Polyphasic taxonomy of the basidiomycetous yeast genus Rhodosporidium : Rhodosporidium kratochvilovae and related anamorphic species

The phenotypic and genetic heterogeneity of the basidiomycetous yeast speci es Rhodosporidium kratochvilovae was investigated in a group of recent isol ates and collection strains. A polyphasic taxonomic approach was followed w hich included micromorphological studies, nuclear staining, determination o f sexual compatibility, physiological characterization, comparison of elect rophoretic isoenzyme patterns, PCR fingerprinting, determination of mol% GC, DNA-DNA reassociation experiments and 26S and ITS rDNA sequence analysis . The results allowed a more natural circumscription of the species, both f rom the genetic and phenotypic perspectives. The relationships with anamorp hic species of the genus Rhodotorula were studied and isolates previously i dentified as Rhodotorula glutinis were found to belong to Rhodosporidium kr atochvilovae. Other isolates included in the study were found to represent members of Rhodotorula glutinis var. dairenensis. Rhodosporidium kratochvil ovae was found to include heterothallic strains, besides those already know n to be self-sporulating. A total of 17 isolates, which were found to belon g to this species, were heterothallic, self-sporulating and anamorphic stra ins. It is anticipated that integrated polyphasic studies of basidiomycetou s yeasts will provide a more coherent classification system and the basis f or accurate identification schemes, which in turn are essential for detaile d ecological studies.