Radiation Effect on Yeasts of the Genus Candida Berkhout

Abstract

SO far investigations of radiation damage on yeasts were solely done on ascosporogenous yeasts of the genus Saccharomyces (Meyen) Reess, mostly on the species cerevisiae Hansen. Major radiation damage to this genus is known^1–4. We irradiated an anascosporogenous yeast Candida tropicalis (Cast.) Berkh. with X-rays (1.54 Å.) and ultra-violet light. This genus is characterized by the ability to form pseudomycelium, that is, filaments similar to the hyphæ of moulds, but consisting of elongated cells which have originated by budding. Formation of pseudomycelium takes place when growth goes on and cell division (budding) is inhibited. By irradiation of C. tropicalis we found all the types of radiation damage discussed in refs. 1–4 and a new radiation effect, the formation of pseudomycelium. The equations of the regression-lines for this effect are: X-rays, y = 3.18 + 2.78x; PPD ₅₀ = 3.6–4.47–5.13 kr. Ultra-violet light: y =−3.66 + 4.7x; PPD ₅₀ = 64.5–69.7−74.1 sec.