The resistance to killing by free radicals of two mutants ofPhaffia rhodozyma was determined. Mutant 5-7 did not produce astaxanthin but produced beta-carotene, while mutant 3-4 did not produce any carotenoid pigments. The resistance of mutant 5-7 was the same as that of the wild type but mutant 3-4 was rapidly killed. Carotenoid pigments increased the resistance to killing by free radicals. We investigated the effects of free radicals, generated by H(2)O(2) and Fe(2+) added to the medium, on wild-type cells and mutants ofP. rhodozyma. Unpigmented mutants of basidiomycetous yeasts (Rhodotorula spp. and others) are more susceptible to killing by UV-irradiation than the pigmented, wild-type strains. Therefore, we investigated the effect of free radicals on a similar basidiomycetous yeast,P. rhodozyma, a species of economic importance, in the biological production of astaxanthin.

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Biochim Biophys Acta. 1992 Jun 22;1126(2):178-84 PubMed

Appl Environ Microbiol. 1989 Jan;55(1):116-24 PubMed

Appl Environ Microbiol. 1993 Mar;59(3):867-73 PubMed

Cloning and nucleotide sequence of a linear DNA plasmid from Xanthophyllomyces dendrorhous (Phaffia rhodozyma)