Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2008
Publication Date: August 15, 2008
Citation: Kurtzman, C.P. 2008. Reclassification of ascomycetous yeasts from gene sequence analyses. Meeting Abstract. Technical Abstract: During the past decade, identification of yeasts and their classification has been based almost exclusively on gene sequence analysis. Primarily as a result of using diagnostic gene sequences, such as D1/D2 LSU and ITS ribosomal RNAs, the number of known species has doubled. With the faster sequencing technologies now available, multigene analyses are being used to examine species boundaries as well as higher levels of classification. Many phenotypically defined genera were discovered to be polyphyletic, which has lead to considerable reclassification. Species of Saccharomyces that were designated ‘sensu lato’ have been reassigned to three new genera and species originally placed in Kluyveromyces have been assigned to six genera. Similarly, the genus Pichia, which has included as many as 100 species, was found to be polyphyletic and species have been reassigned to nearly 20 different genera, many of them newly described, such as Barnettozyma, Lindnera, Scheffersomyces and Wickerhamomyces. Pichia is now based on the P. membranifaciens clade, which also includes species formerly assigned to Issatchenkia. Relationships among the genera require further resolution, but it is clear that the ascomycetous yeasts are members of a single clade, the Saccharomycetales, and the most basal species appear to be Candida caseinolytica and Trigonopsis variabilis. These and other relationships based on multigene sequence analysis will be discussed.