| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1987: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1986: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
This study was undertaken to isolate freeze-tolerant baker's yeasts from natural sources and to breed them by the method of cell fusion. In the first part of this report, we selected several strains of freeze-tolerant yeast from soil and foods which were grown on a medium containing high concentration of sucrose. Two strains of yeast, No. 5 and No. 9-1, which were isolated from soil, had a strong fermentative activity similar to the commercial baker's yeast as well as high freeze-tolerance after pre-fermentation of dough. These yeasts were identified as Saccharomyces species from their cultural and physiological nature, Furthermore, the strain No. 5, an ascosporogenous yeast, was able to ferment maltose and it seemed to be industrially available for breadmaking by freeze-dough method. In the second part of this report, the cell fusion method was applied to obtain freeze-tolerant yeasts with high fermentative activity between Saccharomyces cerevisiae and S. rosei. It was found that all the fusants had relatively high fermentative activity, but retained predominantly the nature of S. cerevisiae than S. rosei, that is, their freeze-tolerance were poor as compared to the paraent strain S. rosei.
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