The antifungal activity against Botrytis cinerea, a pathogen of grape gray mold disease, was validated in vitro for 59 of 225 wild yeast strains isolated from naturally fermented wine samples (69 strains), our university campus plants (129 strains), and commercially available fruits (27 strains). Twenty strains showing strong antifungal activity were identified. The majority of the strains were Saccharomyces cerevisiae (16 of the 20 strains). The S. cerevisiae strains were differentiated by genetic polymorphism analyses with comparisons of their antifungal activities. As a result, it was clarified that each strain type showed different antifungal activity, and that automatic rRNA intergenic spacer analysis was extremely useful for the differentiation of S. cerevisiae strains when compared to other conventional polymerase chain reaction-based methods.

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