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Studies on the Mechanism of Freeze-Injury and Freeze-Tolerance of Yeast

酵母冻伤及耐冻机制的研究

基本信息

批准号：
02680063
负责人：
KAWAI Hiroyasu
金额：
$ 1.28万
依托单位：
Nara Women's University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

Factors that influence the freeze-injury of yeast was investigated to clarify the mechanism of freeze-tolerance of yeast in frozen-dough system. It was found that the temperature and period for freeze-storage influenced markedly the viability of yeast cells in a liquid medium, which depended on the freeze-sensitivity of yeast strains.The fermentative activity of freeze-sensitive strain after frozen-thawed with purothionin, ananti-yeast protein from wheat, was depressed with increasing amounts of the compound, while little effect was observed in freeze-tolerant strain. The amount of UV-absorbing materials leaking out from frozen-thawed cells reached a maxiniuni at PH 3-4 in both strains, and it increased by the concentration of purothionin depending on the freeze-sensitive strain than the freeze-tolerant strain. The result indicated that the lysis of yeast cells, probably their cell membranes, might occur by the freeze-thaw treatment in the presence of purothionin, depending on the freeze-sensitivity of yeast strains.It was also found that the phospholipase activity of yeast cell membrane fraction from the freeze-sensitive strain was highly accelerated by addition of durothionin, while the enzyme activity of freeze-tolerant strain was not affected by purothionin. Therefore, the susceptibility to freeze-injury of yeast was assumed to depend on the activity of phospholipase that catalyzes the degradation of phospholipids in cell membranes of yeast. As the activation of phospholipase from the freeze-sensitive strain by purothionin was depressed by addition of phosphatidylserine or phosphatidylinositol, we concluded that the freeze-sensitivity of yeast was related to the composition of phospholipid in yeast cells.

研究影响酵母冻伤的因素，阐明冷冻面团体系中酵母的耐冻机制。结果发现，冷冻储存的温度和时间对液体培养基中酵母细胞的活力有显着影响，而这取决于酵母菌株的冷冻敏感性。用小麦中的一种抗酵母蛋白嘌呤硫素冻融后，冷冻敏感菌株的发酵活性随着该化合物用量的增加而降低，而耐冷冻菌株的影响很小。在两种菌株中，从冻融细胞中泄漏出的紫外线吸收物质的量在PH 3-4时均达到最大值，并且根据冷冻敏感菌株比耐冷冻菌株的不同，该量随嘌呤硫素浓度的增加而增加。结果表明，根据酵母菌株的冷冻敏感性，在嘌呤硫素存在下进行冻融处理可能会发生酵母细胞（可能是细胞膜）的裂解。还发现，添加杜硫肽可大大促进冷冻敏感菌株的酵母细胞膜部分的磷脂酶活性，而耐冷冻菌株的酶活性则不受影响。通过嘌呤硫氨酸。因此，推测酵母对冻伤的敏感性取决于催化酵母细胞膜中磷脂降解的磷脂酶的活性。由于加入磷脂酰丝氨酸或磷脂酰肌醇会抑制嘌呤硫蛋白对冷冻敏感菌株磷脂酶的激活，因此我们得出结论，酵母的冷冻敏感性与酵母细胞中磷脂的组成有关。