The transcriptome of a wine yeast was monitored throughout an alcoholic fermentation under conditions mimicking an enological environment. Major changes in gene expression occurred during fermentation, affecting more than 2000 genes, as the yeast adapted to changing nutritional, environmental and physiological conditions. The genes of many pathways are regulated in a highly coordinated manner, and genes involved in the key metabolic pathways of fermentation are strongly expressed. We showed that, during fermentation of a synthetic medium mimicking a natural must in which growth arrest was caused by nitrogen exhaustion, entry into the stationary phase triggered major transcriptional reprogramming. Many TOR target genes involved in nitrogen utilization or other functions are induced at this stage, suggesting that this signalling pathway plays a critical role in changes in gene expression in response to nitrogen depletion. Entry into stationary phase is a key physiological event and is followed by a general stress response. The superimposition of multiple stresses, including starvation and ethanol stress, gives rise to a unique stress response, involving hundreds of genes encoding proteins involved in various cellular processes, many of unknown function.
Copyright 2003 John Wiley & Sons, Ltd.