Properties of a high-torularhodin-producing mutant of Rhodotorula glutinis cultivated under oxidative stress.

To characterize the properties of torularhodin, which is one of the carotenoid pigments produced by the yeast Rhodotorula sp., a mutant which produces large amounts of torularhodin was constructed and its tolerance against oxidative stress was investigated. The mutant we obtained was capable of producing large amounts of torularhodin in response to irradiation with blue light. The mutant, incubated under irradiation with white light that resulted in an increased production of torularhodin, exhibited resistance to growth inhibition induced by the addition of methylene blue as the generator of singlet oxygen. Leakage of lactate dehydrogenase to the growth medium from the mutant was not increased as compared to that from a parent strain and a high-beta-carotene-producing mutant. These results suggest that an increase in the production of torularhodin reduces the susceptibility to injury induced by an active oxygen species.