title: 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.
authors.affiliation: Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa.
authors.forename: H
authors.initials: H
authors.lastname: Volschenk
authors.forename: M
authors.initials: M
authors.lastname: Viljoen-Bloom
authors.forename: R E
authors.initials: RE
authors.lastname: Subden
authors.forename: H J
authors.initials: HJ
authors.lastname: van Vuuren
mesh_terms: D001426:Bacterial Proteins; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000235:genetics*; D005818:Genetic Engineering; D007218:Industrial Microbiology / Q000379:methods*; D008291:Malate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D008293:Malates / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D027361:Organic Anion Transporters; D011994:Recombinant Proteins / Q000378:metabolism; D019685:Rosales / Q000382:microbiology; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D012568:Schizosaccharomyces / Q000201:enzymology / Q000235:genetics; D014920:Wine / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D008293:Malates; D026901:Membrane Transport Proteins; D027361:Organic Anion Transporters; D011994:Recombinant Proteins; C098940:malate permease protein, Bacteria; D000431:Ethanol; C030298:malic acid; D008291:Malate Dehydrogenase