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Bibliography on: Biofilm

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ESP: PubMed Auto Bibliography 17 Jan 2019 at 01:33 Created: 

Biofilm

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

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

Citations The Papers (from PubMed®)

RevDate: 2019-01-15

Keller N, Bruchmann J, Sollich T, et al (2019)

Study of Biofilm Growth on Slippery Liquid-Infused Porous Surfaces Made from Fluoropor.

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

Undesired growth of biofilms represents a fundamental problem for all surfaces in long-term contact with aqueous media. Mature biofilms resist most biocide treatments and often are a pathogenic threat. One way to prevent biofilm growth on surfaces is by using slippery liquid-infused porous surfaces (SLIPS). SLIPS consist of a porous substrate which is infused with a lubricant immiscible with the aqueous medium in which the bacteria are suspended. Because of the lubricant, bacteria cannot attach to the substrate surface and thus formation of the biofilm is prevented. For this purpose, we manufactured substrates with different porosity and surface roughness values via UV-initiated free-radical polymerization in Fluoropor. Fluoropor is a class of highly fluorinated bulk-porous polymers with tunable porosity, which we recently introduced. We investigated the growth of the biofilm on the substrates, showing that a reduced surface roughness is beneficial for the reduction of biofilm growth. Samples of low roughness effectively reduced Pseudomonas aeruginosa biofilm growth for 7 days in a flow chamber experiment. The low-roughness samples also become transparent when infused with the lubricant, making such surfaces ideal for real-time observation of biofilm growth by optical examination.

RevDate: 2019-01-15

Wang H, Cai L, Hu H, et al (2019)

Complete Genome Sequence of Salmonella enterica Serovar Enteritidis NCM 61, with High Potential for Biofilm Formation, Isolated from Meat-Related Sources.

Microbiology resource announcements, 8(2): pii:MRA01434-18.

Here, we report the complete genome sequence of strain NMC 61 of Salmonella enterica serovar Enteritidis, which was previously isolated from conveyor belts during chicken slaughter and has the potential to form biofilms on several surfaces. The genome is predicted to contain 110 noncoding small RNAs on the chromosome.

RevDate: 2019-01-15

Henly EL, Dowling JAR, Maingay JB, et al (2019)

Biocide Exposure Induces Changes in Susceptibility, Pathogenicity and Biofilm Formation in Uropathogenic Escherichia coli.

Antimicrobial agents and chemotherapy pii:AAC.01892-18 [Epub ahead of print].

Background: Uropathogenic Escherichia coli (UPEC) are a frequent cause of catheter associated urinary tract infection (CAUTI). Biocides have been incorporated into catheter-coatings to inhibit bacterial colonisation whilst ideally exhibiting low cytotoxicity and mitigating the selection of resistant bacterial populations. We compared the effects of long-term biocide exposure on susceptibility, biofilm-formation and relative-pathogenicity in eight UPEC isolates.Methods: Minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC), minimum biofilm eradication concentrations (MBEC) and antibiotic susceptibilities were determined before and after long-term exposure to triclosan, polyhexamethylene biguanide (PHMB), benzalkonium chloride (BAC) and silver nitrate. Biofilm-formation was quantified using a crystal violet assay and relative-pathogenicity was assessed via a Galleria mellonella waxworm model. Cytotoxicity and resulting biocompatability index values were determined against an L929 murine fibroblast cell line.Results: Biocide exposure resulted in multiple decreases in biocide susceptibility in planktonic and biofilm associated UPEC. Triclosan exposure induced the largest frequency and magnitude of susceptibility decreases at MIC, MBC and MBEC, which correlated to an increase in biofilm biomass in all isolates. Induction of antibiotic-cross-resistance occurred in 6/84 possible combinations of bacteria, biocide and antibiotic. Relative-pathogenicity significantly decreased after triclosan exposure (5/8 isolates), increased after silver nitrate exposure (2/8 isolates) and varied between isolates for PHMB and BAC. Biocompatibility index ranked antiseptic potential as PHMB>triclosan>BAC>silver nitrate.Conclusion: Biocide exposure in UPEC may lead to reductions in biocide and antibiotic susceptibility, changes in biofilm-formation and alterations relative-pathogenicity. These data indicate the multiple consequences of biocide adaptation that should be considered when selecting an anti-infective catheter-coating agent.

RevDate: 2019-01-15

Naha PC, Liu Y, Hwang G, et al (2019)

Dextran Coated Iron Oxide Nanoparticles as Biomimetic Catalysts for Localized and pH-Activated Biofilm Disruption.

ACS nano [Epub ahead of print].

Biofilms are surface-attached bacterial communities embedded within an extracellular matrix that create localized and protected microenvironments. Acidogenic oral biofilms can demineralize the enamel-apatite on teeth causing dental caries (tooth-decay). Current antimicrobials have low efficacy and do not target the protective matrix and acidic pH within the biofilm. Recently, catalytic nanoparticles were shown to disrupt biofilms, but lacked a stabilizing coating required for clinical applications. Here, we report dextran-coated iron oxide nanoparticles termed nanozymes (Dex-NZM) that display strong catalytic (peroxidase-like) activity at acidic pH values, target biofilms with high specificity and prevent severe caries without impacting surrounding oral tissues in vivo. Nanoparticle formulations were synthesized with dextran coatings (molecular weights from 1.5 kDa to 40 kDa were used), and their catalytic performance and bioactivity were assessed. We found that 10 kDa dextran-coating provided maximal catalytic activity, biofilm uptake and antibiofilm properties. Mechanistic studies indicated that iron oxide cores are the source of catalytic activity, whereas dextran on the nanoparticle surface provided stability without blocking catalysis. Dextran-coating facilitated NZM incorporation into exopolysaccharides (EPS) structure and binding within biofilms, which activated hydrogen peroxide (H2O2) for localized bacterial killing and EPS-matrix breakdown. Surprisingly, dextran coating enhanced selectivity towards biofilms, while avoiding binding to gingival cells. Furthermore, Dex-NZM/H2O2 treatment significantly reduced the onset and severity of caries lesions (vs. control or either Dex-NZM or H2O2 alone) without adverse effects on gingival tissues or oral microbiota diversity in vivo. Therefore, dextran-coated nanozymes have potential as an alternative treatment to control tooth-decay and possibly other biofilm-associated diseases.

RevDate: 2019-01-15

Cha Y, Chun J, Son B, et al (2019)

Characterization and Genome Analysis of Staphylococcus aureus Podovirus CSA13 and Its Anti-Biofilm Capacity.

Viruses, 11(1): pii:v11010054.

Staphylococcus aureus is one of the notable human pathogens that can be easily encountered in both dietary and clinical surroundings. Among various countermeasures, bacteriophage therapy is recognized as an alternative method for resolving the issue of antibiotic resistance. In the current study, bacteriophage CSA13 was isolated from a chicken, and subsequently, its morphology, physiology, and genomics were characterized. This Podoviridae phage displayed an extended host inhibition effect of up to 23 hours of persistence. Its broad host spectrum included methicillin susceptible S. aureus (MSSA), methicillin resistant S. aureus (MRSA), local S. aureus isolates, as well as non-aureus staphylococci strains. Moreover, phage CSA13 could successfully remove over 78% and 93% of MSSA and MRSA biofilms in an experimental setting, respectively. Genomic analysis revealed a 17,034 bp chromosome containing 18 predicted open reading frames (ORFs) without tRNAs, representing a typical chromosomal structure of the staphylococcal Podoviridae family. The results presented here suggest that phage CSA13 can be applicable as an effective biocontrol agent against S. aureus.

RevDate: 2019-01-14

Zhang G, Li B, Guo F, et al (2019)

Taxonomic relatedness and environmental pressure synergistically drive the primary succession of biofilm microbial communities in reclaimed wastewater distribution systems.

Environment international, 124:25-37 pii:S0160-4120(18)32748-X [Epub ahead of print].

Compared to drinking water, the higher bacterial abundance, diversity, and organic matter concentration in reclaimed wastewater suggest that it is more likely to form biofilms. Nevertheless, little is known regarding many important aspects of the biofilm ecology in reclaimed wastewater distribution systems (RWDS), such as the long-term microbial community succession and the underlying driving factors. In the present study, by sampling and analysing microbial compositions of pipe wall biofilms from six frequently used pipe materials under NaClOdisinfection (sodium hypochlorite-treated), NONdisinfection (without disinfection), and UVdisinfection (UV-treated) treatments over one year, it was found that the succession of microbial community structure followed a primary succession pattern. This primary succession pattern was reflected as increases in live cell number and α-diversity, along with metagenic succession in taxonomic composition. Proteobacteria, Nitrospirae, Bacteroidetes, Acidobacteria, Planctomycetes, Actinobacteria, and Verrucomicrobia comprised the dominant phyla in biofilm samples. Compared to biofilms in the NaClOdisinfection reactor, the bacterial communities of biofilms in NONdisinfection and UVdisinfection reactors were distributed more evenly among different bacterial phyla. Principal component analysis revealed a clear temporal pattern of microbial community structures in six kinds of pipe wall biofilms albeit a difference in microbial community structures among the three reactors. Adonis testing indicated that the microbial community composition variation caused by disinfection methods (R2 = 0.283, P < 0.01) was more pronounced than that from the time variable (R2 = 0.070, P < 0.01) and pipe material (R2 = 0.057, P < 0.01). Significantly positive correlation between average local abundance and occupancy was observed in biofilm communities of the three reactors, suggesting that the 'core-satellite' model could be applied to identify biofilm-preferential species under specific disinfection conditions in RWDS. The prevalence of family Sphingomonadaceae, known to show chlorine tolerance and powerful biofilm-forming ability in NaClOdisinfection reactors, evidenced the habitat filtering consequent to environment pressure. Correlation-based network analysis revealed that taxonomic relatedness such as similar niches, cooperation, taxa overdispersion, and competition all functioned toward driving the bacterial assembly succession in RWDS.

RevDate: 2019-01-14

Zhang X, Gao J, Ling N, et al (2019)

Short communication: Roles of outer membrane protein W on survival, cellular morphology, and biofilm formation of Cronobacter sakazakii in response to oxidative stress.

Journal of dairy science pii:S0022-0302(19)30021-9 [Epub ahead of print].

Cronobacter species are a group of opportunistic food-borne pathogens that cause rare but severe infections in neonates. Tolerance to environmental stress in Cronobacter is known; however, factors involved in oxidative stress are undefined. In this study, Cronobacter sakazakii survival, cellular morphology, and biofilm formation in response to oxidative stress were evaluated between the wild type (WT) and an outer membrane protein W (OmpW) mutant. The survival rates of ΔOmpW strain after treatment with 1.0 and 1.5 mM hydrogen peroxide were significantly reduced compared with those of WT. Morphological changes, including cell membrane damage and cell fragmentation, in ΔOmpW were more predominant than those in WT. By crystal violet staining, we also observed increased biomass in ΔOmpW biofilms as compared with WT following treatment with 0.5 and 1.0 mM H2O2. Biofilms using scanning electron microscopy and confocal laser scanning microscopy further confirmed the structural changes of biofilms between WT and ΔOmpW in response to oxidative stress. The current findings show that OmpW contributed to survival of planktonic cells under oxidative stress and the deletion of OmpW facilitated the biofilm formation in C. sakazakii to adapt to oxidative stress.

RevDate: 2019-01-14

Bauermeister A, Pereira F, Grilo IR, et al (2019)

Intra-clade metabolomic profiling of MAR4 Streptomyces from the Macaronesia Atlantic region reveals a source of anti-biofilm metabolites.

Environmental microbiology [Epub ahead of print].

The search for new and effective strategies to reduce bacterial biofilm formation is of utmost importance as bacterial resistance to antibiotics continues to emerge. The use of anti-biofilm agents that can disrupt recalcitrant bacterial communities can be an advantageous alternative to antimicrobials, as their use does not lead to the development of resistance mechanisms. Six MAR4 Streptomyces strains isolated from the Madeira Archipelago, at the unexplored Macaronesia Atlantic ecoregion, were used to study the chemical diversity of produced hybrid isoprenoids. These marine actinomycetes were investigated by analysing their crude extracts using LC-MS/MS and their metabolomic profiles were compared using multivariate statistical analysis (PCA), showing a separation trend closely related to their phylogeny. Molecular networking unveiled the presence of a class of metabolites not previously described from MAR4 strains and new chemical derivatives belonging to the napyradiomycin and marinone classes. Furthermore, these MAR4 strains produce metabolites that inhibit biofilm formation of Staphylococcus aureus and Marinobacter hydrocarbonoclasticus. The anti-biofilm activity of napyradiomycin SF2415B3 (1) against S. aureus was confirmed. This article is protected by copyright. All rights reserved.

RevDate: 2019-01-12

Chen Z, Yang G, Lu S, et al (2019)

Design and antimicrobial activities of LL-37 derivatives inhibiting the formation of Streptococcus mutans biofilm.

Chemical biology & drug design [Epub ahead of print].

Dental plaque is closely related to the occurrence of dental caries, of which the main causative bacterium is Streptococcus mutans (S. mutans). In this study, to create potent antibiofilm agents, we chose a human antimicrobial peptide LL-37 as our starting material and modified it by cutting it shorter and varying its charge and hydrophobicity. The results of anti-S. mutans as well as biofilm inhibitory activity tests indicated that two derivatives, IG-13-1 and IG-13-2, were the most potent one toward both planktonic and biofilm S. mutans cells with the minimal inhibitory concentration of 5.0 μM and minimal biofilm inhibitory concentrations of 5.91 ± 0.91 μM and 7.58 ± 0.23 μM, respectively. The modes of action study showed that IG-13-1 and IG-13-2 were functioned by disrupting the bacterial membrane, causing the leakage of inner contents, thereby leading to the death of bacterial cells eventually. In addition, IG-13-1 and IG-13-2 were able to suppress the expression of proinflammatory cytokine of TNF-α and reduce the level of nuclear transcription factor-κB, which indicated the potential anti-inflammatory activity of these peptides. Conclusively, this study indicated that IG-13-1 and IG-13-2 are potent peptides in both anti-S. mutans and anti-inflammatory activities, therefore, showing a potential application for the prevention and treatment of dental caries.

RevDate: 2019-01-12

Vermee Q, Cohen R, Hays C, et al (2019)

Biofilm production by Haemophilus influenzae and Streptococcus pneumoniae isolated from the nasopharynx of children with acute otitis media.

BMC infectious diseases, 19(1):44 pii:10.1186/s12879-018-3657-9.

BACKGROUND: Biofilm production by Haemophilus influenzae and Streptococcus pneumoniae has been implicated in the pathogenesis of otitis media, mainly in chronic and recurrent cases. We studied the "in vitro" biofilm production by these 2 species isolated alone or together from the nasopharynx of children with acute otitis media.

METHODS: The studied strains were from 3 pneumococcal conjugate vaccine (PCV) periods: pre-PCV7, post-PCV7/pre-PCV13 and post-PCV13. A modified microtiter plate assay with crystal violet stain was used to study the biofilm production of 182 H. influenzae and 191 S. pneumoniae strains.

RESULTS: Overall, 117/181 (64.6%) H. influenzae and 128/191 (66.8%) S. pneumoniae strains produced biofilm. The proportion of biofilm-producing H. influenzae strains was greater with than without the isolation of S. pneumoniae in the same sample (75.5% vs 52.3%, p = 0.001). Conversely, the proportion of biofilm-producing S. pneumoniae strains was not affected by the presence or not of H. influenzae (66.3% vs 67.4%). S. pneumoniae serotypes 6B, 15B/C, 19A, 35F and 35B were the better biofilm producers (80%). Serotypes 11A, 14, 15A, 19F and 19A were more associated with H. influenzae biofilm-producing strains. Overall, 89/94 (94.6%) of cases with combined isolation showed biofilm production by S. pneumoniae or H. influenzae.

CONCLUSION: This study emphasizes the high proportion of biofilm production by H. influenzae and S. pneumoniae strains isolated from the nasopharynx of children with acute otitis media, which reinforces the results of studies suggesting the importance of biofilm in the pathogenesis of acute otitis media.

RevDate: 2019-01-11

Ramanjeneya S, Sahoo SC, Pathak R, et al (2019)

Virulence Potential, Biofilm Formation, and Antibiotic Susceptibility of Listeria monocytogenes Isolated from Cattle Housed in a Particular Gaushala (Cattle Shelter) and Organized Farm.

Foodborne pathogens and disease [Epub ahead of print].

OBJECTIVES: The occurrence of Listeria monocytogenes was studied by using cultural and serological methods in cattle housed in a particular gaushala (cattle shelter) and organized dairy farm.

MATERIALS AND METHODS: A total of 1201 samples from cattle comprising blood (n = 207), milk (n = 203), vaginal swabs (n = 210), and serum (n = 207) from an organized farm (n = 210) and blood (n = 100), milk (n = 74), vaginal swabs (n = 100), and serum (n = 100) from a gaushala (n = 100) were collected and analyzed for L. monocytogenes. All samples excluding serum were analyzed for isolation and identification of L. monocytogenes, while the serum samples were screened for seropositivity. The isolates were further subjected to assess their virulence potential (in vitro and in vivo), biofilm formation ability, and antibiotic susceptibility patterns.

RESULTS: Four L. monocytogenes strains were isolated from the cattle; three (0.48%) from the organized farm and one (0.36%) from the gaushala. On serological screening of cattle from the organized dairy farm, 16.42% were found to be positive for antibodies against listeriolysin O, while cattle from the gaushala revealed 36% seropositivity. Furthermore, on characterization of the isolates for their pathogenic potential and biofilm-forming ability, all were found to be pathogenic by both in vitro and in vivo assays and were weak to moderate biofilm formers. The minimum inhibition concentration (MIC) of recovered isolates revealed resistance for ampicillin by two L. monocytogenes isolates (MIC >256 μg/mL), whereas three L. monocytogenes isolates were intermediately resistant (MIC >4 μg/mL) and one resistant against amoxicillin (MIC >8 μg/mL). However, all four isolates were susceptible to gentamicin, cotrimoxazole, and erythromycin.

CONCLUSIONS: Isolation of virulent and antibiotic-resistant strains of L. monocytogenes warrants the need for epidemiological surveillance, antimicrobial susceptibility, and implementation of control measures to combat the occurrence of L. monocytogenes infection in animals as well as humans.

RevDate: 2019-01-11

Qiu MN, Wang F, Chen SY, et al (2019)

Novel 2, 8-bit derivatives of quinolines attenuate Pseudomonas aeruginosa virulence and biofilm formation.

Bioorganic & medicinal chemistry letters pii:S0960-894X(18)31028-X [Epub ahead of print].

Signal molecules are stimulators of multiple quroum-sensing virulence and biofilm formation. Small molecule analogues have been suspected as a potent inhibitor in therapeutic strategy. Herein, we synthesized a series of small molecule compounds from the 2, 8-bit derivatives of quinoline by Suzuki coupling reaction. We found that these compounds have the biofilm inhibitory effect in normal condition instead of phosphate limitation state. Furthermore, lacZ reporter strain assay and rhamnolipids as well as pyocyanin experiments showed that these compounds did not affect las and pqs system but reduced the expression of rhl. All these results suggest that quinoline derivatives can be treated as potent inhibitors against biofilm and reduce virulence through the rhl system. This research will be useful in designing new quorum sensing inhibitors to attenuate the infection of bacteria.

RevDate: 2019-01-10

Cheng L, Flavigny RM, Hossain MI, et al (2018)

Proof of concept of wastewater treatment via passive aeration SND using a novel zeolite amended biofilm reactor.

Water science and technology : a journal of the International Association on Water Pollution Research, 78(10):2204-2213.

The current paper describes a novel passive aeration simultaneous nitrification and denitrification (PASND) zeolite amended biofilm reactor that removes organic carbon and nitrogen from wastewater with low-energy consumption. Next to the ammonium oxidizing bacteria (AOB), this reactor contained naturally enriched glycogen accumulating organisms (GAOs) and zeolite powder to initially adsorb BOD (acetate) and ammonium (NH4+-N) from synthetic wastewater under anaerobic conditions. Draining of the treated wastewater exposed the biofilm directly to air enabling low-energy oxygen supply by passive aeration. This allowed the adsorbed ammonium to be oxidized by the AOB and the produced nitrite and nitrate to be reduced simultaneously by the GAOs using the adsorbed BOD (stored as PHAs) as carbon source. Overall, with an operation mode of 1 h anaerobic and 4 h aerobic phase, the nutrient removal efficiency after single treatment was about 94.3% for BOD and 72.2% for nitrogen (NH4+-N). As high-energy aeration of the bulk solution for oxygen supply is completely avoided, the energy requirement of the proposed PASND biofilm reactor can be theoretically cut down to more than 50% compared to the traditional activated sludge process.

RevDate: 2019-01-10

Liu C, Wang CC, Chen XX, et al (2019)

[Biological Nitrogen Removal Process in a Microbubble-aerated Biofilm Reactor Treating Low C/N Wastewater].

Huan jing ke xue= Huanjing kexue, 40(2):754-760.

The microbubble-aerated biofilm reactor as a new treatment process combines microbubble aeration technology with aerobic biological treatment. A microbubble aerated biofilm reactor was used in this study to treat low C/N ratio wastewater at a low air/water ratio. The process and performance of biological nitrogen removal were investigated, and the functional bacterial populations for nitrogen removal in the biofilm were analyzed. The results showed that the biological nitrogen removal process was converted from simultaneous nitrification-denitrification to simultaneous partial nitrification, ANAMMOX and denitrification (SNAD) processes when DO concentration was controlled by an air/water ratio of lower than 1:2 and the influent C/N ratio was reduced. As a result, the efficient biological nitrogen removal performance was achieved when treating low C/N ratio wastewater. When the DO concentration was lower than 1.0 mg·L-1 and the influent C/N ratio was 1:2.8, the SNAD process became dominant for biological nitrogen removal. In this case, the average total nitrogen (TN) removal efficiency was 76.3%, and the average TN loading rate removed was 1.42 kg·(m3·d)-1. In addition, it was estimated that 86.0% of TN removal was attributed to the ANAMMOX process. The relative abundances of ammonia-oxidizing bacteria populations and ANAMMOX bacteria populations in the biofilm increased gradually, while the relative abundances of nitrite-oxidizing bacteria populations and denitrifying bacteria populations decreased gradually, with a decrease in influent C/N ratio. The variation of functional bacterial populations for nitrogen removal was consistent with the conversion of nitrogen removal process to SNAD process.

RevDate: 2019-01-09

Santos DMSD, Pires JG, Braga AS, et al (2019)

Comparison between static and semi-dynamic models for microcosm biofilm formation on dentin.

Journal of applied oral science : revista FOB, 27:e20180163 pii:S1678-77572019000100422.

OBJECTIVE: Microcosm biofilm has been applied to induce carious lesions in dentin. However, no study has been done to compare the impact of the type of model for providing nutrients to microcosm biofilm formation on dentin. This study compared the performance of two kinds of models (static and semi-dynamic) on the biofilm formation and the development of dentin carious lesions.

MATERIAL AND METHODS: In both models, biofilm was produced using inoculum from pooled human saliva mixed with McBain saliva for the first 8 h (5% CO2 and 37°C). Afterwards, for the static model, the samples were placed in 24-wells microplate containing McBain saliva with 0.2% sucrose, which was replaced at 24 h. In the semi-dynamic model, the samples were submitted to artificial mouth system with continuous flow of McBain saliva with 0.2% sucrose (0.15 ml/min, 37°C) for 10 h a day (for the other 14 h, no flow was applied, similarly to the static model). After 5 days, biofilm viability was measured by fluorescence and dentin demineralization by transverse microradiography.

RESULTS: Biofilm viability was significantly lower for the static compared with semi-dynamic model, while dentin demineralization was significantly higher for the first one (p<0.05). The static model was able to produce a higher number of typical subsurface lesions compared with the semi-dynamic model (p<0.05).

CONCLUSIONS: The type of model (static and semi-dynamic) applied in the microcosm biofilm may have influence on it's viability and the severity/profile of dentin carious lesions.

RevDate: 2019-01-09

Tang C, Sun P, Yang J, et al (2019)

Kinetics simulation of Cu and Cd removal and the microbial community adaptation in a periphytic biofilm reactor.

Bioresource technology, 276:199-203 pii:S0960-8524(19)30001-X [Epub ahead of print].

Periphytic biofilm reactor (PBfR) shows great potential in pollutants removal. However, few studies were focused on mathematical model of pollutants removal in PBfR. A three-step PBfR was designed and a new model was developed to simulate the kinetics of Cu and Cd removal from simulated wastewater. The results show that the PBfR could remove 99.0% Cu and 99.7% Cd from liquid wastewater. The experiment data could be well fitted with a high correlation coefficients both for Cu and Cd. The microbial community in the PBfR could be self-adjusted to tolerate the toxicities of Cu and Cd, resulting in sustainable and high decontamination efficiencies. The eukaryote in the PBfR played a vital role in Cu and Cd removal. The prokaryote showed negative effect on Cu and Cd removal, though it had more diversity than eukaryote. This study provides a new approach for Cu and Cd removal and their kinetics simulation in photoautotrophic bioreactor.

RevDate: 2019-01-09

Hochstrasser R, Kessler A, Sahr T, et al (2019)

The pleotropic Legionella transcription factor LvbR links the Lqs and c-di-GMP regulatory networks to control biofilm architecture and virulence.

Environmental microbiology [Epub ahead of print].

The causative agent of Legionnaires' pneumonia, Legionella pneumophila, colonizes amoebae and biofilms in the environment. The opportunistic pathogen employs the Lqs (Legionella quorum sensing) system and the signaling molecule LAI-1 (Legionella autoinducer-1) to regulate virulence, motility, natural competence, and expression of a 133 kb genomic island, including a putative novel regulator. Here, we show that the regulator termed LvbR is an LqsS-regulated, pleotropic transcription factor that binds to the promoter of lpg1056/hnox1 (encoding an inhibitor of the diguanylate cyclase Lpg1057), and thus regulates proteins involved in c-di-GMP metabolism. LvbR determines biofilm architecture, since L. pneumophila lacking lvbR accumulates less sessile biomass and forms homogeneous mat-like structures, while the parental strain develops more compact bacterial aggregates. Comparative transcriptomics of sessile and planktonic ΔlvbR or ΔlqsR mutant strains revealed concerted (virulence, fitness island, metabolism) and reciprocally (motility) regulated genes in biofilm and broth, respectively. Moreover, ΔlvbR is hyper-competent for DNA uptake, defective for phagocyte infection, outcompeted by the parental strain in amoebae co-infections, and impaired for cell migration inhibition. Taken together, our results indicate that L. pneumophila LvbR is a novel pleotropic transcription factor, which links the Lqs and c-di-GMP regulatory networks to control biofilm architecture and pathogen-host-cell interactions. This article is protected by copyright. All rights reserved.

RevDate: 2019-01-09

Race J, Zilm P, Ratnayake J, et al (2019)

Efficacy of laser and ultrasonic-activated irrigation on eradicating a mixed-species biofilm in human mesial roots.

Australian endodontic journal : the journal of the Australian Society of Endodontology Inc [Epub ahead of print].

This study investigated the efficacy of Er,Cr:YSGG laser and ultrasonic activated irrigation on eradicating a mixed-species biofilm grown in root canals with complex anatomy. The biofilm was grown over 4-weeks in the root canals of decoronated human mandibular molar teeth. Control roots received no further treatment. The remaining roots were chemomechanically prepared using different irrigating protocols: 4% NaOCl and 15% EDTAC with ultrasonic activated irrigation and laser activated irrigation using power settings of 0.5 W and 0.75 W. Cellular viability was determined using serial plating. One tooth from each group was subjected to qualitative SEM analysis. Quantification by culturing revealed significant differences between control group and all other treatment groups. This study demonstrated that chemomechanical irrigation with laser and ultrasonic activated irrigation significantly reduced the bacterial load from complex root canal systems; however, there were no significant differences found between the experimental groups.

RevDate: 2019-01-09

Mohamed MA, Nasr M, Elkhatib WF, et al (2018)

In Vitro Evaluation of Antimicrobial Activity and Cytotoxicity of Different Nanobiotics Targeting Multidrug Resistant and Biofilm Forming Staphylococci.

BioMed research international, 2018:7658238.

Antibiotic-resistant and biofilm-forming bacteria have surprisingly increased over recent years. On the contrary, the rate of development of new antibiotics to treat these emerging superbugs is very slow. Therefore, the aim of this study was to prepare novel nanobiotic formulations to improve the antimicrobial activity of three antibiotics (linezolid, doxycycline, and clindamycin) against Staphylococci. Antibiotics were formulated as nanoemulsions and evaluated for their antimicrobial activities and cytotoxicities. Cytotoxicity of the conventional antibiotics and nanobiotics was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on rat hepatocytes. Half-maximal inhibitory concentration (IC50) was estimated from an experimentally derived dose-response curve for each concentration using GraphPad Prism software. Upon quantitative assessment of Staphylococcus biofilm formation, eighty-four isolates (66.14 %) were biofilm forming. Linezolid and doxycycline nanobiotics exhibited promising antibacterial activities. On the contrary, clindamycin nanobiotic exhibited poor antibacterial activity. Minimum biofilm inhibitory concentrations showed that 73.68 %, 45.6%, and 5.2% of isolates were sensitive to linezolid, doxycycline, and clindamycin nanobiotics, respectively. Results of this study revealed that antibiotics loaded in nanosystems had a higher antimicrobial activity and lower cytotoxicities as compared to those of conventional free antibiotics, indicating their potential therapeutic values.

RevDate: 2019-01-09

Andreasen M, Meisl G, Taylor JD, et al (2019)

Physical Determinants of Amyloid Assembly in Biofilm Formation.

mBio, 10(1): pii:mBio.02279-18.

A wide range of bacterial pathogens have been shown to form biofilms, which significantly increase their resistance to environmental stresses, such as antibiotics, and are thus of central importance in the context of bacterial diseases. One of the major structural components of these bacterial biofilms are amyloid fibrils, yet the mechanism of fibril assembly and its importance for biofilm formation are currently not fully understood. By studying fibril formation in vitro, in a model system of two common but unrelated biofilm-forming proteins, FapC from Pseudomonas fluorescens and CsgA from Escherichia coli, we found that the two proteins have a common aggregation mechanism. In both systems, fibril formation proceeds via nucleated growth of linear fibrils exhibiting similar measured rates of elongation, with negligible fibril self-replication. These similarities between two unrelated systems suggest that convergent evolution plays a key role in tuning the assembly kinetics of functional amyloid fibrils and indicates that only a narrow window of mechanisms and assembly rates allows for successful biofilm formation. Thus, the amyloid assembly reaction is likely to represent a means for controlling biofilm formation, both by the organism and by possible inhibitory drugs.IMPORTANCE Biofilms are generated by bacteria, embedded in the formed extracellular matrix. The biofilm's function is to improve the survival of a bacterial colony through, for example, increased resistance to antibiotics or other environmental stresses. Proteins secreted by the bacteria act as a major structural component of this extracellular matrix, as they self-assemble into highly stable amyloid fibrils, making the biofilm very difficult to degrade by physical and chemical means once formed. By studying the self-assembly mechanism of the fibrils from their monomeric precursors in two unrelated bacteria, our experimental and theoretical approaches shed light on the mechanism of functional amyloid assembly in the context of biofilm formation. Our results suggest that fibril formation may be a rate-limiting step in biofilm formation, which in turn has implications on the protein self-assembly reaction as a target for potential antibiotic drugs.

RevDate: 2019-01-09

Wu S, Huang F, Zhang H, et al (2019)

Staphylococcus aureus biofilm organization modulated by YycFG two-component regulatory pathway.

Journal of orthopaedic surgery and research, 14(1):10 pii:10.1186/s13018-018-1055-z.

BACKGROUND: Staphylococcus aureus (S. aureus) infection accounts for more than 50% of the osteomyelitis cases. Currently, methicillin-resistant S. aureus (MRSA) strains present an urgent medical problem. The YycFG two-component regulatory system (TCS) can allow bacteria to rapidly adapt to physical, chemical, and biological stresses. To define the role of YycFG in modulation virulence of S. aureus in osteomyelitis, we isolated clinical MRSA strains and compared these with ATCC29213 methicillin-sensitive S. aureus (MSSA).

METHODS: In the present study, 13 MRSA strains from chronic osteomyelitis tissues were isolated. The in-depth sequencing of 16S rRNA amplicons of the samples was conducted. Bacterial growth was monitored, and biofilm biomass was determined by crystal violet microtiter assay. Furthermore, quantitative RT-PCR analysis was adopted to identify the expression of yycF/G/H and icaA/D in MRSA and MSSA strains. Analysis of variance with one-way ANOVA was used for statistical analysis.

RESULTS: The in-depth sequencing of 16S rRNA amplicons of the clinical samples indicated a polymicrobial infection, with the phylum Firmicutes made up 13% of the microbial population. The MRSA strains showed an accelerated growth rate compared to the MSSA strains. Of note, MRSA biofilms showed an accumulation of an intercellular polysaccharides matrix and enhanced biomass upon microscopic examination. Furthermore, MRSA strains had a higher expression of the yycF/G/H and icaA/D genes and adhesion force.

CONCLUSIONS: These data suggested the roles of intercellular polysaccharide in S. aureus pathogenesis, indicating a possible association between YycFG pathways and MRSA strain virulence.

RevDate: 2019-01-09

Srinivasan A, Ramasubramanian AK, JL Lopez-Ribot (2019)

Nano-biofilm Arrays as a Novel Universal Platform for Microscale Microbial Culture and High-Throughput Downstream Applications.

Current medicinal chemistry pii:CMC-EPUB-95624 [Epub ahead of print].

Biofilms are the predominant mode of microbial growth and it is now fully accepted that a majority of infections in humans are associated with a biofilm etiology. Biofilms are defined as attached and structured microbial communities surrounded by a protective exopolymeric matrix. Importantly, sessile microorganisms growing within a biofilm are highly resistant to antimicrobial agents. Thus, there is an urgent need to develop new and improved anti-biofilm therapies. Unfortunately, most of the current techniques for in vitro biofilm formation are not compatible with high throughput screening techniques that can speed up discovery of new drugs with anti-biofilm activity. To try to overcome this major impediment, our group has developed a novel technique consisting of microscale culture of microbial biofilms on a microarray platform. Using this technique, hundreds to thousands of microbial biofilms, each with a volume of approximately 30-50 nanolitres, can be simultaneously formed on a standard microscope slide. Despite more than three orders of magnitude of miniaturization over conventional biofilms, these nanobiofilms display similar growth, structural and phenotypic properties, including antibiotic drug resistance. These nanobiofilm chips are amenable to automation, drastically reducing assay volume and costs. This technique platform allows for true high-throughput screening in search for new anti-biofilm drugs.

RevDate: 2019-01-09

Yüksel FN, Buzrul S, Akçelik M, et al (2019)

Inhibition and eradication of Salmonella Typhimurium biofilm using P22 bacteriophage, EDTA and nisin.

Biofouling [Epub ahead of print].

P22 phage >105 PFU ml-1 could be used to inhibit Salmonella Typhimurium biofilm formation by 55-80%. Concentrations of EDTA >1.25 mM and concentrations of nisin >1,200 µg ml-1 were also highly effective in reducing S. Typhimurium biofilm formation (≥96% and ≥95% reductions were observed, respectively). A synergistic effect was observed when EDTA and nisin were combined whereas P22 phage in combination with nisin had no synergistic impact on biofilm formation. Triple combination of P22 phage, EDTA and nisin could be also used to inhibit biofilm formation (≥93.2%) at a low phage titer (102 PFU ml-1), and low EDTA (1.25 mM) and nisin (9.375 µg ml-1) concentrations. A reduction of 70% in the mature biofilm was possible when 107 PFU ml-1 of P22 phage, 20 mM of EDTA and 150 μg ml-1 of nisin were used in combination. This study revealed that it could be possible to reduce biofilm formation by S. Typhimurium by the use of P22 phage, EDTA and nisin, either alone or in combination. Although, removal of the mature biofilm was more difficult, the triple combination could be successfully used for mature biofilm of S. Typhimurium.

RevDate: 2019-01-08

Shipitsyna IV, EV Osipova (2017)

[THE BIOFILM FORMATION ABILITY OF STRAINS SERRATIA SPP., SEPARATED FROM WOUNDS OF PATIENTS WITH CHRONIC OSTEOMYELITIS IN MONO-CULTURES AND IN COMPOSITION OF ASSOCIATION OF MICROORGANISMS HARVESTED IN VITRO].

Klinicheskaia laboratornaia diagnostika, 62(3):188-192.

The article presents analysis of characteristics of 7 clinical strains of Serratia marcescens separated from fistulas in pre-operational period and from nidus of inflammation during operations in 2013-2015. in 7 patients with chronic osteomyelitis of long tubular bones. The bacteria S.marcescens are separated in one patient in monoculture and in 6 patients in composition of associations: S.marcescens + S.warneri + P.aeruginosa (n=1); S.marcescens + S.aureus (n=4); S.marcescens + M.morganii (n=1). According phometric analysis, strains of S.marcescens were characterized by average ability for biofilm formation on the surfaces of polystyrene dishes and cover glass that is substantiated by values of optic density and is conformed to data of their adhesion activity. The biofilm formation ability of association of microorganisms (S.marcescens + P.aeruginosa, S.marcescens + M.morgani) already after 24 hours of experiment were correspondingly higher in 1.4 and 1.2 times of levels of biofilm formation in monocultures. The activity of biofilm formation of association (S.marcescens + S.aureus) on the first day of experiment was low. However, after 48 hours a significant growth of biofilm was observed that is substantiated by values of optical density. The results of study demonstrated ability of all clinical strains of S.marcescens separated from osteomyelitis nidus to adhesion on surface of erythrocytes and to biofilm formation on abiotic surfaces (polystyrene and glass) both in monoculture and associations with other microorganisms. In consideration that microbial films play leading role in chronization of infectious diseases it is necessary to be aware of seriousness of etiologic role of S.marcescens in development of osteomyelitis as a pathogen.

RevDate: 2019-01-08

Heindl JE, Crosby D, Brar S, et al (2019)

Reciprocal control of motility and biofilm formation by the PdhS2 two-component sensor kinase of Agrobacterium tumefaciens.

Microbiology (Reading, England) [Epub ahead of print].

A core regulatory pathway that directs developmental transitions and cellular asymmetries in Agrobacterium tumefaciens involves two overlapping, integrated phosphorelays. One of these phosphorelays putatively includes four histidine sensor kinase homologues, DivJ, PleC, PdhS1 and PdhS2, and two response regulators, DivK and PleD. In several different alphaproteobacteria, this pathway influences a conserved downstream phosphorelay that ultimately controls the phosphorylation state of the CtrA master response regulator. The PdhS2 sensor kinase reciprocally regulates biofilm formation and swimming motility. In the current study, the mechanisms by which the A. tumefaciens sensor kinase PdhS2 directs this regulation are delineated. PdhS2 lacking a key residue implicated in phosphatase activity is markedly deficient in proper control of attachment and motility phenotypes, whereas a kinase-deficient PdhS2 mutant is only modestly affected. A genetic interaction between DivK and PdhS2 is revealed, unmasking one of several connections between PdhS2-dependent phenotypes and transcriptional control by CtrA. Epistasis experiments suggest that PdhS2 may function independently of the CckA sensor kinase, the cognate sensor kinase for CtrA, which is inhibited by DivK. Global expression analysis of the pdhS2 mutant reveals a restricted regulon, most likely functioning through CtrA to separately control motility and regulate the levels of the intracellular signal cyclic diguanylate monophosphate (cdGMP), thereby affecting the production of adhesive polysaccharides and attachment. We hypothesize that in A. tumefaciens the CtrA regulatory circuit has expanded to include additional inputs through the addition of PdhS-type sensor kinases, likely fine-tuning the response of this organism to the soil microenvironment.

RevDate: 2019-01-08

Khatoon Z, McTiernan CD, Suuronen EJ, et al (2018)

Bacterial biofilm formation on implantable devices and approaches to its treatment and prevention.

Heliyon, 4(12):e01067 pii:e01067.

In living organisms, biofilms are defined as complex communities of bacteria residing within an exopolysaccharide matrix that adheres to a surface. In the clinic, they are typically the cause of chronic, nosocomial, and medical device-related infections. Due to the antibiotic-resistant nature of biofilms, the use of antibiotics alone is ineffective for treating biofilm-related infections. In this review, we present a brief overview of concepts of bacterial biofilm formation, and current state-of-the-art therapeutic approaches for preventing and treating biofilms. Also, we have reviewed the prevalence of such infections on medical devices and discussed the future challenges that need to be overcome in order to successfully treat biofilms using the novel technologies being developed.

RevDate: 2019-01-08

Di Salle A, Spagnuolo G, Conte R, et al (2018)

Effects of various prophylactic procedures on titanium surfaces and biofilm formation.

Journal of periodontal & implant science, 48(6):373-382.

Purpose: The aim of this study was to evaluate the effects of various prophylactic treatments of titanium implants on bacterial biofilm formation, correlating surface modifications with the biofilms produced by Pseudomonas aeruginosa PAO1, Staphylococcus aureus, and bacteria isolated from saliva.

Methods: Pure titanium disks were treated with various prophylactic procedures, and atomic force microscopy (AFM) was used to determine the degree to which surface roughness was modified. To evaluate antibiofilm activity, we used P. aeruginosa PAO1, S. aureus, and saliva-isolated Streptococcus spp., Bacteroides fragilis, and Staphylococcus epidermidis.

Results: AFM showed that the surface roughness increased after using the air-polishing device and ultrasonic scaler, while a significant reduction was observed after using a curette or polishing with Detartrine ZTM (DZ) abrasive paste. In addition, we only observed a significant (P<0.01) reduction in biofilm formation on the DZ-treated implant surfaces.

Conclusion: In this study, both AFM and antibiofilm analyses indicated that using DZ abrasive paste could be considered as the prophylactic procedure of choice for managing peri-implant lesions and for therapy-resistant cases of periodontitis.

RevDate: 2019-01-08

Gangneux JP, Cornet M, Bailly S, et al (2018)

Clinical Impact of Antifungal Susceptibility, Biofilm Formation and Mannoside Expression of Candida Yeasts on the Outcome of Invasive Candidiasis in ICU: An Ancillary Study on the Prospective AmarCAND2 Cohort.

Frontiers in microbiology, 9:2907.

Background: The link between Candida phenotypical characteristics and invasive candidiasis (IC) prognosis is still partially unknown. Methods:Candida strains isolated during the AmarCAND2 study were centrally analyzed for species identification, antifungal susceptibility, biofilm formation, and expression of surface and glycoconjugate mannosides. Correlation between these phenotypical features and patient outcome was sought using a multivariable Cox survival model. Results:Candida albicans was predominant (65.4%, n = 285), with a mortality rate significantly lower than that in patients with non-albicans strains [HR 0.67 (0.46-1.00), p = 0.048]. The rate of fluconazole-resistant strains was low (C. albicans and Candida glabrata: 3.5 and 6.2%, respectively) as well as caspofungin-resistant ones (1 and 3.1%, respectively). Early biofilm formation was less frequent among C. albicans (45.4%) than among non-albicans (81.2%). While the strains of C. albicans showed variable levels of surface mannosides expression, strains isolated from candidemia exhibited a high expression of β-man, which was correlated with an increased mortality (p = 0.02). Conclusion:Candida albicans IC were associated with lower mortality, and with strains that exhibited less frequently early biofilm formation than non-albicans strains. A high expression of β-man was associated with increased IC mortality. Further studies are warranted to confirm this data and to evaluate other virulence factors in yeasts.

RevDate: 2019-01-08

Kerkoub N, Panda SK, Yang MR, et al (2018)

Bioassay-Guided Isolation of Anti-Candida Biofilm Compounds From Methanol Extracts of the Aerial Parts of Salvia officinalis (Annaba, Algeria).

Frontiers in pharmacology, 9:1418.

Salvia officinalis is frequently used in traditional Algerian medicine to treat diverse microbial infections, including oral and vaginal candidiasis. The aerial parts of S. officinalis collected in Annaba, Algeria were extracted in parallel by maceration with four solvents viz. hexane, acetone, methanol and water. All the extracts were tested in vitro against several Candida species: C. albicans, C. glabrata, and C. parapsilosis. Furthermore, the activity against biofilm-forming C. albicans was investigated using bioassay-guided fractionation. A large-scale extract was prepared via maceration in methanol, followed by fractionation on a silica gel column using increasingly polar mixtures of n-hexane, ethyl acetate, methanol, and acetic acid as mobile phase, to yield a total of 150 fractions. Two major active fractions (F-31 and F-39), were further separated by HPLC, resulting in several active chromatographic peaks. Carnosol and 12-methoxy-trans-carnosic acid were isolated as two major active compounds, and identified by a combination of NMR and mass spectrometry. The biofilm inhibitory concentration showed that 12-methoxy-trans-carnosic acid is more effective than carnosol with BIC50 values of 94 μM (95% confidence interval, 78.9-112.1 μM) and 314 μM (95% confidence interval, 200.7-491.2 μM), respectively. The present study supports the traditional use of sage in the treatment of various fungal infections caused by Candida. Further studies of the bioactive compounds in an in vivo Candida biofilm model are required to validate their clinical potential as antifungals.

RevDate: 2019-01-08

Peng G, Hou X, Zhang W, et al (2019)

Alkyl rhamnosides, a series of amphiphilic materials exerting broad-spectrum anti-biofilm activity against pathogenic bacteria via multiple mechanisms.

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

As novel amphiphilic materials, six uncharged alkyl rhamnosides incorporating various alkyl chain and one rhamnose amine quaternary ammonium salt were successfully synthesized in this study. Their amphiphilic properties (HLB and CMC), antimicrobial and anti-biofilm activity against S. aureus and P. aeruginosa were investigated. Differentially regulated proteins and pathways were identified by comparative proteomics research to first give a sight on how alkyl rhamnosides performed the anti-biofilm activity at protein and pathway levels. Among the uncharged alkyl rhamnosides, dodecyl rhamnoside and octyl rhamnoside showed the best antimicrobial and anti-biofilm ability against S. aureus and against P. aeruginosa, respectively. Interestingly, the relationships between amphiphilic properties or MIC with anti-biofilm activity were first established. Uncharged alkyl rhamnoside with an optimized HLB value of 5.0 had both the strongest antibacterial and anti-biofilm activity against S. aureus, and MIC was the maximum biofilm inhibitory concentration for all alkyl rhamnosides. Alkyl rhamnosides have a significant overall regulatory effect on the proteomics and pathways of bacterial biofilms, including energy production, substrates transportation, signal transduction, key molecules balance, and so on. These amphiphilic materials have a great potential to be used as additives in pharmaceutic, cosmetic, food industry, hospital and in other non-medical fields.

RevDate: 2019-01-08

Shi C, Liu J, Li W, et al (2019)

Expression of fluconazole resistance-associated genes in biofilm from 23 clinical isolates of Candida albicans.

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] pii:10.1007/s42770-018-0009-2 [Epub ahead of print].

This study aimed to establish the influence of biofilm from clinical isolates of Candida albicans on fluconazole resistance, focusing on efflux pumps and azole-targeted enzymes. Twenty-three C. albicans clinical isolates were collected from two hospitals in Shanghai, China. Antifungal susceptibility tests were performed on biofilm and planktonic cells. A crystal violet assay was used to monitor biofilm growth. Real-time RT-PCR was performed to quantify the expression of the transporter-related genes MDR1, CDR1, and CDR2 as well as ERG11, a gene encoding an enzyme targeted by antifungal drugs. Fluconazole resistance was shown to increase in biofilm in a time-dependent manner. No significant differences were observed between different strains of C. albicans. Genes encoding efflux pumps were overexpressed in early stages of biofilm formation and could also be induced by fluconazole. While ERG11 was not upregulated in biofilm, it was overexpressed upon the addition of fluconazole to biofilm and planktonic cells. Gene expression also appeared to be related to the original genotype of the strain. The upregulation of genes encoding efflux pumps demonstrates their role in the development of fluconazole resistance during the early stages of C. albicans biofilm formation.

RevDate: 2019-01-08

Teh WK, Dramsi S, Tolker-Nielsen T, et al (2019)

Increased intracellular cyclic-di-AMP levels sensitize Streptococcus gallolyticus subsp. gallolyticus to osmotic stress, and reduce biofilm formation and adherence on intestinal cells.

Journal of bacteriology pii:JB.00597-18 [Epub ahead of print].

Cyclic-di-AMP is a recently identified second messenger exploited by a number of Gram-positive bacteria to regulate important biological processes. Here, we studied the phenotypic alterations induced by increased intracellular c-di-AMP levels in Streptococcus gallolyticus, an opportunistic pathogen responsible for septicemia and endocarditis in the elderly. We report that a S. gallolyticus c-di-AMP phosphodiesterase gdpP knock-out mutant, which displays a 1.5-fold higher intracellular c-di-AMP levels as compared to the parental strain UCN34, is more sensitive to osmotic stress and is morphologically smaller than the parental strain. Unexpectedly, we found that a higher level of c-di-AMP reduced biofilm formation of S. gallolyticus on abiotic surfaces, and reduced adherence and cell aggregation on human intestinal cells. A genome-wide transcriptomic analysis indicated that c-di-AMP regulates many biological processes in S. gallolyticus, including the expression of various ABC transporters and disease-associated genes encoding bacteriocin and Pil3 pilus. Complementation of the gdpP in-frame deletion mutant with a plasmid carrying gdpPin trans from its native promoter restored bacterial morphology, tolerance to osmotic stresses, biofilm formation, adherence to intestinal cells, bacteriocin production and Pil3 pilus expression. Our results indicate that c-di-AMP is a pleiotropic signaling molecule in S. gallolyticus that may be important for S. gallolyticus pathogenesis.ImportanceStreptococcus gallolyticus is an opportunistic pathogen responsible for septicemia and endocarditis in the elderly, and is also strongly associated with colorectal cancer. S. gallolyticus can form biofilms, express specific pili to colonize the host tissues, and produce a specific bacteriocin allowing killing of commensal bacteria in the murine colon. Nevertheless, how the expression of these colonization factors is regulated remains largely unknown. Here, we show that c-di-AMP plays pleiotropic roles in S. gallolyticus, controlling the tolerance to osmotic stress, cell size, biofilm formation on abiotic surfaces, adherence and cell aggregation on human intestinal cells, expression of Pil3 pilus and production of bacteriocin. This study indicates that c-di-AMP may constitute a key regulatory molecule for S. gallolyticus host colonization and pathogenesis.

RevDate: 2019-01-07

Høiby N, Henneberg KÅ, Wang H, et al (2019)

Formation of Pseudomonas aeruginosa inhibition zone during Tobramycin disk diffusion is due to a transition from planktonic to biofilm mode of growth.

International journal of antimicrobial agents pii:S0924-8579(18)30385-6 [Epub ahead of print].

Pseudomonas aeruginosa PAO1 (MIC 0.064µg/ml) was used to perform agar diffusion tests employing tobramycin containing tablets. The growth of the bacteria and the formation of inhibition zones were studied by stereomicroscopy and by blotting with microscope slides and staining with Methylene blue, Alcian blue and a fluorescent lectin for the P. aeruginosa PSL which was studied by confocal laser scanning microscopy. The diffusion of tobramycin from the deposit was modelled by using a 3D geometric version of Fick's 2nd law of diffusion. The time-dependent gradual increase of Minimal Biofilm Eradication Concentration (MBEC) was studied by the Calgary Biofilm Devise. The early inhibition zone was visible after 5 h incubation. The corresponding calculated tobramycin concentration at the border was 1.9µg/ml and increased to 3.2µg/ml and 6.3µg/ml after 7 and 24 h incubation. The inhibition zone increased to the stable, final zone after 7 h incubation. Bacterial growth and small aggregate formation (young biofilms) took place inside the inhibition zone until the small aggregates contained ≤≈64 cells and production of polysaccharide matrix including PSL had begun, thereafter the small bacterial aggregates were killed by tobramycin. The bacteria at the border of the stable inhibition zone and beyond continued to grow to a mature biofilm and produced large amount of polysaccharide containing matrix. The formation of the inhibition zone during the agar diffusion antibiotic susceptibility test is due to a switch from the planktonic to the biofilm mode of growth and gives clinical important information about the increased antibiotic tolerance of biofilms.

RevDate: 2019-01-07

Zhang Z, Deng Y, Feng K, et al (2019)

Deterministic assembly and diversity gradient altered the biofilm community performances of bioreactors.

Environmental science & technology [Epub ahead of print].

Community assembly process (determinism vs. stochasticity) determines the composition and diversity of microbial community, and then shapes its functions. Understanding this complex process and its relationship to the community functions becomes a very important task for the applications of microbial biotechnology. In this study, we applied microbial electrolysis cells (MECs) with moderate species numbers and easily tractable functions as a model ecosystem, and constructed a series of biofilm communities with gradient biodiversity to examine the roles of community assembly in determining microbial community structure and functions. After stable biofilms formed, the best MEC reactor performances (e.g., gas productivity, total energy efficiency) were achieved in the group which biofilms had the second highest α-diversity, and biofilms with even lower diversity showed declining performance. Null model analyses indicated that both deterministic and stochastic assembly played roles in the formation of biofilm communities. When deterministic assembly dominates this formation, the higher diversity of biofilm community would generally show better reactor performance. However, when the stochasticity dominates the assembly process, the bioreactor performance would decline. This study provides novel evidence that the assembly mechanism could be one of the key processes to shift the functions, and proposes an important guidance for selecting the most efficient microorganisms for environmental biotechnologies.

RevDate: 2019-01-07

Chen Z, Meng Y, Sheng B, et al (2019)

Linking exoproteome function and structure to anammox biofilm development.

Environmental science & technology [Epub ahead of print].

Extracellular proteins are of paramount importance in the cell-cell interactions of anammox biofilms. However, the inherent aggregation mechanisms of anammox have largely remained elusive. Herein, using a quartz sand extraction protocol and follow-up iTRAQ-based quantitative proteomics, we identified 367 extracellular proteins from initial colonizer, mature and detached biofilms. The extracellular proteins were mainly membrane-associated. Most of the recovered proteins (226, 72.5%) originated from the phylum Planctomycetes. In summary, 251 and 190 out of the 367 proteins recovered were up and/or downregulated at least 1.2-fold during the biofilm formation and detachment periods, respectively. These differentially expressed proteins were dominantly involved in metal ion binding, which was regarded as strong evidence for their abilities to enhance ionic bridges in extracellular polymeric substances (EPS). SEM-EDX analysis of the biofilms further showed substantial levels of calcium and iron minerals. Critically, representative Sec-dependent secretory proteins affiliated with coccoid Planctomycetes, rod-shaped Proteobacteria and filamentous Chloroflexi (11, 4 and 2 with differential expression, respectively) were found to have typical and abundant inner β-sheet structures, wherein hydrophobic moieties can promote anammox aggregation. Overall, these findings highlight links between differentially expressed protein functions and morphologic traits of anammox consortia during biofilm development.

RevDate: 2019-01-07

Roy S, Santra S, Das A, et al (2019)

Staphylococcus aureus Biofilm Infection Compromises Wound Healing by Causing Deficiencies in Granulation Tissue Collagen.

Annals of surgery [Epub ahead of print].

OBJECTIVE: The objective of this work was to causatively link biofilm properties of bacterial infection to specific pathogenic mechanisms in wound healing.

BACKGROUND: Staphylococcus aureus is one of the four most prevalent bacterial species identified in chronic wounds. Causatively linking wound pathology to biofilm properties of bacterial infection is challenging. Thus, isogenic mutant stains of S. aureus with varying degree of biofilm formation ability was studied in an established preclinical porcine model of wound biofilm infection.

METHODS: Isogenic mutant strains of S. aureus with varying degree (ΔrexB > USA300 > ΔsarA) of biofilm-forming ability were used to infect full-thickness porcine cutaneous wounds.

RESULTS: Compared with that of ΔsarA infection, wound biofilm burden was significantly higher in response to ΔrexB or USA300 infection. Biofilm infection caused degradation of cutaneous collagen, specifically collagen 1 (Col1), with ΔrexB being most pathogenic in that regard. Biofilm infection of the wound repressed wound-edge miR-143 causing upregulation of its downstream target gene matrix metalloproteinase-2. Pathogenic rise of collagenolytic matrix metalloproteinase-2 in biofilm-infected wound-edge tissue sharply decreased collagen 1/collagen 3 ratio compromising the biomechanical properties of the repaired skin. Tensile strength of the biofilm infected skin was compromised supporting the notion that healed wounds with a history of biofilm infection are likely to recur.

CONCLUSION: This study provides maiden evidence that chronic S. aureus biofilm infection in wounds results in impaired granulation tissue collagen leading to compromised wound tissue biomechanics. Clinically, such compromise in tissue repair is likely to increase wound recidivism.

RevDate: 2019-01-07

Sun Y, Hu X, Guo D, et al (2019)

Disinfectant Resistance Profiles and Biofilm Formation Capacity of Escherichia coli Isolated from Retail Chicken.

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

Disinfectant resistance and biofilm formation capacity are two important characteristics that contribute to the persistence of microorganisms in food processing environments and contamination of food products. This study investigated the susceptibility of 510 Escherichia coli isolates against 5 disinfectants and the prevalence of 10 disinfectant-resistant genes in these isolates. The biofilm formation capacity of 194 isolates was determined, and the correlation between disinfectant resistance and biofilm formation was analyzed. The minimal inhibitory concentrations (MICs) of cetyltrimethylammonium bromide (CTAB), benzalkonium chloride (BC), cetylpyridinium chloride, and chlorhexidine (CHX) against isolates were 32-512, 16-256, 32-256, and 2-32 mg/L, respectively. The MICs of triclosan against 88.43% of isolates were 8-1,024 mg/L, while the MICs for the rest of isolates exceed 2,048 mg/L. The presence of ydgE, ydgF, and qacF genes was significantly correlated with the CHX resistance of E. coli isolates, while the presence of qacF and qacEΔ1 genes was significantly correlated with CTAB and BC resistance, respectively. The biofilm formation capacity (adjusted optical density value) was positively correlated with BC resistance (r = 0.201, p < 0.01) and showed no correlation with other disinfectants. The presence of sugE(p) was positively correlated with biofilm formation, while four genes were negatively correlated with biofilm formation. This study provides useful data on disinfectant resistance and biofilm formation capacity of E. coli contaminating poultry products, which could be helpful in guiding proper disinfectant usage and establishing effective biofilm eradication strategy in food industry.

RevDate: 2019-01-07

Zhu N, Wang S, Cilai T, et al (2019)

Protection mechanisms of periphytic biofilm to photocatalytic nanoparticles (PNPs) exposure.

Environmental science & technology [Epub ahead of print].

Researchers are devoting great effort to combine photocatalytic nanoparticles (PNPs) with biological process to create efficient environmental purification technologies (i.e. intimately coupled photobiocatalysis). However, little information is available to illuminate the responses of multispecies microbial aggregates against PNP exposure. Periphytic biofilm, as a model multispecies microbial aggregate, was exposed to three different PNPs (CdS, TiO2, and Fe2O3) under Xenon lamp irradiation. There were no obvious toxic effects of PNP exposure on periphytic biofilm as biomass, chlorophyll content and ATPase activity were not negatively impacted. Enhanced production of extracellular polymetric substances (EPS) is the most important protection mechanism for periphytic biofilm against PNPs exposure. Although PNPs exposure produced extracellular superoxide radicals and caused intracellular reactive oxygen species (ROS) accumulation in periphytic biofilm, the interaction between EPS and PNPs could mitigate production of ROS while superoxide dismutase could alleviate biotic ROS accumulation in periphytic biofilm. The periphytic biofilms changed their community composition in the presence of PNPs by increasing the relative abundance of phototrophic and high nutrient metabolic microorganisms (Families Chlamydomonadaceae, Cyanobacteriacea, Sphingobacteriales and Xanthomonadaceae). This study provides insight into the protection mechanisms of microbial aggregates against simultaneous photogenerated and nanoparticle toxicity from PNPs.

RevDate: 2019-01-07

Jarząb N, Walczak M, Smoliński D, et al (2019)

The impact of medicinal brines on microbial biofilm formation on inhalation equipment surfaces.

Biofouling [Epub ahead of print].

Materials such as polyvinyl chloride, polypropylene, and polyethylene are used for the construction of medical equipment, including inhalation equipment. Inhalation equipment, because of the wet conditions and good oxygenation, constitutes a perfect environment for microbial biofilm formation. Biofilms may affect microbiological cleanliness of inhalation facilities and installations and promote the development of pathogenic bacteria. Microbial biofilms can form even in saline environments. Therefore, the aim of this study was to evaluate the effect of medicinal brines on microbial biofilm formation on the surfaces of inhalation equipment. The study confirmed the high risk of biofilm formation on surfaces used in inhalation equipment. Isolated microorganisms belonged to potential pathogens of the respiratory system, which can pose a health threat to hospital patients. The introduction of additional contaminants increased the amount of bacterial biofilm. On the other hand, the presence of brines significantly limited the amount of biofilm, thus eliminating the risk of infections.

RevDate: 2019-01-07

Tailly T, C Van Haute (2019)

Editorial comment on In Vitro Effects of a Novel Coating Agent on Bacterial Biofilm Development on Ureteral Stent.

Journal of endourology [Epub ahead of print].

RevDate: 2019-01-06

Masmoudi Jabri K, Fiedler T, Saidi A, et al (2019)

Steady-state modeling of the biodegradation performance of a multistage moving bed biofilm reactor (MBBR) used for on-site greywater treatment.

Environmental science and pollution research international pii:10.1007/s11356-018-3984-9 [Epub ahead of print].

In this study, the Activated Sludge Model No. 3 (ASM3) was applied for the simulation of the removal of organics and nitrogen in a multistage moving bed biofilm reactor (MBBR) used for biological greywater treatment. The data related to the characterization of the greywater were collected over a period of 5 months to be investigated in the model. The reactor showed a high performance for the removal of chemical oxygen demand (COD), dissolved organic carbon (DOC), biological oxygen demand (BOD5), ammonia (NH4-N), and total nitrogen (TN) with a removal efficiency of 93%, 80.7%, 99%, 89%, and 77%, respectively. The results of modeling showed a good correlation between simulated and experimental concentrations of COD issued from different reactors of the MBBR system. The adaptability of the ASM3 model to fit other parameters such as TN, NH4-N, total suspended solids (TSS), and the dissolved oxygen (DO) was also investigated for two selected reactors: reactor (R1) and the reactor (R5). The simulation results showed an acceptable correlation regarding the evolution of the investigated parameters in R1 and R5 and in the effluent except for total nitrogen TN. The adjustment of the stoichiometric parameters led to a satisfactory simulation of TN concentrations.

RevDate: 2019-01-05

Polak D, Shany-Kdoshim S, Zaydel L, et al (2019)

High-resolution novel method for tracking bacteria in a multi-species biofilm.

Archives of microbiology pii:10.1007/s00203-018-1614-z [Epub ahead of print].

The aim of this study is to establish a novel high resolution tracking ability of a specific bacterium in multispecies biofilm. A periodontal multispecies biofilm was constructed with Streptococcus sanguis, Actinomyces naeslundii, Porphyromonas gingivalis and Fusobacterium nucleatum. A single species was stained with fluorescein isothiocyanate (FITC). The mature biofilm was stained for viability (propidium iodide) and analysis was performed with flow cytometry. The sensitivity of the assay was compared with colony forming units (CFU) counts. A single cell suspension of P. gingivalis was grown in broth and biofilm to identify the location of these events on side scatter and forward scatter. The sensitivity of the assay was comparable to that of the CFU counts. The assay allows quantification of the ratio of a single bacterium within the biofilm, and its viable proportion. The described method is reproducible and of high resolution, and allows the examination of microbes' composition and viability within a biofilm structure.

RevDate: 2019-01-05

Zurob E, Dennett G, Gentil D, et al (2019)

Inhibition of Wild Enterobacter cloacae Biofilm Formation by Nanostructured Graphene- and Hexagonal Boron Nitride-Coated Surfaces.

Nanomaterials (Basel, Switzerland), 9(1): pii:nano9010049.

Although biofilm formation is a very effective mechanism to sustain bacterial life, it is detrimental in medical and industrial sectors. Current strategies to control biofilm proliferation are typically based on biocides, which exhibit a negative environmental impact. In the search for environmentally friendly solutions, nanotechnology opens the possibility to control the interaction between biological systems and colonized surfaces by introducing nanostructured coatings that have the potential to affect bacterial adhesion by modifying surface properties at the same scale. In this work, we present a study on the performance of graphene and hexagonal boron nitride coatings (h-BN) to reduce biofilm formation. In contraposition to planktonic state, we focused on evaluating the efficiency of graphene and h-BN at the irreversible stage of biofilm formation, where most of the biocide solutions have a poor performance. A wild Enterobacter cloacae strain was isolated, from fouling found in a natural environment, and used in these experiments. According to our results, graphene and h-BN coatings modify surface energy and electrostatic interactions with biological systems. This nanoscale modification determines a significant reduction in biofilm formation at its irreversible stage. No bactericidal effects were found, suggesting both coatings offer a biocompatible solution for biofilm and fouling control in a wide range of applications.

RevDate: 2019-01-04

Chen M, Wei J, Xie S, et al (2019)

Bacterial biofilm destruction by size/surface charge-adaptive micelles.

Nanoscale [Epub ahead of print].

Biofilms formed by pathogenic bacteria are one of the most important reasons for multidrug resistance. One of the major limitations in the biofilm treatment is the existence of intensive matrices, which greatly block the diffusion of antimicrobial agents. In the current study, we designed poly(aspartamide)-derived micelles self-assembled from cationic copolymers with azithromycin-conjugated and pH-sensitive copolymers, followed by loading cis-aconityl-d-tyrosine (CA-Tyr) via electrostatic interactions. In response to the acidic microenvironment of the biofilm matrix, the hydrophilic transition of the pH-sensitive copolymers and the removal of CA-Tyr led to a sharp decrease in micelle size from 107 nm to 54 nm and a rapid shift in their zeta potential from -11.7 mV to +26.4 mV, which facilitated the penetration of the micelles into biofilms. The acid-labile release of d-tyrosine disintegrated the biofilm matrix, and the lipase-triggered release of azithromycin eradicated the bacteria in the biofilms. An in vitro test was performed on pre-established P. aeruginosa biofilms in microwells, while biofilms grown on catheters were surgically implanted in rats for in vivo evaluation. The results demonstrated the capabilities of the size/surface charge-adaptive micelles in the intensive infiltration in the biofilm matrix and spatiotemporal release of biofilm dispersion and antibacterial agents for the comprehensive treatment of biofilm-relevant infections.

RevDate: 2019-01-04

Hendiani S, Pornour M, N Kashef (2019)

Sub-lethal antimicrobial photodynamic inactivation: an in vitro study on quorum sensing-controlled gene expression of Pseudomonas aeruginosa biofilm formation.

Lasers in medical science pii:10.1007/s10103-018-02707-y [Epub ahead of print].

During antimicrobial photodynamic inactivation (APDI) in the treatment of an infection, it is likely that microorganisms would be exposed to sub-lethal doses of APDI (sAPDI). Although sAPDI cannot kill microorganisms, it can significantly affect microbial virulence. In this study, we evaluated the effect of sAPDI using methylene blue (MB) on the expression of genes belonging to two quorum sensing (QS) operons (rhl and las systems) and two genes necessary for biofilm formation (pelF and pslA) under QS control in Pseudomonas aeruginosa. Biofilm formation ability of P. aeruginosa ATCC 27853 exposed to sAPDI (MB at 0.012 mM and light dose of 23 J/cm2) was evaluated using triphenyl tetrazolium chloride (TTC) assay and scanning electron microscopy (SEM). The effect of sAPDI on expression of rhlI, rhlR, lasI, lasR, pelF, and pslA were also evaluated by quantitative real-time polymerase chain reaction. Quantitative assay (TTC) results and morphological observations (SEM) indicated that a single sAPDI treatment resulted in a significant decrease in biofilm formation ability of P. aeruginosa ATCC 27853 compared to their non-treated controls (P = 0.012). These results were consistent with the expression of genes belonging to rhl and las systems and pelF and pslA genes. The results suggested that the transcriptional decreases caused by MB-sAPDI did lead to phenotypic changes.

RevDate: 2019-01-04

Jin Z, Jiang Q, Fang B, et al (2018)

The ArlR-MgrA regulatory cascade regulates PIA-dependent and protein-mediated biofilm formation in Rbf-dependent and Rbf-independent pathways.

International journal of medical microbiology : IJMM pii:S1438-4221(18)30129-2 [Epub ahead of print].

The two-component system response regulator ArlR and the global regulator MgrA in Staphylococcus aureus participated in numerous biological processes including biofilm formation inhibition. Previous studies have shown that these two regulators could function as a regulatory cascade. Rbf is a positive regulator of biofilm formation enhancing the production of PIA (polysaccharide intercellular adhesin). Here we have demonstrated that both ArlR and MgrA can directly bind to the promoter of rbf and repress its expression. ArlR and MgrA can also directly bind to the promoter of ica operon and enhance the expression of icaA and PIA production, revealing that the ArlR-MgrA regulatory cascade controls PIA-dependent biofilm formation. In addition, we have found that Rbf can directly bind to the aur promoter and repress the expression of aur, which encodes a protease initiating a protease cascade to inhibit protein-mediated biofilm formation. Moreover, our data indicate that the ArlR-MgrA regulatory cascade can promote the expression of aur by directly binding to its promoter and inhibit protein-mediated biofilm formation. These findings shed light on the molecular mechanisms of both PIA-dependent and protein-mediated biofilm formation modulated by the ArlR-MgrA regulatory cascade and the new role of Rbf in protein-mediated biofilm formation, and broaden our understanding of the biofilm formation regulation in S. aureus.

RevDate: 2019-01-03

Bino E, Lauková A, Kandričáková A, et al (2018)

Assessment of biofilm formation by faecal strains of Enterococcus hirae from different species of animals.

Polish journal of veterinary sciences, 21(4):747-754.

Enterococcus hirae belongs in the Enterococcus faecium group within the genus Enterococcus. This species occurs naturally in the environment, commensally in the alimentary tracts of animals, and pathologically for example in humans with urinary infections. Some strains of E. hirae possess virulence factors, including biofilm formation. Biofilm growth protects bacteria against host de- fences; biofilm can be a source of persistent infection. Testing bacterial strains for their ability to form biofilm might therefore facilitate their treatment or prevention. This study focuses on bio- film formation by E. hirae strains derived from various animals. This kind of testing has never been done before. A total of 64 identified E. hirae from laying hens, ducks, pheasants, ostriches, rabbits, horses and a goat were tested by means of three methods; using Congo red agar, the tube method and microtiter plate agar. The majority of strains were found to form biofilm. 62.5% of strains were biofilm-forming, four categorized as highly positive (OD570 ≥1); most strains were low-grade biofilm positive (0.1 ≤ OD 570 ⟨ 1). Related to poultry, 55 E. hirae strains were tested and found to produce biofilm; 24 strains did not form biofilm, 31 strains were biofilm-forming; 27 strains showed low-grade biofilm formation, and four strains were highly biofilm-forming. Four strains from hens and ostriches reached the highest OD570 values, more than 0.500. Rabbit-de- rived E. hirae strains as well as strains isolated from horses and the goat were low-grade bio- film-forming. Microtiter plate assay proved to be the best tool for testing the in vitro biofilm for- mation capacity of E. hirae strains from different species of animals.

RevDate: 2019-01-03

Dominguez EG, Zarnowski R, Choy HL, et al (2019)

Conserved Role for Biofilm Matrix Polysaccharides in Candida auris Drug Resistance.

mSphere, 4(1): pii:4/1/e00680-18.

Candida auris has emerged as an outbreak pathogen associated with high mortality. Biofilm formation and linked drug resistance are common among Candida species. Drug sequestration by the biofilm matrix accounts for much of the antifungal tolerance. In this study, we examine the biofilm matrix composition and function for a diverse set of C. auris isolates. We show that matrix sequesters nearly 70% of the available triazole antifungal. Like the biofilms formed by other Candida spp., we find that the matrix of C. auris is rich in mannan-glucan polysaccharides and demonstrate that their hydrolysis reduces drug tolerance. This biofilm matrix resistance mechanism appears conserved among Candida species, including C. aurisIMPORTANCECandida auris is an emerging fungal threat linked to poor patient outcomes. The factors responsible for this apparent increase in pathogenicity remain largely unknown. Biofilm formation has been suggested as an important factor for persistence of this organism in patients and the environment. Our findings reveal one mechanism utilized by C. auris to evade the effect of triazole antifungal therapy during biofilm growth. The conservation of the protective biofilm matrix among Candida spp. suggests that is a promising pan-fungal Candida biofilm drug target.

RevDate: 2019-01-02

Liu Y, Shi L, Su L, et al (2019)

Nanotechnology-based antimicrobials and delivery systems for biofilm-infection control.

Chemical Society reviews [Epub ahead of print].

Bacterial-infections are mostly due to bacteria in an adhering, biofilm-mode of growth and not due to planktonically growing, suspended-bacteria. Biofilm-bacteria are much more recalcitrant to conventional antimicrobials than planktonic-bacteria due to (1) emergence of new properties of biofilm-bacteria that cannot be predicted on the basis of planktonic properties, (2) low penetration and accumulation of antimicrobials in a biofilm, (3) disabling of antimicrobials due to acidic and anaerobic conditions prevailing in a biofilm, and (4) enzymatic modification or inactivation of antimicrobials by biofilm inhabitants. In recent years, new nanotechnology-based antimicrobials have been designed to kill planktonic, antibiotic-resistant bacteria, but additional requirements rather than the mere killing of suspended bacteria must be met to combat biofilm-infections. The requirements and merits of nanotechnology-based antimicrobials for the control of biofilm-infection form the focus of this Tutorial Review.

RevDate: 2019-01-02

Feng J, Cheng L, Zhou X, et al (2018)

Effects of water aging on the mechanical and anti-biofilm properties of glass-ionomer cement containing dimethylaminododecyl methacrylate.

Dental materials : official publication of the Academy of Dental Materials pii:S0109-5641(18)30757-7 [Epub ahead of print].

OBJECTIVES: The aims of this study were to investigate the effects of water aging for up to 6months on the mechanical and anti-biofilm properties of a novel antibacterial glass ionomer cement (GIC) containing dimethylaminododecyl methacrylate (DMADDM).

METHODS: GIC specimens (n=180) which contained DMADDM (0wt.%, 1.1wt.% or 2.2wt.%) were prepared. The mechanical properties surface roughness, microhardness and the surface charge density of ammonium groups were measured before and after water aging for 3 and 6months at 37°C. Further six months aged specimens (n=216) were worn by 6 volunteers in their oral cavities for 24h and 72h. Biofilm formation was analyzed and rated by fluorescence microscopy (FM) and by scanning electron microscopy (SEM). Biofilm viability was analyzed by FM.

RESULTS: Water aging did not show any adverse effects on the surface roughness and hardness of the material. The surface charge density of the GIC samples containing DMADDM decreased due to the aging procedure, however, was still higher than that of the GIC without DMADDM. In situ biofilm formation was significantly reduced after 24h on DMADDM containing GIC (p<0.05). FM results showed a higher ratio of red/green fluorescence on GIC-DMADDM samples.

SIGNIFICANCE: Incorporating DMADDM into GIC affected the material properties in a tolerable manner even after 6months of storage in water. The new GIC is a promising material to affect the biofilm formation on the surface of restorations.

RevDate: 2019-01-01

Gambino M, Sanmartín P, Longoni M, et al (2018)

Surface colour: An overlooked aspect in the study of cyanobacterial biofilm formation.

The Science of the total environment, 659:342-353 pii:S0048-9697(18)35251-3 [Epub ahead of print].

Cyanobacteria can grow as biofilms, communities that colonize surfaces and that play a fundamental role in the ecology of many diverse habitats and in the conversion of industrial production to green platforms. Although biofilm growth is known to be significantly affected by several characteristics, the effect of colour surface is an overlooked aspect that has not yet been investigated. In this study, we describe the effect of colour hues (white, red, blue and black) on the growth of cyanobacterial biofilms on air-exposed substrates. We measured growth, architecture, pigment production and levels of ATP and reactive oxygen species in cyanobacterial biofilms formed on different coloured substrates. The study findings demonstrate, for the first time, that the colour of a surface affects biofilm formation at the air-solid interface (with more biomass accumulating on white and red substrates than on blue and black substrates) and also alters the biofilm architecture. In addition, the roles of chromatic adaptation, phototrophic cells and reactive oxygen species as intermediates between colour sensing and biofilm response are discussed. Our results support the importance of colour as a new factor that favours surface colonization by cyanobacteria and its contribution to biofilm formation.

RevDate: 2019-01-01

Li Y, Hu X, Ruan J, et al (2018)

Bonding durability, antibacterial activity and biofilm pH of novel adhesive containing antibacterial monomer and nanoparticles of amorphous calcium phosphate.

Journal of dentistry pii:S0300-5712(18)30476-7 [Epub ahead of print].

OBJECTIVES: The dentin bonding often fails over time, leading to secondary caries and restoration failure. The objectives of this study were to develop an adhesive with dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the effects of storage in artificial saliva for six months on the bonding durability, antibacterial activity, ion release and biofilm pH properties for the first time.

METHODS: DMAHDM was added at 5% (by mass) to Scotchbond Primer and Adhesive (SBMP). NACP was added at 10%, 20%, and 30% to SBMP adhesive. Dentin bonding durability, antibacterial activity against Streptococcus mutans biofilms, and calcium (Ca) and phosphate (P) ion liberation properties were investigated after 1 day and 6months of storage in artificial saliva.

RESULTS: Dentin bond strength (n = 50) had 25% loss after 6 months of aging for SBMP control. However, SBMP + DMAHDM+10NACP and SBMP + DMAHDM+20NACP showed no loss in bond strength after storage in artificial saliva for 6 months. The DMAHDM + NACP incorporation method dramatically reduced the biofilm metabolic activity and acid production, and decreased the biofilm CFU by four orders of magnitude, compared to SBMP control, even after 6 months of aging (p > 0.1). DMAHDM + NACP had long-lasting Ca and P ion releases, and raised the biofilm pH to 6.8, while the control group had a cariogenic biofilm pH of 4.5.

CONCLUSIONS: Incorporating DMAHDM + NACP in bonding agent yielded potent and long-lasting antibacterial activity and ions liberation ability, and much higher long-term dentin bond strength after 6-month of aging. The new bonding agent is promising to inhibit caries at the restoration margins and increase the resin-dentin bonding longevity.

CLINICAL SIGNIFICANCE: The novel bioactive adhesive is promising to protect tooth structures from biofilm acids and secondary caries. NACP and DMAHDM have great potential for applications to a wide range of dental materials to reduce plaque and achieve therapeutic effects.

RevDate: 2018-12-31

Lagarde A, Millot M, Pinon A, et al (2018)

Antiproliferative and anti-biofilm potentials of endolichenic fungi associated with the lichen Nephroma laevigatum.

Journal of applied microbiology [Epub ahead of print].

AIMS: The objective of this study was to explore the diversity of endolichenic fungi from Nephroma laevigatum and to investigate their antiproliferative and anti-biofilm potential.

METHODS AND RESULTS: Forty-six isolates were obtained and identified by DNA barcoding. They belonged to genera Nemania, Daldinia, Peziza and Coniochaeta. Six strains belonging to the most represented species were selected and tested for their antiproliferative and anti-biofilm activities. Extracts were analyzed by reversed-phase HPLC. Activities against fungal and bacterial biofilm were evaluated using tetrazolium salt (XTT) assay and crystal violet assay, respectively. Antiproliferative responses of extracts were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induction by two extracts was observed in two cell-lines (HT-29 and PC-3) via morphological changes, pro-apoptotic and anti-apoptotic proteins analysis (western blotting) and DNA fragmentation. Four extracts displayed activities against Candida albicans biofilm with IC50 values ranging from 25 to 200 μg ml-1 . All extracts were inactive against Staphylococcus aureus and Pseudomonas aeruginosa biofilms. The most active isolates against human colorectal (HT-29 and HCT116) and prostate (PC-3 and DU145) cancer cell lines were Nemania serpens (NL08) and N. aenea var. aureolatum (NL38) with IC50 values ranging from 13 to 39 μg ml-1 . These extracts induced an apoptotic process through activation of caspases 8 and 3, poly(ADP-ribose) polymerase (PARP) cleavage and DNA fragmentation.

CONCLUSIONS: Selected crude fungal extracts have antiproliferative and anti-biofilm activities. Data suggest that this antipoliferative effect is due to apoptosis process. This is the first report showing the effects of endolichenic fungi from Nephroma laevigatum.

This study highlights the therapeutic potential of endolichenic fungi metabolites as sources for drug discovery programs. This article is protected by copyright. All rights reserved.

RevDate: 2018-12-31

Zancan RF, Calefi PHS, Borges MMB, et al (2018)

Antimicrobial activity of intracanal medications against both Enterococcus faecalis and Candida albicans biofilm.

Microscopy research and technique [Epub ahead of print].

Enterococcus faecalis and Candida albicans have been associated with cases of secondary and persistent root canal infections, been resistant to calcium hydroxide. So, the evaluation of the susceptibility of these microorganisms biofilms to new drugs is an important practice for establishing the best drug and consequently success of treatment. For this, in vitro biofilm formation of E. faecalis and C. albicans was induced separately on blocks obtained from bovine teeth. After the period of specimen incubation for biofilm maturation, the samples were immersed in the pastes: 1 - calcium hydroxide (CH), 2 - chlorhexidine (C), 3 - ciprofloxacin (CP), 4 - metronidazole (MT), 5 - ketoconazole (KE), 6 - double antibiotic (DB), 7 - triple antibiotic (TA), 8 - ciprofloxacin + ketoconazole (CPKE); 9 - ciprofloxacin + metronidazole + ketoconazole (CPMTKE), 10 - metronidazole + ketoconazole (MTKE), and 11 - control (CO) for 7 days. Next, the specimens were live/dead stained for analysis by confocal microscopy. By means of the Bioimage program, the biovolume and percentage of live cells were measured. The data were statistically compared (p = .05). For the C. albicans biofilm, the best antimicrobial action was found for MTKE, CPKE, and MT groups. Whereas for E. faecalis biofilm, the lowest percentage of live bacteria was found in TA, DB, and CP groups; however, KE, CPKE, CPMTKE, and MTKE groups shown to be effective. The authors concluded calcium hydroxide paste and chlorhexidine was not effective for both biofilms. The MTKE and CPKE pastes presented effectiveness for both biofilms. TA and DB pastes were effective just in the E. faecalis biofilms.

RevDate: 2018-12-31

Sun L, Jiang W, Zhang H, et al (2018)

Photosensitizer-Loaded Multifunctional Chitosan Nanoparticles for Simultaneous in Situ Imaging, Highly Efficient Bacterial Biofilm Eradication, and Tumor Ablation.

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

In recent decades, bacterial and viral infections and chronic inflammatory response have emerged as important causes of cancer. Also, infections remain a significant cause of morbidity and mortality in cancer patients. In this work, carboxymethyl chitosan nanoparticles (CMC NPs) were synthesized in a facile and green way and further combined with ammonium methylbenzene blue (MB) as a cross-linking agent as well as a fluorescent molecule and a photosensitizer for self-imaging photodynamic therapy (PDT). The obtained CMC-MB NPs exhibited an apparent pH-responsive release behavior of MB, which was released for a prolonged period in a simulated physiological environment (pH 7.4) for more than 15 days and the time reduced to only 3.5 h in acidic conditions (pH 5.5). When irradiated by a 650 nm laser at 202 mW/cm2 for 5 min, the CMC-MB NPs showed efficient bactericidal and biofilm eradication properties as well as suppression of tumor cell growth in a similar acidified microenvironment. Furthermore, in an in vivo rabbit wound bacterial infection model, the rapid sterilization of CMC-MB NPs played a crucial role in bacterial infections, inflammation inhibition, and wound healing. As a PDT treatment against cancer, the CMC-MB NPs also exhibited an efficient antitumor therapeutic effect in a subcutaneous tumor mice model.

RevDate: 2018-12-31

Areid N, Söderling E, Tanner J, et al (2018)

Early Biofilm Formation on UV Light Activated Nanoporous TiO2 Surfaces In Vivo.

International journal of biomaterials, 2018:7275617.

Purpose: To explore early S. mutans biofilm formation on hydrothermally induced nanoporous TiO2 surfaces in vivo and to examine the effect of UV light activation on the biofilm development.

Materials and Methods: Ti-6Al-4V titanium alloy discs (n = 40) were divided into four groups with different surface treatments: noncoated titanium alloy (NC); UV treated noncoated titanium alloy (UVNC); hydrothermally induced TiO2 coating (HT); and UV treated titanium alloy with hydrothermally induced TiO2 coating (UVHT). In vivo plaque formation was studied in 10 healthy, nonsmoking adult volunteers. Titanium discs were randomly distributed among the maxillary first and second molars. UV treatment was administered for 60 min immediately before attaching the discs in subjects' molars. Plaque samples were collected 24h after the attachment of the specimens. Mutans streptococci (MS), non-mutans streptococci, and total facultative bacteria were cultured, and colonies were counted.

Results: The plaque samples of NC (NC + UVNC) surfaces showed over 2 times more often S. mutans when compared to TiO2 surfaces (HT + UVHT), with the number of colonized surfaces equal to 7 and 3, respectively.

Conclusion: This in vivo study suggested that HT TiO2 surfaces, which we earlier showed to improve blood coagulation and encourage human gingival fibroblast attachment in vitro, do not enhance salivary microbial (mostly mutans streptococci) adhesion and initial biofilm formation when compared with noncoated titanium alloy. UV light treatment provided Ti-6Al-4V surfaces with antibacterial properties and showed a trend towards less biofilm formation when compared with non-UV treated titanium surfaces.

RevDate: 2018-12-31

Khan FAK, Kaduskar RN, Patil R, et al (2018)

Synthesis, biological evaluations and computational studies of N-(3-(-2-(7-Chloroquinolin-2-yl)vinyl) benzylidene)anilines as fungal biofilm inhibitors.

Bioorganic & medicinal chemistry letters pii:S0960-894X(18)30993-4 [Epub ahead of print].

In the present investigation, new chloroquinoline derivatives bearing vinyl benzylidene aniline substituents at 2nd position were synthesized and screed for biofilm inhibitory, antifungal and antibacterial activity. The result of biofilm inhibition of C. albicans suggested that compounds 5j (IC50 value = 51.2 μM) and 5a (IC50 value = 66.2 μM) possess promising antibiofilm inhibition when compared with the standard antifungal drug fluconazole (IC50 = 40.0 μM). Two compounds 5a (MIC = 94.2 μg/mL) and 5f (MIC = 98.8 μg/mL) also exhibited good antifungal activity comparable to standard drug fluconazole (MIC = 50.0 μg/mL). The antibacterial screening against four strains of bacteria viz. E. coli, P. aeruginosa, B. subtilis, and S. aureus suggested their potential antibacterial activity and especially all the compounds except 5g were found more active than the standard drug ciprofloxacin against B. subtilis. To further gain insights into the possible mechanism of these compounds in biofilm inhibition through the agglutinin like protein (Als), molecular docking and molecular dynamics simulation studies were carried out. Molecular modeling studies suggested the clear role in inhibition of this protein and the resulting biofilm inhibitory activity.

RevDate: 2018-12-30

Zhang X, Chen Z, Ma Y, et al (2018)

Response of Anammox biofilm to antibiotics in trace concentration: Microbial activity, diversity and antibiotic resistance genes.

Journal of hazardous materials, 367:182-187 pii:S0304-3894(18)31231-7 [Epub ahead of print].

Long-term impacts of two antibiotics-norfloxacin (NOR) and erythromycin (ERY) in trace concentration (1ug L-1) on Anammox biofilm were investigated. The specific Anammox activity (SAA) and dehydrogenase activity (DHA) of Anammox biofilm were detected by batch experiments, the microbial diversity was analyzed using high-throughput sequencing technology and the antibiotic resistance genes (ARGs) were measured by qPCR. Results showed that long-term NOR feeding decreased 30% SAA and 39.6% DHA, and also decreased the abundance of the OTUs related to autotrophic nitrogen removal, while ERY had slight impact on Anammox. Only two ARGs targeted to ERY (ermB, mphA) were detected in the two Anammox systems while those targeted to NOR (qnrA, qnrB, qnrD, and qnrS) were not detected. The relative expression of ermB to 16S rRNA increased from 2.08±0.32×10-4 to 3.53±1.18×10-4, and that of mphA increased to 5.00±0.48×10-4 from 4.48±1.32×10-5. The induced ARGs in the Anammox system help it resist the ERY shock.

RevDate: 2018-12-30

Tao D, Li F, Feng X, et al (2018)

Plaque biofilm microbial diversity in infants aged 12 months and their mothers with or without dental caries: a pilot study.

BMC oral health, 18(1):228 pii:10.1186/s12903-018-0699-8.

BACKGROUND: A number of studies on oral microbial diversity of early childhood caries (ECC) have tended to focus on mid- or late-stage of ECC, with a lack of research into early stage of tooth eruption and maternal influence. The aims of this study are to compare the supragingival plaque biofilm microbiota diversity between mothers with or without dental caries and their 12-month-old infants, and to explore the relationship of microbial diversity between infants and their mothers, using sequencing analysis.

METHODS: Supragingival plaque biofilm samples were collected from 20 pairs of mothers and their infants aged 12 months (10 mothers with dental caries and their 10 infants vs. 10 caries-free mothers and their 10 infants). The basic information of the mothers and infants had been collected through self-completed questionnaire. Pooled plaque biofilm DNA was extracted and DNA amplicons of the V4-V5 hypervariable region of the bacterial 16S rRNA gene were generated. Ilumina Miseq PE300 was used for 16S rRNA sequencing.

RESULTS: The results showed that high bacterial diversity was noted in the plaque biofilm of infants and their mothers with or without dental caries (dental caries mothers vs. caries-free mothers: 774 operational taxonomical units (OTUs) vs. 761 OTUs at a 3% divergence; infants whose mothers have dental caries vs. infants whose mothers are caries-free: 815 OTUs vs. 684 OTUs at 3% divergence). The Shannon microbial diversity index showed no statistically significant differences both on infants and their mothers between two groups (p > 0.05). Mother's microbial diversity was higher than infants' based on Shannon index (p < 0.05). Significant positive correlations were found between mothers' and their infants' Shannon index (r = 0.656, p = 0.002).

CONCLUSION: Oral microbial diversity is significantly different between mothers and infants regardless of dental caries status, but no significant difference was found between mothers with and without dental caries or between their infants. Mother's oral microbial diversity has an overall impact on the infants aged 12 months.

RevDate: 2018-12-29

Gora SL, Rauch KD, Ontiveros CC, et al (2018)

Inactivation of biofilm-bound Pseudomonas aeruginosa bacteria using UVC light emitting diodes (UVC LEDs).

Water research, 151:193-202 pii:S0043-1354(18)31038-8 [Epub ahead of print].

Ultraviolet light emitting diodes (UV LEDs) are a promising technology for the disinfection of water and wetted surfaces, but research into these applications remains limited. In the drinking water field, UV LEDs emitting at wavelengths ranging from 254 nm to 285 nm (UVC LEDs) have been shown to be effective for the inactivation of numerous pathogens and pathogen surrogate organisms at UV doses comparable to conventional germicidal UV lamps. Surface disinfection with UV light, from UVC LEDs or from conventional UV lamps, is not as well understood. As the technology underlying the design and construction of UV LEDs matures and their energy efficiency improves, it is likely that they will become ubiquitous in small scale water treatment applications and surface disinfection in various industries, including the medical and dental fields. A simple, easily replicated methodology was developed and optimized to grow, irradiate, and recover biofilms from coupons. It was hypothesized that higher UV doses would be required to inactivate biofilm-bound bacteria than planktonic (free-floating) bacteria because the biofilm would provide some degree of protection from the effects of UVC irradiation. Indeed, UV LED irradiation at 265 nm achieved 1.3 ± 0.2 log inactivation of biofilm-bound Pseudomonas aeruginosa at a UV dose of 8 mJ/cm2. This inactivation level is lower than those that have been reported by researchers using UVC LEDs to inactivate planktonic P. aeruginosa, a finding that can be explained by the higher resistance of biofilm-bound bacteria to UV inactivation. A dose-response curve was developed and fitted to three disinfection models: the Chick-Watson model, the multi-target model, and the Geeraerd model. This last, which posits a subpopulation of organisms that are resistant to treatment, was a good fit to the dose-response data. ATP results obtained using the biomass recovery ATP method (ATPBR), a method that includes a 4 h incubation period after treatment, was well correlated to the results of conventional plate counts.

RevDate: 2018-12-29

Zhang C, Brown PJB, Miles RJ, et al (2018)

Inhibition of regrowth of planktonic and biofilm bacteria after peracetic acid disinfection.

Water research, 149:640-649 pii:S0043-1354(18)30859-5 [Epub ahead of print].

Peracetic acid (PAA) is a promising alternative to chlorine for disinfection; however, bacterial regrowth after PAA disinfection is poorly understood. This study compared the regrowth of bacteria (Gram-negative Pseudomonas aeruginosa PAO1 and Gram-positive Bacillus sp.) after disinfection with PAA or free chlorine. In the absence of organic matter, PAA and free chlorine prevented the regrowth of planktonic cells of P. aeruginosa PAO1 at C·t (= disinfectant concentration × contact time) doses of (28.5 ± 9.8) mg PAA·min·L-1 and (22.5 ± 10.6) mg Cl2·min·L-1, respectively, suggesting that they had comparable efficiencies in preventing the regrowth of planktonic bacteria. For comparison, the minimum C·t doses of PAA and free chlorine to prevent the regrowth of P. aeruginosa PAO1 biofilm cells in the absence of organic matter were (14,000 ± 1,732) mg PAA·min·L-1 and (6,500 ± 2,291) mg Cl2·min·L-1, respectively. PAA was less effective than free chlorine in killing bacteria within biofilms in the absence of organic matter most likely because PAA reacts with biofilm matrix constituents slower than free chlorine. In the presence of organic matter, although the bactericidal efficiencies of both disinfectants significantly decreased, PAA was less affected due to its slower reaction with organic matter and/or slower self-decomposition. For instance, in a dilute Lysogeny broth-Miller, the minimum concentrations of PAA and free chlorine to prevent the regrowth of planktonic P. aeruginosa PAO1 were 20 mg PAA·L-1 and 300 mg Cl2·L-1, respectively. While both disinfectants are strong oxidants disrupting cell membrane, environmental scanning electron microscopy (ESEM) revealed that PAA made holes in the center of the cells, whereas free chlorine desiccated the cells. Overall, this study shows that PAA is a powerful disinfectant to prevent bacterial regrowth even in the presence of organic matter.

RevDate: 2018-12-29

Sun X, Wang L, Lynch CD, et al (2018)

Nanoparticles having amphiphilic silane containing Chlorin e6 with strong anti-biofilm activity against periodontitis-related pathogens.

Journal of dentistry pii:S0300-5712(18)30542-6 [Epub ahead of print].

OBJECTIVES: The objectives of this study were to: (1) develop the multifunctional nanoparticles containing Chlorin e6 (Ce6), Coumarin 6 (C6) and Fe3O4 nanoparticles (NPs); and (2) investigate the inhibitory effects of the nanoparticles via antibacterial photodynamic therapy (aPDT) against three species of periodontitis-related pathogens for the first time.

MATERIALS AND METHODS: Ce6 and C6 were co-loaded into the Fe3O4-silane core-shell structure to form multifunctional nanoparticles (denoted "Fe3O4-silane@Ce6/C6 MNPs"). The physical and chemical properties of nanoparticles were characterized. Biofilm properties of Streptococcus sanguinis, Porphyromonas gingivalis and Fusobacterium nucleatum were tested. Colony-forming units (CFU), live/dead assay, and metabolic activity of biofilms were determined to evaluate the aPDT function mediated by the Fe3O4-silane@Ce6/C6 MNPs. Fluorescence imaging and the targeted antibacterial effects were also investigated.

RESULTS: Fe3O4-silane@Ce6/C6 MNPs showed superparamagnetic properties, chemical stability and water-solubility, with no cytotoxicity. Fe3O4 NPs did not compromise the emission peaks of C6 and Ce6. The Fe3O4-silane@Ce6/C6-mediated aPDT had much greater reduction in biofilms than the control groups (p < 0.05). Biofilm CFU was reduced by about 4-5 orders of magnitude via Fe3O4-silane@Ce6/C6-mediated aPDT. The co-loading of Ce6 and C6 enabled the real-time aPDT monitoring by ratio emissions with the same wavelength. Fe3O4 with magnetic field enabled the targeting of infection sites by killing bacteria via magnetic field.

CONCLUSION: The multifunctional nanoparticles exerted strong anti-biofilm activity against periodontitis-related pathogens, with excellent biocompatibility, real-time monitoring, and magnetically-targeting capacities. The multifunctional nanoparticles have great potential in antibacterial applications to inhibit the occurrence and progression of periodontitis.

RevDate: 2018-12-28

Zhu J, Yan Y, Wang Y, et al (2018)

Competitive interaction on dual-species biofilm formation by spoilage bacteria, Shewanella baltica and Pseudomonas fluorescens.

Journal of applied microbiology [Epub ahead of print].

AIMS: This study aims to characterize the biofilm produced by mono- and dual-species of Shewanella baltica and Pseudomonas fluorescens as fish spoilers at the different incubation temperature, and to elucidate the interactive behavior of dual-species biofilm development.

METHODS AND RESULTS: The mono- and dual-species biofilm formation and adhesion characteristics of Shewanella baltica and Pseudomonas fluorescens were evaluated by using crystal violet staining, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Results showed that P. fluorescens had significantly higher biofilm biomass and polysaccharides production than S. baltica, and two isolates reached the maximum biofilm biomass during the early stationary phase. Lower biomass and polysaccharides in dual-species biofilms were observed compared to mono-species of P. fluorescens. Meanwhile, S. baltica and P. fluorescens formed fragile and viscous pellicles with different spatial architectures, respectively. In dual-species pellicle few large microcolonies were dominated by P. fluorescens. Compared to mono-species of PF07, adherent cell population and biofilm thickness at the developing phase significantly decreased, and biofilm-forming cycle prolonged in the dual-species biofilms. Biofilm formation and adhesion of mono- and dual-species at 4°C or 15°C were significantly higher than at 30°C during the same phase. The culture supernatant extracts (CSEs) of the two spoilage strains greatly inhibited biofilm development to each other.

CONCLUSIONS: S. baltica and P. fluorescens had different biofilm and pellicle characteristics, and the inhibitory development on dual-species biofilm was associated with the competitive interaction by the two psychrotrophic spoilage bacteria.

This work contributes to a better understanding of interactive behavior of multispecies biofilm communities by psychrotrophic spoilage bacteria at low temperature, which could contribute to further control contamination of spoilage organism during the preservation and processing of aquatic products. This article is protected by copyright. All rights reserved.

RevDate: 2018-12-28

Nuño G, Alberto MR, Arena ME, et al (2018)

Effect of Zuccagnia punctata Cav. (Fabaceae) extract on pro-inflammatory enzymes and on planktonic cells and biofilm from Staphylococcus aureus. Toxicity studies.

Saudi journal of biological sciences, 25(8):1713-1719.

Zuccagnia punctata Cav. (Fabaceae), a native plant from Argentina has been used traditionally as medicinal species. The aim of the study was to validate the antibiotic and anti-inflammatory potential of Z. punctata organic extract (ZpE) and the major compounds; 2',4'-dihydroxy-3'-methoxychalcone (DHMC), 2',4'-dihydroxychalcone (DHC), 7-hydroxyflavanone (7-HF) and 3,7-dihydroxyflavone (DHF); using an in vitro model. The antibiotic activity was determined using a broth microdilution method and the minimum inhibitory concentration (MIC) was determined. The extract and the isolation compounds affect the normal growth of all assayed Staphylococcus aureus strains. The MIC values for ZpE and isolated compounds were between 125 and 500 μg/mL and between 25 and 400 μg/mL, respectively, against all assayed strains. The inhibitory effect of extract and isolated compounds on biofilm formation and on pro-inflammatory enzymes (sPLA2, COX-2, LOX) was analyzed. The compound DHC was the most active on sPLA2 while DHF and DHMC showed the highest activity on LOX. Both the extract and pure compounds except DHMC were active against COX-2. It can be concluded that the phytocomplex and the pure compounds possessed antibiotic and anti-inflammatory activities under the conditions tested, and could be a good alternative therapy for infective and inflammatory processes.

RevDate: 2018-12-27

Milho C, Andrade M, Vilas Boas D, et al (2018)

Antimicrobial assessment of phage therapy using a porcine model of biofilm infection.

International journal of pharmaceutics pii:S0378-5173(18)30908-6 [Epub ahead of print].

Antibiotic resistant bacterial communities persist in many types of wounds, chronic wounds in particular, in the form of biofilms. Biofilm formation is a major cause of severe infections and the main reason for a negative treatment outcome and slow healing progression. Chronic wounds are a silent epidemic essentially affecting people with co-morbid conditions such as diabetes and obesity and elderly persons particularly those with movement limitations. The development of complementary and alternative effective strategies to antibiotics for the treatment of chronic wounds is highly desired. Phage therapy constitutes a very promising approach in the control of topical microbial populations. In this work newly isolated phages were tested for their efficacy to control bacterial species that predominate in chronic wounds. Phage effectiveness was studied on 24-h old biofilms formed in polystyrene microplates and in porcine skin explants using two treatment approaches: individual phage and a cocktail of phages against four main pathogens commonly isolated from chronic wounds. The two models produced variations in the surface colonization ability, assessed by viable bacterial counts and microscopy visualization after using peptide nucleic acid (PNA) or locked nucleic acid probes (LNA) and 2'-O-methyl (2'-OMe) in fluorescence in situ hybridization (FISH), and in the phage-host interactions. Phages alone and combined caused greater reductions in the number of viable cells when biofilms had been formed on porcine skins and with greater variations detected at 4 h and 24 h of sampling. These results suggest that porcine skin models should be preferentially used to assess the use of phages and phage cocktails intended for topical use in order to understand the fate, throughout treatment time, of the population when dealing with biofilm-related infections.

RevDate: 2018-12-27

Ostapska H, Howell PL, DC Sheppard (2018)

Deacetylated microbial biofilm exopolysaccharides: It pays to be positive.

PLoS pathogens, 14(12):e1007411 pii:PPATHOGENS-D-18-01719.

RevDate: 2018-12-27

Pathak R, Bierman SF, P d'Arnaud (2018)

Inhibition of bacterial attachment and biofilm formation by a novel intravenous catheter material using an in vitro percutaneous catheter insertion model.

Medical devices (Auckland, N.Z.), 11:427-432 pii:mder-11-427.

Introduction: Despite sterile barrier precautions and vigorous skin antisepsis, percutaneous insertion of intravenous catheters has been shown to result in attachment to the catheter surface of bacteria residing in the deep structures of the skin. Such attachment poses the risk of biofilm formation and eventual catheter-related bloodstream infection (CRBSI). This study was undertaken to assess whether the non-coated surface treatment of a unique catheter material (ChronoFlex C® with BioGUARD™) could inhibit bacterial attachment and biofilm formation.

Methods: A novel in vitro model and fluorescence microscopy were used to compare two intravascular catheter materials with respect to bacterial attachment and biofilm formation. The control material was a commonly used polyurethane. The study material was a unique copolymer, treated so as to remove surface additives, alter hydrophobicity and create surface micro-patterning. Outcomes were assessed using both a membrane potential indicator and a cell death reporter with appropriate fluorescent channels. Thus, bacterial cells attached to the catheter surface (living and dead) were imaged without mechanical disruption.

Results: Both bacterial attachment and biofilm formation are significantly inhibited by the study catheter material. In fact, over 5 times more bacteria were able to attach and grow on the control polyurethane material than on the study material (P=0.0020). Moreover, those few bacteria that were able to attach to the study material had a 1.5 times greater likelihood of dying.

Conclusion: Using a novel in vitro percutaneous catheter insertion model, ChronoFlex C with BioGUARD is proven to significantly inhibit bacterial attachment and biofilm formation as compared with a commonly used polyurethane catheter material.

RevDate: 2018-12-27

Khalid R, Jaffar Q, Tayyeb A, et al (2018)

Peganum harmalapeptides (PhAMP) impede bacterial growth and biofilm formation in burn and surgical wound pathogens.

Pakistan journal of pharmaceutical sciences, 31(6 (Supplementary):2597-2605.

Many clinical-pathogens have developed resistance against known antibiotics and there is an urgent need for the discovery of novel antibiotics. In this study, low molecular weight peptides were isolated from seeds/leaves of 20 medicinal plants and tested for their antibacterial activity against laboratory strains of S. aureusand P. aeruginosa. Peptides isolated from Peganum harmala (PhAMP) exhibited maximum activity against laboratory strains. As clinical-isolates are more virulent and resistant to antibiotics, we tested the potential of PhAMP on these bacterial strains isolated from infected wounds. Pathogens isolated from burn-wounds (S. aureus, P. aeruginosa and K. pneumoniae) and surgical-wounds (P. aeruginosa and K. pneumoniae) exhibited zones of inhibition against PhAMP when tested by disc diffusion method. Biofilm formation of wound pathogens in the presence/absence of PhAMP was analyzed to check its effect. Surgical-wound pathogens and K. pneumoniae from burn-wound showed significant reduction in biofilm formation and planktonic bacteria. While biofilms of S. aureus and P. aeruginosa from burn-wound showed resistance against PhAMP. An effective antibiotic treatment should not only inhibit but should also disrupt already developed biofilms. PhAMP was very effective in the disruption of developed biofilm of all pathogens after 36 hours. This data unravels the potential of PhAMP as a novel, natural antibiotic against clinical-pathogens.

RevDate: 2018-12-26

Felipe V, Breser ML, Bohl LP, et al (2018)

Chitosan disrupts biofilm formation and promotes biofilm eradication in Staphylococcus species isolated from bovine mastitis.

International journal of biological macromolecules pii:S0141-8130(18)36015-X [Epub ahead of print].

Staphylococci are the main pathogens associated with hard-to-control intramammary infections in dairy cattle, and bacterial biofilms are suspected to be responsible for the antimicrobial resistance and persistence of this disease. Biofilms have the ability to resist to higher levels of antibiotics and reduce their efficacy. It is thus necessary to develop strategies targeted to bacterial biofilm infections. Chitosan is a polysaccharide with a proven broad spectrum of antimicrobial activity against fungi and bacteria. The aim of this study was assess the effect of low molecular weight (LMW) chitosan against biofilm hyperproducer Staphylococcus spp. (S. aureus and S. xylosus) strains usually involved in chronic bovine mastitis, and to test their efficacy in biofilm formation and eradication. The results obtained showed that LMW chitosan is able to inhibit S. aureus and S. xylosus planktonic growth in a dose-dependent manner and reduce bacterial viability. LMW chitosan inhibits biofilm formation, reduces biofilm viability and disrupts established biofilm. These results indicate the inhibitory effects of chitosan on biofilm formation, and these effects are observed at lower concentrations for S. xylosus. Our studies show the potential of this biopolymer to be used as an effective antibiofilm agent able to act upon staphylococcal infections.

RevDate: 2018-12-26

Dhakal J, Sharma CS, Nannapaneni R, et al (2018)

Effect of Chlorine-Induced Sublethal Oxidative Stress on the Biofilm-Forming Ability of Salmonella at Different Temperatures, Nutrient Conditions, and Substrates.

Journal of food protection [Epub ahead of print].

The present study was conducted to evaluate the effect of chlorine-induced oxidative stress on biofilm formation by various Salmonella strains on polystyrene and stainless steel (SS) surfaces at three temperatures (30, 25 [room temperature], and 4°C) in tryptic soy broth (TSB) and 1/10 TSB. Fifteen Salmonella strains (six serotypes) were exposed to a sublethal chlorine concentration (150 ppm of total chlorine) in TSB for 2 h at the predetermined temperatures. The biofilm-forming ability of the Salmonella strains was determined in 96-well polystyrene microtiter plates by using a crystal violet staining method and on SS coupons in 24-well tissue culture plates. All tested strains of Salmonella produced biofilms on both surfaces tested at room temperature and at 30°C. Of the 15 strains tested, none (chlorine stressed and nonstressed) formed biofilm at 4°C. At 30°C, Salmonella Heidelberg (ID 72), Salmonella Newport (ID 107), and Salmonella Typhimurium (ATCC 14028) formed more biofilm than did their respective nonstressed controls on polystyrene (P ≤ 0.05). At room temperature, only stressed Salmonella Reading (ID 115) in 1/10 TSB had significantly more biofilm formation than did the nonstressed control cells (P ≤ 0.05). Salmonella strains formed more biofilm in nutrient-deficient medium (1/10 TSB) than in full-strength TSB. At 25°C, chlorine-stressed Salmonella Heidelberg (ATCC 8326) and Salmonella Enteritidis (ATCC 4931) formed stronger biofilms on SS coupons (P ≤ 0.05) than did the nonstressed cells. These findings suggest that certain strains of Salmonella can produce significantly stronger biofilms on plastic and SS upon exposure to sublethal chlorine.

RevDate: 2018-12-25

Jadoun J, Mreny R, Saad O, et al (2018)

Fate of bacterial indicators and Salmonella in biofilm developed on ultrafiltration membranes treating secondary effluents of domestic wastewater.

Scientific reports, 8(1):18066 pii:10.1038/s41598-018-36406-z.

The fate of representative indicator and pathogenic bacteria on ultrafiltration (UF)-membrane surfaces treating secondary wastewater effluent, as well as their reaction to common biofouling-removal techniques was investigated. Field-condition experiments showed that the number of heterotrophic bacteria, fecal coliforms, E. coli and Salmonella on membrane surface increased rapidly and continuously until the end of the experiment, reaching 9, 6.5, 6, and 2.4 logs, respectively. Similar results were obtained under controlled laboratory conditions. However, the increase in the bacterial numbers was dependent on the supply of fresh wastewater. Quantitative real-time PCR verified the behavior of attached E. coli cells, although the numbers were 1-2 logs higher compared to the standard culture-based method. The number of attached bacteria was positively correlated to increases in DNA and protein content and negatively correlated to the membrane flux. In-situ membrane cleaning using sodium hypochlorite significantly reduced the number of attached bacteria. However, the effect was temporary and affected bacterial cell cultivability rather than viability. Taken together, these findings suggest that, under the studied conditions, indicator and pathogenic bacteria can initiate rapid biofilm development, persist on UF membrane surfaces, and survive membrane cleaning with sodium hypochlorite.

RevDate: 2018-12-24

Jing X, Liu X, Deng C, et al (2018)

Chemical signals stimulate Geobacter soli biofilm formation and electroactivity.

Biosensors & bioelectronics, 127:1-9 pii:S0956-5663(18)30951-5 [Epub ahead of print].

Biofilm formation and maturation have been demonstrated to be regulated by distinct forms of cell-cell communication factors such as chemical and physical signals. However, whether the Geobacter sp. biofilms, which are typical electroactive biofilms, are affected by chemical signals is poorly understood. This research investigated the effects and corresponding mechanisms of endogenous and exogenous chemical signals (i.e., N-acylhomoserine lactones, AHLs) on the Geobacter soli biofilm. The results showed that Geobacter soli GSS01 secreted detectable endogenous AHLs to facilitate the formation and electrochemical activity of the biofilm, and that exogenous AHLs could further promoted these activities. Analyses of surface proteins revealed that the mechanisms promoted by endogenous and exogenous AHLs were somewhat different. Endogenous AHLs improved the relative abundance of external membrane proteins, while exogenous AHLs further facilitated the formation of amide II and a stronger H-bond between the carbonyl group and the amide. Furthermore, the proteomics analysis indicated that endogenous AHLs enhanced extracellular polymeric substance production by up-regulating the expression of key enzymes participating in EPS production, and simultaneously affected the physiological performance of individual cells. These results demonstrate, for the first time, the importance of chemical signals in Geobacter sp. and provide a comprehensive understanding of the chemical signals involved in biofilm formation and electrochemical activity of Geobacter sp..

RevDate: 2018-12-24

Dua P, Karmakar A, C Ghosh (2018)

Virulence gene profiles, biofilm formation, and antimicrobial resistance of Vibrio cholerae non-O1/non-O139 bacteria isolated from West Bengal, India.

Heliyon, 4(12):e01040 pii:e01040.

Vibrio cholerae is the causative agent of acute dehydrating diarrhoeal disease cholera. Among 71 V. cholerae non-O1/non-O139 isolates, all yielded negative results for ctxA, ctxB and tcpA genes in PCR assay. Few strains were positive for stn (28.38%), and ompU (31.08%) genes. While all isolates were negative for ace gene, only two were positive for zot gene. All strains expressed toxR and toxT genes. It was also found that all isolates were slime-producer and these were capable of forming moderate to high biofilm. Biofilm formation was controlled positively by the transcriptional regulators VpsR and VpsT and was regulated negatively by HapR, as well as CRP regulatory complex. These isolates were resistant to ampicillin, furazolidone, doxycycline, vancomycin, erythromycin, while these were susceptible to ciprofloxacin, gentamycin, kanamycin, polymixin B, norfloxacin, chloramphenicol, sulphamethoxazole-trimethoprim, tetracycline, nalidixic acid, and streptomycin. Indeed, 69.01% isolates were resistant to multiple antibiotics (MAR: resistance to 3 or more antibiotics). Treatment protocols for cholera patients should be based on local antibiogram data.

RevDate: 2018-12-24

Diaconu O, Siriopol I, Poloșanu LI, et al (2018)

Endotracheal Tube Biofilm and its Impact on the Pathogenesis of Ventilator-Associated Pneumonia.

Journal of critical care medicine (Universitatea de Medicina si Farmacie din Targu-Mures), 4(2):50-55 pii:jccm-2018-0011.

Ventilator-associated pneumonia (VAP) is a common and serious nosocomial infection in mechanically ventilated patients and results in high mortality, prolonged intensive care unit- (ICU) and hospital-length of stay and increased costs. In order to reduce its incidence, it is imperative to better understand the involved mechanisms and to identify the source of infection. The role of the endotracheal tube (ET) in VAP pathogenesis became more prominent over the last decades, along with extensive research dedicated to medical device-related infections and biofilms. ET biofilm formation is an early and constant process in intubated patients. New data regarding its temporal dynamics, composition, germ identification and consequences enhance knowledge about VAP occurrence, microbiology, treatment response and recurrence. This paper presents a structured analysis of the medical literature to date, in order to outline the role of ET biofilm in VAP pathogenesis and to review recommended methods to identify ET biofilm microorganisms and to prevent or decrease VAP incidence.

RevDate: 2018-12-24

Ghasemian A, Mobarez AM, Peerayeh SN, et al (2019)

The association of surface adhesin genes and the biofilm formation among Klebsiella oxytoca clinical isolates.

New microbes and new infections, 27:36-39 pii:S2052-2975(18)30057-X.

Bacterial adhesins mediate the attachment and biofilm production leading to the persistence of colonized strains. The aim of this study was evaluation of the association of surface adhesin genes with the biofilm formation among Klebsiella oxytoca isolates. Among 50 isolates of K. oxytoca from patients with antibiotic-associated diarrhoea, the susceptibility test, MIC (according to CLSI 2016) and phenotypic biofilm formation (with microtitre tissue-plate assay) were performed. The presence of adhesins was investigated using PCR. Thirty-three (66%) isolates produced moderate-level biofilms, but none of them exhibited strong biofilm formation. The presence of adhesins was as follows: fimA, 60% (n = 30), mrkA, 42% (n = 21), matB, 96% (n = 48) and pilQ, 92% (n = 46). The biofilm formation was related to the presence of fimA (odds ratio (OR) 0.8571, 95% CI 1.733-6.267, p <0.0001), mrkA (OR 0.2462, 95% CI 2.723-4.622, p 0.001), matB (OR 0.4521, 95% CI 1.353-5.332, p 0.008) and pilQ (OR 0.1481, 95% CI 1.691-6.117, p <0.0001). The npsB toxin-encoding gene was detected among 46 (92%) isolates. Resistance to non-β-lactam antibiotics was significantly associated with the presence of adhesin-encoding genes. The presence of adhesins and the capsular encoding gene was significantly associated with biofilm formation among K. oxytoca isolates. The presence of surface adhesin-encoding genes was significantly associated with the biofilm formation and also with resistance to non-β-lactam antibiotics among K. oxytoca clinical isolates. In addition, biofilm production was not significantly associated with β-lactam resistance among the isolates.

RevDate: 2018-12-23

Canette A, Deschamps J, R Briandet (2019)

High Content Screening Confocal Laser Microscopy (HCS-CLM) to Characterize Biofilm 4D Structural Dynamic of Foodborne Pathogens.

Methods in molecular biology (Clifton, N.J.), 1918:171-182.

The functional properties of biofilms are intimately related to their spatial architecture. Structural data are therefore of prime importance to dissect the complex social and survival strategies of biofilms and ultimately to improve their control. Confocal laser microscopy (CLM) is the most widespread microscopic tool to decipher biofilm structure, enabling noninvasive 3D investigation of their dynamics down to single cell scale. The emergence of fully automated high content screening (HCS) systems, associated with large-scale image analysis, radically amplifies the flow of available biofilm structural data. In this contribution, we present an HCS-CLM protocol used to analyze biofilm 4D structural dynamics at high throughput. Meta-analysis of the quantitative variates extracted from HCS-CLM will contribute to a better biological understanding of biofilm traits.

RevDate: 2018-12-23

Dubois-Brissonnet F (2019)

Characterization of Bacterial Membrane Fatty Acid Profiles for Biofilm Cells.

Methods in molecular biology (Clifton, N.J.), 1918:165-170.

When exposed to environmental stresses, bacteria can modulate its fatty acid composition of membrane phospholipids in order to optimize membrane fluidity. Characterization of bacterial membrane fatty acid profiles is thus an interesting indicator of cellular physiological state. The methodology described here aims to improve the recovering of biofilm cells for the characterization of their fatty acid profiles. The saponification reagent is directly applied on the whole biofilm before the removal of cells from the inert surface. In this way, maximum of the cells and their fatty acids can be recovered from the deepest layers of the biofilm.

RevDate: 2018-12-23

He L, Wang H, Zhang R, et al (2018)

The regulation of Porphyromonas gingivalis biofilm formation by ClpP.

Biochemical and biophysical research communications pii:S0006-291X(18)32714-1 [Epub ahead of print].

Porphyromonas gingivalis is one of the most commonly detected pathogens in periodontal disease and root canal infections. Its viability and pathogenicity are greatly increased in plaque biofilms. Some caseinolytic proteases (Clp) reportedly regulate biofilm formation by various pathogenic bacteria, including P. gingivalis. However, the specific influence of ClpP and its mechanism of regulating biofilm formation by P. gingivalis remains unclear. Hence, in this study, a clpP deletion strain and complemented strain were constructed by homologous recombination, and an in vitro biofilm model was established. Biofilm architecture was observed by scanning electron microscopy. Bacterial cells within the biofilms were examined using confocal scanning laser microscopy. Crystal violet staining was used to determine the amount of formed biofilm. mRNA levels of related regulatory genes were assessed using real-time PCR. The clpP deletion and complemented strains of P. gingivalis were successfully constructed. The biofilm formation ability of the deletion strain was significantly reduced compared with that of the wild-type strain, while that of the complemented strain did not differ from that of the wild-type strain. The expression of fimA, mfa1, and luxS in the deletion strain was lower than in the wild-type and complemented strains at each timepoint. It can be concluded that ClpP increases the biofilm formation of P. gingivalis by regulating the expression levels of fimA, mfa1, and luxS.

RevDate: 2018-12-22

Bag PK, Roy N, Acharyya S, et al (2018)

In vivo fluid accumulation-inhibitory, anticolonization and anti-inflammatory and in vitro biofilm-inhibitory activities of methyl gallate isolated from Terminalia chebula against fluoroquinolones resistant Vibrio cholerae.

Microbial pathogenesis pii:S0882-4010(16)30327-8 [Epub ahead of print].

Acute Vibrio cholerae infection triggers significant inflammatory response and immense fluid secretion in the intestine. In the present study, methyl gallate (MG) isolated from Terminalia chebula was evaluated to determine the in vivo fluid accumulation-inhibitory, anticolonization and anti-inflammatory and in vitro biofilm-inhibitory activities against multi-drug resistant (MDR) V. cholerae. Bacterial membrane-damaging and biofilm-inhibitory activities were determined by membrane perturbation and transmission electron microscopy (TEM); and microdilution assays, respectively. Fluid accumulation-inhibitory and anticolonization activities of MG (23.80-95.23 mg/kg body weight) were determined in 4-5 days old BALB/c mice with an incubation time of 18 h. The effect of MG (1, 50 and 500 mg/kg body weight) on intestinal inflammatory reaction induced by V. cholerae was studied by performing histology in Swiss albino mice. MIC and MBC of MG against the test strains were 32-64 and 64-256 μg/ml, respectively. MG showed the fluid accumulation-inhibitory activity with inhibition values of 42.86-89.08% at doses between 23.80 and 95.23 mg/kg body weight and significant anticolonization activity (p < 0.0001) against V. choleare in the suckling mouse intestine. MG (500 mg/kg body weight) significantly inhibited the inflammatory reactions induced by V. cholerae compared to the vehicle control. MG exhibited 70% minimum biofilm inhibition concentration of 64 μg/ml and bacterial membrane damaging activity at 1 × MBC. The results obtained in the present study suggest that MG has potential as an effective agent for the treatment of severe secretory and inflammatory diarrheal disease caused by MDR V. cholerae.

RevDate: 2018-12-22

Rainey K, Michalek SM, Wen ZT, et al (2018)

Glycosyltransferase mediated biofilm matrix dynamics and virulence of Streptococcus mutans.

Applied and environmental microbiology pii:AEM.02247-18 [Epub ahead of print].

Streptococcus mutans is a key cariogenic bacterium responsible for initiation of tooth decay. Biofilm formation is a crucial virulence property. We discovered a putative glycosyltransferase SMU_833 in S. mutans capable of modulating dynamic interactions between two key biofilm matrix components, glucan and extracellular DNA. Deletion of smu_833 decreases glucan and increases eDNA but maintains the overall biofilm biomass. The decrease in glucan is caused by a reduction in GtfB and GtfC, two key enzymes responsible for the synthesis of glucan. The increase in eDNA was accompanied by an elevated production of membrane vesicles, suggesting SMU_833 modulates the release of eDNA via the membrane vesicles, thereby altering biofilm matrix constituents. Furthermore, glucan and eDNA were colocalized. Complete deletion of gtfBC from the smu_833 mutant significantly reduced the biofilm biomass despite the elevated eDNA suggesting the requirement of minimal glucans as a binding substrate for eDNA within the biofilm. Despite no changes in overall biofilm biomass, the mutant biofilm was altered in biofilm architecture and less acidic in vitro. Concurrently, the mutant was less virulent in an in vivo rat model of dental caries, demonstrating SMU_833 is a new virulence factor. Taken together, we conclude that SMU_833 is required for optimal biofilm development and virulence of S. mutans by modulating extracellular matrix components. Our study of SMU_833-modulated biofilm matrix dynamics uncovered a new target that can be used to develop potential therapeutics that prevent and treat dental caries.ImportanceTooth decay, a costly and painful disease affecting the vast majority of people worldwide, is caused by the bacterium Streptococcus mutans The bacteria utilize dietary sugars to build and strengthen its biofilm, trapping acids onto the tooth's surface causing demineralization and decay of teeth. As knowledge of our bodies' microbiomes increases, the need for developing therapeutics targeted to disease-causing bacteria has arisen. The significance of our research is in studying and identifying a novel therapeutic target, a dynamic biofilm matrix that is mediated by a new virulence factor and membrane vesicles. The study increases our understanding of S. mutans virulence, and also offers a new opportunity to develop effective therapeutics targeting S. mutans In addition, the mechanisms of membrane vesicle-mediated biofilm matrix dynamics are also applicable to other biofilm driven infectious diseases.

RevDate: 2018-12-22

Ledwoch K, JY Maillard (2018)

Candida auris Dry Surface Biofilm (DSB) for Disinfectant Efficacy Testing.

Materials (Basel, Switzerland), 12(1): pii:ma12010018.

Candida auris is an emerging pathogen that needs to be controlled effectively due to its association with a high mortality rate. The presence of biofilms on dry surfaces has been shown to be widespread in healthcare settings. We produced a C. auris dry surface biofilm (DSB) on stainless steel surfaces following sequential hydration and desiccation cycles for 12 days. The ASTM2967-15 was used to measure the reduction in viability of 12 commercially wipe-based disinfectants and sodium hypochlorite (1000 ppm) against C. auris DSB. We also evaluated C. auris transferability and biofilm regrowth post-treatment. A peracetic acid (3500 ppm) product and two chlorine-based products (1000 ppm available chlorine) were successful in reducing C. auris viability and delaying DSB regrowth. However, 50% of the products tested failed to decrease C. auris viability, 58% failed to prevent its transferability, and 75% did not delay biofilm regrowth. Using three different parameters to measure product efficacy provided a practical evaluation of product effectiveness against C. auris DSB. Although log10 reduction in viability is traditionally measured, transferability is an important factor to consider from an infection control and prevention point of view as it allows for determination of whether the surface is safe to touch by patients and hospital staff post-treatment.

RevDate: 2018-12-22

Shi LD, Du JJ, Wang LB, et al (2018)

Formation of nanoscale Te0 and its effect on TeO32- reduction in CH4-based membrane biofilm reactor.

The Science of the total environment, 655:1232-1239 pii:S0048-9697(18)34692-8 [Epub ahead of print].

Formation and recovery of elemental tellurium (Te0) from wastewaters are required by increasing demands and scarce resources. Membrane biofilm reactor (MBfR) using gaseous electron donor has been reported as a low-cost and benign technique to reduce and recover metal (loids). In this study, we demonstrate the feasibility of nanoscale Te0 formation by tellurite (TeO32-) reduction in a CH4-based MBfR. Biogenic Te0 intensively attached on cell surface, within diameters ranging from 10 nm to 30 nm and the hexagonal nanostructure. Along with the Te0 formation, the TeO32- reduction was inhibited. After flushing, biofilm resumed the TeO32- reduction ability, suggesting that the formed nanoscale Te0 might inhibit the reduction by hindering substrate transfer of TeO32- to microbes. The 16S rRNA gene amplicon sequencing revealed that Thermomonas and Hyphomicrobium were possibly responsible for TeO32- reduction since they increased consecutively along with the experiment operation. The PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) analysis showed that the sulfite reductases were positively correlated with the TeO32- flux, indicating they were potential enzymes involved in reduction process. This study confirms the capability of CH4-based MBfR in tellurium reduction and formation, and provides more techniques for resources recovery and recycles.

RevDate: 2018-12-20

Zhao Z, Qin Z, Xia L, et al (2018)

The responding and ecological contribution of biofilm-leaves of submerged macrophytes on phenanthrene dissipation in sediments.

Environmental pollution (Barking, Essex : 1987), 246:357-365 pii:S0269-7491(18)31485-4 [Epub ahead of print].

The bacterial communities and ecological contribution of biofilm-leaves of the Vallisneria natans (VN), Hydrilla verticillata (HV) and artificial plant (AP) settled in sediments with different polluted levels of phenanthrene were investigated by high-throughput sequencing in different growth periods. There was no significant difference among the detected Alpha diversity indices based on three classification, attached surface, spiking concentration and incubation time. While Beta diversity analysis assessed by PCoA on operational taxonomic units (OTU) indicated that bacterial community structures were significantly influenced in order of attached surface > incubation time > spiking concentration of phenanthrene in sediment. Moreover, the results of hierarchical dendrograms and heat maps at genus level were consistent with PCoA analysis. We speculated that the weak influence of phenanthrene spiking concentration in sediment might be related to lower concentration and smaller concentration gradient of phenanthrene in leaves. Meanwhile, difference analysis suggested that attached surface was inclined to influence the rare genera up to significant level than incubation time. In general, the results proved that phenanthrene concentrations, submerged macrophytes categories and incubation time did influence the bacterial community of biofilm-leaves. In turn, results also showed a non-negligible ecological contribution of biofilm-leaves in dissipating the phenanthrene in sediments (>13.2%-17.1%) in contrast with rhizosphere remediation (2.5%-3.2% for HV and 9.9%-10.6% for VN).

RevDate: 2018-12-20

Singh N, Rajwade J, KM Paknikar (2018)

Transcriptome analysis of silver nanoparticles treated Staphylococcus aureus reveals potential targets for biofilm inhibition.

Colloids and surfaces. B, Biointerfaces, 175:487-497 pii:S0927-7765(18)30913-5 [Epub ahead of print].

The biofilms of Staphylococcus aureus on the implanted materials and chronic wounds are life-threatening and are a substantial financial burden on the healthcare system. Silver nanoparticles (SNP), known for their multi-level physiological effects in planktonic cells could be a promising agent in the treatment of biofilm-related infections also. To gain insight into the effects of SNP on various physiological processes in biofilms we studied the transcriptome of Staphylococcus aureus ATCC 29213. To distinguish between 'nanoparticles-specific' and 'ion-specific' effect of silver, we performed a comparative analysis of the functional genes in response to Ag+. As compared to untreated biofilms, 21% (i.e. 629 genes) and 28.5% (i. e. 830 genes) of the total functional coding genes were differentially regulated upon exposure to SNP and Ag+. Genes encoding capsular polysaccharides, intercellular adhesion, virulence were downregulated in SNP and Ag+ treated biofilms. Genes involved in carbohydrate, protein metabolism including DNA and RNA synthesis, oxidative stress etc. were differentially expressed. Further, activation of efflux pumps and multidrug export proteins was observed, which clearly indicates the presence of metal stress resistance determinants in S. aureus. Silver blocked the integration of mobile genetic elements in S. aureus genome. Our study points out quorum sensing and virulence determinants as possible targets for inhibition of biofilms possibly with/without existing antibiotics. However, further studies on these aspects are warranted. Scanning electron microscopy (SEM) and confocal microscopy revealed changes in biofilm morphology, architecture and thickness in presence of silver nanoparticles and ionic silver, substantiating the transcriptome data.

RevDate: 2018-12-20

Boas DV, Almeida C, Azevedo N, et al (2019)

Techniques to Assess Phage-Biofilm Interaction.

Methods in molecular biology (Clifton, N.J.), 1898:137-146.

Biofilms are ubiquitous in nature found on nearly every type of living and inert surface. They basically consist of microorganisms attached to surfaces and surrounded by a self-produced matrix of extracellular polymeric substances. Phages have proven to be successful in controlling biofilms. Here, we describe methods to characterize phage-biofilm interactions, specifically to assess biofilm biomass and to visualize the biofilm structure, discriminating infected cells using targeted molecular probes.

RevDate: 2018-12-20

Alim D, Sircaik S, SL Panwar (2018)

The Significance of Lipids to Biofilm Formation in Candida albicans: An Emerging Perspective.

Journal of fungi (Basel, Switzerland), 4(4): pii:jof4040140.

Candida albicans, the dimorphic opportunistic human fungal pathogen, is capable of forming highly drug-resistant biofilms in the human host. Formation of biofilm is a multistep and multiregulatory process involving various adaptive mechanisms. The ability of cells in a biofilm to alter membrane lipid composition is one such adaptation crucial for biofilm development in C. albicans. Lipids modulate mixed species biofilm formation in vivo and inherent antifungal resistance associated with these organized communities. Cells in C. albicans biofilms display phase-dependent changes in phospholipid classes and in levels of lipid raft formation. Systematic studies with genetically modified strains in which the membrane phospholipid composition can be manipulated are limited in C. albicans. In this review, we summarize the knowledge accumulated on the impact that alterations in phospholipids may have on the biofilm forming ability of C. albicans in the human host. This review may provide the requisite impetus to analyze lipids from a therapeutic standpoint in managing C. albicans biofilms.

RevDate: 2018-12-19

Kim SI, H Yoon (2018)

Roles of YcfR in Biofilm Formation in Salmonella Typhimurium ATCC 14028 in vitro and in planta.

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

An increasing number of foodborne diseases are currently attributable to farm produce contaminated with enteric pathogens such as Salmonella entrica. Recent studies have shown that a variety of enteric pathogens are able to colonize plant surfaces by forming biofilms and thereby persist for long periods, which can subsequently lead to human infections. Therefore, biofilm formation by enteric pathogens on plants poses a risk to human health. Here, we deciphered the roles of YcfR in biofilm formation by Salmonella enterica. YcfR is a putative outer membrane protein associated with bacterial stress responses. The lack of YcfR facilitated the formation of multicellular aggregates on cabbage leaves as well as glass surfaces while reducing bacterial motility. ycfR deletion caused extensive structural alterations in the outer membrane, primarily in lipopolysaccharides, outer membrane proteins, cellulose and curli fimbria, thereby increasing cell surface hydrophobicity. However, the absence of YcfR rendered Salmonella susceptible to stressful treatments, despite the increased multicellular aggregation. These results suggest that YcfR is an essential constituent of Salmonella outer membrane architecture and its absence may cause multifaceted structural changes, thereby compromising bacterial envelope integrity. In this context, YcfR may be further exploited as a potential target for controlling Salmonella persistence on plants.

RevDate: 2018-12-19

Stone SJ, Kumar PS, Offenbacher S, et al (2018)

Exploring a temporal relationship between biofilm microbiota and inflammatory mediators during resolution of naturally-occurring gingivitis.

Journal of periodontology [Epub ahead of print].

BACKGROUND: This study uses multiple, contemporary methodologies to expand our knowledge of the temporal relationship between host-microbial interactions and clinical signs of gingivitis.

METHODS: Subgingival plaque and crevicular fluid samples were collected from 31 systemically healthy adults with naturally occurring plaque-induced gingivitis. Professional prophylaxis was administered and participants were followed over seven weeks. Microbial characterization was performed using a bead-based hybridization assay and cytokine analysis using bead-based flow cytometry.

RESULTS: The provision of sequential interventions, oral hygiene instruction and subsequent professional prophylaxis brought about significant reduction of plaque and resolution of gingivitis at all post baseline points baseline (p < 0.0001). Candidate cytokines that increased significantly (95% level) were interleukin (IL)-1β, matrix metalloproteinases (MMP)-1, MMP-3, MMP-8, MMP-9, from baseline to week 2; Regulated on Activation, Normal T Cell Expressed and Secreted (RANTES) at week 4 and week 8; macrophage inflammatory protein (MIP)-1α and MIP-1β at week 8. Resolution of inflammation was accompanied by a shift in the microbiological flora towards those species associated with health.

CONCLUSION: This study provides further evidence of the dynamic relationships that exist between the overt clinical signs, the microbial biofilm and the host response in gingivitis and upon resolution following clinical interventions. Understanding the interactions between the host immune system and subgingival microbial communities during the resolution of established gingivitis continues to evolve as additional knowledge is achieved through using new analytical technologies. The present study confirms a critical effect of oral hygiene measures on restoration of microbial eubiosis in subgingival communities, confirming the important role for home care and professional intervention in maintaining oral health. This article is protected by copyright. All rights reserved.

RevDate: 2018-12-19

Polst BH, Anlanger C, Risse-Buhl U, et al (2018)

Hydrodynamics Alter the Tolerance of Autotrophic Biofilm Communities Toward Herbicides.

Frontiers in microbiology, 9:2884.

Multiple stressors pose potential risk to aquatic ecosystems and are the main reasons for failing ecological quality standards. However, mechanisms how multiple stressors act on aquatic community structure and functioning are poorly understood. This is especially true for two important stressors types, hydrodynamic alterations and toxicants. Here we perform a mesocosm experiment in hydraulic flumes connected as a bypass to a natural stream to test the interactive effects of both factors on natural (inoculated from streams water) biofilms. Biofilms, i.e., the community of autotrophic and heterotrophic microorganisms and their extracellular polymeric substances (EPS) in association with substratum, are key players in stream functioning. We hypothesized (i) that the tolerance of biofilms toward toxicants (the herbicide Prometryn) decreases with increasing hydraulic stress. As EPS is known as an absorber of chemicals, we hypothesize (ii) that the EPS to cell ratio correlates with both hydraulic stress and herbicide tolerance. Tolerance values were derived from concentration-response assays. Both, the herbicide tolerance and the biovolume of the EPS significantly correlated with the turbulent kinetic energy (TKE), while the diversity of diatoms (the dominant group within the stream biofilms) increased with flow velocity. This indicates that the positive effect of TKE on community tolerance was mediated by turbulence-induced changes in the EPS biovolume. This conclusion was supported by a second experiment, showing decreasing effects of the herbicide to a diatom biofilm (Nitzschia palea) with increasing content of artificial EPS. We conclude that increasing hydrodynamic forces in streams result in an increasing tolerance of microbial communities toward chemical pollution by changes in EPS-mediated bioavailability of toxicants.

RevDate: 2018-12-19

Wang C, Zhang Q, Tang X, et al (2018)

Effects of CwlM on autolysis and biofilm formation in Mycobacterium tuberculosis and Mycobacterium smegmatis.

International journal of medical microbiology : IJMM pii:S1438-4221(18)30391-6 [Epub ahead of print].

Tuberculosis is a highly infectious disease and of high incidence in low-income countries that is caused by Mycobacterium tuberculosis (M. tuberculosis). M. tuberculosis can form biofilms in vitro and in vivo, and the cells in the biofilm can survive at high concentrations of antibiotics. CwlM is a peptidoglycan hydrolase (amidase) and can hydrolyze bacterial cell walls, and the effects of CwlM on autolysis and biofilms is worthy of in-depth study. In this study, we successfully constructed an in vitro biofilm model of M. tuberculosis and Mycobacterium smegmatis (M. smegmatis). Reverse transcription followed by real-time quantitative PCR (qPCR) revealed that the expression of cwlM in M. tuberculosis and M. smegmatis was significantly up-regulated during the middle stage of biofilm formation. Treatment with recombinant CwlM enhanced the autolytic ability of M. tuberculosis and M. smegmatis and reduced the formation of their biofilms. As M. smegmatis is a model bacterium of M. tuberculosis, we built the M. smegmatis cwlM-deletion strain MSΔ6935, whose autolytic ability, biofilm production, and eDNA and eRNA content were determined to be lower than those of its parental strain. In conclusion, the cwlM gene plays a key regulatory role in biofilm formation in M. tuberculosis and M. smegmatis. This study provided a theoretical basis for using peptidoglycan hydrolase as a target for the inhibition of biofilms.

RevDate: 2018-12-19

Dua K, Gupta G, Chellapan DK, et al (2018)

Nanoparticle-based therapies as a modality in treating wounds and preventing biofilm.

Panminerva medica, 60(4):237-238.

RevDate: 2018-12-19

Toma S, Behets C, Brecx MC, et al (2018)

In Vitro Comparison of the Efficacy of Peri-Implantitis Treatments on the Removal and Recolonization of Streptococcus gordonii Biofilm on Titanium Disks.

Materials (Basel, Switzerland), 11(12): pii:ma11122484.

Objective: To compare the efficacy of four commonly used clinical procedures in removing Streptococcus gordonii biofilms from titanium disks, and the recolonization of the treated surfaces. Background: Successful peri-implantitis treatment depends on the removal of the dental biofilm. Biofilm that forms after implant debridement may threaten the success of the treatment and the long-term stability of the implants. Methods:S. gordonii biofilms were grown on titanium disks for 48 h and removed using a plastic curette, air-abrasive device (Perio-Flow®), titanium brush (TiBrush®), or implantoplasty. The remaining biofilm and the recolonization of the treated disks were observed using scanning electron microscopy and quantified after staining with crystal violet. Surface roughness (Ra and Rz) was measured using a profilometer. Results:S. gordonii biofilm biomass was reduced after treatment with Perio-Flow®, TiBrush®, and implantoplasty (all p < 0.05), but not plastic curette (p > 0.05), compared to the control group. Recolonization of S. gordonii after treatment was lowest after Perio-Flow®, TiBrush®, and implantoplasty (all p < 0.05 vs. control), but there was no difference between the plastic curette and the control group (p > 0.05). Ra and Rz values ranged from 1⁻6 µm to 1⁻2 µm and did not differ statistically between the control, plastic curette, Perio-Flow, and TiBrush groups. However, the implantoplasty group showed a Ra value below 1 µm (p < 0.01, ANOVA, Tukey). Conclusions: Perio-Flow®, TiBrush®, and implantoplasty were more effective than the plastic curette at removing the S. gordonii biofilm and preventing recolonization. These results should influence the surgical management of peri-implantitis.

RevDate: 2018-12-18

Deva AK (2018)

Commentary on: Back to Basics: Could the Preoperative Skin Antiseptic Agent Help Prevent Biofilm-Related Capsular Contracture?.

Aesthetic surgery journal pii:5252024 [Epub ahead of print].

RevDate: 2018-12-18

Silva PLAPA, Goulart LR, Reis TFM, et al (2018)

Biofilm Formation in Different Salmonella Serotypes Isolated from Poultry.

Current microbiology pii:10.1007/s00284-018-1599-5 [Epub ahead of print].

Little is known about Salmonella biofilm assembly, making the prevention of the disease a challenge in the poultry production chain. The objective of the present study was then to evaluate biofilm formation from different serotypes of Salmonella spp. in both polystyrene plates and eggshells. Salmonella Gallinarum and S. Minnesota were both classified as producers of biofilms of moderate intensity. Interestingly, S. Gallinarum produces biofilm even though being a serotype without flagellum and not having the lux gene in its genome, suggesting that there might be other important structures and genes associated with biofilm formation. Regarding Enteritidis, Typhimurium, Typhimurium variant, and Heidelberg serotypes, despite having high counts, BFI (Biofilm Formation Index) showed low biofilm production, probably due to the scarcity of extracellular matrix produced by such strains. A turkey eggshell model was then used for S. Enteritidis and S. Heidelberg biofilm formation. The results from the microbial count and scanning electron microscopy showed that Salmonella serotypes were also able to generate biofilm in eggshells, suggesting the presence of biofilms in poultry producing farms, a main concern for the poultry production industry.

RevDate: 2018-12-18

Wang T, Shao J, Da W, et al (2018)

Strong Synergism of Palmatine and Fluconazole/Itraconazole Against Planktonic and Biofilm Cells of Candida Species and Efflux-Associated Antifungal Mechanism.

Frontiers in microbiology, 9:2892.

Fungal infections caused by Candida albicans and non-albicans Candida [NAC] species are becoming a growing threat in immunodeficient population, people with long-term antibiotic treatment and patients enduring kinds of catheter intervention. The resistance to one or more than one conventional antifungal agents contributes greatly to the widespread propagation of Candida infections. The severity of fungal infection requires the discovery of novel antimycotics and the extensive application of combination strategy. In this study, a group of Candida standard and clinical strains including C. albicans as well as several NAC species were employed to evaluate the antifungal potentials of palmatine (PAL) alone and in combination with fluconazole (FLC)/itraconazole (ITR) by microdilution method, checkerboard assay, gram staining, spot assay, and rhodamine 6G efflux test. Subsequently, the expressions of transporter-related genes, namely CDR1, CDR2, MDR1, and FLU1 for C. albicans, CDR1 and MDR1 for Candida tropicalis and Candida parapsilosis, ABC1 and ABC2 for Candida krusei, CDR1, CDR2, and SNQ2 for Candida glabrata were analyzed by qRT-PCR. The susceptibility test showed that PAL presented strong synergism with FLC and ITR with fractional inhibitory concentration index (FICI) in a range of 0.0049-0.75 for PAL+FLC and 0.0059-0.3125 for PAL+ITR in planktonic cells, 0.125-0.375 for PAL+FLC and 0.0938-0.3125 for PAL+ITR in biofilms. The susceptibility results were also confirmed by gram staining and spot assay. After combinations, a vast quantity of rhodamine 6G could not be pumped out as considerably intracellular red fluorescence was accumulated. Meanwhile, the expressions of efflux-associated genes were evaluated and presented varying degrees of inhibition. These results indicated that PAL was a decent antifungal synergist to promote the antifungal efficacy of azoles (such as FLC and ITR), and the underlying antifungal mechanism might be linked with the inhibition of efflux pumps and the elevation of intracellular drug content.

RevDate: 2018-12-18

Di Domenico EG, Cavallo I, Bordignon V, et al (2018)

The Emerging Role of Microbial Biofilm in Lyme Neuroborreliosis.

Frontiers in neurology, 9:1048.

Lyme borreliosis (LB) is the most common tick-borne disease caused by the spirochete Borrelia burgdorferi in North America and Borrelia afzelii or Borrelia garinii in Europe and Asia, respectively. The infection affects multiple organ systems, including the skin, joints, and the nervous system. Lyme neuroborreliosis (LNB) is the most dangerous manifestation of Lyme disease, occurring in 10-15% of infected individuals. During the course of the infection, bacteria migrate through the host tissues altering the coagulation and fibrinolysis pathways and the immune response, reaching the central nervous system (CNS) within 2 weeks after the bite of an infected tick. The early treatment with oral antimicrobials is effective in the majority of patients with LNB. Nevertheless, persistent forms of LNB are relatively common, despite targeted antibiotic therapy. It has been observed that the antibiotic resistance and the reoccurrence of Lyme disease are associated with biofilm-like aggregates in B. burgdorferi, B. afzelii, and B. garinii, both in vitro and in vivo, allowing Borrelia spp. to resist to adverse environmental conditions. Indeed, the increased tolerance to antibiotics described in the persisting forms of Borrelia spp., is strongly reminiscent of biofilm growing bacteria, suggesting a possible role of biofilm aggregates in the development of the different manifestations of Lyme disease including LNB.

RevDate: 2018-12-18

Tabassum R, Shafique M, Khawaja KA, et al (2018)

Complete genome analysis of a Siphoviridae phage TSK1 showing biofilm removal potential against Klebsiella pneumoniae.

Scientific reports, 8(1):17904 pii:10.1038/s41598-018-36229-y.

Multidrug-resistant Klebsiella pneumoniae is a nosocomial pathogen, produces septicemia, pneumonia and UTI. Excessive use of antibiotics contributes towards emergence of multidrug-resistance. Bacteriophage-therapy is a potential substitute of antibiotics with many advantages. In this investigation, microbiological and genome characterization of TSK1 bacteriophage and its biofilm elimination capability are presented. TSK1 showed narrow host range and highest stability at pH 7 and 37 °C. TSK1 reduced the growth of K. pneumoniae during the initial 14 hours of infection. Post-treatment with TSK1 against different age K. pneumoniae biofilms reduced 85-100% biomass. Pre-treatment of TSK1 bacteriophage against the biofilm of Klebsiella pneumoniae reduced > 99% biomass in initial 24 hr of incubation. The genome of TSK1 phage comprised 49,836 base pairs with GC composition of 50.44%. Total seventy-five open reading frames (ORFs) were predicted, 25 showed homology with known functional proteins, while 50 were called hypothetical, as no homologs with proved function exists in the genome databases. Blast and phylogenetic analysis put it in the Kp36 virus genus of family Siphoviridae. Proposed packaging strategy of TSK1 bacteriophage genome is headful packaging using the pac sites. The potential of TSK1 bacteriophage could be used to reduce the bacterial load and biofilm in clinical and non-clinical settings.

RevDate: 2018-12-18

Chen L, Qiu Y, Tang H, et al (2018)

ToxR Is Required for Biofilm Formation and Motility of Vibrio Parahaemolyticus.

Biomedical and environmental sciences : BES, 31(11):848-850.

RevDate: 2018-12-17

Meng J, Li J, He J, et al (2018)

Nutrient removal from high ammonium swine wastewater in upflow microaerobic biofilm reactor suffered high hydraulic load.

Journal of environmental management, 233:69-75 pii:S0301-4797(18)31436-1 [Epub ahead of print].

To understand the ability of an upflow microaerobic biofilm reactor (UMBR) to remove nutrient from manure-free swine wastewater rich in NH4+ with a COD/TN ratio less than 1.00, effect of hydraulic loading rate (HLR) on the microaerobic process was evaluated with a constant reflux ratio of 25 at 25 °C. The results showed that changes in HLR had a remarkable effect on the performance of the UMBR in nutrient removal from the wastewater. With the favorable HLR 3.0 m3/(m3·d) (Hydraulic Retention Time (HRT) 8 h), average removal of COD, NH4+ and TN in the microaerobic process reached 59.3%, 87.7% and 84.7%, respectively, though the COD/TN ratio was as low as 0.84. With an over HLR of 4.0 m3/(m3·d) (HRT decreased to 6 h), bad performance of the UMBR was observed with an average removal of COD, NH4+ and TN as low as 45.0%, 59.0% and 57.5%, respectively. Since the HLR was decreased to 2.4 m3/(m3·d) (HRT 10 h), the microaerobic process regained the efficiency in nutrient removal with a removal of COD, NH4+ and TN averaged 59.0%, 95.3% and 87.8%, respectively. The microaerobic condition allowed anammox bacteria, ammonia-oxidizing bacteria and archaea, nitrite-oxidizing bacteria and denitrifiers to all thrive in the UMBR, resulting in the efficient synchronous removal of organic carbon and nitrogen. As the dominant approach to nitrogen removal, anaerobic ammonium oxidation (anammox) pathway contributing to the TN removal in the microaerobic process exceeded 59.5% at HLR 3.0 m3/(m3·d). The results demonstrated that the UMBR can remove nitrogen and carbon from swine wastewater, with a suitable HLR.

RevDate: 2018-12-17

Megarajan S, Subramaniyan SB, Prakash SA, et al (2018)

Revised version - Correction unmarked effective elimination of biofilm formed with waterborne pathogens using copper nanoparticles.

Microbial pathogenesis pii:S0882-4010(18)31728-5 [Epub ahead of print].

In this paper, the self assembling properties of taurolipids were used to prepare stable copper nanoparticles (CuNPs), and demonstrated the ability of CuNPs to eradicate the biofilms formed by waterborne pathogens. The synthesized CuNPs display wine red color and exhibited surface plasmon resonance with a maximum at 590 nm. Transmission electron microscopy showed that the CuNPs are well-dispersed with spherical morphology and the size range between 5 and 12 nm. The powder X-ray diffraction study revealed that the CuNPs was free from copper oxide impurities and crystalline with the face centered cubic structure. The CuNPs exhibited excellent anti-biofilm activity against water borne pathogens such as Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Shigella flexneri. Light microscopy and scanning electron microscopy (SEM) study revealed that CuNPs eliminates the mature biofilm at the minimum biofilm eradication concentration of 12.5 μM. The antimicrobial activity of the CuNPs was observed at the minimum inhibitory concentration of 25 μM, indicating the reported CuNPs exhibit true anti-biofilm effect. Fluorescence microscopy and SEM study proved that CuNPs kills the bacteria through membrane damage. The possibility to use CuNPs in cleaning biofilm formed on storage containers was demonstrated through removing the mature biofilm formed on a glass pipe.

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ESP Origins

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

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

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

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

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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.

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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.

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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.

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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).

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Selected Bibliographies

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