Project description:Sorbic acid (SA) is widely used as a preservative, but the effect of SA on spore germination and outgrowth has gained limited attention up to now. Therefore, the effect of sorbic acid on germination of spores of B. cereus strain ATCC 14579 was analyzed both at phenotype and transcriptome level. Spore germination and outgrowth was assessed at pH 5.5 without and with 0.75, 1.5 and 3.0mM (final concentrations) undissociated sorbic acid (HSA). This resulted in distinct HSA concentration-dependent phenotypes, varying from delays in germination and outgrowth to complete blockage of germination at 3.0mM HSA. The phenotypes reflecting different stages in the germination process could be confirmed using flow cytometry and could be recognized at transcriptome level by distinct expression profiles. In the absence and presence of 0.75 and 1.5mM HSA, similar cellular ATP levels were found up to the initial stage of outgrowth, suggesting that HSA-induced inhibition of outgrowth is not caused by depletion of ATP. Transcriptome analysis revealed the presence of a limited number of transcripts in dormant spores, outgrowth related expression, and genes specifically associated with sorbic acid stress, including alterations in cell envelope and multi-drug resistance. The potential role of these HSA-stress associated genes in spore outgrowth is discussed.
Project description:Sorbic acid (SA) is widely used as a preservative, but the effect of SA on spore germination and outgrowth has gained limited attention up to now. Therefore, the effect of sorbic acid on germination of spores of B. cereus strain ATCC 14579 was analyzed both at phenotype and transcriptome level. Spore germination and outgrowth was assessed at pH 5.5 without and with 0.75, 1.5 and 3.0mM (final concentrations) undissociated sorbic acid (HSA). This resulted in distinct HSA concentration-dependent phenotypes, varying from delays in germination and outgrowth to complete blockage of germination at 3.0mM HSA. The phenotypes reflecting different stages in the germination process could be confirmed using flow cytometry and could be recognized at transcriptome level by distinct expression profiles. In the absence and presence of 0.75 and 1.5mM HSA, similar cellular ATP levels were found up to the initial stage of outgrowth, suggesting that HSA-induced inhibition of outgrowth is not caused by depletion of ATP. Transcriptome analysis revealed the presence of a limited number of transcripts in dormant spores, outgrowth related expression, and genes specifically associated with sorbic acid stress, including alterations in cell envelope and multi-drug resistance. The potential role of these HSA-stress associated genes in spore outgrowth is discussed. Per concentration of undissociated sorbic acid (0, 0.75, and 1.5mM) four exposure times (10, 30, 60, and 120 minutes) were each compared with dormant spores (i.e., t0). The experiments were performed in duplicate and the duplicate samples were hybridized with a dye-swap
Project description:This SuperSeries is composed of the following subset Series: GSE13711: Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strain ATCC 14579 GSE13729: Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strain ATCC 10987 Refer to individual Series
Project description:The stress response of B. cereus ATCC 14579 is monitored true time, showing an enormous response in gene expression. Keywords: Stress response, comparative transcriptome analysis.
Project description:The Bacillus cereus ATCC 14579 alternative σ factor σZ and its putative regulon have been characterized. σZ shows overall similarity with ECF σ factors and sigZ constitutes an operon together with asfZ encoding its putative anti-σ factor. Expression analysis revealed sigZ to be induced by an array of stresses, including exposure to ethanol, alkaline pH and heat shock, and a typical promoter binding site for the sigZ-operon was identified by 5’RACE. Phenotypic characterization of B. cereus ATCC 14579 and its sigZ-deletion strain revealed diminished growth performance and sporulation capacity. The σZ-regulon was successfully established by transcriptome analysis of a nisin inducible sigZ-overexpression strain. Overexpression of sigZ was shown to affect expression of 42 genes, including 33 genes encoding proteins located in the extracytoplasm. The identified σZ regulon contained genes encoding proteins situated in the extracytoplasm involved in cell surface modifications and transport. The regulation of genes encoding cell surface modification proteins implies σZ to be involved in the regulation of interaction of B. cereus ATCC 14579 with its environments, which includes human intestinal cells, possibly influencing its virulence status. Keywords: Comparative transcriptome study
Project description:Planktonic and biofilm cells of Bacillus cereus ATCC 14579 and ATCC 10987 were studied using microscopy and transcriptome analysis. By microscopy, clear differences could be observed between biofilm and planktonic cells as well as between the two strains. By using hierarchical clustering of the transcriptome data, little difference was observed between the biofilm cells of B. cereus ATCC 14579 and ATCC 10987. Different responses between biofilm and planktonic cells could be identified using transcriptome analysis. Biofilm formation seemed to cause a shift in metabolism with up- or down-regulation of genes involved in different metabolic pathways. Genes involved in motility were down-regulated. No clear up-regulation related to capsular or extracellular polysaccharides was observed. Sporulation was observed in biofilm cells using microscopy, which was corroborated with up-regulation of genes involved in sporulation in biofilm cells. The results obtained in this study provide insight in general and strain specific behavior of B. cereus cells in multicellular communities.
Project description:The stress response of B. cereus ATCC 14579 is monitored true time, showing an enormous response in gene expression. The wild-type strain of B. cereus ATCC 14579 was cultured to an OD600 of ~0.6. Here the first RNA sample was taken, 0 min. After sampling 4% of ethanol was added (v/v), and samples were taken after 10, 30 and 60 minutes of exposure. Comparisons performed were 0 min - 10 min, 0 min - 30 min, and 0 min - 60 min.
Project description:Heat-treated spores show delayed and slower germination and outgrowth compared to untreated spores presumably due to spore damage repair. This study was performed to identify genes possibly involved in spore damage repair in B. cereus. In this study we compared the transcriptomic profiles of untreated and heat-treated spores during germination and outgrowth in BHI at 30C.
Project description:Here, the role of σM and its regulon in stress response and survival of B. cereus ATCC 14579 was assessed by comparative transciptome and phenotypic analysis of this strain and its sigM deletion strain. Exposure of B. cereus ATCC 14579 to a wide range of stresses revealed expression of sigM, encoding σM, to be up-regulated mainly in the presence of ethanol and after alkaline pH-shock. Next to this, disc diffusion tests showed the sigM deletion strain to be more sensitive to oxidizing agents and to be more resistant to cell-wall targeting antibiotics than the wild-type strain. The σM regulon was subsequently determined by comparative transcriptional analyses of the wild-type and its sigM-deletion strain after exposure to ethanol. The putative σM-regulon was shown to consist of 29 genes, several of these genes are predicted to be involved in counteracting oxidative stress, such as an NADH oxidase, a ferredoxin, and a lysine decarboxylase or could encode enzymes involved in methionine metabolism, leading toward L-cysteine production, including luxS. Screening of promoter upstream regions allowed for the assessment of a B. cereus consensus promoter binding site for σM. Since the consensus promoter binding site for B. cereus ATCC 14579 σM, its regulon and the predicted functionalities are different from the corresponding features in B. subtilis, it can be concluded that σM plays a unique role in B. cereus stress response and survival. Keywords: Stress response, comparative transcriptome study