Project description:The life-threatening pathogen Leptospira interrogans navigates a dual existence: surviving in environmental reservoirs and infecting mammalian hosts. Leptospira biofilm formation is thought to be an important survival strategy in environmental contexts and may also contribute to the persistence of leptospirosis in maintenance hosts. Examining the correlation between biofilm formation and the virulence of pathogenic strains might improve our comprehension of the epidemiology of leptospirosis. To further explore Leptospira’s survival strategy, our study focused on elucidating the biological state of pathogenic Leptospira within biofilms, particularly aiming to uncover the adaptations and regulatory mechanisms that are involved in such complex microenvironments. To determine the transcriptional profile of pathogenic Leptospira in biofilm, we compared the genome-wide transcriptomic profiles in late biofilms (21 days old) with those in exponential planktonic cultures (5 days old), revealing a pronounced transcriptomic shift. While genes linked to motility, energy production, and metabolism were downregulated, those governing the general stress response, defense against metal stress, and redox homeostasis showed a significant upsurge, hinting at a tailored defensive strategy against stress in late biofilms. A standout finding was the increased expression of the csoR, copZ, and copA locus, integral to copper ion stress response in other bacterial genera, suggesting a unique adaptation to metal-induced stress. Further, despite a reduced metabolic state in biofilms, their disruption swiftly restored metabolic activity. Crucially, bacteria either in late biofilms or resulting from biofilm disruption retained virulence in a hamster infection model, defying the notion that biofilm maturation abolishes pathogenicity. In summary, our study highlights Leptospira's adaptive equilibrium in biofilms: minimizing cellular energy expenditure to conserve resources, potentially aiding in withstanding stresses while maintaining its pathogenicity. These insights are important for explaining the survival strategies of Leptospira, revealing that a biofilm lifestyle may confer an advantage in maintaining virulence. This understanding is essential for managing leptospirosis across both environmental reservoirs and mammalian hosts.
Project description:There is a wide diversity of potential applications for direct electron transfer from electrodes to microorganisms, which might be better optimized if the mechanisms for this novel electrode-biofilm interaction were better understood. Geobacter sulfurreducens is one of the few microorganisms available in pure culture that is known to be capable of directly accepting electrons from a negatively poised electrode. A microarray comparison of cells accepting electrons from the electrode versus cells donating electrons to the electrode reveals that the genes previously observed to be upregulated in current-producing biofilms are not highly expressed in current-consuming biofilms.
Project description:Is there a universal genetically programmed defense providing tolerance to antibiotics when bacteria grow as biofilms? A comparison between biofilms of three different bacterial species by transcriptomic and metabolomic approaches uncovered no evidence of one. Single-species biofilms of three bacterial species (Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii) were grown in vitro for three days then challenged with respective antibiotics (ciprofloxacin, daptomycin, tigecycline) for an additional 24 h. All three microorganisms displayed reduced susceptibility in biofilms compared to planktonic cultures. Global transcriptomic profiling of gene expression comparing biofilm to planktonic and antibiotic-treated biofilm to untreated biofilm was performed. Extracellular metabolites including 18 amino acids, glucose, lactate, acetate, formate, and ethanol were measured to characterize the utilization of carbon sources between biofilms, treated biofilms, and planktonic cells. While all three bacteria exhibited a species-specific signature of stationary phase, no conserved gene, gene set, or common functional pathway could be identified that changed consistently across the three microorganisms. Across the three species, glucose consumption was increased in biofilms compared to planktonic cells and alanine and aspartic acid utilization were decreased in biofilms compared to planktonic cells. The reasons for these changes were not readily apparent in the transcriptomes. No common shift in the utilization pattern of carbon sources was discerned when comparing untreated to antibiotic-exposed biofilms. Overall, our measurements do not support the existence of a common genetic or biochemical basis for biofilm tolerance against antibiotics. Rather, there are likely myriad genes, proteins, and metabolic pathways that influence the physiological state of microorganisms in biofilms contributing to antibiotic tolerance. The Staphylococcus aureus microarray data from the study described above is deposited here.
Project description:Is there a universal genetically programmed defense providing tolerance to antibiotics when bacteria grow as biofilms? A comparison between biofilms of three different bacterial species by transcriptomic and metabolomic approaches uncovered no evidence of one. Single-species biofilms of three bacterial species (Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii) were grown in vitro for three days then challenged with respective antibiotics (ciprofloxacin, daptomycin, tigecycline) for an additional 24 h. All three microorganisms displayed reduced susceptibility in biofilms compared to planktonic cultures. Global transcriptomic profiling of gene expression comparing biofilm to planktonic and antibiotic-treated biofilm to untreated biofilm was performed. Extracellular metabolites including 18 amino acids, glucose, lactate, acetate, formate, and ethanol were measured to characterize the utilization of carbon sources between biofilms, treated biofilms, and planktonic cells. While all three bacteria exhibited a species-specific signature of stationary phase, no conserved gene, gene set, or common functional pathway could be identified that changed consistently across the three microorganisms. Across the three species, glucose consumption was increased in biofilms compared to planktonic cells and alanine and aspartic acid utilization were decreased in biofilms compared to planktonic cells. The reasons for these changes were not readily apparent in the transcriptomes. No common shift in the utilization pattern of carbon sources was discerned when comparing untreated to antibiotic-exposed biofilms. Overall, our measurements do not support the existence of a common genetic or biochemical basis for biofilm tolerance against antibiotics. Rather, there are likely myriad genes, proteins, and metabolic pathways that influence the physiological state of microorganisms in biofilms contributing to antibiotic tolerance. The Acinetobacter baumannii microarray data from the study described above is deposited here.
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.