Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: May 8, 1997
Publication Date: N/A
Technical Abstract: Sequences were determined for a ca. 600-nucleotide variable region at the 5'-end of large subunit (26S) ribosomal DNA from all known ascomycetous yeasts that can be grown in culture, including species of Candida and other anamorphic genera. In addition, sequences from certain other regions of the nuclear and mitochondrial rDNA genes were compared for selected taxa. These data allowed phylogenetic placement of taxa as well as detection of synonymous species. Topologies of phylogenetic trees suggest that the ascomycetous yeasts underwent a massive radiation, possibly following the late Permian mass extinction. Species assigned to the genera Saccharomyces, Zygosaccharomyces, Kluyveromyces, Arxiozyma, Pachytichospora and Torulaspora comprise a single large clade. Genera assigned to the Lipomycetaceae (Lipomyces, Smithiozyma, Babjevia, Zygozyma, Dipodascopsis, Myxozyma) also intergrade. The circumscription of ascomycetous yeast genera will be discussed on the basis of phylogenetic analysis of nucleotide sequences as well as from phenotypic similarities.