Project description:Here, we investigated for the first time the systems-wide response of B. subtilis to different simultaneous stresses, i.e. nutrient limitation and high osmolarity. To address the anticipated complexity of the cellular response networks, we combined chemostat experiments under conditions of carbon limitation, salt stress and osmoprotection with multi-omics analyses at the transcriptome, proteome, metabolome and fluxome levels. Our results indicate that the flux through central carbon and energy metabolism is very robust under all conditions studied. The key to achieve this robustness is the adjustment of the biocatalytic machinery to compensate for solvent-induced impairment of enzymatic activities during osmotic stress. The accumulation of the exogenously provided osmoprotectant glycine betaine helps the cell to rescue enzyme activities in the presence of high salt. A major effort of the cell during osmotic stress is the production of the compatible solute proline. This is achieved by the concerted adjustment of multiple reactions around the 2-oxoglutarate node, which drives metabolism towards the proline precursor glutamate. The fine-tuning of the transcriptional and metabolic networks involves functional modules that overarch the individual pathways.
Project description:Here, we investigated for the first time the systems-wide response of B. subtilis to different simultaneous stresses, i.e. nutrient limitation and high osmolarity. To address the anticipated complexity of the cellular response networks, we combined chemostat experiments under conditions of carbon limitation, salt stress and osmoprotection with multi-omics analyses at the transcriptome, proteome, metabolome and fluxome levels. Our results indicate that the flux through central carbon and energy metabolism is very robust under all conditions studied. The key to achieve this robustness is the adjustment of the biocatalytic machinery to compensate for solvent-induced impairment of enzymatic activities during osmotic stress. The accumulation of the exogenously provided osmoprotectant glycine betaine helps the cell to rescue enzyme activities in the presence of high salt. A major effort of the cell during osmotic stress is the production of the compatible solute proline. This is achieved by the concerted adjustment of multiple reactions around the 2-oxoglutarate node, which drives metabolism towards the proline precursor glutamate. The fine-tuning of the transcriptional and metabolic networks involves functional modules that overarch the individual pathways. We applied transcriptomic, mass spectrometry-based protein, metabolite and 13C-metabolic flux analysis techniques to B. subtilis cells grown under well-controlled conditions in a glucose-limited chemostat at a growth rate of 0.1 h-1 under i) reference conditions, ii) in the presence of 1.2 M NaCl, and iii) in the presence of 1.2 M NaCl and 1 mM GB. Microarray hybridizations were performed with RNA from three biological replicates. The individual samples were labeled with Cy5; a reference pool containing equal amounts of RNA from all 9 samples was labeled with Cy3.
Project description:Bacillus subtilis is exposed to a wide range of transitory stress and starvation conditions. Here we investigate the expression changes observed in the B. subtilis wild type strain 168 and its isogenic sigB mutant(BSM29) with respect to each stress condition tested. Gene expression was queried for the stress conditions: ethanol-, butanol-, osmotic- and oxidative stress, heat shock, low temperature growth, glucose as well as oxygen limitation. For butanol-, ethanol-, osmotic-, and oxidative stress as well as heat shock : time points (0min, 5min, 10min, 15min and 20min) ; for glucose limitation and oxygen limitation : time points (0min, 15min, 30min, 45min, 60min or 90min) and for low temperature growth, samples for recording of expression values were taken during mid-exponential growth at OD540 0.9 and 1.0.
Project description:Whole-genome microarray technology and state-of-the-art proteomic techniques were applied to provide a global and time-resolved picture of the physiological response of B. subtilis cells exposed to a severe and sudden osmotic up-shift. This combined experimental approach provided quantitative data for 3961 mRNA profiles, 590 expression profiles of proteins detected in the cytosol and 383 expression profiles of proteins detected in the membrane fraction. Our study uncovered a well-coordinated induction of gene expression subsequent to an osmotic up-shift that involves large parts of the SigB, SigW, SigM and SigX regulons and additionally osmotic up-regulation of a large number of genes that do not belong to these regulons. In total, osmotic up-regulation of about 500 B. subtilis genes was observed. Our data provide an unprecedented rich basis for further in-depth investigation on the physiological and genetic responses of B. subtilis to hyperosmotic stress.
Project description:Characterization of the putative genetic determinants of the VBNC state in a known spore-forming Gram-positive organism Bacillus subtilis 168. The VBNC state was induced under osmotic stress and aminoglycoside treatment. The transcriptome landscape of VBNC cells was compared to the viable, antibiotic sensitive B. subtilis cells and to the viable cells with no antibiotic treatment.
Project description:Translational control during the intricate process of sporulation in Bacillus subtilis as a response to nutrient limitation is still underexplored. Here, we employed a comprehensive approach including RNA-seq, ribosome profiling and fluorescence microscopy to dissect the translational landscape of B. subtilis during sporulation. We identified two events of translation silencing and described the spatiotemporal changes in the subcellular location of translational machinery during sporulation. Using a triple knock-out strain (3KO) of zinc-independents paralogs of three zinc-dependent ribosomal proteins L31, L33 and S14, we investigated the potential regulatory role of ribosome during sporulation. The 3KO strain exhibited delayed sporulation, reduced germination efficiency, and dysregulated translation including expression of key metabolic and sporulation-related genes as well as disruptions in translation silencing, particularly in late sporulation.
Project description:Translational control during the intricate process of sporulation in Bacillus subtilis as a response to nutrient limitation is still underexplored. Here, we employed a comprehensive approach including RNA-seq, ribosome profiling and fluorescence microscopy to dissect the translational landscape of B. subtilis during sporulation. We identified two events of translation silencing and described the spatiotemporal changes in the subcellular location of translational machinery during sporulation. Using a triple knock-out strain (3KO) of zinc-independents paralogs of three zinc-dependent ribosomal proteins L31, L33 and S14, we investigated the potential regulatory role of ribosome during sporulation. The 3KO strain exhibited delayed sporulation, reduced germination efficiency, and dysregulated translation including expression of key metabolic and sporulation-related genes as well as disruptions in translation silencing, particularly in late sporulation.
Project description:Here, we described comparative transcriptomic analysis of B. subtilis strain stably expressing rho with the wild type and rho-deficient strains. We show that maintaining a stable Rho level caused global changes of B. subtilis transcriptome including both strong down-regulation of the antisense transcription and considerable modifications of the sense transcription. The observed changes were more noticeable upon entering the stationary phase and comprised majority of genes controlled by global transcription regulators AbrB and CodY, competence transcription factor ComK, and stringent response. Constitutively expressed rho reprograms stationary phase-specific cellular physiology, affects adaptation of cells to nutrient limitations by attenuating the stringent response and alters cell-fate decision-making to such an extent that it blocks competence development and sporulation.
Project description:Whole-genome microarray technology and state-of-the-art proteomic techniques were applied to provide a global and time-resolved picture of the physiological response of B. subtilis cells exposed to a severe and sudden osmotic up-shift. This combined experimental approach provided quantitative data for 3961 mRNA profiles, 590 expression profiles of proteins detected in the cytosol and 383 expression profiles of proteins detected in the membrane fraction. Our study uncovered a well-coordinated induction of gene expression subsequent to an osmotic up-shift that involves large parts of the SigB, SigW, SigM and SigX regulons and additionally osmotic up-regulation of a large number of genes that do not belong to these regulons. In total, osmotic up-regulation of about 500 B. subtilis genes was observed. Our data provide an unprecedented rich basis for further in-depth investigation on the physiological and genetic responses of B. subtilis to hyperosmotic stress. Cells were grown in a minimal medium to early exponential phase and were then exposed to a strong osmotic up-shift by the addition of 6% (w/v) NaCl. Samples were taken before and 10, 30, 60 and 120 min subsequent to the addition of NaCl. Microarray hybridizations were performed with RNA from three biological replicates. The individual samples were labeled with Cy5; a reference pool consisting of equal amounts of RNA from all 15 samples was labeled with Cy3 (common reference design). After intensity-dependent (Lowess) normalization, the ratios of duplicate spots were averaged resulting in three biologically independent expression values per gene and time point.