Genetic transformation in yeasts.

Abstract

SUMMARY: The transformability of 25 strains of yeasts belonging to 23 species in three genera - Saccharomyces, Hansenula and Candida- was investigated with respect to ten characters. Eighteen hour cultures at about the end of the log phase of growth, addition of 10 μg DNA/ml, and an incubation time of 30 min at 30 to 37 °C usually yielded best results. Of the 109 pairs of strains investigated 11 yielded positive results, which included intraspecific, interspecific and intergeneric transformation. Three adenine-requiring mutants of S. cerevisiae were transformed to prototrophy with the DNA of S. cerevisiae var. ellipsoicleus. DNA of the latter strain also transformed three other species of Saccharomyces. In Candida, reciprocal transformation was observed between C. utilis and C. lipolytica. Hansenula petersonii transformed H. jadinii to rhamnose utilization. In intergeneric experiments, H. mrakii was transformed with S. cerevisiae var. ellipsoicleus DNA and C. utilis with the DNA from H. petersonii. Attempts at transformation between Saccharomyces and Candida were unsuccessful. The GC content of DNA from the strains which yielded positive results varied from 36·0 to 37·3 mol %. The implications of these findings for the inter-relationships and taxonomy of yeasts are discussed.