Project description:In this work we evaluated the impact of nutritional unbalances, as lipids/nitrogen unbalances, on wine yeast survival during alcoholic fermentation. We showed that lipids limitations (actually ergosterol limitation) lead to a rapid loss of viability during the stationary phase of fermentation but that cell death rate is strongly modulated by the amount of nitrogen sources. Yeast survival is reduced when an excess of nitrogen is available in lipid-limited fermentations. Such rapid dying yeast cells fermenting with high nitrogen level and lipids-limited amounts displayed a low storage of carbohydrate trehalose and glycogen compared to nitrogen limited cells. Consistently, examination of the cells stress response using an HSP12 promoter-driven GFP expression showed that lipids limitation triggered a weaker stress response than nitrogen limitation. We examined the involvement of nitrogen signalling pathway in the triggering of cell death using a sch9-deleted strain. We showed that deletion of SCH9 restored a high yeast viability indicating that the signaling pathway acting through Sch9p is involved in the enhanced cell death triggered by nitrogen excess. In addition we showed that various nitrogen sources provoked cell death but that histidine and proline did not trigger a similar effect. As a whole our data indicate that lipids limitation does not elicit a transcriptional program leading to a stress response which protects yeast cells and that nitrogen excess triggers cell death through a modulation of this stress response, but not by HSP12. These results point a potential negative role of nitrogen in fermentation which has until now never been described and taken into account in the management of alcoholic fermentations. 2 conditions with 2 biological replicates compared: 59A and 59A-Sch9
Project description:In this work we evaluated the impact of nutritional unbalances, as lipids/nitrogen unbalances, on wine yeast survival during alcoholic fermentation. We showed that lipids limitations (actually ergosterol limitation) lead to a rapid loss of viability during the stationary phase of fermentation but that cell death rate is strongly modulated by the amount of nitrogen sources. Yeast survival is reduced when an excess of nitrogen is available in lipid-limited fermentations. Such rapid dying yeast cells fermenting with high nitrogen level and lipids-limited amounts displayed a low storage of carbohydrate trehalose and glycogen compared to nitrogen limited cells. Consistently, examination of the cells stress response using an HSP12 promoter-driven GFP expression showed that lipids limitation triggered a weaker stress response than nitrogen limitation. We examined the involvement of nitrogen signalling pathway in the triggering of cell death using a sch9-deleted strain. We showed that deletion of SCH9 restored a high yeast viability indicating that the signaling pathway acting through Sch9p is involved in the enhanced cell death triggered by nitrogen excess. In addition we showed that various nitrogen sources provoked cell death but that histidine and proline did not trigger a similar effect. As a whole our data indicate that lipids limitation does not elicit a transcriptional program leading to a stress response which protects yeast cells and that nitrogen excess triggers cell death through a modulation of this stress response, but not by HSP12. These results point a potential negative role of nitrogen in fermentation which has until now never been described and taken into account in the management of alcoholic fermentations.
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:Gene expression analysis of time course experiment of [1] a synthetic must (nitrogen-rich) fermentation by a natural wine yeast; [2] a synthetic must (nitrogen-poor) fermentation by a natural wine yeast; and [3] a synthetic must (nitrogen-poor) fermentation by a natural wine yeast, supplemented at 72 hours with 200 mg/l of nitrogen. This SuperSeries is composed of the SubSeries listed below.
Project description:We performed here the transcriptomic profile of 44 segregants from a cross between S288c and 59A (a spore of EC1118 strain). The analysis was performed in wine fermentation condition in stationary phase during nitrogen starvation and in alcoholic stress. These data, associated with an individual genotyping by Affymetrix array allow us to highlight genetic variations involved in perturbation of regulatory network and fermentative behavior.
Project description:Gene expression analysis of time course experiment of [1] a synthetic must (nitrogen-rich) fermentation by a natural wine yeast; [2] a synthetic must (nitrogen-poor) fermentation by a natural wine yeast; and [3] a synthetic must (nitrogen-poor) fermentation by a natural wine yeast, supplemented at 72 hours with 200 mg/l of nitrogen. This SuperSeries is composed of the following subset Series: GSE5835: Normal Fermentation GSE5836: Sluggish Fermentation GSE5837: Recovered Fermentation Keywords: SuperSeries Refer to individual Series, and to genomic hybridization of the individual membranes used for normalizing single samples.
Project description:Transcriptomic analyses of fermenting yeast are increasingly being carried out under small scale simulated winemaking conditions. It is not known to what degree data generated from such experiments are a reflection of transcriptional processes in large-scale commercial fermentation tanks. In this experiment we set out to determine the effect of scale, or fermentation volume, on the transcriptional respone of wine yeast strains. Parallel fermentations were carried out in laboratory fermentation vials and commercial fermentation tanks using the same wine media and inoculated yeast strain. Comparative transcriptomic analyses were carried out at three time points during alcoholic fermentation.
Project description:Gene expression analysis of a time course experiment of a synthetic must (nitrogen-poor) fermentation by a natural wine yeast, supplemented at 72 hours with 200 mg/l of nitrogen Keywords: Time course
Project description:Gene expression analysis of a time course experiment of a synthetic must (nitrogen-rich) fermentation by a natural wine yeast. Keywords: Time course
Project description:Gene expression analysis of a time course experiment of a synthetic must (nitrogen-poor) fermentation by a natural wine yeast. Keywords: Time course