Global analysis of gene expression of the wine yeast EC1118 during rehydration and following inoculation.
Bruno Blondin, Tristan Rossignol, Julien Storai, Olivier Postaire
Microbiology, INRA - Agro.M, 1, place Viala, Montpellier, 34060, France
The transcriptome of the wine yeast EC1118 was monitored before and after rehydration and in the first hours after inoculation in a synthetic must. We show that strong transcriptional remodeling occurs during this period which affected 1918 genes more than 3-fold regulated. Dried yeasts displayed an expression profile typical of respiratory-grown cells which had been starved for nitrogen and carbon and which had been highly stressed. During rehydration many genes involved biosynthetic pathways, in transcription or in protein synthesis were coordinately induced while genes submitted to glucose repression and genes involved in stress response were down-regulated. The transcriptional response was very rapid indicating that yeast recovered quickly the capacity to sense environmental signals and to respond properly. Most of the transcriptional responses in relation with a nutrient up-shift continued after inoculation. Surprisingly, inoculation into the must did not trigger a stress response despite that a high level of sugars in the medium. During rehydration yeast exhibited a specific acid stress which disappeared after inoculation. The glycolytic genes were found transiently repressed after inoculation in the fermentation medium simultaneously with acid stress-responsive genes suggesting that glycolytic genes regulation may correspond to an adjustment to cells energetic needs.