Search

From comparisons of ITS1-5.8S-ITS2 and gene sequences for nuclear D1/D2 LSU rRNA, nuclear SSU (18S) rRNA, translation elongation factor 1-α (EF1-α) and RNA polymerase II subunit 2 (RPB2), the following four new ascosporogenous yeast species were resolved and are described as Metschnikowia anglica (NRRL Y-7298 T [type strain], CBS 15342, MycoBank MB 823167), Metschnikowia leonuri (NRRL Y-6546 T , CBS 15341, MB 823166), Metschnikowia peoriensis (NRRL Y-5942 T , CBS 15345, MB 823164) and Metschnikowia rubicola (NRRL Y-6064 T , CBS 15344, MB 823165). The following six species of Candida are members of the Metschnikowia clade and are proposed for transfer to Metschnikowia as new combinations: Candida chrysomelidarum (NRRL Y-27749 T , CBS 9904, MB 823223), Candida gelsemii (NRRL Y-48212 T , CBS 10509, MB 823192), Candida kofuensis (NRRL Y-27226 T , CBS 8058, MB 823195), Candida picachoensis (NRRL Y-27607 T , CBS 9804, MB 823197), Candida pimensis (NRRL Y-27619 T , CBS 9805, MB 823205) and Candida rancensis (NRRL Y-48702 T , CBS 8174, MB 823224). Candida fructus (NRRL Y-17072 T , CBS 6380, MB 823206) is transferred to Clavispora as a new combination, and Candida musae is shown to be a synonym of C. fructus. Apparent multiple alleles for ITS, D1/D2, EF1-α and RPB2 were detected in strains of some species.

The new anamorphic yeast Kuraishia piskuri, f.a., sp. nov. is described for three strains that were isolated from insect frass from trees growing in Florida, USA (type strain, NRRL YB-2544, CBS 13714). Species placement was based on phylogenetic analysis of nuclear gene sequences for the D1/D2 domains of large subunit rRNA, small subunit rRNA, translation elongation factor-1α, and subunits B1 and B2 of RNA polymerase II B. From this analysis, the anamorphic species Candida borneana, Candida cidri, Candida floccosa, Candida hungarica, and Candida ogatae were transferred to the genus Kuraishia as new combinations and Candida anatomiae, Candida ernobii, Candida ishiwadae, Candida laoshanensis, Candida molendini-olei, Candida peltata, Candida pomicola, Candida populi, Candida wickerhamii, and Candida wyomingensis were transferred to the genus Nakazawaea., (Published 2014. This article is a U.S. Government work and is in the public domain in the USA.)

Three new non-ascosporic, ascomycetous yeast genera are proposed based on their isolation from currently described species and genera. Phylogenetic placement of the genera was determined from analysis of nuclear gene sequences for D1/D2 large subunit rRNA, small subunit rRNA, translation elongation factor-1α and RNA polymerase II, subunits B1 and B2. The new taxa are: Deakozyma gen. nov., type species Deakozyma indianensis sp. nov. (type strain NRRL YB-1937, CBS 12903); Danielozyma gen. nov., type species Danielozyma ontarioensis comb. nov. (type strain NRRL YB-1246, CBS 8502); D. litseae comb. nov. (type strain NRRL YB-3246, CBS 8799); Middelhovenomyces gen. nov., type species Middelhovenomyces tepae comb. nov. (type strain NRRL Y-17670, CBS 5115) and M. petrohuensis comb. nov. (type strain NRRL Y-17663, CBS 8173).

Ambrosiozyma oregonensis sp. nov. is described from two strains, one isolated from a mountain stream in Oregon, USA (NRRL Y-6106(T) = CBS 5560(T)), and a second (NRRL YB-4169) from an unknown substrate from Marion, Illinois, USA. The species forms four hat-shaped ascospores in each deliquescent ascus and appears to be homothallic. Abundant true hyphae are produced with some having apparent dolipore-like septa. Analyses of nuclear gene sequences for the D1/D2 domains of large-subunit rRNA, small-subunit rRNA, translation elongation factor-1α, and subunits B1 and B2 of RNA polymerase II show the proposed novel species to be distinct from other species of the Ambrosiozyma clade. Because of their placement in the Ambrosiozyma clade, Candida kashinagacola, Candida llanquihuensis, Candida maleeae, Candida pseudovanderkliftii and Candida vanderkliftii are reassigned to the genus Ambrosiozyma as new combinations, and the description of the genus Ambrosiozyma is emended to reflect the resulting changes in phenotypic characters.

The relatedness among methanol-assimilating yeasts assigned to the genus Ogataea and neighboring taxa (Phylum Ascomycota, Subphylum Saccharomycotina, Class Saccharomycetes, Order Saccharomycetales) was determined from phylogenetic analyses of gene sequences for nuclear large and small subunit (SSU) rRNAs, translation elongation factor-1alpha and mitochondrial SSU rRNA. On the basis of the analyses, Williopsis salicorniae and seven species of Pichia are proposed for transfer to the genus Ogataea, which has been emended, and Pichia angophorae, a nonhyphal species, is proposed for transfer to the mycelium forming genus Ambrosiozyma. Pichia toletana and Pichia xylosa form an independent lineage and are assigned to the genus Peterozyma, which is newly proposed.

Relationships among species assigned to the yeast genera Pichia, Issatchenkia and Williopsis, which are characterized by the ubiquinone CoQ-7 and inability to utilize methanol, were phylogenetically analyzed from nucleotide sequence divergence in the genes coding for large and small subunit rRNAs and for translation elongation factor-1alpha. From this analysis, the species separated into five clades. Species of Issatchenkia are members of the Pichia membranifaciens clade and are proposed for transfer to Pichia. Pichia dryadoides and Pichia quercuum are basal members of the genus Starmera. Williopsis species are dispersed among hat-spored taxa in each of the remaining three clades, which are proposed as the new genera Barnettozyma, Lindnera and Wickerhamomyces. Lineages previously classified as varieties of Pichia kluyveri, 'Issatchenkia'scutulata, Starmera amethionina and 'Williopsis'saturnus are elevated to species rank based on sequence comparisons.

Relationships among species assigned to the ascosporic yeast genera Sporopachydermia, Stephanoascus, Trichomonascus, Wickerhamiella and Zygoascus, and to the associated anamorphic genera Arxula, Blastobotrys, Sympodiomyces and Trigonopsis, were determined from phylogenetic analyses of gene sequences from the nearly complete large-subunit rRNA gene, the mitochondrial small-subunit rRNA gene, and cytochrome oxidase II. The genus Stephanoascus is polyphyletic, resulting in reassignment of two species to the older genus Trichomonascus and the third to Sugiyamaella gen. nov. (type species Sugiyamaella smithiae). The genera Sporopachydermia, Wickerhamiella and Zygoascus appear to be monophyletic. The species Pichia ofunaensis and P. tannicola are proposed for transfer to Zygoascus. Arxula, Blastobotrys and Sympodiomyces are members of the Trichomonascus clade, with the genus Blastobotrys having taxonomic priority for anamorphic states. Trigonopsis variabilis and three species of Candida represent a distinct clade. From the foregoing gene sequence analyses, the new ascosporic genus Sugiyamaella is proposed, as are 14 new species combinations and the new family Trichomonascaceae.

A yeast causing widespread infection of laboratory mice was identified from 26S rRNA gene sequences as Candida pintolopesii. To determine the relationship of C. pintolopesii with other members of the Kazachstania (Arxiozyma) telluris species complex, nucleotide sequences from domains 1 and 2 of the 26S rRNA gene, the mitochondrial small-subunit rRNA gene, and the RNA polymerase II gene were phylogenetically analyzed. That analysis resolved the 48 strains examined into five closely related species: K. telluris, Candida bovina, C. pintolopesii, Candida slooffiae, and a previously unknown species. One or more strains of each of the last four species formed an ascosporic state much like that of K. telluris. To place these ascosporogenous strains taxonomically, it is proposed that they be assigned to the teleomorphic genus Kazachstania as K. bovina (type strain NRRL Y-7283, CBS 9732, from the nasal passage of a pigeon), K. heterogenica (type strain NRRL Y-27499, CBS 2675, from rodent feces), K. pintolopesii (type strain NRRL Y-27500, CBS 2985, from the peritoneal fluid of a dead guinea pig), and K. slooffiae (type strain NRRL YB-4349, CBS 9733, from the cecum of a horse). On the basis of multigene sequence analyses, K. heterogenica appears to be a hybrid of K. pintolopesii and a presently unknown species. With the exception of K. bovina, the phylogenetically defined species show a moderate degree of host specificity.

Extent of divergence in partial nucleotide sequences from large and small subunit ribosomal RNAs was used to estimate the evolutionary relationship between the genera Wingea and Debaryomyces. These data showed the monotypic genus Wingea to be congeneric with Debaryomyces, and it is proposed to transfer W. robertsii to Debaryomyces.

Species of the genera Saccharomyces, Schizosaccharomyces, Debaryomyces and Schwanniomyces were compared from their extent of divergence in three regions from small (18S) and large (25S) subunit ribosomal RNAs comprising a total of 900 nucleotides. With the exception of the closely related Saccharomyces bayanus and S. pastorianus, which appear to have identical sequences, all other species could be distinguished by nucleotide differences in a variable region of the large subunit, and genus-specific nucleotides were discernible in all three regions. The taxon D. tamarii differed markedly from other species and is excluded from Debaryomyces. By contrast, Schwanniomyces occidentalis showed few nucleotide differences with Debaryomyces spp. and its transfer to Debaryomyces is proposed. Schizosaccharomyces proved to be somewhat more divergent than Saccharomyces and Debaryomyces, but species differences appear insufficient for dividing the genus. Some of the factors influencing estimates of phylogenetic distances from rRNA sequences are discussed.