中文摘要：

研究了6种金属离子在合成培养基中对摇瓶培养的自絮凝酵母乙醇耐性的影响,发现锌离子对高浓度乙醇冲击下的酵母细胞活性有保护作用,并进一步研究了乙醇连续发酵过程中锌的添加对自絮凝酵母乙醇耐性的影响。发酵培养基中分别添加0.01、0.05和0.1g·L^-1的硫酸锌时,自絮凝酵母颗粒平均粒度减小,同时乙醇耐性和高温耐性都得到明显提高,并且发现细胞活性的提高与酵母细胞内麦角固醇和海藻糖的增加密切相关。对酵母细胞内锌的含量的分析表明,3个添加组胞内锌的积累量基本相似,比对照组均增加了6倍。相关性分析表明,酵母胞内锌含量与酵母细胞的胁迫耐性密切相关并显著影响其胁迫耐性。各添加组的乙醇产量均有提高,其中添加0.05g·L^-1的硫酸锌时乙醇产量最高,比对照组高8.4%。以上研究结果表明,调控连续乙醇发酵过程中培养基中锌离子浓度,是提高酵母细胞乙醇耐受性、高温度耐受性和乙醇产量的有效途径。

英文摘要：

The effects of metal ions on ethanol tolerance of self-flocculating yeast was studied by using a defined medium in shake flask culture. The observed improvement of zinc ion supplementation on ethanol tolerance promoted the further examination of zinc ion effect on continuous ethanol fermentation. Zinc sulfate was supplemented into the fermentation medium at the concentrations of 0.01, 0.05 and 0.1 g·L^-1 , respectively. The average floc size of the sel-flocculating yeast decreased in zinc-addition cultures, but both its ethanol tolerance and thermal tolerance were significantly improved, which correlated well with the increased ergosterol and trehalose contents in the yeast flocs. Intracellular zinc content was found to be about six folds higher than that of control, and no significant difference was observed in the three addition levels. Correlation analysis indicated close correlation between zinc addition and ethanol/thermal tolerance. Ethanol production increased in all the zinc-supplemented cultures, with the most significant effect observed when 0.05 g· L^-1 zinc sulfate was supplied. Thus, zinc ion supplementation was proved to be an efficient strategy for enhanced ethanol tolerance, thermal tolerance and ethanol production in continuous ethanol fermentation of the self-flocculating yeast.