A taxonomic study on cellulolytic yeasts and yeast-like microorganisms isolated in Japan. II. The genus Cryptococcus.

Abstract

Seven strains of cellulolytic anamorphic basidiomycetous yeasts isolated from natural materials collected in Japan were identified as three species in the genus Cryptococcus; Cryptococcus flavus (1 strain), Cryptococcus cellulolyticus sp. nov. (5 strains) and Cryptococcus sp. (1 strain). Cr. cellulolyticus resembles Cr. flavus in the taxonomic criteria traditionally employed for yeasts but is differentiated from this species in DNA-DNA reassociation experiments. Practically, Cr. cellulolyticus is discriminated from Cr. flavus in the assimilation of erythritol and the lack of assimilation of ethanol. A strain assigned to Cryptococcus sp. produces septated mycelium and has Q-9 as the major ubiquinone. These characteristics resemble those of Q-9-equipped strains of Cryptococcus humicolus. However, differences are found in the lack of assimilation of melezitose and in growth without vitamins. We retained it as unidentified because Cr. humicolus itself is assumed to be a heterogeneous species and a revision of the species concept is required.