To establish a method for breeding an auxotrophic mutant of a useful yeast with diploid or higher by modifying mutation conditions including ultraviolet irradiation, to provide the industrially useful autotrophic mutant, and to provide a new transformant system through utilizing the autotrophic mutant as a host cell for developing a gene manipulation system and using auxotrophy as a selected marker.
The objective auxotrophic mutant of useful yeast with diploid or higher is obtained by considering the optimum conditions for mutation treatment such as ultraviolet irradiation. The auxotrophic mutant thus obtained can be used for producing fermented foods including wines, vinegar, soy sauce and bread. The 2nd objective method for breeding and obtaining the above auxotrophic mutant by mutation treatment is provided as described above. The other objective transformant strain using the above auxotrophic mutant is also provided.
HASHIMOTO NOBUTSUGU
NISHIZAWA YOSHINORI
