bacterial counts. On all surfaces, the Pg count was significantly higher than both the Pi and Aa counts (P = 0.0001). The highest count of periodontal pathogens was found on laser-treated surfaces. The second highest and the lowest counts were found on zirconia and titanium surfaces, respectively.

RevDate: 2018-09-06

Maquera-Huacho PM, Tonon CC, Correia MF, et al (2018)

In vitro antibacterial and cytotoxic activities of carvacrol and terpinen-4-ol against biofilm formation on titanium implant surfaces.

Biofouling [Epub ahead of print].

This study evaluated the antibacterial properties of carvacrol and terpinen-4-ol against Porphyromonas gingivalis and Fusobacterium nucleatum and its cytotoxic effects on fibroblast cells. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were examined. The minimum biofilm inhibition concentration (MBIC) was evaluated by XTT assay. Biofilm decontamination on titanium surfaces was quantified (CFU ml-1), evaluated by confocal laser scanning microscopy (CLSM) and cytotoxic activity by MTT. The MIC and MBC for carvacrol were 0.007% and 0.002% for P. gingivalis and F. nucleatum, and 0.06% for terpinen-4-ol for both microorganisms. The MBIC for carvacrol was 0.03% and 0.06% for P. gingivalis and F. nucleatum, and for terpinen-4-ol was 0.06% and 0.24%. The results indicated anti-biofilm activity using carvacrol (0.26%, 0.06%) and terpinen-4-ol (0.95%, 0.24%) and showed cytotoxic activity similar to chlorohexidine (CHX). However, terpinen-4-ol (0.24%) showed higher cell viability than other treatments. Carvacrol and terpinen-4-ol showed antibacterial activity in respect of reducing biofilms. Moreover, CHX-like cytotoxicity was observed.

RevDate: 2018-09-06

Calvillo-Medina RP, Martínez Neria M, Mena-Portales J, et al (2018)

Identification and biofilm development by a new fungal keratitis etiologic agent.

Mycoses [Epub ahead of print].

BACKGROUND: In recent years, human keratitis caused by fungal plant pathogens has become more common. Biofilm is a structure that confers adaptations and virulence to fungi in keratitis. Neoscytalidium spp. are phytopathogenic and recently have been recognized as a human pathogen, using biofilm formation as a virulence factor.

OBJECTIVES: The aim of this study was isolation, identification (at the species level) and characterization of a new fungal keratitis agent.

PATIENTS/METHODS: The fungus was isolated from a 67-year-old male patient with a corneal ulcer. Biofilm formation and structure were evaluated by colorimetric methods and microscopy. To identify the fungus, morphological characteristics were examined and a phylogenetic analysis was performed.

RESULTS AND CONCLUSIONS: We report the identification of a fungus, a member of the genus Neoscytalidium which is associated with human keratitis. Phylogenetic analysis and morphological observations on conidiogenous cells, which occur only in arthric chains in aerial mycelium and the coelomycetous synasexual morph is absent identified a new species, Neoscytalidium oculus sp. nov. The fungus formed biofilm at a concentration of 1 x 106 conidia/ml, during 96h of incubation at 37°C, and also manifested hemolysis and melanin production. This is the first report in Latin America of a new species of Neoscytalidium from a clinical isolate has been identified. This article is protected by copyright. All rights reserved.

RevDate: 2018-09-06

Zhang Y, Sass A, Van Acker H, et al (2018)

Coumarin Reduces Virulence and Biofilm Formation in Pseudomonas aeruginosa by Affecting Quorum Sensing, Type III Secretion and C-di-GMP Levels.

Frontiers in microbiology, 9:1952.

As one of the major pathogens in wound infections, Pseudomonas aeruginosa produces several virulence factors and forms biofilms; these processes are under the regulation of various quorum sensing (QS) systems. Therefore, QS has been regarded as a promising target to treat P. aeruginosa infections. In the present study, we evaluated the effect of the plant-derived QS inhibitor coumarin on P. aeruginosa biofilms and virulence. Coumarin inhibited QS in the P. aeruginosa QSIS2 biosensor strain, reduced protease and pyocyanin production, and inhibited biofilm formation in microtiter plates in different P. aeruginosa strains. The effects of coumarin in inhibiting biofilm formation in an in vitro wound model and reducing P. aeruginosa virulence in the Lucilia sericata infection model were strain-dependent. Transcriptome analysis revealed that several key genes involved in the las, rhl, Pseudomonas quinolone signal (PQS), and integrated QS (IQS) systems were downregulated in coumarin-treated biofilms of P. aeruginosa PAO1. Coumarin also changed the expression of genes related to type III secretion and cyclic diguanylate (c-di-GMP) metabolism. The cellular c-di-GMP level of P. aeruginosa PAO1 and recent clinical P. aeruginosa strains was significantly reduced by coumarin. These results provide new evidence for the possible application of coumarin as an anti-biofilm and anti-virulence agent against P. aeruginosa in wound infections.

RevDate: 2018-09-06

Knight DB, Rudin SD, Bonomo RA, et al (2018)

Acinetobacter nosocomialis: Defining the Role of Efflux Pumps in Resistance to Antimicrobial Therapy, Surface Motility, and Biofilm Formation.

Frontiers in microbiology, 9:1902.

Acinetobacter nosocomialis is a member of the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex. Increasingly, reports are emerging of the pathogenic profile and multidrug resistance (MDR) phenotype of this species. To define novel therapies to overcome resistance, we queried the role of the major efflux pumps in A. nosocomialis strain M2 on antimicrobial susceptibility profiles. A. nosocomialis strains with the following mutations were engineered by allelic replacement; ΔadeB, ΔadeJ, and ΔadeB/adeJ. In these isogenic strains, we show that the ΔadeJ mutation increased susceptibility to beta-lactams, beta-lactam/beta-lactamase inhibitors, chloramphenicol, monobactam, tigecycline, and trimethoprim. The ΔadeB mutation had a minor effect on resistance to certain beta-lactams, rifampicin and tigecycline. In addition, the ΔadeJ mutation resulted in a significant decrease in surface motility and a minor decrease in biofilm formation. Our results indicate that the efflux pump, AdeIJK, has additional roles outside of antibiotic resistance in A. nosocomialis.

RevDate: 2018-09-06

Igumnova EM, Mishchenko E, Haug T, et al (2018)

Amphipathic sulfonamidobenzamides mimicking small antimicrobial marine natural products; investigation of antibacterial and anti-biofilm activity against antibiotic resistant clinical isolates.

Bioorganic & medicinal chemistry pii:S0968-0896(18)30897-6 [Epub ahead of print].

There is an urgent need for novel antimicrobial agents to address the threat of bacterial resistance to modern society. We have used a structural motif found in antimicrobial marine hit compounds as a basis for synthesizing a library of antimicrobial sulfonamidobenzamide lead compounds. Potent in vitro antimicrobial activity against clinically relevant bacterial strains was demonstrated for two compounds, G6 and J18, with minimal inhibitory concentrations (MIC) of 4-16 μg/ml against clinical methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). The two compounds G6 and J18, together with several other compounds of this library, also caused ≥90% eradication of pre-established biofilm of methicillin-resistant S. epidermidis (MRSE) at 40 μg/ml. Using a luciferase assay, the mechanism of action of G6 was shown to resemble the biocide chlorhexidine by targeting the bacterial cell membrane.

RevDate: 2018-09-06

Pezzoni M, Pizarro RA, CS Costa (2018)

Exposure to low doses of UVA increases biofilm formation in Pseudomonas aeruginosa.

Biofouling [Epub ahead of print].

The establishment of bacterial biofilms on abiotic surfaces is a complex process regulated by multiple genetic regulators and environmental factors which are able to modulate the passage of planktonic cells to a sessile state. Solar ultraviolet-A radiation (UVA, 315-400) is one of the main environmental stress factors that bacteria must face at the Earth´s surface. The deleterious effects of UVA are mainly due to oxidative damage. This paper reports that exposure to low UVA doses promotes biofilm formation in three prototypical strains of Pseudomonas aeruginosa, a relevant opportunistic human pathogen. It demonstrates that exposure of planktonic cells to sublethal doses of UVA can increase cell surface hydrophobicity and swimming motility, two parameters known to favor cell adhesion. These results suggest that UVA radiation acts, at least in part, by promoting the first stages of biofilm development.

RevDate: 2018-09-06

Alvarado-Gomez E, Martínez-Castañon G, Sanchez-Sanchez R, et al (2018)

Evaluation of anti-biofilm and cytotoxic effect of a gel formulation with Pluronic F-127 and silver nanoparticles as a potential treatment for skin wounds.

Materials science & engineering. C, Materials for biological applications, 92:621-630.

The skin wounds cause serious burden to healthcare systems. The lack of sterility of the innate barrier function of the skin facilitates the development of microbial communities within the wound environment especially in biofilm form. Since biofilm is difficult to eradicate, new treatments have been established, such as silver nanoparticles (AgNPs), which antimicrobial and anti-biofilm properties have been studied, nevertheless, their toxic effects are known too. Different concentrations of AgNPs stabilized with a biocompatible and thermo-reversible vehicle as hydrogel Pluronic F-127 were synthesized, those formulations presented interesting thermo-reversibility which could be used to apply on wounds. The formulations (Gel 62.5, 125, and 250 ppm of AgNPs) proposed in this study showed in vitro a total inhibition of clinical strains (Staphylococcus aureus and Pseudomonas aeruginosa) in planktonic form, as well as, anti-biofilm activity was archived with the formulation of Gel 250 ppm, a total inhibition of biofilm formation with mixed culture was registered in the first 30 min of biofilm growth; even more, the viability of human fibroblasts with all gels formulations was >95%, in contrast to silver sulfadiazine cream 1% which showed the highest cytotoxic effect. PF-127 gel with AgNPs could be a prophylactic treatment for skin wounds, because its activity in critical steps on biofilm formation.

RevDate: 2018-09-05

Kim HJ, Oh T, SY Baek (2018)

Multidrug Resistance, Biofilm Formation, and Virulence of Escherichia coli Isolates from Commercial Meat and Vegetable Products.

Foodborne pathogens and disease [Epub ahead of print].

Escherichia coli is an important food safety and public health concern because of its pathogenicity and potential for antimicrobial resistance. E. coli isolates as food contaminants and their antimicrobial resistance, biofilm-forming ability, and virulence genes were analyzed to identify the potential of E. coli in food as a major transmission route for antimicrobial resistance and infectious agents. Among the 709 samples of minced meat and fresh vegetable products tested, 18.6% were positive for E. coli. One hundred nine (29.2%) out of 383 E. coli isolates were resistant to 1 or more of the 25 tested antimicrobials. Among the isolates from minced pork, the highest rate of resistance was observed for tetracycline (52.8%), followed by ampicillin (41.6%). The highest resistance rates against tetracycline were coincident with the high amount of tetracycline sold for veterinary use. Because penicillin is the most frequently used antimicrobial in humans, with 4.52 defined daily doses per 1000 people per day, the high rate of resistance to ampicillin (41.6%) supported the potential risk of E. coli food contaminants. However, only 1.3% of the isolates possessed the virulence genes commonly involved in foodborne outbreaks of E. coli. Sixty-seven isolates (17.5%) were multidrug-resistant (MDR), and the highest MDR was observed against 14 antimicrobials. Most of the MDR E. coli isolates showed biofilm-forming ability. Therefore, these isolates will have additional protection from environmental stresses, including antimicrobials. Given the importance of E. coli to food safety and public health, our results on the prevalence of antimicrobial resistance and virulence factors provide useful information for risk management options to protect public health.

RevDate: 2018-09-05

D'Abrosca G, Paladino A, Cuoco E, et al (2018)

Structural Characterization of the Lactobacillus Plantarum FlmC Protein Involved in Biofilm Formation.

Molecules (Basel, Switzerland), 23(9): pii:molecules23092252.

Lactobacillus plantarum is one of the most predominant species in the human gut microbiota of healthy individuals. We have previously characterized some probiotic features of L. plantarum LM3, as the high resistance to different stress, the binding ability toward some extracellular matrix proteins and plasminogen and the immunomodulatory role of the surface expressed adhesin EnoA1. We have also identified the flmA, flmB and flmC genes, coding for putative proteins named FlmA, FlmB and FlmC, whose null mutations partially impaired biofilm development; the L. plantarum LM3⁻6 strain, carrying a deletion in flmC, showed a high rate of autolysis, supporting the hypothesis that FlmC might be involved in cell wall integrity. Here, we report the in-silico characterization of ΔTM-FlmC, a portion of the FlmC protein. The protein has been also expressed, purified and characterized by means of CD spectroscopy, ICP-mass and UHPLC-HRMS. The obtained experimental data validated the predicted model unveiling also the presence of a bound lipid molecule and of a Mg(II) ion. Overall, we provide strong evidences that ΔTM-FlmC belongs to the LytR-CpsA-Psr (LCP) family of domains and is involved in cell envelope biogenesis.

RevDate: 2018-09-05

Ge X, Cai Y, Chen Z, et al (2018)

Bifunctional enzyme SpoT is involved in biofilm formation of Helicobacter pylori with multidrug resistance by upregulating efflux pump Hp1174 (gluP).

Antimicrobial agents and chemotherapy pii:AAC.00957-18 [Epub ahead of print].

The drug resistance of Helicobacter pylori (H. pylori) is gradually becoming a serious problem. Biofilm formation is an important factor that leads to multidrug resistance in bacteria. The ability of H. pylori to form biofilms on the gastric mucosa is known. However, there are few studies on the regulatory mechanisms of H. pylori biofilm formation and multidrug resistance. Guanosine 3'-diphosphate 5'-triphosphate and guanosine 3',5'-bispyrophosphate [(p)ppGpp] are global regulatory factors and are synthesized in H. pylori by the bifunctional enzyme SpoT. It has been reported that (p)ppGpp is involved in the biofilm formation and multidrug resistance of various bacteria. In this study, we found that SpoT also plays an important role in H. pylori biofilm formation and multidrug resistance. Therefore, it is necessary to carry out some further studies regarding its regulatory mechanism. Considering that efflux pumps are of great importance in the biofilm formation and multidrug resistance of bacteria, we tried to determine whether efflux pumps controlled by SpoT participate in these activities. We found that Hp1174 (glucose/galactose transporter, gluP), an efflux pump of the major facilitator superfamily (MFS), is highly expressed in biofilm-forming and multidrug-resistant (MDR) H. pylori and is upregulated by SpoT. Through further research, we determined that gluP involved in H. pylori biofilm formation and multidrug resistance. Furthermore, the average expression level of gluP in the clinical MDR strains (C-MDR) was considerably higher than that in the clinical drug-sensitive strains (C-DSS). Taken together, our results revealed a novel molecular mechanism of H. pylori resistance to multidrug exposure.

RevDate: 2018-09-05

Kampf J, Gerwig J, Kruse K, et al (2018)

Selective Pressure for Biofilm Formation in Bacillus subtilis: Differential Effect of Mutations in the Master Regulator SinR on Bistability.

mBio, 9(5): pii:mBio.01464-18.

Biofilm formation by Bacillus subtilis requires the expression of genes encoding enzymes for extracellular polysaccharide synthesis and for an amyloid-like protein. The master regulator SinR represses all the corresponding genes, and repression of these key biofilm genes is lifted when SinR interacts with its cognate antagonist proteins. The YmdB phosphodiesterase is a recently discovered factor that is involved in the control of SinR activity: cells lacking YmdB exhibit hyperactive SinR and are unable to relieve the repression of the biofilm genes. In this study, we have examined the dynamics of gene expression patterns in wild-type and ymdB mutant cells by microfluidic analysis coupled to time-lapse microscopy. Our results confirm the bistable expression pattern for motility and biofilm genes in the wild-type strain and the loss of biofilm gene expression in the mutant. Moreover, we demonstrated dynamic behavior in subpopulations of the wild-type strain that is characterized by switches in sets of the expressed genes. In order to gain further insights into the role of YmdB, we isolated a set of spontaneous suppressor mutants derived from ymdB mutants that had regained the ability to form complex colonies and biofilms. Interestingly, all of the mutations affected SinR. In some mutants, large genomic regions encompassing sinR were deleted, whereas others had alleles encoding SinR variants. Functional and biochemical studies with these SinR variants revealed how these proteins allowed biofilm gene expression in the ymdB mutant strains.IMPORTANCE Many bacteria are able to choose between two mutually exclusive lifestyles: biofilm formation and motility. In the model bacterium Bacillus subtilis, this choice is made by each individual cell rather than at the population level. The transcriptional repressor SinR is the master regulator in this decision-making process. The regulation of SinR activity involves complex control of its own expression and of its interaction with antagonist proteins. We show that the YmdB phosphodiesterase is required to allow the expression of SinR-repressed genes in a subpopulation of cells and that such subpopulations can switch between different SinR activity states. Suppressor analyses revealed that ymdB mutants readily acquire mutations affecting SinR, thus restoring biofilm formation. These findings suggest that B. subtilis cells experience selective pressure to form the extracellular matrix that is characteristic of biofilms and that YmdB is required for the homeostasis of SinR and/or its antagonists.

RevDate: 2018-09-05

Alizadeh S, Ghoshal S, Y Comeau (2018)

Fate and inhibitory effect of silver nanoparticles in high rate moving bed biofilm reactors.

The Science of the total environment, 647:1199-1210 pii:S0048-9697(18)33039-0 [Epub ahead of print].

Municipal water resource recovery facilities are the primary recipients of a significant fraction of discharged silver nanoparticle (AgNP)-containing wastes, yet the fate and potential risks of AgNPs in attached-growth biological wastewater treatment processes are poorly understood. The fate and inhibitory effects of polyvinylpyrrolidone (PVP)-coated AgNPs at environmentally-relevant nominal concentrations (10, 100, 600 μg/L) were investigated, for the first time, in high rate moving bed biofilm reactors (MBBRs) for soluble organic matter removal. The behavior and removal of continuously added AgNPs were characterized using single-particle inductively coupled plasma mass spectrometry (spICP-MS). While no inhibitory effect at average influent concentration of 10.8 μg/L Ag was observed, soluble COD removal efficiency was significantly decreased at 131 μg/L Ag in 18 days and 631 μg/L Ag in 5 days with suppressed biofilm viability. The inhibitory effect of AgNPs on treatment efficiency was highly correlated to the retained mass of total Ag in attached biofilm on the carriers. Biofilm demonstrated limited retention capacity for AgNPs over 18 days. Considerable mass of Ag (38% to 75%) was released via effluent, predominantly as NPs. We detected some chemically transformed and potentially less toxic forms of silver nanoparticles (Ag2S, AgCl), over the exposure period. This study demonstrated the distinct interaction dynamics, bioavailability and inhibitory effects of AgNPs in a biofilm system. Release of bioavailable AgNPs via effluent and AgNP-rich biofilm, sloughing off the carriers, can affect the treatment chain efficiency of downstream processes. Thus, the inhibitory effects of AgNPs can be a concern even at concentrations as low as 100 to 600 μg/L Ag in biological attached growth wastewater treatments.

RevDate: 2018-09-04

Ni H, Zhou X, Zhang X, et al (2018)

Feasibility of using basalt fiber as biofilm Carrier to construct bio-nest for wastewater treatment.

Chemosphere, 212:768-776 pii:S0045-6535(18)31611-4 [Epub ahead of print].

Generally, biofilms developed for wastewater treatment readily detach from carrier medium once available thickness exceeds about 2 mm. Carrier media made of basalt fibers (BFs) could form ball-like aggregates (more than 10 cm in size, and called bio-nest). To demonstrate its feasibility for wastewater treatment, both reactors with and without BF carriers (RBF and RCO) were evaluated in terms of nutrient removal, oxygen mass transport and biological viabilities as well as biofilm adsorption characteristics. Therefore, oxygen microprofiles and confocal images for bio-nest as well as functional groups for biofilm-attached BF were performed on microsensor systems, confocal laser scanning microscopy (CLSM) and Fourier transform infrared (FTIR). Despite COD:N ratio, both reactors removed about 90% of COD, while only RBF reactor achieved high denitrification capabilities, with nitrogen removal efficiencies varying between 60.10 ± 0.45% and 82.07 ± 0.64%. Microprofile and confocal images showed that dissolved oxygen could reach the core with depth up to 50 mm, at which viable bacteria were detected. Characteristic peaks on FT-IR spectrum demonstrated that various functional groups of polysaccharide and proteins in EPS played a key role in aggregating biofilm-attached BFs into a bio-nest. Thus, BF provides a promising alternative to conventional carrier medium for wastewater treatment.

RevDate: 2018-09-04

Li B, Qiu Y, Zhang J, et al (2018)

Real-time study of rapid spread of antibiotic resistance plasmid in biofilm using microfluidics.

Environmental science & technology [Epub ahead of print].

Gene transfer in biofilms is known to play an important role in antibiotic resistance dissemination. However, the process remains poorly understood. In this study, microfluidics with time-lapse imaging was used for real-time monitoring of plasmid-mediated horizontal gene transfer (HGT) in biofilms. Pseudomonas putida KT2440 harbouring an antibiotic resistance plasmid RP4 was chosen as the donor while Escherichia coli and activated sludge bacteria were used as the recipient cells. Dynamic features of the transfer process, including the transfer rate, cell growth rate and kinetic changes of the transfer frequency, were determined. It was found that the routes for gene transfer strongly depend on the structure and composition of a biofilm. While intra-species HGT is essential to initiate a transfer event, the secondary re-transfer from transconjugants to the same species is more efficient and can cause cascading gene spread in single-strain biofilms. For the activated sludge biofilm, only small and scattered colonies formed and vertical gene transfer appears to be the dominant route after initial intra-species transfer. Furthermore, more than 46% of genera in the activated sludge were permissive to plasmid RP4, many of which are associated with human pathogens. These phenomena imply early prevention and interruptions to biofilm structure could provide an effect way to inhibit rapid antibiotic resistance gene spread and reduce the likelihood of catastrophic events associated with antibiotic resistance.

RevDate: 2018-09-04

Zhang Y, Xu D, Shi L, et al (2018)

Association Between agr Type, Virulence Factors, Biofilm Formation and Antibiotic Resistance of Staphylococcus aureus Isolates From Pork Production.

Frontiers in microbiology, 9:1876.

Livestock-associated Staphylococcus aureus colonization and/or infections exist in pigs and people in frequent contact with pigs. In this study, a total of 130 S. aureus isolates obtained from different stages of pork production were subjected to antimicrobial susceptibility, biofilm formation, as well as PCR screening to identify virulence genes, and the accessory gene regulator alleles (agr). Among all 130 S. aureus isolates, 109 (83.8%, 109/130) isolates were positive for agr. All swine farms isolates belonged to agr IV, whereas S. aureus isolated from slaughterhouse and retail indicated diverse agr types. All isolates exhibited biofilm formation ability, and raw meat isolates (belonging to agr I) exhibited a greater ability to form strong biofilms than swine farms isolates (belonging to agr IV). agr-positive isolates were associated with more virulence genes than agr-negative isolates. Most biofilm-producing isolates were positive for microbial surface component recognizing adhesive matrix molecule (MSCRAMM), capsule type and ica group genes. The results illustrate a significant association between the prevalence rate of MSCRAMM, capsule type and ica group genes among isolates producing weak, moderate and strong biofilms. The high prevalence of resistance to ciprofloxacin, gentamicin, tetracycline, clarithromycin, clindamycin, and trimethoprim-sulfamethoxazole were mainly observed in moderate and weak biofilm producers. Our findings indicate that S. aureus isolates from pork production displayed diverse molecular ecology.

RevDate: 2018-09-04

Zhang J, CL Poh (2018)

Regulating exopolysaccharide gene wcaF allows control of Escherichia coli biofilm formation.

Scientific reports, 8(1):13127 pii:10.1038/s41598-018-31161-7.

While biofilms are known to cause problems in many areas of human health and the industry, biofilms are important in a number of engineering applications including wastewater management, bioremediation, and bioproduction of valuable chemicals. However, excessive biofilm growth remains a key challenge in the use of biofilms in these applications. As certain amount of biofilm growth is required for efficient use of biofilms, the ability to control and maintain biofilms at desired thickness is vital. To this end, we developed synthetic gene circuits to control E. coli MG1655 biofilm formation by using CRISPRi/dCas9 to regulate a gene (wcaF) involved in the synthesis of colanic acid (CA), a key polysaccharide in E. coli biofilm extracellular polymeric substance (EPS). We showed that the biofilm formation was inhibited when wcaF was repressed and the biofilms could be maintained at a different thickness over a period of time. We also demonstrated that it is also possible to control the biofilm thickness spatially by inhibiting wcaF gene using a genetic light switch. The results demonstrate that the approach has great potential as a new means to control and maintain biofilm thickness in biofilm related applications.

RevDate: 2018-09-04

Tan Y, Ma S, Leonhard M, et al (2018)

Enhancing antibiofilm activity with functional chitosan nanoparticles targeting biofilm cells and biofilm matrix.

Carbohydrate polymers, 200:35-42.

Bacterial biofilms play a key role during infections, which are associated with an increased morbidity and mortality. The classical antibiotic therapy cannot eradicate biofilm-related infections because biofilm bacteria display high drug resistance due to biofilm matrix. Thus, novel drug delivery to overcome biofilm resistance and eliminate biofilm-protected bacteria is needed to be developed. In this study, positively charged chitosan nanoparticles (CSNP) loaded with oxacillin (Oxa) and Deoxyribonuclease I (CSNP-DNase-Oxa) were fabricated. The antibiofilm activity was evaluated against Staphylococcus aureus biofilms. Biofilm architecture on silicone surfaces was investigated by scanning electron microscopy (SEM). Confocal laser scanning microscopy (CLSM) was used to examine live/dead organisms within biofilm. CSNP-DNase-Oxa exhibited higher antibiofilm activity than Oxa-loaded nanoparticles without DNase (CSNP-Oxa) and free Oxa (Oxa and Oxa + DNase) at each concentration in all in-vitro tests. CSNP-DNase-Oxa inhibited biofilm formation in-vitro and eradicated mature biofilm effectively. CSNP-DNase-Oxa could disrupt the biofilm formation through degradation of eDNA, reduced biofilm thickness and the amount of viable cells on silicone. Repeated treatment with CSNP-DNase-Oxa for two days resulted in 98.4% biofilm reduction. Moreover, CSNP-DNase-Oxa was not only able to affect the biofilm of a standard S. aureus strain, but also showed the highest eradication of biofilms of clinical isolates compared with control groups. These results suggest the potential applicability of NPs for the treatment of biofilm-related infections and provide a platform for designing novel drug delivery with more functions.

RevDate: 2018-09-03

Sun G, Wan J, Sun Y, et al (2018)

Enhanced biodegradation of pyridine using sequencing batch biofilm reactor under intermittent micro-aerobic condition.

Environmental technology [Epub ahead of print].

A sequencing batch biofilm reactor (SBBR) under intermittent micro-aerobic or anaerobic conditions was investigated to remove pyridine at various concentrations from synthetic wastewater. The results showed that over 98% of pyridine (influent concentration ≤ 200 mg L-1) was degraded under intermittent micro-aerobic condition, while about 21% of pyridine was removed under anaerobic condition. Additionally, at least 60% of nitrogen located in the pyridine ring was transformed to ammonium. At the same time, the sulfate reduction was obviously inhibited under intermittent micro-aerobic conditions. The microscopic observation showed that abundant microorganisms were attached on the surface or inside of porous biocarriers under intermittent micro-aerobic conditions after a short-term period of operation. High-throughput sequencing analysis demonstrated that Azotobacter, Rhodobacteraceae and Tolumonas were the dominant species in the intermittent micro-aerobic system. The kinetic study at steady period showed that pyridine degradation was fitted well with the pseudo first-order model (R2 > 0.96). The two possible intermediate products were identified and the possible biodegradation pathway of pyridine was proposed under micro-aerobic condition.

RevDate: 2018-09-03

Zhang Y, Zhang H, Zhang Z, et al (2018)

Autohydrogenotrophic Denitrification Using the Membrane Biofilm Reactor for Removing Nitrate from High Sulfate Concentration of Water.

Archaea (Vancouver, B.C.), 2018:9719580.

This study investigated the performance of an autohydrogenotrophic membrane biofilm reactor (MBfR) to remove nitrate from water with high sulfate concentrations. The results of simulated running showed that TN removal could be over than 98.8% with the maximum denitrification rate of 134.6 g N/m3 d under the conditions of the influent sulfate concentrations of 300 mg SO42-/l. The distribution ratio of H2 electron donor for nitrate and sulfate was 70.0 : 26.9 at the high influent loading ratio of sulfate/nitrate of 853.3 g SO42-/m3 d : 140.5 g N/m3 d, which indicated that denitrification bacteria (DB) were normally dominated to complete H2 electron with sulfate bacteria (SRB). The results of molecular microbiology analysis showed that the dominated DB were Rhodocyclus and Hydrogenophaga, and the dominated SRB was Desulfohalobium, under the high influent sulfate concentrations.

RevDate: 2018-09-02

Jafari M, Desmond P, van Loosdrecht MCM, et al (2018)

Effect of biofilm structural deformation on hydraulic resistance during ultrafiltration: A numerical and experimental study.

Water research, 145:375-387 pii:S0043-1354(18)30667-5 [Epub ahead of print].

Biofilm formation in membrane systems negatively impacts the filtration system performances. This study evaluated how biofilm compression driven by permeate flow increases the hydraulic resistance and leads to reduction in permeate flux. We analysed the effect of biofilm compression on hydraulic resistance and permeate flux through computational models supported by experimental data. Biofilms with homogeneous surface structure were subjected to step-wise changes in flux and transmembrane pressure during compression and relaxation tests. Biofilm thickness under applied forces was measured non-invasively in-situ using optical coherence tomography (OCT). A numerical model of poroelasticity, which couples water flow through the biofilm with biofilm mechanics, was developed to correlate the structural deformation with biofilm hydraulics (permeability and resistance). The computational model enabled extracting mechanical and hydrological parameters corresponding to the experimental data. Homogeneous biofilms under elevated compression forces experienced a significant reduction in thickness while only a slight increase in resistance was observed. This shows that hydraulic resistance of homogeneous biofilms was affected more by permeability decrease due to pore closure than by a decrease in thickness. Both viscoelastic and elastoplastic models could describe well the permanent biofilm deformation. However, for biofilms under study, a simpler elastic model could also be used due to the small irreversible deformations. The elastic moduli fitting the measured data were in agreement with other reported values for biofilm under compression. Biofilm stiffening under larger flow-driven compression forces was observed and described numerically by correlating inversely the elastic modulus with biofilm porosity. The importance of this newly developed method lies in estimation of accurate biofilm mechanical parameters to be used in numerical models for both membrane filtration system and biofouling cleaning strategies. Such model can ultimately be used to identify optimal operating conditions for membrane system subjected to biofouling.

RevDate: 2018-09-02

Zeng XC, He Z, Chen X, et al (2018)

Effects of arsenic on the biofilm formations of arsenite-oxidizing bacteria.

Ecotoxicology and environmental safety, 165:1-10 pii:S0147-6513(18)30820-0 [Epub ahead of print].

Arsenite-oxidizing bacteria (AOB) play a key role in the biogeochemical cycle of arsenic in the environment, and are used for the bioremediation of As contaminated groundwater; however, it is not yet known about how arsenic affects biofilm formations of AOB, and how biofilm formations affect bacterial arsenite-oxidizing activities. To address these issues, we isolated seven novel AOB strains from the arsenic-contaminated soils. They can completely oxidize 1.0 mM As(III) in 22-60 h. Their arsenite oxidase sequences show 43-99% identities to those of other known AOB. Strains Cug1, Cug2, Cug3, Cug4, and Cug6 are able to form biofilms with thickness of 15-95 µm, whereas Cug8 and Cug9 cannot form biofilms. It is interesting to see that arsenite inhibited the biofilm formations of heterotrophic AOB strains, but promoted the biofilm formations of autotrophic strains in a concentration-dependent manner. The arsenite-oxidizing rates of Cug1 and Cug4 biofilms are 31.6% and 27.6% lower than those of their suspension cultures, whereas the biofilm activities of other strains are similar to those of their suspension cultures. The biofilm formation significantly promoted the bacterial resistance to arsenic. This work is the first report on the complex correlations among environmental arsenic, bacterial biofilm formations and bacterial arsenite-oxidizing activities. The data highlight the diverse lifestyle of different AOB under arsenic stress, and provide essential knowledge for the screening of efficient AOB strains used for constructions of bioreactors.

RevDate: 2018-09-02

Yao H, Kang M, Wang Y, et al (2018)

An essential role for hfq involved in biofilm formation and virulence in serotype 4b Listeria monocytogenes.

Microbiological research, 215:148-154.

Regulator factor Hfq has been widely detected among both Gram-positive and Gram-negative bacteria; however, its role in Gram-positive bacteria is less well established and varies among species. In Listeria monocytogenes (Lm), an organism able to adapt to a range of environments and live both saprobiotic and parasitic lifestyles, the role of Hfq is not fully understood. Serotype 4b Listeria monocytogenes strains associated with the majority of listeriosis outbreak, while the function of hfq in serotype 4b strains still not referenced. Here, we constructed hfq deletion and reversion mutants of serotype 4b Lm NTSN and analysed the biological characteristics both in vitro and in vivo. The deletion of hfq resulted in a growth deficiency in medium containing 4.5% ethanol or 1% Triton X-100, and the growth of the mutant was significantly reduced at 4 °C. Furthermore, the hfq deletion dramatically decreased biofilm formation in BHI medium and gastric fluid medium, and reduced the invasion and replication rate into the Caco-2BBe cells and RAW264.7 cells. However, complementation restored the wild-type phenotype. Importantly, mouse infection experiments demonstrated that hfq played a more important role in the colonisation and virulence in serotype 4b strain Lm NTSN than in the serotype 1/2a strain Lm EGDe. Taken together, these results demonstrated that hfq is a novel factor associated with biofilm formation, and plays an essential role in the stress response and pathogenisis in serotype 4b strain Lm NTSN. Our data provide the basis for further research into the function of Hfq in serotype 4b Listeria monocytogenes.

RevDate: 2018-09-02

Yang W, Yan H, Zhang J, et al (2018)

Inhibition of biofilm formation by Cd2+ on Bacillus subtilis 1JN2 depressed its biocontrol efficiency against Ralstonia wilt on tomato.

Microbiological research, 215:1-6.

Bacillus subtilis 1JN2 can serve as an effective biocontrol agent against Ralstonia wilt on tomato, but the efficiency of control depends on the levels of heavy metals in the rhizosphere soil. Here, we investigated how the heavy metal Cd2+ affects the biocontrol efficacy of B.subtilis 1JN2 on Ralstonia wilt. We found that low Cd2+ content of 2 mM or lower had no effects on the biofilm formation of 1JN2, while media containing 3 mM or higher Cd2+ levels inhibited biofilm formation. Interestingly, high concentration of Cd2+ (5 mM) showed inhibition of B.subtilis 1JN2 cell growth. We next tested the effects of Cd2+ on the colonization of 1JN2 by supplementing artificial Cd2+ in the tomato rhizosphere in a greenhouse setting. We found that 3 mM Cd2+ in the tomato rhizosphere inhibited the colonization of B.subtilis 1JN2, Only 103 CFU/mL 1JN2 was detected one week post treated with 107 CFU/mL but 105 CFU/mL could be detected without Cd2+ in the soil. The presence of Cd2+ had no effect on the colonization of Ralstonia solanacearum on tomato, but the biocontrol efficacy against Ralstonia wilt by 1JN2 decreased 54.2% when the soil contained 3 mM Cd2+ compared to the control without Cd2+. Taken together, we found that the failure of biofilm formation of Bacillus subtilis 1JN2 that affected by Cd2+ lead to the decrease of its biocontrol efficacy against Ralstonia wilt on tomato.

RevDate: 2018-09-02

Lotha R, Shamprasad BR, Sundaramoorthy NS, et al (2018)

Zero valent silver nanoparticles capped with capsaicinoids containing Capsicum annuum extract, exert potent anti-biofilm effect on food borne pathogen Staphylococcus aureus and curtail planktonic growth on a zebrafish infection model.

Microbial pathogenesis, 124:291-300 pii:S0882-4010(18)31067-2 [Epub ahead of print].

Food plants Hungarian wax pepper (HWP) and Green Bell pepper (GBP), belonging to Capsicum annuum were utilized for biogenic fabrication of zero valent, nano-silver (AgNPs) through a photo-mediation procedure. In the bacterial strains evaluated, HWP/GBP AgNPs demonstrated effective bacteriostatic and bactericidal effect against Staphylococcus aureus. Time kill results portrayed that HWP/GBP nano-silver exhibited comparable bactericidal potency on S. aureus. Anti-biofilm potential of HWP/GBP AgNPs displayed significant effects at sub MIC levels, by triggering 50% biofilm reduction of the food spoilage microbe S. aureus, inferring that the anti-biofilm outcome is not dependent on antibacterial result, and this was confirmed by SEM and fluorescence studies. Histopathological analyses of S. aureus infected zebrafish liver did not display any abnormality changes such as extensive cell death and degeneration, upon treatment with HWP/GBP AgNPs and the zero-valent silver nanoparticles were comparatively less toxic and more operative in restraining the bioburden in S. aureus infected zebrafish model by a >1.7 log fold. Ability of light reduced HWP/GBP AgNPs to alleviate the in vitro and in vivo planktonic mode of growth and curb the biofilm formation of S. aureus is also demonstrated.

RevDate: 2018-09-01

Zhang M, Wang L, Xu M, et al (2018)

Selective antibiotic resistance genes in multiphase samples during biofilm growth in a simulated drinking water distribution system: Occurrence, correlation and low-pressure ultraviolet removal.

The Science of the total environment, 649:146-155 pii:S0048-9697(18)33268-6 [Epub ahead of print].

The aim of this study was to gain comprehensive insights into the characteristics of antibiotic resistance genes (ARGs) in multiphase samples from drinking water distribution pipelines using a simulated biofilm reactor. During 120 d of continuous operation, common parameters and six ARGs (ermA, ermB, aphA2, ampC, sulII, and tetO) in samples of three phases (water, particle, and biofilm) from the reactor were investigated, which demonstrated secondary contamination by ARGs. Abundances of the six ARGs in the reactor effluent increased gradually, and in the 120 d effluent, the relative abundances of aphA2 and sulII were the highest, at 9.9 × 10-4 and 1.3 × 10-3, respectively, with a 1.5-fold and 2.8-fold increase, compared with those in the influent. The relative abundances of the six ARGs in the biofilm phase increased significantly (P < 0.05) at 120 d, which was caused by robust bacteria in biofilm that was newly exposed following the detachment of a large piece of aging biofilm. In the particle phase, four of the ARGs did not change significantly during the 120 d period. The six ARGs in the samples of three phases showed a negative correlation with residual chlorine in the pipe water, which demonstrated that low abundance of ARGs in the samples of three phases was related to the improvement of residual chlorine. The proportion of cultivable bacteria illustrated that the robust and active bacteria were negatively correlated with the six ARGs in the biofilm. Total organic carbon (TOC) in the pipeline showed a positive correlation with the proportion of cultivable bacteria in both the water and biofilm phases, which indicated that a TOC reduction in the pipeline contributed to low abundance of ARGs. With low-pressure ultraviolet (LP-UV) irradiation of 20 mJ/cm2, ARGs in the samples of three phases were efficiently controlled, which showed that LP-UV can be used for ARG removal in terminal water for supplemental bactericidal treatment of pipeline effluent.

RevDate: 2018-08-31

Tamayo-Ramos JA, Rumbo C, Caso F, et al (2018)

Analysis of polycaprolactone microfibers as biofilm carriers for biotechnologically-relevant bacteria.

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

Polymeric electrospun fibers are becoming popular in microbial biotechnology due to their exceptional physicochemical characteristics, biodegradability, surface-to-volume ratio, and compatibility with biological systems, which give them a great potential as microbial supports to be used in production processes or environmental applications. In this work we analyzed and compared the ability of Escherichia coli, Pseudomonas putida, Brevundimonas diminuta, and Sphingobium fuliginis to develop biofilms on different types of polycaprolactone (PCL) microfibers. These bacterial species are relevant in the production of bio-based chemicals, enzymes and proteins for therapeutic use, and bioremediation. The obtained results demonstrated that all selected species were able to attach efficiently to the PCL microfibers. Also, the ability of pure cultures of S. fuliginis (former Flavobacterium sp. ATCC 27551, a very relevant strain in the bioremediation of organophosphorus compounds) to form dense biofilms was observed for the first time, opening the possibility of new applications for this microorganism. This material showed to have a high microbial loading capacity, regardless of the mesh density and fiber diameter. A comparative analysis between PCL and polylactic acid (PLA) electrospun microfibers indicated that both surfaces have a similar bacterial loading capacity, but the former material showed higher resistance to microbial degradation than PLA.

RevDate: 2018-08-31

Xu G, Abdullah Al M, Sikder MNA, et al (2018)

Identifying indicator redundancy of biofilm-dwelling protozoa for bioassessment in marine ecosystems.

Environmental science and pollution research international pii:10.1007/s11356-018-3063-2 [Epub ahead of print].

A multivariate peeling method of data analysis was applied to determine indicator redundancy and for identifying indicator units (IUs) among biofilm-dwelling ciliate communities used for bioassessment of marine water quality. Samples were taken monthly over a 1-year period at four stations in coastal waters of the Yellow Sea: one heavily polluted, one moderately polluted, one intermittently polluted, and one unpolluted. Four IUs (IU1-4) were identified consisting of 22, 13, 14, and 17 species, respectively, out of a total of 144 species. The IUs showed significant correlation with temporal and spatial variations in environmental variables. The redundancy levels of IUs were interchangeable in time and space. However, IU1 and IU2 generally dominated the communities in moderately and intermittently polluted areas during cool (e.g., early spring, late autumn, and winter) and warm (late spring and early autumn) seasons; IU3 dominated in warm seasons (e.g., late spring to autumn) in the heavily polluted area; and IU4 mainly dominated the samples in the unpolluted and moderately polluted areas during the late summer and early autumn. Furthermore, different trophic-functional groupings were represented within the four IUs and these were generally associated with water quality status. These findings suggest that there is high indicator redundancy in marine biofilm-dwelling ciliate communities subjected to different levels of water quality.

RevDate: 2018-08-31

Pakshir K, Ravandeh M, Khodadadi H, et al (2018)

Evaluation of Exoenzyme Activities, Biofilm Formation, and Co-hemolytic Effect in Clinical Isolates of Candida parapsilosis Species Complex.

Journal of global infectious diseases, 10(3):163-165.

Candida parapsilosis species complex is considered as important emerging pathogens and little is known about their pathogenicity factors and co-hemolytic activity with different bacteria species. The aim of this study was to determine in vitro exoenzyme activities, biofilm formation, and co-hemolytic effect of different bacteria species on clinical C. parapsilosis complex isolates. In total, 67 C. parapsilosis complex isolates consist of C. parapsilosis sensu stricto 63/67 and Candida orthopsilosis 4/67 were used in this study. To determine the hemolytic activity of these species, Sabouraud dextrose sheep blood agar was used. Evaluation of the CAMP-like phenomenon carried out in the presence of Staphylococcus aureus, Staphylococcus saprophyticus, Staphylococcus epidermidis, and Streptococcus agalactiae. Tube test method with ethylenediaminetetraacetic acid-rabbit plasma was used to determine coagulase activity, and biofilm formation was assessed by the tube method in assist of Sabouraud glucose broth (8%) medium. Fisher's exact tests were used for data statistical analysis. Sixty-six of 67 (98.5%) and 3/67 (4.5%) of the species showed hemolysin and coagulase activity, respectively. Fifty-five of 67 (82.1%) of species had ability for biofilm formation, and none of the samples exhibited co-hemolytic effect in the presence of four mentioned bacteria. No significant difference was found between the level of enzyme production and biofilm formation among the isolates.

RevDate: 2018-08-31

Liu L, Yan Y, Feng L, et al (2018)

Quorum sensing asaI mutants affect spoilage phenotypes, motility, and biofilm formation in a marine fish isolate of Aeromonas salmonicida.

Food microbiology, 76:40-51.

Microbial spoilage is associated with the regulation of quorum sensing (QS). A. salmonicida AE03 with QS mediated acylated homoserine lactones (AHLs) activity was isolated from spoiled large yellow croaker (Pseudosciaena crocea). In this study the activity and role of AHLs in spoilage phenotypes, motility and biofilm formation of AE03 were investigated. The strain AE03 could induce Chromobacterium violaceum CV026 to produce the violacein pigment both at 28 °C and 4 °C in a density-dependent manner. Five types of AHLs were detected in AE03 culture by LC-MS/MS analysis, and N-butanoyl-l-homoserine lactone (C4-HSL) was a major signal molecule, reaching the highest concentration when incubated for 30 h at 28 °C. An asaI-mutant, constructed by a suicide plasmid, failed to produce short chain AHLs signal. Compared with wild type (WT) strain, the production of trimethylamine (TMA), biogenic amino and protease significantly increased in asaI-mutant during the exponential and stationary phase, while the growth rate did not differ. Swimming motility in asaI-mutant was comparatively stronger than that of WT strain, whereas, asaI-mutant resulted in the decrease of maturing biofilm. Furthermore, supplementation of exogenous C4-HSL restored the production of spoilage metablites, protease and biofilm formation in mutant. In accordance with the effect of asaI deletion on the spoilage phenotypes and motility, asaI-mutant was showed to significantly up-regulate the transcript levels of torA, cadA and fliR, as well as asaR, indicating that C4-HSL could be involved in the modulation of the spoilage related enzymes and flagella. Indeed, the asaI-mutant promoted the spoilage progress of fish fillets stored at 4 °C, while exogenous C4-HSL repressed the sensory change and TVB-N accumulation. The present study highlighted that AsaI/C4-HSL was an important regulator in spoilage, motility and biofilm formation of A. salmonicida, and spoilage potential was under the negative control of AsaI/AsaR-type system.

RevDate: 2018-08-31

Tango CN, Akkermans S, Hussain MS, et al (2018)

Modeling the effect of pH, water activity, and ethanol concentration on biofilm formation of Staphylococcus aureus.

Food microbiology, 76:287-295.

In this work, the effect of environmental factors on Staphylococcus aureus (ATCC 13150) biofilm formation in tryptic soy broth was investigated under different ranges of pH (3.0-9.5), ethanol concentration (EtOH 0.0-20.0%), and aw (NaCl, 0.866-0.992). Biofilm formation was quantified using the crystal violet staining method and optical density (OD: 590 nm) measurements. Biofilm formation was significantly stronger at pH and aw close to S. aureus optimal growth conditions, while it was high at EtOH around 2.5-3.5%. Data sets from the difference between the OD measurements of the test and control (ΔOD) were fitted to the cardinal parameter model (CPM) and cardinal parameter model with inflection (CPMI) to describe the effect of the environmental factors. The models showed good quality of fit for the experimental data in terms of calculated RMSE, with the latter ranging from 0.276 to 0.455. CPM gave a good quality of fit compared to CPMI for the environmental factors tested. Optimal pH was close to neutral (6.76-6.81) and biofilm formation was possible till pH = 3.81-3.78 for CPM and CPMI, respectively. Optimum EtOH and aw conditions for biofilm formation were in the range of 1.99-2.75 and 0.98-0.97, respectively. Predicted OD values observed using strain 13150 were very closely correlated to the OD values predicted with strain 12600 with R2 of 0.978, 0.991, and 0.947 for pH, EtOH, and aw, respectively. The cultivable bacterial cells within the biofilm were enumerated using standard plate counting and a linear model was applied to correlate the attached biofilm cells to ΔOD of biofilm formation. It was found that the biofilm formation correlated with S. aureus population growth. At 2.5-3.5% of EtOH the maximum population density was lower than that observed at 0.0% of EtOH. As 2.5-3.5% of EtOH initiated a stronger biofilm formation, biofilm formation seems to be induced by ethanol stress. The development of cardinal parameter models to describe the effect environmental factors of importance to biofilm formation, offers a promising predictive microbiology approach to decrypting the S. aureus population growth and survival ability on food processing surfaces.


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

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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 )