Ninety-six yeast isolates associated with dung beetles (Heliocopris bucephalus Fabricius) were examined based on a culture-dependent method. A comparison of the colony morphology and PCR-fingerprints obtained by (GTG)5 microsatellite-primed PCR indicated that 84 of these isolates belonged to one group. Five strains (DD1-1T, DD2-33, DD4-11, DD5-15 and DD6-1) were selected as the representatives of this main group, where each of the five selected strains had been derived from a different dung beetle collected in northern Thailand. A comparison of the D1/D2 domain sequence of the large subunit rRNA gene (LSU D1/D2) and the internal transcribed spacer (ITS) sequences revealed that these five strains were the same and were related to the genus Trichosporon. Phylogenetic analysis based on the LSU D1/D2 plus ITS sequences placed this group within the Trichosporon brassicae clade, but it was clearly separated from any known species. In addition, physiological tests showed that this group had the unusual property of the inability to hydrolyse urea, which was distinctly different from the related taxon. Therefore a novel yeast species named Trichosporon heliocopridis sp. nov. (ex-type strain DD1-1T = TISTR 5946T = JCM 30786T = CBS 14168T) is proposed. The MycoBank number is MB812098.
Four strains of a novel ascomycetous yeast species were isolated from flowers in Iran and China. Phylogenetic analysis of the sequences of the ITS region (including 5.8S rRNA gene) and the LSU rRNA gene D1/D2 domains indicated that these strains belong to the Starmerella clade and show divergence from previously described species in this clade. Growth reactions on carbon and nitrogen sources were similar to those observed in related species of the Starmerella clade. Sexual reproduction was not observed after mating tests on different sporulation media. Based on physiological characteristics and phylogeny of rRNA gene sequences, the novel species is most closely related to Candida (iter. nom. Starmerella) powellii and Candida (iter. nom. Starmerella) floricola. It is therefore assigned to the genus Starmerella and described as Starmerella orientalis f.a., sp. nov. The type strain is SAM09T ( = IBRC-M 30204T = CBS 14142T). The MycoBank accession number is MB 814379.
Species of the genus Prototheca are achlorophyllous algae and ubiquitous in nature, and so far, six species have been listed in this genus: Prototheca wickerhamii, Prototheca zopfii, Prototheca blaschkeae, Prototheca cutis, Prototheca stagnora and Prototheca ulmea. A strain of the genus Prototheca, IFM 53848T, was isolated in Japan from a patient with systemic protothecosis and had been designated P. wickerhamii. Our previous study, by using PCR analysis, revealed that its SSU rRNA gene (rDNA) was distinctively larger than that of P. wickerhamii and other species of the genus Prototheca. In this study, molecular analysis showed that the exceptionally large SSU rDNA of IFM 53848T contains four group I introns. The morphology of IFM 53848T was indistinguishable from those of P. wickerhamii or P. cutis, and phylogenetic analyses, based on the sequences of the SSU rDNA exons and the D1/D2 region of the large subunit rDNA, indicated that IFM 53848T was closely related to P. cutis. On the other hand, unlike P. cutis, IFM 53848T failed to assimilate fructose or lysine and grew well at higher temperatures of up to 42 °C. In addition, the nucleotide sequence of the ribosomal internal transcribed spacer and the matrix assisted laser desorption ionization time-of-flight mass spectrometry profile of IFM 53848T were clearly distinct from those of P. cutis. The results strongly suggest that IFM 53848T represents a novel species, and so the seventh member of the genus Prototheca, which we have named Prototheca miyajii sp. nov. The unique characteristics of the strain may provide useful insights into the systematic taxonomy of the genus Prototheca.