Abstract
Glutathione (GSH) is an antioxidant molecule of great technological interest due to its wide range of applications in the food and beverage industry. In winemaking, although glutathione is produced during fermentation, its addition is possible for the control of oxidative spoilage of wine. Recently, to improve wine quality, mixed fermentation has been proposed by introducing a selection of non-Saccharomyces yeasts as complementary starters to the oenological species S. cerevisiae. Among them, Starmerella bacillaris, an osmophilic and high glycerol producer yeast, has been extensively studied. In the present study, the genomes of two S. bacillaris strains were compared with S. cerevisiae to identify the GSH metabolic pathway. The results showed that GSH biosynthesis includes the GSH1 and GSH2 genes in both species. The identification of a new transcription factor which binds sites in the promoter region of these genes underlined differences in the transcriptional regulation of both species. Additionally, between S. bacillaris strains, a high number of polymorphisms was found in genes involved in GSH redox balance. Preliminary laboratory scale fermentations revealed marked differences in the cell glutathione content of the two S. bacillaris strains. By comparing genomes, it was possible to gain a better understanding of the genes involved in the GSH metabolism pathway in S. bacillaris.
Highlights
IntroductionSugars present in grape must are transformed into ethanol
During alcoholic fermentation, sugars present in grape must are transformed into ethanol
Comparison of the genes involved in the GSH metabolism pathway in S. bacillaris strains and S. cerevisiae
Summary
Sugars present in grape must are transformed into ethanol. When used as a starter culture in sequential fermentation with S. cerevisiae strains, this yeast contributes to decreasing ethanol levels and increasing glycerol content while maintaining moderate volatile acid production (Jolly et al, 2014; Bely et al, 2013). This novel non-conventional wine yeast showed biocontrol activity against the fungal pathogens Botrytis cinerea and Penicillium expansum (Lemos Junior et al, 2016; Nadai et al, 2018)
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