乙醇胁迫处理对酒酒球菌SD-2a生理特性的影响

为制备高效的葡萄酒乳酸菌发酵剂,以酒酒球菌SD-2a为试验材料,研究了5%、10%不同浓度的乙醇胁迫处理对菌体生长、细胞内MLE活性、冻干存活率及细胞膜脂肪酸组分的影响。试验结果表明乙醇胁迫处理明显降低了菌体的生长速率和生物产量。与对照相比,5%乙醇胁迫处理降低了菌体的冻干存活率,而10%乙醇处理却显著增加了菌体的冻干存活率。细胞膜脂肪酸组分的测定结果表明,前者细胞膜U/S比值为1.12,比对照降低了26.3%,而后者细胞膜U/S比值为2.29,比对照增加了50.6%。故认为酒酒球菌SD-2a为适应不同浓度的乙醇胁迫环境,在细胞膜脂肪酸水平上所采用的机制不同,且菌体的冻干存活率与其细胞膜脂肪酸组分密切相关。

The effects of alcohol stress treatment on physiological properties of Oenococcus oeni SD-2a

To obtain high efficiency of MLF starter cultures, the effects of alcohol stress treatments on the growth, intracellular malolactic enzyme (MLE) activity, freeze-drying viability, and membrane fatty acid composition of Oenococcus oeni SD-2a strain were studied. The results showed that alcohol stress treatments did strongly decrease bacterial growth rate and cell biomass, but increased distinctly MLE activity. Compared with control treatment, 5% alcohol stress treatment decreased bacterial freeze-drying viability, and 10% alcohol stress treatment increased bacterial freeze-drying viability. Concerning the membrane fatty acid composition, it was observed that the unsaturated : saturated fatty acid ratio in the former treatment is 1.12, which is lower than that of control by 26.3%, and the unsatu-rated : saturated fatty acid ratio in the latter treatment is 2.28, which is higher than that of control by 50.6%. So it was assumed that O. oeni SD-2a adopted different adaptive mechanisms in the membrane levels under different alcohol stress conditions, and its membrane fatty acid composition might have a close relationship with bacterial freeze-drying viability.