酿酒酵母呼吸突变株的高糖胁迫反应研究

The Response of a Saccharomyces cerevisiae Respiratory Mutant to High Sugar Stress

关键词:  酿酒酵母  呼吸突变体  高糖胁迫  生理特性

Key words:  Saccharomyces cerevisiae  respiratory mutant  sugar stress  physiological characters

摘要:

[目的]研究野生型甘蔗糖蜜发酵高产乙醇菌株MF1002及其糖分利用能力显著提高的呼吸突变菌株MF15c在高糖胁迫下的生理特性变化。[方法]测定在高糖胁迫下菌株的生长速率、出芽率、乙醇产量和超氧化物歧化酶(SOD)活力、过氧化氢酶活力、过氧化物酶活力以及细胞质和线粒体的ATP酶活力。[结果]在葡萄糖浓度分别为25%、30%和40%的高糖培养基中,MF15c菌株生长和乙醇发酵受抑制的程度均明显低于MF1002。当葡萄糖浓度为30%和40%时,MF15c的最大菌体数目、最高出芽率和乙醇发酵浓度等均显著高于MF1002。当葡萄糖浓度为30%时,两菌株胞内的SOD活力、过氧化氢酶活力、过氧化物酶活力以及细胞质和线粒体的ATP酶活力均显著上升。其中,MF15c的胞内SOD活力、胞内过氧化物酶活力、细胞质ATP酶活力和线粒体ATP酶活力在高糖胁迫下的上升幅度显著高于MF1002。[结论]MF15c较MF1002具有更强的高糖耐受能力。SOD活力、过氧化氢酶活力、过氧化物酶活力以及细胞质和线粒体的ATP酶均参与了两菌株的高糖胁迫反应,胞内SOD活力、胞内过氧化物酶活力、细胞质ATP酶活力和线粒体ATP酶活力可能与MF15c菌株的高糖耐受能力有关,可作为进一步改造该菌株的指导指标。

Abstract:

[Objective] The wild type Saccharomyces cerevisiae strain MF1002 that was a high yield strain of molasses ethanol fermentation, and its respiratory mutant MF15c of which the sugar utilizing capacity was significantly enhanced, were employed to investigate the physiologic response to the high sugar stress.[Method] The strains' growth rate, budding ratio, ethanol yield and enzyme activity of superoxide dismutase (SOD), catalase, peroxidase, ATPase activity in cytoplasm and the ATPase activity in mitochondria were conducted under high sugar stress.[Result] When the strains were cultivated in the medium containing 25%, 30% and 40% glucose, the growth and ethanol fermentation of MF1002 were repressed significantly stronger than MF15c by high sugar stress.When 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 MF15c were all significantly higher than that of MF1002.The enzymes activity assay exhibited that the activities of five enzyme afore mentioned were all significantly increased for both strains after they were cultivated in the medium containing 30% glucose for 24h under high sugar stress, of which the activity of 4 enzymes increased significant higher in MF15c than in MF1002, except for the catalase activity in cell extract.[Conclusion] MF15c has stronger tolerance than MF1002 to high sugar stress.Thus the activity of these 5 enzymes was involved in the response of both strains to high sugar stress, among which 4 enzyme activities may be correlated with the high sugar tolerance of MF15c and could be used as the indicator for further improvement of the strain.