1996 Fiscal Year Final Research Report Summary
Correlation Between Freeze-tolerance of Bakers' Yeasts and Their Cellular Content of Trehalose
| Project/Area Number |
07680019
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
家政学
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| Research Institution | Nara Women's University |
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Principal Investigator |
KAWAI Hiroyasu Nara Women's University, Department of Food Science and Nutrition, Professor, 生活環境学部, 教授 (80026525)
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| Co-Investigator(Kenkyū-buntansha) |
ISOBE Yuka Nara Women's University, Department of Food Science and Nutrition, Assistant, 生活環境学部, 助手 (80218544)
YOKOIGAWA Kumio Nara Women's University, Department of Food Science and Nutrition, Associate Pro, 生活環境学部, 助教授 (60230637)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Bakers' Yeast / Freeze-tolerant Yeast / Mechanism of Freeze-tolerance / Torulaspora delbrueckii / Trehalose / Saccharomyces cerevisiae |
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| Research Abstract |
This study was undertaken to clarify the correlation between freeze-tolerance of bakers' yeasts and their intracellular trehalose, a reserve carbohydrate in yeast. 1. The amount of trehalose in a freeze-tolerant cells of Torulaspora delbrueckii was higher than that of a freeze-sensitive mutant. The result suggested that the freeze-tolerance of yeast has a close relationship to its trehalose content. 2. The trehalose content of growing yeast cells was increased by a heat-shock, i.e., a temporal increase in culture temperature, and these yeast cells were found to have higher survival ratio after freeze-thawing. This indicated that intracellular trehalose of yeast has an important role to lower the freeze-injury of yeast. 3. There were found no clear correlation between trehalose content of commercial compressed bakers' yeasts belonging to Saccharomyces cerevisiae and their freeze-tolerance, but their cultured yeast cellsshowed a positive relationship between them. 4. A trehalase-deficient mutant of T.delbrueckii had a high trehalose content, while a mutant having a weak trehalose-phosphate synthetase activity had a low trehalose content. These results reflected a close relationship between freeze-tolerance and cellular content of trehalose. 5. It was found that freeze-tolerant strain had a higher trehalose-phoshpate synthetase activity and a lower neutral trehalase activity than that of freeze-sensitive strain, the results indicating that those enzyme activities were closely related to the amount of cellular trehalose and freeze-tolerance of yeast.
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