Evolved Saccharomyces cerevisiae wine strains with enhanced glutathione production obtained by an evolution-based strategy

In winemaking, the application of glutathione (GSH) has been the subject of ever-growing interest because of its important role in limiting must and wine oxidation and in protecting various aromatic compounds. Glutathione concen- tration in wine is highly variable, involving as it does several factors from must, through alcoholic fermentation, to yeast strain activity. Consequently, the development of new wine yeast strains able to improve flavor stability is in great demand. To generate evolved Saccharomyces cerevisiae strains with enhanced GSH production, we have applied an evolution-based strategy that combines the sexual recombination of spores with the application of molyb- date, which is toxic for the cells at high concentration, as specific selective pres- sure. Eight molybdate-resistant strains were selected and further screened for GSH production in synthetic grape must and in microvinification assay. By this nongenetically modified strategy, we obtained two evolved strains, Mo21T2-5 and Mo21T2-12, both able to enhance GSH content in wine with an increase of 100% and 36%, respectively, compared with the parental strain 21T2, and 120% and 50% compared with initial GSH content in the must. Introduction