Significance of the coenzyme Q system in the classification of yeasts and yeast-like organisms. XLIX. The phylogenetic relationships of the Q6-equipped species in the teleomorphic apiculate yeast genera Hanseniaspora, Nadsonia, and Saccharomycodes based on the partial sequences of 18S and 26S ribosomal ribonucleic acids.

Abstract

Eleven strains of species in the apiculate yeast genera Hanseniaspora, Nadsonia, and Saccharomycodes were examined for partial base sequence determinations of 18S and 26S rRNAs. In the partial base sequence of 26S rRNA (positions 493-622, 130 bases), percent similarities were 65-79, 76-84, and 70-76 between the genera Hanseniaspora and Nadsonia, the genera Hanseniaspora and Saccharomycodes, and the genera Nadsonia and Saccharomycodes, respectively. These apiculate yeasts showed 72-85 percent similarity with S. cerevisiae. In the partial base sequences of 26S rRNA (positions 1611-1835, 225 bases) and of 18S rRNA (positions 1451-1618, 168 bases), the number of base differences was calculated to be 38-26, 27-9, and 30-23, and 12-8, 11-5, and 13-8 between the above-mentioned genera, respectively. These apiculate yeasts showed 33-9, and 12-4 base differences, respectively, with S. cerevisiae. The three apiculate yeast genera were recognized phylogenetically based on the sequence data obtained. Some discussions were made, especially on dividing the members of the genus Hanseniaspora into two groups at the generic level.