Malo‐ethanolic fermentation in grape must by recombinant strains of Saccharomyces cerevisiae

Abstract Recombinant strains of Saccharomyces cerevisiae with the ability to reduce wine acidity could have a significant influence on the future production of quality wines, especially in cool climate regions. L ‐Malic acid and L ‐tartaric acid contribute largely to the acid content of grapes and wine. The wine yeast S. cerevisiae is unable to effectively degrade L ‐malic acid, whereas the fission yeast Schizosaccharomyces pombe efficiently degrades high concentrations of L ‐malic acid by means of a malo‐ethanolic fermentation. However, strains of Sz. pombe are not suitable for vinification due to the production of undesirable off‐flavours. Heterologous expression of the Sz. pombe malate permease ( mae1 ) and malic enzyme ( mae2 ) genes on plasmids in S. cerevisiae resulted in a recombinant strain of S. cerevisiae that efficiently degraded up to 8 g/l L ‐malic acid in synthetic grape must and 6.75 g/l L ‐malic acid in Chardonnay grape must. Furthermore, a strain of S. cerevisiae containing the mae1 and mae2 genes integrated in the genome efficiently degraded 5 g/l of L ‐malic acid in synthetic and Chenin Blanc grape musts. Furthermore, the malo‐alcoholic strains produced higher levels of ethanol during fermentation, which is important for the production of distilled beverages. Copyright © 2001 John Wiley & Sons, Ltd.