Low-dose gamma irradiation as means of isolating carotenoid-hyperproducing yeast mutant

Abstract

In order to isolate carotenoid-hyperproducing yeast, low-dose gamma irradiation was used as means of mutagenesis. Phaffia rhodozyma was treated by gamma irradiation of less than 10 kGy, which is considered to be a wholesome irradiation condition established by the Food and Drug Administration. Through repeated rounds of gamma irradiation and visual screening, mutant 3A4-8 was obtained. It produced a 3,824 μg carotenoid/g yeast, 69% higher content than 2,265 μg/g yeast of the unirradiated one. This result indicates that low-dose gamma irradiation could be used as means of mutagenesis to obtain carotenoid-hyperproducing strain of Phaffia rhodozyma, since only carotenoid-hyperproducing yeast survived gamma irradiation by scavenging oxygen radicals generated by radiolysis of water.