Submitted to: Biotechnology International Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/1996
Publication Date: N/A
Technical Abstract: The question of whether yeasts represent members of a single evolutionary lineage or whether they represent reduced forms of many lineages has been debated for well over a century without satisfactory resolution. The recent reexamination of this question from the perspective of molecular genetics has begun to provide definitive answers. Furthermore, a practical side to this work is the development of simple molecular technologies for rapid strain identification that will have enormous impact in medicine, agriculture and industry. From phylogenetic analysis of rDNA sequences, the ascomycetous yeasts are shown to represent a sister group to the euascomycetes and that Schizosaccharomyces, Taphrina, Protomyces, Pneumocystis, and Saitoella are basal to the preceding two groups. Basidiomycetous yeasts are broadly related to the smut fungi and clearly separate from the Agaricales. Sequence analyses have given species groupings that in some cases correspond with presently accepted genera, but often show that earlier taxonomic proposals were erroneous. Not unexpectedly, species of Candida are distributed throughout the ascomycetous yeast domain. Molecular analysis has demonstrated which Candida species are conspecific with one another and with known teleomorphic species. For example, Pichia mexicana, Candida terebra, C. veronae and C. entomaea represent the same species. Molecular comparisons show close relationships among certain species of Saccharomyces, Zygosaccharomyces, Torulaspora and Kluyveromyces, thus changing the present circumscription of these genera.