Project description:Bacillus subtilis forms dormant spores upon nutrient depletion. Under favorable environmental conditions, the spore breaks its dormancy and resumes growth in a process called spore germination and outgrowth. To elucidate the physiological processes that occur during the transition of the dormant spore to an actively growing vegetative cell, we studied this process in a time-dependent manner by a combination of microscopy, analysis of extracellular metabolites and a genome-wide analysis of transcription. The results indicate the presence of abundant levels of late sporulation transcripts in dormant spores. In addition, results suggest the existence of a complex and well-regulated spore outgrowth program, involving the temporal expression of at least 30 % of the B. subtilis genome. Keywords: time course, spore outgrowth
Project description:To gain insight into spore germination and outgrowth, the transcriptome changes during Bacillus subtilis spore conversion to vegetative cells were analyzed. The transcriptome analysis also allowed us to trace the different functional groups of genes expressed during this conversion. . Our analysis identified 34 abundant mRNA transcripts in the dormant spores, at least 31 of which were rapidly degraded after the phase transition and observed 3152 differentially expressed genes during spore germination and outgrowth.
Project description:Description
Bacillus subtilis forms highly resistant, metabolically inactive spores upon nutrient limitation. These endospores pose challenges to the food and medical sectors. Spores reactivate their metabolism upon contact with germinants through germination and outgrowth, and then develop into vegetative cells. However, the mechanism of the activation of the molecular machinery that triggers spore germination and outgrowth is unclear. To gain further insight into spore germination and outgrowth, the transcriptome and proteome changes during Bacillus subtilis spore conversion to vegetative cells were analyzed. The transcriptome analysis also allowed us to trace the different functional groups of genes expressed during this conversion. For each time-point sampled, the change in the spore proteome was quantitatively monitored relative to the reference proteome of 15N metabolically labelled vegetative cells. Of the quantified proteins, 60 percent are common to vegetative cells and spores, indicating that spores have a minimal set of proteins sufficient for the resumption of metabolism upon completion of germination. The shared proteins thus represent the most basic survival kit for spore-based life. Until the phase transition, defined as the completion of germination, we observed no significant change in the proteome or the transcriptome. Our analysis identified 34 abundant mRNA transcripts in the dormant spores, at least 31 of which were rapidly degraded after the phase transition. We observed 3152 differentially expressed genes, and demonstrated with our mass spectrometry analyses the differential expression of 323 proteins. Our data show that 173 proteins from dormant spores, both proteins unique to spores and proteins shared with vegetative cells, are lost after completion of germination. Further analysis is required to functionally interpret the observed protein loss. The observed diverse timing of the synthesis of different protein sets reveals a putative core-strategy of the revival of life starting from the B. subtilis spore.
Project description:Bacillus subtilis strain R0179 is found in a number of commercially-available probiotic products. The mechanism(s) of action of B. subtilis in the host are poorly understood, but may involve the immune system response to switching between spore and vegetative forms. In order to help elucidate this mechanism, we challenged the immune response of a human colonic epithelial HT-29 cell model for 3 hours with the two forms of B. subtilis. The cellular response was evaluated using a custom-designed two-color expression microarray targeting 1354 genes of the human immune system. The data obtained in this study indicates that the vegetative cell form of the strain moderately induced TH1 pro-inflammatory response through IL-17C and TNF signaling pathway while down-regulating anti-inflammatory response genes IL-10 and TGFβ-2. The spore form had an opposite effect and acted primarily by down-regulating the Mitogen-Activated Protein Kinase pathway. The overall design consisted of 2 samples of HT-29 cells treated with Bacillus subtilis R0179 spores or vegetative states versus unchallenged HT-29 cells. A minimum of four dye-swap hybridizations (4 biological replicates) were performed for each of the 2 samples analyzed. Unchallenged HT-29 cells were controls and challenged HT-29 cells with Bacillus subtilis R0179 spores or vegetative were treated samples.
Project description:The transcriptome of 8 strains were studied during 7 stages of the Morphological phases of sporulation P0 = Resuspention of cells in sporulation medium; P1 = Onset of sporulation before asymmetric division; P2 = Visible asymmetric septum; P3 = Ongoing engulfment of the forespore compartment by the mother cell compartment of sporulating cells; P4 = Completed engulfment (engulfed phase-dark forespores are surrounded by the mother-cell cytoplasm); P5 = Maturation (ongoing dehydration of the forespore core seen as a transition of phase-dark forespores into phase-bright foresppores); P6 = Phase-bright forespores (sporulation almost completed, mother-cells contain phase-bright dehydrated forespores).
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:Pathogenic species belonging to Bacillus cereus sensu lato group possess a high evolutionary advantage in the environment and in food matrices thanks to their capacity to survive as silent spores to harsh environmental insults and grow at relatively low temperatures. Ready to re-heat products are at severe risk for contamination by members of Bacillus cereus s.l. group if not stored at proper conditions. In this work, the goal was to assess, by means of a genome-wide transcriptional assay, the isolated strain Bacillus cereus UC10070 gene expression behind the process of spore germination and consequent outgrowth in an artificially contaminated vegetable-based food model. A vegetable food model subjected to a heat treatment was determined to present favourable conditions for spores germination. Microscopic analyses together with OD measurements were applied to select the key steps of B. cereus cell cycle to be used for the microarray analysis. Using this approach we found a total of 1,646 probe sets differentially expressed and modulated during the entire B. cereus life cycle in the vegetable foodstuff.
Project description:Using RNA-seq, we cataloged messenger RNAs in highly purified dormant Bacillus subtilis spores prepared either on plates or in liquid. Almost all of the most abundant spore mRNAs are encoded by genes expressed only in the developing spore late in sporulation under control of the forespore-specific RNA polymerase sigma factor, sG. Given the levels of the ~40 most abundant mRNAs in dormant spores, we calculated the great majority of the low abundance mRNAs can be present in only a small fraction of the spore population.
Project description:High-temperature fermentation of the Bacillus subtilis isolated from the black part of maotai Daqu. Studying on the gene expression profile using microarray for analyzing the connection between metabolites and the maotai flavor substances. 84 differential expressed genes were obtained, including 40 up-regulated genes and 44 down-regulated genes.The differentially expressed genes involved in the metabolic pathways were just only KBL (glycine C - acetyltransferase) and ripA (bifunctional 3, 4 - dihydroxy - 4-2 - butanone phosphate synthase), up-regulated 2.9 and 2.9 times respectively, and their catalytic reaction prodction of aminobutyric acid and dihydroxy ethyl ketone phosphate, respectively. They may be further derived into alcohol and ketone flavoring substances. However, a large number of differential expressed genes was related to sporulation, such as ybaN (polysaccharide deacetylase) and rapA (aspartic acid phosphatase), they were up-regulated 17.5 times and down-regulated 112.5 times. YbaN is closely related to the formation of spore cortex and high temperature group spore cortex obvious thickening by TEM. RapA is signaling molecules to restrain spore formation, its lower expression can promote the sporulation in group A. Formation and release of peptidoglycan and the DPA (2, 6 - Pyridinedicarboxylic acid) of spore cortex during theseveral rounds of low temperature to high temperature circulation fermentation may be the main source of furan and pyranand nitrogen heterocyclic compounds in maotai flavor substances . In this paper, the formation of high-temperature fermentation Bacillus subtilis spores is closely related to the generation of maotai flavor substances.
Project description:The gene expression of Bacillus subtilis 168 showed 3 major patterns including early expression, transition expression and late expression We monitored Bacillus subtilis gene expression by using microarray at differernt time points