The Phylogenetic Relationships of Methanol-assimilating Yeasts Based on the Partial Sequences of 18S and 26S Ribosomal RNAs: The Proposal ofKomagataellaGen. Nov. (Saccharomycetaceae)

Twelve strains of methanol-assimilating yeast species were examined for their partial base sequences of 18S and 26S rRNAs. In the partial base sequencings of 18S rRNA (positions 1451-1618, 168 bases), P. kodamae had the same partial base sequence as Ogataea minuta, and P. finlandica, P. pini, P. trehalophila, C. maris, and C. methanolovescens were the same in the partial base sequences as O. glucozyma. Candida boidinii and C. methylica were similar to O. glucozyma, but somewhat different from O. minuta (the base differences, one and four, respectively). Pichia naganishii had seven, four, six, and nine base differences with O. minuta, O. glucozyma, P. anomala, and P. membranaefaciens, respectively, and C. methanosorbosa did four, three, five, and twelve base differences. Pichia pastoris was quite different (the base differences among the methanol-assimilating yeasts, 32-31), and no bases were found in the fingerprint segment. In the partial base sequencings of 26S rRNA (positions 1611-1835, 225 bases; positions 493-622, 130 bases), P. finlandica, P. kodamae, P. pini, P. trehalophila, C. maris, C. methanolovescens, and C. methanosorbosa were similar to O. minuta and O. glucozyma. Pichia naganishii, C. boidinii, and C. methylica had somewhat different partial base sequences. The base differences and the percent similarities of P. pastoris were quite high (101-89) and quite low (40-47). Based on the sequence data obtained, the methanol-assimilating yeast species are discussed taxonomically and phylogenetically. A new genus, Komagataella was proposed for P. pastoris with a new combination, Komagataella pastoris.