Volschenk H, Viljoen-Bloom M, Subden R E, van Vuuren H J
Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa.
Yeast. 2001 Jul;18(10):963-70. doi: 10.1002/yea.743.
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.
具有降低葡萄酒酸度能力的酿酒酵母重组菌株可能会对未来优质葡萄酒的生产产生重大影响，尤其是在凉爽气候地区。L-苹果酸和L-酒石酸在很大程度上构成了葡萄和葡萄酒的酸含量。酿酒酵母无法有效降解L-苹果酸，而裂殖酵母粟酒裂殖酵母则通过苹果酸-乙醇发酵有效地降解高浓度的L-苹果酸。然而，由于会产生不良异味，粟酒裂殖酵母菌株不适合用于酿酒。在酿酒酵母中通过质粒对粟酒裂殖酵母苹果酸通透酶（mae1）和苹果酸酶（mae2）基因进行异源表达，得到了一种酿酒酵母重组菌株，该菌株在合成葡萄汁中能有效降解高达8 g/L的L-苹果酸，在霞多丽葡萄汁中能有效降解6.75 g/L的L-苹果酸。此外，一种基因组中整合了mae1和mae2基因的酿酒酵母菌株在合成葡萄汁和白诗南葡萄汁中能有效降解5 g/L的L-苹果酸。此外，苹果酸-酒精发酵菌株在发酵过程中产生的乙醇含量更高，这对蒸馏酒的生产很重要。
