A CLARIFICATION OF THE RELATIONSHIP OF CANDIDA GUILLIERMONDII TO OTHER YEASTS BY A STUDY OF THEIR MATING TYPES

Abstract

Mating expts. have shown some spp. of the nonascosporogenous genus Candida to be heterothallic haploid yeasts capable of forming ascospores when sexually active strains of opposite sex are mixed. The ability or inability of yeasts classified as separate spp. or vars. to mate helps to clarify taxonomic relationships. Strains of Candida guilliermondii and Candida melibiosi mate to produce hat-shaped ascospores and these strains are identical physiologically and morphologically. Therefore they are considered to belong to a single sp. rather than to 2. The mating types of Candida guilliermondii var. membranaefaciens do not mate with the mating types of C. guilliermondii. and strains of the 2 yeasts are very different physiologically and morphologically. C. guilliermondii var. membranaefaciens is shown to be identical with Endomycopsis ohmeri, Candida melibiosi var. membranaefaciens is raised to species rank.