Project description:Sulfonamides are traditional synthetic antimicrobial agents used in clinical and veterinary medical settings. Their long-term excessive overuse has resulted in widespread microbial resistance, limiting their application for medical interventions. Resistance to sulfonamides is primarily conferred by the alternative genes sul1, sul2, and sul3 encoding dihydropteroate synthase in bacteria. Studying the potential fitness cost of these sul genes is crucial for understanding the evolution and transmission of sulfonamide-resistant bacteria. In vitro studies have been conducted on the fitness cost of sul genes in bacteria. In this study, we provide critical insights into bacterial adaptation and transmission using an in vivo approach.
Project description:We evolved Escherichia coli cells over 500 generations under five environments that include four abiotic stressors: osmotic, acidic, oxidative, n-butanol, and control The goal of the experiment: Bacterial populations have a remarkable capacity to cope with extreme environmental fluctuations in their natural environments. In certain cases, adaptation to one stressful environment provides a fitness advantage when cells are exposed to a second stressor, a phenomenon that has been coined as cross-stress protection. A tantalizing question in bacterial physiology is how the cross-stress behavior emerges during adaptation and what the genetic basis of acquired stress resistance is.
Project description:We evolved Escherichia coli cells over 500 generations under five environments that include four abiotic stressors: osmotic, acidic, oxidative, n-butanol, and control The goal of the experiment: Bacterial populations have a remarkable capacity to cope with extreme environmental fluctuations in their natural environments. In certain cases, adaptation to one stressful environment provides a fitness advantage when cells are exposed to a second stressor, a phenomenon that has been coined as cross-stress protection. A tantalizing question in bacterial physiology is how the cross-stress behavior emerges during adaptation and what the genetic basis of acquired stress resistance is. RNA profiles were obtained for six E. coli strains evolved for 500 generations under abiotic stressors; two technical replicates for each strain where sequenced by Illumina GAII analyzer
Project description:We used microarrays to study the changes in whole-genome expression profiles accompanying the evolution of one bacterial population propagated in glucose minimal medium for 20,000 generations.
Project description:Since their discovery, archaea have not only proven a fascinating domain in their own right, but also helped us understand the evolution and function of molecular components they share with bacteria or eukaryotes. Archaeal histones are homologous to their eukaryotic counterparts, but operate in a less constrained bacterial-like cellular environment and their role in transcription and genome function remains obscure. In order to understand how archaeal histones affect transcriptional processes, we induced expression of the two histones from the archaeon Methanothermus fervidus in a naive bacterial system (E. coli) that has not evolved to integrate this kind of proteins. We show, using a series of MNase digestion experiments, that these histones bind the bacterial genome and wrap DNA in vivo in a pattern consistent with a previously proposed multimerisation model, in a similar pattern observed natively. We correlate genome-wide occupancy maps and gene expression profiles in different phases of growth to show that – although expression of archaeal histones triggers morphological changes in E. coli – there appears to only be an indirect effect on transcription. Since their discovery, archaea have not only proven a fascinating domain in their own right, but also helped us understand the evolution and function of molecular components they share with bacteria or eukaryotes. Archaeal histones are homologous to their eukaryotic counterparts, but operate in a less constrained bacterial-like cellular environment and their role in transcription and genome function remains obscure. In order to understand how archaeal histones affect transcriptional processes, we induced expression of the two histones from the archaeon Methanothermus fervidus in a naive bacterial system (E. coli) that has not evolved to integrate this kind of proteins. We show, using a series of MNase digestion experiments, that these histones bind the bacterial genome and wrap DNA in vivo in a pattern consistent with a previously proposed multimerisation model, in a similar pattern observed natively. We correlate genome-wide occupancy maps and gene expression profiles in different phases of growth to show that – although expression of archaeal histones triggers morphological changes in E. coli – there appears to only be an indirect effect on transcription.
Project description:Type IV secretion systems (T4SSs) are central to bacterial pathogenesis due to their versatile functions. While traditionally known for their role in DNA transfer via conjugation and secretion of effector proteins, T4SSs have been shown to mediate biofilm formation in various bacteria. These biofilms are critical for the fitness of adherent-invasive strains of Escherichia coli (AIEC), which are commonly isolated from Crohn’s disease patients and are known for propelling gut inflammation. Many AIEC strains carry F-like plasmids encoding the IncF subgroup of T4SSs. Unlike minimized systems that comprise 12 core components, the IncF family has evolved into an expanded T4SS through the acquisition of additional genes that enhance conjugation. Here, we show that a biofilm-forming AIEC strain harbors an unusual IncF plasmid that lacks two conserved components otherwise considered essential for T4SS functionality. We demonstrate that this strain forms a natural hybrid T4SS, where the two components missing in the plasmid are supplied by a co-residing chromosomal T4SS present on an integrative and conjugative element (ICE). Using biochemical assays, we show that this functional machine is a mosaic of IncF and ICE-encoded proteins that co-operatively drive pilin polymerization and biofilm formation on epithelial cells. Furthermore, we show that a subpopulation of bacteria expresses the IncF and ICE-encoded genes in response to host cells, leading to the assembly of biofilms that promote AIEC fitness in the gut. Together, these findings uncover a crosstalk between two co-residing and evolutionary distant mobile genetic elements to form a hybrid T4SS that mediates biofilm biogenesis by a Crohn’s disease-associated pathogen.
Project description:Despite the characterization of many aetiologic genetic changes. The specific causative factors in the development of sporadic colorectal cancer remain unclear. This study was performed to detect the possible role of Enteropathogenic Escherichia coli (EPEC) in developing colorectal carcinoma.
Project description:BACKGROUND:Isobutanol is a promising next generation biofuel with demonstrated high yield microbial production, but the toxicity of this molecule reduces fermentation volumetric productivity and final titers. Organic solvent tolerance is a complex, multigenic phenotype that has been recalcitrant to rational engineering approaches. We apply experimental evolution followed by genome resequencing and a gene expression study to elucidate genetic bases on adaptation to exogenous isobutanol stress. RESULTS:The adaptations acquired in our evolved lineages exhibit antagonistic pleiotropy between minimal and rich medium, and appear to be specific to the effects of longer chain alcohols. By examining genotypic adaptation in multiple independent lineages, we find evidence of parallel evolution in hfq, mdh, acrAB, gatYZABCD, and rph genes. Many isobutanol tolerant lineages show reduced rpoS activity, perhaps related to mutations in hfq or acrAB. Consistent with the complex, multigenic nature of solvent tolerance, we observe adaptations in a diversity of cellular processes. Many adaptations appear to involve epistasis between different mutations, implying a rugged fitness landscape for isobutanol tolerance. We observe a trend of evolution targeting post-transcriptional regulation and high centrality nodes of biochemical networks. Collectively, the genotypic adaptations we observe suggest mechanisms of adaptation to isobutanol stress based on remodelling the cell envelope and surprisingly, stress response attenuation. CONCLUSIONS:We have discovered a set of genotypic adaptations that confer increased tolerance to exogenous isobutanol stress. Our results are immediately useful to efforts to engineer more isobutanol tolerant host strains of E. coli for isobutanol production. We suggest that rpoS and post-transcriptional regulators, such as hfq, RNA helicases, and sRNAs may be interesting mutagenesis targets for futurue global phenotype engineering. Two strains (WT strain and G3.2 mutant strain), each with two culture conditions (with and without isobutanol in medium). Three biological replicates for each strain/culture condition. Twelve samples in total.
Project description:BACKGROUND:Isobutanol is a promising next generation biofuel with demonstrated high yield microbial production, but the toxicity of this molecule reduces fermentation volumetric productivity and final titers. Organic solvent tolerance is a complex, multigenic phenotype that has been recalcitrant to rational engineering approaches. We apply experimental evolution followed by genome resequencing and a gene expression study to elucidate genetic bases on adaptation to exogenous isobutanol stress. RESULTS:The adaptations acquired in our evolved lineages exhibit antagonistic pleiotropy between minimal and rich medium, and appear to be specific to the effects of longer chain alcohols. By examining genotypic adaptation in multiple independent lineages, we find evidence of parallel evolution in hfq, mdh, acrAB, gatYZABCD, and rph genes. Many isobutanol tolerant lineages show reduced rpoS activity, perhaps related to mutations in hfq or acrAB. Consistent with the complex, multigenic nature of solvent tolerance, we observe adaptations in a diversity of cellular processes. Many adaptations appear to involve epistasis between different mutations, implying a rugged fitness landscape for isobutanol tolerance. We observe a trend of evolution targeting post-transcriptional regulation and high centrality nodes of biochemical networks. Collectively, the genotypic adaptations we observe suggest mechanisms of adaptation to isobutanol stress based on remodelling the cell envelope and surprisingly, stress response attenuation. CONCLUSIONS:We have discovered a set of genotypic adaptations that confer increased tolerance to exogenous isobutanol stress. Our results are immediately useful to efforts to engineer more isobutanol tolerant host strains of E. coli for isobutanol production. We suggest that rpoS and post-transcriptional regulators, such as hfq, RNA helicases, and sRNAs may be interesting mutagenesis targets for futurue global phenotype engineering.