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.

研究了影响酵母冷冻伤害的因素，以阐明冷冻面团系统中酵母冻结的机制。发现冻结储存的温度和周期显着影响液体培养基中酵母细胞的生存能力，这取决于酵母菌菌株的冻结率。小麦的Ananti-yeast蛋白随着化合物量增加而降低，而在耐热菌株中几乎没有效果。从两种菌株中，pH 3-4处渗出的紫外线量渗出的含量渗出的含量在pH 3-4处达到了最大的含量，并且根据冷冻耐耐耐热菌株的浓度，它通过纯素蛋白的浓度而增加。结果表明，酵母菌细胞的裂解可能是在纯蛋白质的情况下通过冻融治疗而发生的，这取决于酵母菌菌株的冻结性。它还发现酵母菌细胞的磷脂酶活性通过添加durothionin，可以高度加速冻敏菌株的膜分数，而耐耐耐菌株的酶活性不受纯素蛋白的影响。因此，假定对酵母冷冻伤害的易感性取决于磷脂酶的活性，磷脂酶的活性催化了酵母细胞膜中磷脂降解的降解。由于添加磷脂酰丝氨酸或磷脂酰肌醇的磷脂蛋白从冻素菌株中激活磷脂酶，我们得出的结论是，酵母的冷冻敏感性与酵母细胞中磷脂的组成有关。