Biofilm Consortia Research Articles

Electrochemical Testing of Biocide Enhancement by a Mixture ofd-Amino Acids for the Prevention of a Corrosive Biofilm Consortium on Carbon Steel

Problematic biofilms cause microbiologically influenced corrosion (MIC) and biofouling in many industries such as the oil and gas industry, water utilities, and the power generation industry. Equipment failures cause not only economic losses but also environmental damages. A high biocide concentration is required to treat mixed-culture biofilms due to their various defense mechanisms. A biocide enhancer can reduce the dosage or make a biocide more effective. In this work, an equimolar mixture with 100 ppm (w/w) of four d-amino acids (d-tyrosine, d-methionine, d-leucine, and d-tryptophan) labeled as d-mix enhanced 60 ppm alkyldimethylbenzylammonium chloride (ADBAC) against a field biofilm consortium on C1018 carbon steel coupons by achieving at least an extra 2-log reduction of sessile cell counts in the biofilm prevention test. Scanning electron microscopy images, confocal laser scanning microscopy images, weight loss, and pitting data all corroborated the electrochemical tests.

Enhanced treatment of contaminated domestic wastewater using bacterial consortium biofilm

Enhanced treatment of contaminated domestic wastewater using bacterial consortium biofilm

Biological Fixed Film

The review includes literature published in the year of 2015 regarding the uses of biofilm in full-scale and lab-scale bioreactors to treat wastewater. The topics considered include biofilm formation and factors impacting biofilm formation; extracellular polymeric substance from biofilms; biofilm consortia and quorum sensing; biofilm reactors and biofilm in bioelectrochemical systems.

Metabolic modeling of a chronic wound biofilm consortium predicts spatial partitioning of bacterial species.

BackgroundChronic wounds are often colonized by consortia comprised of different bacterial species growing as biofilms on a complex mixture of wound exudate. Bacteria growing in biofilms exhibit phenotypes distinct from planktonic growth, often rendering the application of antibacterial compounds ineffective. Computational modeling represents a complementary tool to experimentation for generating fundamental knowledge and developing more effective treatment strategies for chronic wound biofilm consortia.ResultsWe developed spatiotemporal models to investigate the multispecies metabolism of a biofilm consortium comprised of two common chronic wound isolates: the aerobe Pseudomonas aeruginosa and the facultative anaerobe Staphylococcus aureus. By combining genome-scale metabolic reconstructions with partial differential equations for metabolite diffusion, the models were able to provide both temporal and spatial predictions with genome-scale resolution. The models were used to analyze the metabolic differences between single species and two species biofilms and to demonstrate the tendency of the two bacteria to spatially partition in the multispecies biofilm as observed experimentally. Nutrient gradients imposed by supplying glucose at the bottom and oxygen at the top of the biofilm induced spatial partitioning of the two species, with S. aureus most concentrated in the anaerobic region and P. aeruginosa present only in the aerobic region. The two species system was predicted to support a maximum biofilm thickness much greater than P. aeruginosa alone but slightly less than S. aureus alone, suggesting an antagonistic metabolic effect of P. aeruginosa on S. aureus. When each species was allowed to enhance its growth through consumption of secreted metabolic byproducts assuming identical uptake kinetics, the competitiveness of P. aeruginosa was further reduced due primarily to the more efficient lactate metabolism of S. aureus. Lysis of S. aureus by a small molecule inhibitor secreted from P. aeruginosa and/or P. aeruginosa aerotaxis were predicted to substantially increase P. aeruginosa competitiveness in the aerobic region, consistent with in vitro experimental studies.ConclusionsOur biofilm modeling approach allows the prediction of individual species metabolism and interspecies interactions in both time and space with genome-scale resolution. This study yielded new insights into the multispecies metabolism of a chronic wound biofilm, in particular metabolic factors that may lead to spatial partitioning of the two bacterial species. We believe that P. aeruginosa lysis of S. aureus combined with nutrient competition is a particularly relevant scenario for which model predictions could be tested experimentally.Electronic supplementary materialThe online version of this article (doi:10.1186/s12918-016-0334-8) contains supplementary material, which is available to authorized users.

Individual, co-transport and deposition of TiO2 and ZnO nanoparticles over quartz sand coated with consortium biofilm

The transport of TiO2 and ZnO nanoparticles was assessed using column experiments in a porous media containing biofilm. In order to understand the influence of bacteria encountered in the natural aquatic environment when nanoparticles are introduced in the surroundings, nanoparticles transport has been studied through quartz coated with a biofilm composing of a consortium of Pseudomonas aeruginosa (Gram-negative), Bacillus alitudinis and Bacillus subtilis (Gram-positive). The influence on individual and co-transport mobility and deposition kinetics of TiO2 (10, 15mg/L) and ZnO (5, 10mg/L) nanoparticles based on variations in ionic strength was also determined. Various environmentally related ionic strengths were studied for the experiment using NaCl (0.1–10mM), by keeping the pH fixed to pH 7.0. At pH 7.0, TiO2 NPs transport declined, when the ZnO nanoparticles were present, whereas, enhanced ZnO nanoparticles transport was observed in the presence of TiO2 nanoparticles. The solution chemistries of the nanoparticles can be inferred from the breakthrough curves (BTCs), wherein an increase in ionic strength results in a decline in the BTC plateau. The inverse of BTC plateaus provided the retention profiles, which could also be anticipated from the mass balance contemplation. Altogether, the upshot of this work explains the transport behavior of both the nanoparticles in biofilm coated sand depends on suspension chemistries (pH and ionic strength) are likely the primary factors that control. Further research could thus be focused on enhancing our knowledge of the basic mechanisms governing nanoparticles transport and fate in typical biofilm containing aquatic environment.

Isolation of Bdellovibrio bacteriovorus from a tropical wastewater treatment plant and predation of mixed species biofilms assembled by the native community members.

It is reported here that a predatory bacterium belonging to the Genus Bdellovibrio, was isolated from activated sludge at the Ulu Pandan Water Reclamation Plant, Singapore. 16S rDNA gene sequencing analysis revealed that this isolate was 99% identical to 'Bdellovibrio bacteriovorus strain Tiberius' and hence is designated as 'Bdellovibrio bacteriovorus UP'. Using a novel approach based on fluorescence in situ hybridization (FISH), a prey cell density-dependent growth pattern of B. bacteriovorus UP was established. B. bacteriovorus UP preyed upon a broad range of bacterial species (60 species) isolated from the activated sludge. Except for Ochrobactrum anthropi, all Gram-negative species were sensitive to predation by B. bacteriovorus UP irrespective of the mode of growth (planktonic or biofilm). Similarly, the predation-sensitive species were not protected by the predation-resistant species, O. anthropi, as determined in multiple dual-species planktonic and biofilm consortia. Given the broad prey spectrum, B. bacteriovorus UP may impact functional community members, which are largely members of the Proteobacteria. Thus, these results provide an important insight to the role of predatory bacteria in shaping of community structure and function in both natural and engineered ecosystems.

Antibacterial fatty acids destabilize hydrophobic and multicellular aggregates of biofilm in S. aureus.

Present study is based on 20 methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered from different food items. These isolates were identified on the basis of colony morphology, Gram staining and growth on different selective and differential media. Studies on 16S RNA and positive reactions on DNase agar and Prolex Latex Agglutination system confirm it as Staphylococcus aureus. Oxacillin susceptibility testing and PCR with mecA gene-specific primer results showed that these isolates are MRSA-carrying mecA gene that belongs to SCCmecA type IV and also harbor agr type II. Phenotypic study revealed that these isolates adopt biofilm mode of growth after exposure to subinhibitory doses of oxacillin. The biofilm and cell surface hydrophobicity have a strong correlation. It was noticed that affinity to hexadecane (apolar-solvent) of planktonic cells was low, suggesting its hydrophilic character. However, as the cells are exposed to oxacillin, they adopt biofilm mode of life and the affinity to apolar solvent increases, indicating a hydrophobic character. In biofilm consortia, the cells with more hydrophobic surfaces show incomplete septation and produce multicellular aggregates. This is due to reduced expression of atl gene. This was confirmed by real-time PCR studies. Moreover, the planktonic or wild-type phenotypes of these isolates were more tolerant to antibacterial effect of the fatty acids used; that is, cis-2-decanoic acid and cis-9-octadectanoic acid. These fatty acids were more effective against biofilms. After exposure to these fatty acids, established biofilms were dispersed and surviving cells were unable to readopt biofilm mode of life. The planktonic or wild-type phenotypes produce fatty acid-modifying enzyme (FAME) to inactivate the bactericidal activity of fatty acids by esterification to cholesterol. The biofilm indwellers are metabolically inactive and unable to produce FAME; hence, they are vulnerable to antibiofilm effect of cis-2-decanoic acid and cis-9-octadectanoic acid.

Antibiofilm efficacy of honey and bee-derived defensin-1 on multispecies wound biofilm.

Many clinically relevant biofilms are polymicrobial. Examining the effect of antimicrobials in a multispecies biofilm consortium is of great clinical importance. The goal of this study was to investigate the effect of different honey types against bacterial wound pathogens grown in multispecies biofilm and to test the antibiofilm activity of honey defensin-1 (Def-1) in its recombinant form. A modified Lubbock chronic wound biofilm formed by four bacterial species (Staphylococcus aureus, Streptococcus agalactiae, Pseudomonas aeruginosa and Enterococcus faecalis) was used for evaluation of honey and recombinant bee-derived Def-1 antibiofilm efficacy. Recombinant Def-1 was prepared by heterologous expression in Escherichia coli. We showed that different types of honey (manuka and honeydew) were able to significantly reduce the cell viability of wound pathogens (Staphylococcus aureus, Streptococcus agalactiae and Pseudomonas aeruginosa) in mature polymicrobial biofilm. None of the tested honeys showed the ability to eradicate Enterococcus faecalis in biofilm. In addition, recombinant Def-1 successfully reduced the viability of Staphylococcus aureus and Pseudomonas aeruginosa cells within established polymicrobial biofilm after 24 and 48 h of treatment. Interestingly, recombinant Def-1 did not affect the viability of Streptococcus agalactiae cells within the biofilm, whereas both natural honeys significantly reduced the viable bacteria. Although Enterococcus faecalis was highly resistant to Def-1, Def-1 significantly affected the biofilm formation of Enterococcus faecalis and Streptococcus agalactiae after 24 h of treatment, most likely by inhibiting its extracellular polymeric substances production. In conclusion, our study revealed that honey and Def-1 are effective against established multispecies biofilm; however, Enterococcus faecalis grown in multispecies biofilm was resistant to both antimicrobials.

Spatiotemporal Metabolic Modeling of a Chronic Wound Biofilm Consortium

Abstract: Chronic wounds are often colonized by consortia comprised of different bacterial species growing as biofilms on a complex mixture of wound exudate. The spatial organization of biofilm consortia cause bacteria to exhibit phenotypes distinct from planktonic growth and often render the application of antibacterial compounds ineffective. We developed a spatiotemporal model to analyze the multispecies metabolism of a biofilm consortium comprised of two common chronic wound isolates: the aerobe Pseudomonas aeruginosa and the facultative anaerobe Staphylococcus aureus. By combining genome-scale metabolic reconstructions with partial differential equations for metabolite diffusion, the model was able to provide both temporal and spatial predictions with genome-scale resolution. The model was used to analyze the metabolic differences between single species and multispecies biofilms and to demonstrate the tendency of the two bacteria to spatially partition due to nutrient gradients. The model predicted that S. aureus would dominant throughout the biofilm, especially in the anaerobic region where P. aeruginosa had very low growth rates. Lactate secreted by S. aureus and consumed by both species was predicted to further diminish P. aeruginosa competitiveness due to its lower cell densities. Lysis of S. aureus by inhibitors secreted from P. aeruginosa was predicted to enhance spatial partitioning of the two species and to substantially enhance the competitiveness of P. aeruginosa in partially aerobic regions of the biofilm interior.

Biological Fixed Film.

The review includes literatures published in the year of 2014 regarding the uses of biofilm and bioreactor to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance from biofilms; biofilm consortia and quorum sensing; biofilm reactors and biofilm in bioelectrochemical systems.

Energy-Efficient Nitrification and Microbial Community in a Completely Stirred Membrane Biofilm Reactor

Oxygen-based membrane biofilm reactor, in which oxygen diffuses from the inside of membrane fibers to the biofilm located on the outer surface of each fiber, accomplished effective nitrification because the gas substrate under even low pressures was completely utilized as an electron acceptor. Oxygen flux reached 19.7 g O2/m2-day at an ammonium loading of 11.15 g N/m2-day and the system tolerated the ammonium loading of 4.4 g N/m2-day at an oxygen pressure as low as 0.034 atm and hydraulic retention time (HRT) of 2.5 h by achieving complete nitrification. To better understand the microbial composition of biofilm, polymerase chain reaction–denaturing gradient gel electrophoresis analysis was applied. Molecular technique based on 16S rRNA gene sequences indicated that the biofilm consortium included Nitrosospira sp. and Nitrosopumilus maritimus, which have played an important role in efficient nitrification.

Biofilm composite design on pumice stone for phenol degradation in batik industrial waste

Biofilm formed by bacterial activity of Acinetobacter sp. and cow's stomach bacteria consortium has been developed on pumice stone. The biofilm were characterised by scanning electron microscopy to find out the morphology of pumices surface. Total plate count (TPC) analysis was also conducted to investigate the cell density. Observation by scanning electron microscopy evidenced the present of abundant exopolymeric material surrounding the cells in the biofilm. The two variant of biofilm will be tested to degrade phenol, a pollutant from batik industry's waste. The influence of aeration on biofilm's activity for phenol degradation was also determined. Phenol degradation monitored during four hours operation. With the addition of aeration, cow's stomach bacteria consortium biofilm can degrade 89% of 10 ppm phenol while Acinetobacter sp. biofilm can only degrade 77% of 10 ppm phenol. It can then be concluded that biofilm from cow's stomach bacteria consortium can degrade phenol better than Acinetobacter sp.

Biological Fixed Film

Literature published during the year 2013 regarding the use of biofilms and bioreactors to treat water and wastewater is revie\ ed herein. The review is organized into the following sections: biofilm fornl. ationand factors Ulat impact biofilm fom13tion; xtracellular polymeric substance and its e rtraction from biofihns; biofilm consortia and quorum sensing; biofilm imaging teclmiques; biofilm carriers and biofilm reactors.

Copper removal using a heavy-metal resistant microbial consortium in a fixed-bed reactor

A heavy-metal resistant bacterial consortium was obtained from a contaminated river in São Paulo, Brazil and utilized for the design of a fixed-bed column for the removal of copper. Prior to the design of the fixed-bed bioreactor, the copper removal capacity by the live consortium and the effects of copper in the consortium biofilm formation were investigated. The Langmuir model indicated that the sorption capacity of the consortium for copper was 450.0 mg/g dry cells. The biosorption of copper into the microbial biomass was attributed to carboxyl and hydroxyl groups present in the microbial biomass. The effect of copper in planktonic cells to form biofilm under copper rich conditions was investigated with confocal microscopy. The results revealed that biofilm formed after 72 h exposure to copper presented a reduced thickness by 57% when compared to the control; however 84% of the total cells were still alive. The fixed-bed bioreactor was set up by growing the consortium biofilm on granular activated carbon (GAC) and analyzed for copper removal. The biofilm-GAC (BGAC) column retained 45% of the copper mass present in the influent, as opposed to 17% in the control column that contained GAC only. These findings suggest that native microbial communities in sites contaminated with heavy metals can be immobilized in fixed-bed bioreactors and used to treat metal contaminated water.

Pathogenicity phenomena in three model systems: from network mining to emerging system-level properties

Understanding the interconnections of microbial pathogenicity phenomena, such as biofilm formation, quorum sensing and antimicrobial resistance, is a tremendous open challenge for biomedical research. Progress made by wet-lab researchers and bioinformaticians in understanding the underlying regulatory phenomena has been significant, with converging evidence from multiple high-throughput technologies. Notably, network reconstructions are already of considerable size and quality, tackling both intracellular regulation and signal mediation in microbial infection. Therefore, it stands to reason that in silico investigations would play a more active part in this research. Drug target identification and drug repurposing could take much advantage of the ability to simulate pathogen regulatory systems, host-pathogen interactions and pathogen cross-talking. Here, we review the bioinformatics resources and tools available for the study of the gram-negative bacterium Pseudomonas aeruginosa, the gram-positive bacterium Staphylococcus aureus and the fungal species Candida albicans. The choice of these three microorganisms fits the rationale of the review converging into pathogens of great clinical importance, which thrive in biofilm consortia and manifest growing antimicrobial resistance.

Biological Fixed Film

The review includes literature published during the year 2012 regarding the use of biofilms and bioreactors to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance and its extraction from biofilms; biofilm consortia and quorum sensing; biofilm imaging techniques; biofilm reactors and modeling.

Application of Biofilm-Forming Bacteria on the Enhancement of Organophosphorus Fungicide Degradation

ABSTRACT This study aimed to develop technology enhancing the biodegradation efficacy against organophosphorus fungicide with biofilm-forming bacteria in situ. Using the crystal violet staining method, two bacterial strains having biofilm formation capability were isolated and identified as Pseudomonas sp. C7 and Bacillus sp. E5. Compared with the culture of tolclofos-methyl degrader Sphingomonas sp. 224, biofilm formation was improved by co-inoculation with biofilm-forming bacterium Bacillus sp. E5. Evaluated in liquid culture conditions, this two-species mixed consortium was observed to degrade tolclofos-methyl more effectively than Sphingomonas sp. 224 alone, with an approximately 90% degradation efficiency within 48 h of dosing. The improved effectiveness of the consortium biofilm was reflected using soil in situ with an approximately 7% increased degradation ratio over Sphingomonas sp. 224 alone. This is the first report demonstrating improved bioremediation degradation efficacy against tolclofos-methyl exhibited by a consortium biofilm. This work presents a possible effective bioremediation strategy using a specific biofilm composition against pollutants containing organophosphorus compounds in situ.

SLIME THROUGH TIME: THE FOSSIL RECORD OF PROKARYOTE EVOLUTION

Prokaryota in natural environments form biofilms, which are benthic assemblages of a variety of microorganisms embedded within their extracellular mucilage. Biofilms are firmly attached to surfaces such as aquatic sediments. Quorum sensing by the many microbes in a biofilm is collective decision making and cooperation for responding to internal and external parameters affecting the community. This communication is based on chemical signaling affecting gene expression of the microorganisms. Microorganisms situated in a biofilm change behaviors and metabolic activities to comply with the requirements of the entire biofilm cooperative. Consequently, reconstruction of the evolution of prokaryotes in Earth history must consider the biofilm way of microbial life. Biogenic sedimentary structures might not represent certain microbial groups, but in fact may be relics of modified cooperative microbial activities. Future research should focus on detectable biosignatures caused by biofilm consortia as a whole instead of on the appearance or extinction of individual microbial groups. Such sedimentary structures as stromatolites and microbially induced sedimentary structures (MISS) are intrinsically controlled by biofilms, but also affected by extrinsic (environmental) conditions.

Biological Fixed Film

The review includes literature published during the year 2011 regarding the use of biofilm and bioreactors to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance and its extraction from biofilms; biofilm consortia and quorum sensing; biofilm imaging techniques; biofilm reactors and modeling.

Self-Organization, Layered Structure, and Aggregation Enhance Persistence of a Synthetic Biofilm Consortium

Microbial consortia constitute a majority of the earth's biomass, but little is known about how these cooperating communities persist despite competition among community members. Theory suggests that non-random spatial structures contribute to the persistence of mixed communities; when particular structures form, they may provide associated community members with a growth advantage over unassociated members. If true, this has implications for the rise and persistence of multi-cellular organisms. However, this theory is difficult to study because we rarely observe initial instances of non-random physical structure in natural populations. Using two engineered strains of Escherichia coli that constitute a synthetic symbiotic microbial consortium, we fortuitously observed such spatial self-organization. This consortium forms a biofilm and, after several days, adopts a defined layered structure that is associated with two unexpected, measurable growth advantages. First, the consortium cannot successfully colonize a new, downstream environment until it self-organizes in the initial environment; in other words, the structure enhances the ability of the consortium to survive environmental disruptions. Second, when the layered structure forms in downstream environments the consortium accumulates significantly more biomass than it did in the initial environment; in other words, the structure enhances the global productivity of the consortium. We also observed that the layered structure only assembles in downstream environments that are colonized by aggregates from a previous, structured community. These results demonstrate roles for self-organization and aggregation in persistence of multi-cellular communities, and also illustrate a role for the techniques of synthetic biology in elucidating fundamental biological principles.