Analysis of the stress resistance of commercial wine yeast strains.

Alcoholic fermentation is an essential step in wine production that is usually conducted by yeasts belonging to the species Saccharomyces cerevisiae. The ability to carry out vinification is largely influenced by the response of yeast cells to the stress conditions that affect them during this process. In this work, we present a systematic analysis of the resistance of 14 commercial S. cerevisiae wine yeast strains to heat shock, ethanol, oxidative, osmotic and glucose starvation stresses. Significant differences were found between these yeast strains under certain severe conditions, Vitilevure Pris Mouse and Lalvin T73 being the most resistant strains, while Fermiblanc arom SM102 and UCLM S235 were the most sensitive ones. Induction of the expression of the HSP12 and HSP104 genes was analyzed. These genes are reported to be involved in the tolerance to several stress conditions in laboratory yeast strains. Our results indicate that each commercial strain shows a unique pattern of gene expression, and no clear correlation between the induction levels of either gene and stress resistance under the conditions tested was found. However, the increase in mRNA levels in both genes under heat shock indicates that the molecular mechanisms involved in the regulation of their expression by stress function in all of the strains.