Rhodosporidium BANNO: Inaktivierende Wirksamkeit von ultraviolettem Licht und N‐Methyl‐N′‐nitro‐N‐nitrosoguanidin in der Hefephase

The inactivation of stationary phase cells by ultraviolet light (UV) and N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG) was examined in eight wild strains of Rhodotorula , six of which are the sporidial yeast phase of Rhodosporidium , a basidiomycetous fungus. It thas been found that (1) the UV‐resistance of Rhodosporidium and Rhodotorula yeasts is higher and the MNNG‐resistance lower than the resistance of Candida and Hansenula yeasts, (2) the shape of the survival curves is sigmoid in the case of UV and two‐phase exponential in the case of MNNG, (3) the mutagen sensitivities but not the inactivation kinetics of the strains are different, (4) the UV‐ and MNNG‐ sensitivities for each of the strains are correlated, (5) the relatively high resistance to UV cannot be due to the carotenoid pigments of the cells, (6) mutations to UV‐sensitivity can be induced with a high rate, (7) the sigmoidal character of the UV survival curves were reduced or transformed to an exponential shape by the UVS‐mutations.