Molecular relationships among hyphal ascomycetous yeasts and yeastlike taxa

Abstract

The circumscription of mycelial genera among the ascomycetous yeasts has been controversial because of widely different interpretations of the taxonomic significance of their phenotypic characters. Relationships among species assigned to mycelial genera were determined from extent of divergence in a ca. 600-nucleotide region near the 5′ end of the large subunit (26S) ribosomal DNA gene. Phylogenetic analyses showed that Stephanoascus is distinct from Zygoascus and that Blastobotrys, Sympodiomyces, and Arxula represent anamorphs of the Stephanoascus clade. The analyses demonstrated the following teleomorphic taxa to be congeneric: Ambrosiozyma/Hormoascus, Saccharomycopsis/Guilliermondella/Botryoascus/Arthroascus, Dipodascus/Galactomyces, and Eremothecium/Ashbya/Nematospora/Holleya. Species assigned to Dipodascus comprise two separate clades. New taxonomic combinations are proposed that reflect the phylogenetic relationships determined. Key words: mycelial yeasts, ribosomal rRNA/rDNA, molecular systematics.

Two distinct 18S rRNA secondary structures in Dipodascus (Hemiascomycetes) The DDBJ accession numbers for the sequences reported in this paper are shown in Table 1 T1 .

“…The grouping of species into group 1 (subgroups 1a, 1b and 1c except Geotrichum fermentans) and group 2 species is observed in the domain D1\D2 26S rRNA parsimony tree (Kurtzman & Robnett, 1995). Group 1 sequences of domain D1\D2 26S rRNA sequences from GenBank are 545-554 nt in length, corresponding to that of most ascomycetous yeasts (Kurtzman & Robnett, 1998), whereas group 2 sequences are 404-407 nt in length, i.e.…”

“…Dipodascus and Galactomyces are distinguishable by their physiological characters. Domain D1\D2 26S rRNA gene sequence analysis has shown that species of Dipodascus and its anamorph Geotrichum separate into two clades, one of which includes species of Galactomyces (Kurtzman & Robnett, 1995).…”

Molecular-genetic diversity of the ascomycetous yeast genus Arthroascus: Arthroascus babjevae sp. nov., Arthroascus fermentans var. arxii var. nov. and geographical populations of Arthroascus schoenii

“…The nucleotide sequences determined for Arthroascus strains have been deposited in GenBank (see Table 1 for details). Existing sequences for the type cultures of Arthroascus species and other members of the Saccharomycopsis clade (Kurtzman & Robnett, 1995;Kurtzman, 1999;Lachance et al, 2000) were retrieved from GenBank.…”

“…More recently, three strains isolated from soil in Taiwan were assigned to the genus Arthroascus on the basis of morphological and physiological properties (Lee et al, 1994); based on DNA-DNA reassociation data, the species Arthroascus fermentans was described. Kurtzman & Robnett (1995), using sequence data of the D1/D2 domain of the large subunit (26S) rDNA, considered Arthroascus to be congeneric with the genus Saccharomycopsis. The latter genus also contains predatory yeasts.…”

Isolation and Characterization of Amylase Producing Yeasts and Improvement of Amylase Production

“…In recent years, many researchers have suggested that a polyphasic approach may be the best way to achieve proper microbial identification. So, in the present study, accurate identification of yeast strains was performed using different molecular techniques [21][22][23].…”