Comparative transcriptomics analysis of L-alanine-induced Bacillus subtilis S-2 and 312 strains
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ABSTRACT: Two wide type strains of Bacillus subtilis, S-2 and 312, were selected to study their genic differences treated by L-alanine through comparative transcriptomics analysis. The spores of B. subtilis S-2 were selected because of their high germination potential to L-alanine. The spores of B. subtilis 312 without a response to L-alanine were used as the control. The spores with or without L-alanine (100 mm) pretreatment were both cultured in the synthetic medium for 9 h, and then collected for sequencing.
Project description:Sporulation as a typical bacterial differentiation process has been studied for decades. However, two crucial aspects of sporulation, (i) the energy sources supporting the process, and (ii) the maintenance of spore dormancy throughout sporulation, are scarcely explored. Here, we reported the crucial role of RocG-mediated glutamate catabolism in regulating mother cell lysis, a critical step for successful sporulation of Bacillus subtilis, likely by providing energy metabolite ATP. Notably, rocG overexpression resulted in an excessive ATP accumulation in sporulating cells, leading to adverse effects on future spore properties, e.g. increased germination efficiency, reduced DPA content, and lowered heat resistance. Additionally, we revealed that Ald-mediated alanine metabolism was highly related to the inhibition of premature germination and the maintenance of spore dormancy during sporulation, which might be achieved by decreasing the typical germinant L-alanine concentration in sporulating environment. Our data inferred that sporulation of B. subtilis was a highly orchestrated biological process requiring a delicate balance in diverse metabolic pathways, hence ensuring both the completion of sporulation and production of high-quality spores.
Project description:Because of their ubiquity and resistance to spacecraft decontamination, bacterial spores are considered likely potential forward contaminants on robotic missions to Mars. Thus it is important to understand their global responses to long-term exposure to space or Mars environments. As part of the PROTECT experiment, spores of B. subtilis 168 were exposed to real space conditions and to simulated martian conditions for 559 days in low Earth orbit mounted on the EXPOSE-E exposure platform outside the European Columbus module on the International Space Station. Upon return, spores were germinated, total RNA extracted and fluorescently labeled, and used to probe a custom Bacillus subtilis microarray to identify genes preferentially activated or repressed relative to ground control spores. Increased transcript levels were detected for a number of stress-related regulons responding to DNA damage (SOS response, SPβ prophage induction), protein damage (CtsR/Clp system), oxidative stress (PerR regulon) and cell envelope stress (SigV regulon). Spores exposed to space demonstrated a much broader and more severe stress response than spores exposed to simulated Mars conditions. The results are discussed in the context of planetary protection for a hypothetical journey of potential forward contaminant spores from Earth to Mars and their subsequent residence on Mars.
Project description:Bacterial endospores (spores) are among the most resistant living forms on earth. Spores of Bacillus subtilis A163 show extremely high resistance to wet heat compared to spores of laboratory strains. In this study, we found that spores of B. subtilis A163 were indeed very wet heat resistant and released dipicolinic acid (DPA) very slowly during heat treatment. We also determined the proteome of vegetative cells and spores of B. subtilis A163 and the differences in these proteomes from those of the laboratory strain PY79, spores of which are much less heat resistant. This proteomic characterization identified 2011 proteins in spores and 1901 proteins in vegetative cells of B. subtilis A163.
Project description:Investigation of whole genome gene expression level changes in sporulating Bacillus subtilis 168 delta-prpE mutant, compared to the wild-type strain. The mutation engineered into this strain results in impaired germination of spores.
Project description:The general assumption is that when bacteria run out of nutrients they become dormant or form spores. Here we show, using a new technique, that under deep starvation conditions non-sporulating Bacillus subtilis cells do not become dormant but continue to grow. B. subtilis can form (endo)spores and this has been regarded as the principal mechanism through which it survives long periods of nutrient depletion. However, in this study we demonstrate that non-sporulating B. subtilis cells can survive deep starvation conditions for many months. During this period, cells adopt an almost coccoid shape and become tolerant to antibiotics and oxidative stress. Interestingly, these cells appeared to be metabolically active, and transcriptome analyses indicated that their gene-expression profile differs substantially from both stationary phase cells, and exponentially growing cells. Surprisingly, using an inhibitor for cell division, we discovered that these coccoid-like B. subtilis cells are not dormant but actually grow and divide, albeit with a doubling time of ~4 days. It emerged that secreted proteases, allowing acquisition of nutrients from lysed brethren, are essential for this growth mode. In fact, nutrient levels comparable to 10,000 times diluted LB (Lysogeny broth) appeared to be sufficient to sustain this growth. The very slow growth provides an alternative strategy for B. subtilis to survive nutrient depletion and environmental stresses. We propose to call this the oligotrophic growth state. This state might be common among bacterial species to survive deep starvation conditions.
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:Differential gene expression analysis of C. glutamicum C1 in presence of 3 mM indole-alanine dipeptide compared to control conditions without indole-alanine dipeptide. C. glutamicum C1 cells were cultivated in CGXII minimal medium with 40 g per litre glucose in presence or absence of 3 mM indole-alanine dipeptide and harvested during exponential phase (o.d.600 6).