多不饱和脂肪酸与红冬孢酵母低温适应性的关系研究

以一株产油酵母——红冬孢酵母(Rhodosporidium kratochvilovae)YM25235作为出发菌株,分析其低温生长适应性与细胞膜流动性、膜脂脂肪酸含量的变化和多不饱和脂肪酸合成关键基因——Δ12-脂肪酸脱氢酶基因mRNA表达水平的关系.结果显示,YM25235在5～35 ℃温度条件下均能生长,最适生长温度为30 ℃.低温条件下细胞膜流动性明显降低,但是多不饱和脂肪酸质量分数由从30 ℃时的24.35%增加到15 ℃时的40.32%,而且15 ℃时Δ12-脂肪酸脱氢酶基因mRNA水平提高了3.4倍.结果说明低温条件下细胞膜流动性下降,导致多不饱和脂肪酸合成相关基因表达水平提高,使得细胞膜脂中多不饱和脂肪酸含量增加,促进了菌株低温生长适应性.

Correlation of polyunsaturated fatty acids and the cold adaptation of Rhodosporidium kratochvilovae

The ability of certain yeasts to accumulate high amounts of lipids has been known for years,but only in the last decades,real efforts have been made to unravel the underlying biochemical pathways.In this study,an oleaginous yeast strain Rhodosporidium kratochvilovae YM25235 was used to analyze the correlation between its cold adaptation and membrane fluidity,changes in the content of polyunsaturated fatty acids and mRNA expression level of Δ12-desaturase gene.The results showed that YM25235 could grow at 5—35 ℃,with the optimum temperature of 30 ℃.The membrane fluidity of YM25235 cells was significantly reduced when the culture temperature decreased,but the content of polyunsaturated fatty acids (Linoleic acid and α-Linolenic acid) was increased significantly from 24.35% to 40.32%,and the mRNA abundance of Δ12-desaturase gene was 3.4-fold higher in cells grown at 15 ℃ than in cells grown at 30 ℃.These results indicated that reduced membrane fluidity at low temperature induced genes expression of polyunsaturated fatty acids biosynthesis,which caused higher content of polyunsaturated fatty acids accumulating in cells and enhanced the cold adaptation.