ABSTRACT: Different genetic responses to oenological conditions between a flocculent wine yeast and its FLO5 deleted strain: insights from the transcriptome
Project description:In wine fermentation, the blending of non-Saccharomyces yeast with Saccharomyces cerevisiae to improve the complexity of wine has become common practice, but data regarding the impact on yeast physiology and on genetic and metabolic regulation remain limited. Here we describe a transcriptomic analysis of single species and mixed species fermentations.
Project description:Oxygen additions play a critical role in winemaking. However, few studies have focused on how this oxygen affects yeast metabolism and physiology in wine making conditions. We performed microarrays to unveil the oxygen response in wine making conditions.
Project description:Effect of FLO8 or MSS11 deletion and -overexpression on yeast transcript profiles compared to wild type in laboratory yeast strains ?1278b and S288c. We used two laboratory yeast strains that behave different with regard to adhesion phenotypes. By comparing yeast deleted in either FLO8 or MSS11 to wild type, or yeast overexpressing these genes, in both genetic backgrounds, we investigate the role of Flo8p and Mss11p on yeast transcription. By using similar growth conditions to what we use for adhesion phenotype determination we aim to correlate transcription profile changes to yeast behaviour (phenotypes).
Project description:Oxygen additions play a critical role in winemaking. However, few studies have focused on how this oxygen affects yeast metabolism and physiology in wine making conditions. We performed microarrays to unveil the oxygen response in wine making conditions. We extracted RNA from nitrogen-limited chemostats, simulating wine making conditions, sparged with nitrogen and 1%, 5% and 20% oxygen-nitrogen mixtures to achieve different dissolved oxygen levels representative of those found during wine making. These correspond to 0, 0.8, 4 and 11 micromolar dissolved oxygen
Project description:We used genome-wide expression analyses to study the response of Saccharomyces cerevisiae to stress throughout a 15-day wine fermentation. Forty percent of the yeast genome significantly changed expression levels to mediate long-term adaptation to an environment in which ethanol is both a stressor and a carbon source. Within this set, we identify a group of 223 genes, designated as the Fermentation Stress Response (FSR), that are dramatically and permanently induced; FSR genes exhibited changes ranging from four-to eighty-fold. The FSR is novel; 62% of the genes involved have not been implicated in global stress responses and 28% of the genes have no functional annotation. Genes involved in respiratory metabolism and gluconeogenesis were expressed during fermentation despite the presence of high concentrations of glucose. Ethanol, rather than nutrient depletion, was responsible for entry of yeast cells into stationary phase. Ethanol seems to regulate yeast metabolism through hitherto undiscovered regulatory networks during wine fermentation. Keywords: time course, stress response, fermentation
