Unknown,Transcriptomics,Genomics,Proteomics

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Time-resolved heat stress response of Saccharomyces cerevisiae

ABSTRACT: Whole-genome transcriptional response of S. cerevisiae to an increase in temperature from 28M-BM-0C to 41M-BM-0C under well-controlled conditions. Two subsequent phases of response with very different dynamics: a short term response for the first hour after the temperature increase and a long term one for up to six hours. The initial response was strongest with almost half of the ORFs being induced or repressed to a statistically significant level (here 1.5 fold). The data was grouped based on the function of the encoded proteins. Analysis showed that the cells overexpressed genes involved in energy conservation processes. Genes encoding molecular chaperones were overexpressed as well, presumably to counteract the effect of the temperature increase on protein denaturation. Furthermore, genes encoding parts of the translation and transcription systems were repressed temporarily, in line with the observed lag in growth. More detailed analysis of certain small groups of genes involved in energy metabolism supported the notion that, although the expression level of genes represent a part of the stress response, they cannot be directly linked to the level of activity of their products. Samples were taken from three replicate control cultures at 28M-BM-0C at three timepoints and from three replicate stressed cultures at six timepoints

ORGANISM(S): Saccharomyces cerevisiae

SUBMITTER: Femke Mensonides

PROVIDER: E-GEOD-25503 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:A koji mold Aspergillus kawachii is used for making a Japanese distilled spirit, shochu. During making shochu, A. kawachii is grown in a solid-state culture comprised of steamed grains such as rice or barley, termed koji, to convert the starch to glucose and also to produce citric acid. During this process, cultivation temperature of A. kawachii is generally controlled by raising to 40M-BM-0C and then lowering to 30M-BM-0C. The cultivation at 40M-BM-0C and the following at lower temperature of 30M-BM-0C has important roles in the elevated activity of amylase and starting an accumulation of a large amount of citric acid, respectively. In this study, we investigated the effect of temperature on the gene expression of A. kawachii when barley was used as ingredient for making koji. The results of DNA microarray and gene ontology analysis showed that the expression of genes involved in the metabolic processes of glycerol, trehalose, and pentose phosphate that branch from glycolysis was down-regulated by shifting the cultivation temperature from 40M-BM-0C from 30M-BM-0C. In addition, reduction in the expression of the genes related with heat shock responses and increasing in the expression of the genes related with amino acid transport after the temperature lowering were found to be significant change. These results suggested that the cultivation at 40M-BM-0C is stressful event for the A. kawachii and the heat adaption lead to the depression of citric acid accumulation through activation of the branching pathways from glycolysis. The gene expression profile obtained in this study will help to understand the gene regulation during koji-making process to optimize A. kawachii as industrial microorganism. Gene expression of Aspergillus kawachii in barley koji was measured at 25, 26.5, and 44 hours at two different temperature control. Three independent experiments were performed at each time (25, 26.5, or 44 hours) using different barley koji for each expreriment.

Project description:Profound understanding of the mechanisms foodborne pathogenic bacteria utilize in adaptation to the environmental stress they encounter during food processing and storage is of paramount importance in design of control measures. Chill temperature is a central control measure applied in minimally processed foods; however, data on the mechanisms the foodborne pathogen Clostridium botulinum activates upon cold stress are scarce. Global gene expression analysis on the C.M-BM- botulinum ATCC 3502 strain upon temperature downshift from 37 M-BM-0C to 15M-BM- M-BM-0C was performed to identify the cold-responsive gene set of this organism. Significant up- or down-regulation of 16 and 11 genes, respectively, was observed already 1 h after the cold shock. At 5 h after the temperature downshift, 199 and 210 genes were up- and down-regulated, respectively. Thus, the cold shock rapidly affected the expression of a gene set of a relatively small size, indicating a targeted acute response to cold shock, whereas extensive metabolic remodeling took place after prolonged exposure to cold. Induction of genes related to fatty acid biosynthesis, oxidative stress response, and iron uptake and storage was observed, in addition to mechanisms previously characterized as cold-tolerance related in bacteria. Furthermore, induction of several uncharacterized DNA-binding transcriptional regulator-encoding genes was observed, suggesting involvement of novel regulatory mechanisms in the cold shock response of C.M-BM- botulinum. The role of such regulatory proteins, CBO0477 and CBO0558A, in cold tolerance of C.M-BM- botulinum ATCC 3502 was demonstrated by the deteriorated growth of mutants of the respective genes at 17M-BM- M-BM-0C. C. botulinum ATCC 3502 wild type cold-shocked vs. pre-cold-shock; 3 replicates; growth at 37C in TPGY broth batch culture and subjected to cold shock to 15C; sampling at mid-log growth phase before cold shock, and 1 h and 5 h after temperature downshift to 15C (= 3 time points). Dye-swapped hybridization.

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Time-resolved heat stress response of Saccharomyces cerevisiae

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