Genomic studies on killer yeasts belonging to the genus Pichia.

Twenty-four species belonging to the genus Pichia were investigated using restriction fragment length polymorphism (RFLP) and Southern blot hybridization of their genomic DNA. Saccharomyces cerevisiae, Kluyveromyces lactis, Williopsis mrakii and Candida albicans were also included in this study. The RFLP patterns were obtained from digestion of yeast DNA with several restriction endonuclease enzymes, and showed various bands with different mobility; in most isolates, the more deeply stained bands were species-specific. This observation was confirmed by the results obtained from Southern blot hybridization of the EcoRI and XhoI RFLP patterns with P. anomala UCSC 25F DNA, digested with the same enzymes, used as probes. These bands are likely to be ribosomal DNA as shown by hybridization of digested DNA from unrelated yeast species (S. cerevisiae, K. lactis and C. albicans). However, one hybridized band, located at 3.9-4.1 Kb, seems to be peculiar to the Pichia species. Our study confirms the usefulness of molecular tools in studying genetic relatedness among yeasts.