Changes in the composition and peroxidation of yeast membrane lipids during ethanol stress.

Lipid peroxidation in Saccharomyces cerevisiae cells increased with ethanol treatment of the cells. Such cells have decreased amount of total lipid, phospholipid and free sterols. Sterol:phospholipid ratio decreased slightly in the cells treated with 4% ethanol. However, this ratio significantly increased with further rise in ethanol concentration to 12%. Relative content of glycolipids (glycolipid to phospholipid ratio) increased in ethanol-treated yeast cells. Diphosphatidylglycerol content increased significantly and phosphatidylcholine to phosphatidylethanolamine ratio decreased in ethanol-treated cells. The amount of alpha-tocopherol decreased during ethanol stress. Catalase failed to counter the effect of ethanol. The results from the present study indicated that ethanol might be interfering with the antioxidant defence mechanisms of the yeast cells.