Abstract
New isolates of Saccharomyces cerevisiae from natural habitats are needed in order to give new characteristics to fermented foods such as alcoholic beverages and breads. Although many attempts to isolate S. cerevisiae strains from flowers and fruits have been made in Japan, there are few successful reports. These results indicate that an efficient method of isolating S. cerevisiae should be developed. Therefore, we tried and succeeded in isolating selective strains of S. cerevisiae from flowers in Aichi prefecture by a combination of selective enrichment culturing and PCR analysis of the rDNA 5.8S-ITS region. Six strains of S. cerevisiae were successfully isolated, and their fermentation and sugar assimilation properties were determined. Fermentation and sugar assimilation profiles were identical among five isolates, but was different in one isolate. The sugar assimilation profiles of all six isolates were different from those of the S. cerevisiae K7 used in sake-brewing and the S. cerevisiae By used in bread-making. They did not produce any killer toxins against K7 and By. The mtDNA RFLP analysis of the six isolates showed a high level of polymorphism, although identical patterns were found for two isolates. PCR analysis of the Ty1 delta element revealed that both the number and the size of the amplification products differed among the six isolates, K7 and By. These results showed genetic diversity among the six S. cerevisiae isolates.
