Abstract
Taxonomic studies on D. hamsenii and related yeast species were carried out using chemotaxonomic methods including DNA base compositions, DNA-DNA hybridization, ubiquinone system, PMR spectrum of mannan and serological methods. The 50 strains employed were classified into 3 groups, I, II and III, based on DNA-DNA hybridization experiments. These groups were considered to represent 3 distinct species. Group I consisted of 2 subgroups, Ia and Ib, which were considered to represent 2 distinct varieties. These groups were also characterized by PMR spectra of alkali-extracted mannans and cell surface antigens; they could not be discriminated by DNA base composition and ubiquinone systems, in addition to the taxonomic criteria commonly employed in yeast taxonomy. Group Ia comprised 34 strains including the type or authentic strains of D. hansenii, D. nicotianae, D. nicotianae var. minor, D. kloeckeri, D. kloeckeri var. major, D. tyrocola, D. gruetzii, D. matruchoti, D. matruchoti var. cesari, D. hildegaardi, D. guilliermondii, D. miso, Torulopsis westerdijkii, T. famata and T. minor. Group Ib comprised 6 strains including the type or authentic strains of D. subglobosus, D. fukuyamaensis, Pichia adzetii and Candida flareri. Group II comprised 4 strains including the type or authentic strains of D. nepalensis, D. cavensis and D. japonicus. Group III comprised 6 strains including the type strain of T. candida.