一个酿酒酵母呼吸突变株在高糖胁迫下的生理特性研究

MF11a为甘蔗糖蜜乙醇发酵野生型高产菌株MF1002的呼吸突变体，对糖分的利用能力显著高于MF1002。本文研究了这两菌株应激高糖胁迫的生理特性变化。结果表明，高糖培养条件下，MF11a菌株的生长和乙醇发酵受抑制的程度均明显低于MF1002，培养基的葡萄糖浓度为30％和40％时，其最大菌体密度、最高出芽率和乙醇浓度等已显著高于MF1002，表明MF11a较MF1002具有更强的高糖耐受能力。在30％葡萄糖的胁迫培养条件下，两菌株胞内的总超氧化物歧化酶（SOD）活力、过氧化氢酶活力、过氧化物酶活力，及它们细胞质和线粒体的ATP酶活力均显著上升，说明这五种酶均参与了两菌株的高糖胁迫反应。其中，MF11a的胞内过氧化氢酶活性、过氧化物酶活力、细胞质ATP酶活力在高糖胁迫下的上升幅度显著高于MF1002，表明这三种酶活力可能与MF11a菌株的高糖耐受能力有关，可作为该菌株进一步改造的指导指标。

The Physiological Characters of a Saccharomyces cerevisiae Respiratory Mutant under High Sugar Stress

The wild type Saccharomyces cerevisiae strain MF1002 that was a high yield strain of molasses ethanol fermentation, and its respiratory mutant MF1 la of which the sugar utilizing capacity was significantly enhanced, were employed to investigate the physiologic response to the high sugar stress. When cultivated in the medium con- taining high concentration glucose, the growth and ethanol fermentation of MF1002 were repressed significantly stronger than MF1 la by high sugar stress. With the glucose concentration in medium was increased to 30% and 40%, the maximum cell number, the maximum cell budding ratio and the ethanol fermentation concentration of MF1 la were all significantly higher than that of MF1002, indicating that MF1 la was stronger tolerance than MF1002 to high sugar stress. The enzymes activity assay exhibited that five enzyme activities of both strains, e.g. the superoxide dismutase （SOD） activity in cell extract, the catalase activity in cell extract, the peroxidase activity in cell extract, the ATPase activity in cytoplasm and the ATPase activity in mitochondria, were all significantly increased atter the strains were cultivated in the medium containing 30% glucose for 24 h for high sugar stress, indicating these enzymes were involved in the response of both strains to high sugar stress. Of which, the increment of the catalase activity in cell extract, the peroxidase activity in cell extract and the ATPase activity in cytoplasm for MF11a was significant higher than for MF1002, implying that these three enzyme activities may be correlation with the high sugar tolerance of MF 11a, and could be used as the indicator for further improvement of the strain.