A natural chimeric yeast containing genetic material from three species

The Saccharomyces sp, CID1 isolate (CBS 8614) and several other Saccharomyc es sensu stricto yeasts were analysed for their mitochondrial and nuclear g enes. The data show that Saccharomyces sp. CID1, found so far only in one l ocation in Europe, is a natural hybrid between three different Saccharomyce s yeast species. Two of them, Saccharomyces cerevisiae-like and Saccharomyc es bayanus-like, are ubiquitous and contributed parts of the nuclear genome ; the third, Saccharomyces sp. IFO 1802-like, which has been found only in Japan, contributed the mitochondrial DNA molecule. These data suggest that the yeast cell is able to accommodate, express and propagate genetic materi al that originates from different species, and the very existence of the re sulting natural hybrids indicates that such hybrids are well adapted to the ir habitats.