Some genetic properties of wild strains of Saccharomyces cerevisiae isolated in Japan and Brazil

Wild strains of S. cerevisiae were collected from natural habitats in Japan (Yaeyama islands) and Brazil (S_??_o Paulo, Campinas, and Manaus), and some of their genetic properties were examined. One-fourth of 31 strains isolated in Brazil were heterothallic, while no heterothallism was found in 65 strains isolated in Japan. Most of the Brazilian strains had 4 to 7 double stranded RNA (dsRNA) species in the same cells, while 56% of the Japanese strains had 1 or 2 dsRNA species and the rest had none. The most dominant killer strains found in Brazil were of K1 type, and this was also the case in Japan. The K1-dsRNA encoding killer toxin gene was identified in the multiple dsRNA of a Brazilian killer strain.