Project description:In Burkholderia cenocepacia H111, the large surface protein BapA plays a crucial role in the formation of highly structured communities, known as biofilms. We have recently demonstrated that Quorum sensing (QS) is necessary for the maximal expression of bapA. In this study we identify a protein from the IclR family of transcriptional regulators that, in conjunction with QS, controls biofilm formation by affecting the expression of bapA. We present evidence that, in addition to BapA, BapR influences the expression of extracellular protease, swimming motility and has a profound impact in the abundance of persister cells, making this regulator an interesting target for persister and biofilm eradication. Identification of a new regulator BapR controlling biofilm formation
Project description:In Burkholderia cenocepacia H111, the large surface protein BapA plays a crucial role in the formation of highly structured communities, known as biofilms. We have recently demonstrated that Quorum sensing (QS) is necessary for the maximal expression of bapA. In this study we identify a protein from the IclR family of transcriptional regulators that, in conjunction with QS, controls biofilm formation by affecting the expression of bapA. We present evidence that, in addition to BapA, BapR influences the expression of extracellular protease, swimming motility and has a profound impact in the abundance of persister cells, making this regulator an interesting target for persister and biofilm eradication.
Project description:In nature, bacteria reside in biofilms - multicellular differentiated communities held together by extracellular matrix. In this work, we identified a novel subpopulation essential for biofilm formation – mineral-forming cells in Bacillus subtilis biofilms. This subpopulation contains an intracellular calcium-accumulating niche, in which the formation of a calcium carbonate mineral is initiated. As the biofilm colony develops, this mineral grows in a controlled manner, forming a functional macrostructure that serves the entire community. Consistently, biofilm development is prevented by inhibition of calcium uptake. Taken together, our results provide a clear demonstration of the orchestrated production of calcite exoskeleton, critical to morphogenesis in simple prokaryotes. We expect future research exploring this newly discovered process to shed further light on mechanisms of bacterial development.
Project description:The principal opportunistic human fungal pathogen Candida albicans forms biofilms resistant to antifungal therapeutics. Biofilms are a class of soft matter with viscoelastic properties and response to flow, but little is known regarding the genes contributing to these rheological phenotypes in fungal biofilms. Here, we identify C. albicans genes with deletion phenotypes of altered biofilm viscoelasticity. We analyzed mutants deleted for genes contributing to cell wall structure or extracellular matrix (ECM) production, and we identified increased elastic moduli, indicative of higher viscoelasticity, in strains singly deleted for PMR1, KRE5, and ALG11. PMR1 encodes a secretory pathway calcium pump. KRE5 encodes a UDP-glucose:glycoprotein glucosyltransferase, and ALG11 encodes alpha-1,2-mannosyltransferase. These mutants form less biofilm ECM by weight relative to wild type when cultured on agar. For these strains, biofilm morphology is smooth, with reduced hyphal formation. The mutants exhibit decreased resistance to the antifungal agent fluconazole relative to wild type biofilm cultures. To identify intracellular changes underlying these altered rheological properties, we globally profiled transcript levels in the respective mutants. Genes encoding membrane proteins were enriched in the set of transcripts differentially abundant in the alg11 deletion mutant. RNA levels are altered for genes associated with translation in the pmr1 deletion mutant and protein catabolism in the kre5 deletion strain. Genes involved in lipid metabolism and filamentous development are differentially expressed in cells from alg11, kre5, and pmr1 deletion mutant biofilms. Collectively, the data indicate C. albicans biofilm rheology as a phenotype affected by ECM production and cell morphology, while identifying genes for the investigation of mechanisms underlying properties of fungal biofilm viscoelasticity.
Project description:To explain enhanced biofilm formation and increased dissemination of S. epidermidis in mixed-species biofilms, microarrays were used to explore differential gene expression of S. epidermidis in mixed-species biofilms. One sample from single species biofilm (S1) and mixed-species biofilm (SC2) were excluded from analyses for outliers. We observed upregulation (2.7%) and down regulation (6%) of S. epidermidis genes in mixed-species biofilms. Autolysis repressors lrgA and lrgB were down regulated 36-fold and 27-fold respectively and was associated with increased eDNA possibly due to enhanced autolysis in mixed-species biofilms. These data suggest that bacterial autolysis and release of eDNA in the biofilm matrix may be responsible for enhancement and dissemination of mixed-species biofilms of S. epidermidis and C. albicans. Staphylococcal gene expression in mixed-species biofilms with Candida and in single species biofilms of S. epidermidis were analyzed. The experiment was repeated thrice on 3 different days (3 biological replicates each for single species biofilms of S. epidermidis and mixed-species biofilms). Only 2 biological replicates were analyzed and one biological replicate was not analyzed (S1 and SC1 - raw data files are provided on the Series record). Single species biofilms of S. epidermidis (strain 1457) and C. albicans (strain 32354) and mixed-species biofilms were formed on 6-well tissue culture plates. Five ml of organism suspensions (O.D. 0.3, S. epidermidis 107 CFU/ml or C. albicans 105 CFU/ml) or 2.5 ml each for mixed-species biofilms for 24 hr. RNA was harvested from single species and mixed-species biofilms.
Project description:To explain enhanced biofilm formation and increased dissemination of S. epidermidis in mixed-species biofilms, microarrays were used to explore differential gene expression of S. epidermidis in mixed-species biofilms. One sample from single species biofilm (S1) and mixed-species biofilm (SC2) were excluded from analyses for outliers. We observed upregulation (2.7%) and down regulation (6%) of S. epidermidis genes in mixed-species biofilms. Autolysis repressors lrgA and lrgB were down regulated 36-fold and 27-fold respectively and was associated with increased eDNA possibly due to enhanced autolysis in mixed-species biofilms. These data suggest that bacterial autolysis and release of eDNA in the biofilm matrix may be responsible for enhancement and dissemination of mixed-species biofilms of S. epidermidis and C. albicans.
Project description:Yeast whole cells have been widely used in modern biotechnology as biocatalysts to generate numerous compounds of industrial, chemical, and pharmaceutical importance. Since many of the biocatalysis utilizing manufactures have become more concerned about environmental issues, seawater is now considered a sustainable alternative to freshwater for biocatalytic processes. This approach plausibly commenced new research initiatives into exploration of salt tolerant yeast strains. Recently, there has also been a growing interest in possible applications of microbial biofilms in the field of biocatalysis. In these complex communities, cells demonstrate higher resistance to adverse environmental conditions due to their embedment in an extracellular matrix, in which physical, chemical, and physiological gradients exist. Considering these two topics, seawater and biofilms, in this work we characterized biofilm formation in seawater-based growth media by several salt tolerant yeast strains with previously demonstrated bocatalytic capacities. The tested strains formed both air-liquid-like biofilms and biofilms on silicone surfaces, with Debaryomyces fabryi, Schwanniomyces etchellsii, S. polymorphus and Kluyveromyces marxianus showing the highest biofilm formation. The extracted biofilm extracellular matrices mostly consisted of carbohydrates and proteins. The latter group was primarily represented by enzymes involved in metabolic processes, particularly the biosynthetic ones, and in the response to stimuli. Specific features were also found in the carbohydrate composition of the extracellular matrix, which were dependent both on the yeast isolate and the nature of formed biofilms. Overall, our findings presented herein provide a unique data resource for further development and optimization of biocatalytic processes and applications employing seawater and halotolerant yeast biofilms.
Project description:Biofilms are broadly formed by a diversity of microorganisms that enable them to adapt stressful environments. Biofilms often impose harmful influences in many niches, as they can cause food contamination, antibiotics resistance, and environmental issues. However, eradicating biofilms remains difficult since the formation mechanism of biofilms are still incompletely clarified. In this study, we aimed at exploring the regulatory role of magnesium (Mg2+) on biofilm formation in Escherichia coli (E. coli) using phenotype visualization combined with targeted metabolomics method. We found that Mg2+ could exert significant influence on biofilm formation in a concentration-dependent manner by regulating phenotypic morphology and triggering metabolic modifications of biofilm. Phenotypic imaging revealed that increasing concentration of Mg2+ gradually inhibited biofilm formation, Mg2+ was observed to restore the microstructure of E. coli strain in biofilms to that in the relevant planktonic cells. In addition, our metabolomics analysis characterized 20 differential metabolites and associated 2 metabolic pathways including nucleotide metabolism and amino acid metabolism that were notably modified during biofilm formation under the treatments of different concentrations of Mg2+. Altogether, our work provides a novel insight into the influence of Mg2+ on biofilm formation at a metabolic level, which are implicated in the novel solution to disturb biofilm formation through the regulation of Mg2+ and functional metabolite interaction, then biofilms associated harmful impacts in different niches could be well tangled accordingly.
Project description:Biofilms are broadly formed by a diversity of microorganisms that enable them to adapt stressful environments. Biofilms often impose harmful influences in many niches, as they can cause food contamination, antibiotics resistance, and environmental issues. However, eradicating biofilms remains difficult since the formation mechanism of biofilms are still incompletely clarified. In this study, we aimed at exploring the regulatory role of magnesium (Mg2+) on biofilm formation in Escherichia coli (E. coli) using phenotype visualization combined with targeted metabolomics method. We found that Mg2+ could exert significant influence on biofilm formation in a concentration-dependent manner by regulating phenotypic morphology and triggering metabolic modifications of biofilm. Phenotypic imaging revealed that increasing concentration of Mg2+ gradually inhibited biofilm formation, Mg2+ was observed to restore the microstructure of E. coli strain in biofilms to that in the relevant planktonic cells. In addition, our metabolomics analysis characterized 20 differential metabolites and associated 2 metabolic pathways including nucleotide metabolism and amino acid metabolism that were notably modified during biofilm formation under the treatments of different concentrations of Mg2+. Altogether, our work provides a novel insight into the influence of Mg2+ on biofilm formation at a metabolic level, which are implicated in the novel solution to disturb biofilm formation through the regulation of Mg2+ and functional metabolite interaction, then biofilms associated harmful impacts in different niches could be well tangled accordingly.
Project description:Salmonella spp. biofilms have been implicated in persistence in the environment and plant surfaces. In addition, Salmonella is able to form biofilms on the surface on cholesterol gallstones. The ability of Salmonella spp. on these surfaces is superior to biofilm formation on surfaces on glass or plastic. Thus, we hypothesized that Salmonella gene expression is specific during biofilm development on cholesterol surfaces.