细胞膜磷脂棕榈酸含量对自絮凝颗粒酵母耐酒精能力的影响及作用机制

Influence of Phospholipid Fatty Acid Composition of Plasma Membrane of a Self-flocculating Yeast on its Tolerance to Ethanol and the Mechanism

研究揭示细胞膜磷脂脂肪酸组成与酵母菌耐酒精能力的一种新颖关系及其机制。分别培养于添加 0 6mmol L棕榈酸、亚油酸或亚麻酸不同条件下的自絮凝颗粒酵母 ,其细胞膜富含各自所添加的脂肪酸。细胞膜富含棕榈酸、亚油酸或亚麻酸的三种菌体于 30℃经 2 0 %(v v)酒精冲击 6h的存活率分别为 5 2 %、1 8%和 0。通过考察三种菌体于 30℃在 1 5 %(v v)酒精冲击下的细胞膜透性发现 ,细胞膜富含棕榈酸的菌体的胞外核苷酸平衡浓度分别仅为细胞膜富含亚油酸或亚麻酸菌体的 48%和 32 %,其细胞膜透性系数 (P′)分别仅为后者的 37%和 2 0 %,且三者的胞外核苷酸浓度和P′由小到大的排列顺序均与它们的存活率由高到低的排列顺序完全一致。因此 。

A novel relationship between phospholipid fatty acid composition of plasma membrane and yeast ethanol tolerance, and its mechanism are revealed in this work. When grown with exogenously supplemented fatty acid (0 6 mmol/L), such as palmitic, linoleic or linolenic acid, cells of a self flocculating fusant of Schizosaccharomyces pombe and Saccharomyces cerevisiae were enriched in the kind of added fatty acid in the plasma membranes. After 6 h of exposure to 20% (v/v) ethanol at 30℃, 52%, 18% and 0% of viability levels remained for palmitic, linoleic and linolenic acid enriched cells respectively. When subjected to 15% (v/v) ethanol at 30℃, the equilibrium nucleotide concentration of palmitic acid enriched cells accounted for only 48% and 32% that of linoleic or linolenic acid enriched cells respectively, with its plasma membrane permeability coefficient ( P ′) being only 37% and 20% that of linoleic or linolenic acid enriched cells respectively. Furthermore, both extracellular nucleotide concentration and ( P ′) were lowest in the order of palmitic, linoleic and linolenic acid enriched cells, precisely corresponding to the ranked order of their ethanol tolerances from the highest to the lowest. Thus, the increased ethanol tolerance of palmitic acid enriched cells is closely associated with its ability to maintain a lower plasma membrane permeability when cells are exposed to high concentration of ethanol. ;