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:Saccharomyces cerevisiae’s requirement of reduced sulfur to synthesise methionine and cysteine during alcoholic fermentation, is mainly fulfilled through the sulfur assimilation pathway. S. cerevisiae reduces sulfate into sulfur dioxide (SO2) and sulfide (H2S), whose overproduction is a major issue in winemaking, due to its negative impact on wine aroma. The amount of H2S produced is highly strain-specific and depends as well on the SO2 concentration, often added to the grape must. Applying a Bulk Segregant Analysis to a 96 strain-progeny derived from two strains with different ability to produce H2S, and comparing the allelic frequencies along the genome of pools of segregants producing opposite H2S quantities, we identified two causative regions involved in H2S production in the presence of SO2. A functional genetic analysis allowed the identification of variants in four genes: ZWF1, ZRT2, SNR2 and YLR125W, able to impact H2S formation, involved in functions and pathways until now not associated with sulfur metabolism. This data points that redox status and zinc homeostasis are linked to H2S formation in wine fermentation conditions and provides new insights into the regulation of H2S production during wine fermentation, giving a new vision of the interplay between the sulfur assimilation pathway and cell metabolism. This archive contains the transcriptome data of the result of allelic swp for three genes : ZWF1, ZRT2, YLR125w under fermentation.
Project description:The yeast Dekkera bruxellensis is as ethanol tolerant as Saccharomyces cerevisiae and may be found in bottled wine. It causes the spoilage of wine, beer, cider and soft drinks. In wines, the metabolic products responsible for spoilage by Dekkera bruxellensis are mainly volatile phenols. These chemical compounds are responsible for the taints described as ‘‘medicinal’’ in white wines (due to vinyl phenols) and as ‘‘leather’’, ‘‘horse sweat’’ and ‘‘stable’’ in red wines (due to ethyl phenols mainly 4-ethylphenol). Apart from the negative aroma nuances imparted by these yeasts, positive aromas such as ‘smoky’, ‘spicy’ and ‘toffee’ are also cited. Our goal was to identify the impact that the wine spoilage yeast Dekkera bruxellensis has on fermenting S. cerevisiae cells, especially on its gene expression level. To this end we co-inoculated both yeast species at the start of fermentation in a synthetic wine must, using S. cerevisiae-only fermentations without Dekkera bruxellensis as a control. All fermentations were employed in special membrane reactors (1.2 um pore size cut-off) physically separating Dekkera bruxellensis from wine yeast S. cerevisiae. Biomass separation with this membrane was done to abolish the possibility of hybridizing also D. bruxellensis probes on Agilent V2 (8x15K format) G4813 DNA microarrays designed just for S. cerevisiae ORF targets. The 1.2 um pore membrane separating both yeasts allowed the exchange of ethanol, metabolites and sugars during the fermentation.
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
Project description:In our previous work, we showed the positive effect of the magnesium and the negative effect of the copper on yeast fermentation performance. The magnesium increases the ethanol yield and a faster glucose consumption by the yeast, on the other hand, the copper provides an opposite effect in yeast under fermentation condition. Therefore, from this contrasting effect we performed the gene-wide expression analysis in the industrial yeast Saccharomyces cerevisiae JP1 under fermentation condition in order to reveal the gene expression profile upon magnesium and copper supplementation.
Project description:The yeast Dekkera bruxellensis is as ethanol tolerant as Saccharomyces cerevisiae and may be found in bottled wine. It causes the spoilage of wine, beer, cider and soft drinks. In wines, the metabolic products responsible for spoilage by Dekkera bruxellensis are mainly volatile phenols. These chemical compounds are responsible for the taints described as M-bM-^@M-^XM-bM-^@M-^XmedicinalM-bM-^@M-^YM-bM-^@M-^Y in white wines (due to vinyl phenols) and as M-bM-^@M-^XM-bM-^@M-^XleatherM-bM-^@M-^YM-bM-^@M-^Y, M-bM-^@M-^XM-bM-^@M-^Xhorse sweatM-bM-^@M-^YM-bM-^@M-^Y and M-bM-^@M-^XM-bM-^@M-^XstableM-bM-^@M-^YM-bM-^@M-^Y in red wines (due to ethyl phenols mainly 4-ethylphenol). Apart from the negative aroma nuances imparted by these yeasts, positive aromas such as M-bM-^@M-^XsmokyM-bM-^@M-^Y, M-bM-^@M-^XspicyM-bM-^@M-^Y and M-bM-^@M-^XtoffeeM-bM-^@M-^Y are also cited. Our goal was to identify the impact that the wine spoilage yeast Dekkera bruxellensis has on fermenting S. cerevisiae cells, especially on its gene expression level. To this end we co-inoculated both yeast species at the start of fermentation in a synthetic wine must, using S. cerevisiae-only fermentations without Dekkera bruxellensis as a control. All fermentations were employed in special membrane reactors (50 KDa pore size cut-off) physically separating Dekkera bruxellensis from wine yeast S. cerevisiae. Biomass separation with this membrane was done to abolish the possibility of hybridizing also D. bruxellensis probes on Agilent V2 (8x15K format) G4813 DNA microarrays designed just for S. cerevisiae ORF targets. The 50 KDa pore membrane separating both yeasts allowed the exchange of ethanol, metabolites and sugars during the fermentation. Fermentations were carried out in synthetic wine must in duplicate for both the control S. cerevisiae (strain Lalvin EC1118) and mixed fermentation. Sampling of yeast S. cerevisiae for RNA extractions were performed at 22 h of fermentation, during the exponential growth phase of S. cerevisiae, at 92 h and 144 h of fermentation, during its early and late stationary growth phase and at 187 h of fermentation, during its phase of growth decline.
Project description:Natural grape-juice fermentations involve the sequential development of different yeast species which strongly influence the chemical and sensorial traits of the final product. In the present study,we aimed to examine the transcriptomic response of Saccharomyces cerevisiae to the presence of Hanseniaspora guilliermondii wine fermentation.
Project description:In order to asses yeast EC1118® strain expression changes during wine alcoholic fermentation triggered by various nutrient starvations, this experiment describes the gene expression under micronutrient starvations that lead to yeast cell death (oleic acid starvation, ergosterol starvation, pantothenic acid starvation and nicotinic starvation) or allow the maintenance of yeast viability (nitrogen starvation).
Project description:During fermentation Saccharomyces yeast produces various aroma-active metabolites determining the different characteristics of aroma and taste in fermented beverages. Amino acid utilization by yeast during brewer´s wort fermentation is seen as linked to flavour profile. To better understand the relationship between the biosynthesis of aroma relevant metabolites and the importance of amino acids, DNA microarrays were performed for Saccharomyces cerevisiae strain S81 and Saccharomyces pastorianus var. carlsbergensis strain S23, respectively. Thereby, changes in transcription of genes were measured, which are associated with amino acid assimilation and its derived aroma-active compounds during fermentation.