Multigene phylogenetic analysis of pathogenic candida species in the Kazachstania (Arxiozyma) telluris complex and description of their ascosporic states as Kazachstania bovina sp. nov., K. heterogenica sp. nov., K. pintolopesii sp. nov., and K. slooffiae sp. nov

Abstract

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.

FIG. 1.

One of four most parsimonious trees from MP analysis of the D1 and D2 26S rRNA gene sequences from species of the K. telluris clade. Tree length = 95, consistency index = 0.853, retention index = 0.956, rescaled consistency index = 0.815, homoplasy index = 0.147. Bootstrap values ≥50% are given above the branches; and branch lengths, indicated as the number of steps, are given below the branches. Naumovia castellii was the designated outgroup species. Strains are designated by NRRL accession numbers followed by GenBank accession numbers for strains with unique DNA sequences. T, type strain of the designated Kazachstania species; TA, type strain of the previously described Candida anamorph.

FIG. 2.

One of 100 most parsimonious trees from MP analysis of mitochondrial small-subunit rRNA gene sequences from species of the K. telluris clade. Tree length = 79, consistency index = 0.924, retention index = 0.947, rescaled consistency index = 0.875, homoplasy index = 0.076. Other designations are as defined in the legend to Fig. 1. Because of sequencing difficulties, NRRL Y-27538 and NRRL Y-27546 were excluded from the analysis.

FIG. 3.

One of 100 most parsimonious trees from MP analysis of RNA polymerase II nucleotide sequences from species of the K. telluris clade. Tree length = 198, consistency index = 0.798, retention index = 0.926, rescaled consistency index = 0.739, homoplasy index = 0.202. Other designations are as defined in the legend to Fig. 1.

FIG. 4.

Comparison of divergence among type strains of species of Saccharomyces and Kazachstania from MP analysis of the D1and D2 domains of the 26S rRNA gene sequences. One of three most parsimonious trees is shown. Tree length = 126, consistency index = 0.794, retention index = 0.867, rescaled consistency index = 0.688, homoplasy index = 0.206. Other designations are as defined in the legend to Fig. 1.

FIG. 5.

(A and B) K. bovina NRRL Y-7283: (A) budding cells; (B) asci with a single ascospore, YM agar, 15 days. (C and D) K. heterogenica NRRL Y-27499: (C) budding cells; (D) ascus with an ascospore, YM agar, 25 days. (E and F) K. pintolopesii NRRL Y-27500: (E) budding cells; (F) ascus with an ascospore, YM agar, 23 days. (G to J) K. slooffiae NRRL YB-4349: (G) budding cells; (H) pseudohyphae, Dalmau plate with yeast morphology agar, 7 days, 37°C (NRRL Y-27498); (I) asci with a single ascospore, acetate agar, 22 days; (J) conjugation between two cells, acetate agar, 22 days. (K and L) K. telluris NRRL YB-4302: (K) budding cells; (L) asci with ascospores, acetate agar, 8 days. For all panels, budding cells, YM agar, 2 days, 37°C and ascospore formation, 25°C. Bar, 5 μm.