Teleomorphic Yeast Research Articles

Molecular phylogenetic analysis reveals the new genus Hemisphaericaspora of the family Debaryomycetaceae.

Four strains of a novel ascomycetous yeast species were recovered from the frass of wood-boring beetles collected from the Baotianman Nature Reserve and the Laojieling Nature Reserve in Henan Province, China. This species produced unconjugated and deliquescent asci with hemispheroid or helmet-shaped ascospores. Analysis of gene sequences for the D1/D2 domain of the large subunit (LSU) rRNA, as well as analysis of concatenated gene sequences for the nearly complete small subunit (SSU) rRNA and D1/D2 domain of the large subunit (LSU) rRNA placed the novel species in a small clade including only one recognised species, Candida insectamans, in the family Debaryomycetaceae (Saccharomycotina, Ascomycota). DNA sequence analyses demonstrated that the novel species was distinct from all currently recognised teleomorphic yeast genus. The name Hemisphaericaspora nanyangensis gen nov., sp. nov. is proposed to accommodate the novel genus and species. The new genus can be distinguished from closely related teleomorphic genera Lodderomyces and Spathaspora through sequence comparison and ascospore morphology. The ex-type strain of H. nanyangensis is CBS 13020T ( = CICC 33021 = NYNU 13717). Furthermore, based on phenotypic and genotypic characteristics, C. insectamans is transferred to the newly described genus as Hemisphaericaspora insectamans comb. nov., in accordance with the changes in the International Code of Nomenclature for algae, fungi and plants.

Diddensiella caesifluorescens gen. nov., sp. nov., a riboflavin-producing yeast species of the family Trichomonascaceae

Four strains of a novel heterothallic yeast species were isolated from rotten wood collected in or near the Pilis Mountains in Hungary. The strains produced riboflavin in liquid culture. Analysis of gene sequences for the D1/D2 domains of the LSU nuclear rRNA, as well as analysis of concatenated gene sequences for the D1/D2 nuclear LSU rRNA, mitochondrial SSU rRNA and cytochrome oxidase II placed the novel species in a small clade including only two recognized species, Candida santjacobensis and Candida transvaalensis, in the family Trichomonascaceae. DNA sequence analyses demonstrated that the novel species was distinct from all currently recognized teleomorphic yeast genera. The name Diddensiella caesifluorescens gen nov., sp. nov. is proposed to accommodate the novel genus and species. The new genus proposed here can be recognized only from gene sequence analysis, because the characters of its asexual reproduction and ascospore formation are shared by several members of the genera Trichomonascus, Sugiyamaella and Spencermartinsiella. The type and isotype strains of D. caesifluorescens are NCAIM Y.01949(T) ( = NRRL Y-48781(T) = CBS 12613(T)) and NCAIM Y.01956(I) ( = NRRL Y-48782(I) = CBS 12614(I)), respectively. In view of their close relatedness to D. caesifluorescens, C. santjacobensis and C. transvaalensis are transferred to the genus Diddensiella as new combinations in accordance with changes in the International Code of Nomenclature for algae, fungi and plants.

Molecular characterization of carotenogenic yeasts from aquatic environments in Patagonia, Argentina.

Fifteen aquatic environments (lakes, lagoons and rivers) of glacial origin in the northern Andean Patagonia (Argentina) were surveyed for the occurrence of red yeasts. Subsurface water samples were filtered and used for colony counting and yeast isolation. A preliminary quantitative analysis indicated that total yeast counts ranged between 0 and 250 cells l(-1). A polyphasic approach including physiological and molecular methods was used for the identification of 64 carotenogenic yeast strains. The molecular characterisation of the isolates was based on the mini/microsatellite-primed PCR technique (MSP-PCR) employing the (GTG)5 and the M13 primers. Comparison of representative fingerprints of each group with those of the type strains of pigmented yeasts allowed the expeditious identification of 87.5% isolates. The sequence analysis of the D1/D2 domains of the 26S rDNA was employed to confirm identifications and in the characterization of the unidentified MSP-PCR groups. Teleomorphic yeast species were detected by performing sexual compatibility assays. The isolates corresponded to 6 genera and 15 yeast species, including four new yeast species of the genera Cryptococcus (1), Rhodotorula (1) and Sporobolomyces (2). Rhodotorula mucilaginosa was found in the majority of the samples and represented ca. 50% of the total number of isolates. However, this yeast was not detected in aquatic environments with very low anthropic influence. Other frequent yeast isolates were teleomorphic yeast species of Rhodosporidium babjevae, R. kratochvilovae and Sporidiobolus salmonicolor. This study represents the first report on red yeast occurrence and biodiversity in northwestern Patagonia.

Three distinct genotypes within Candida parapsilosis from clinical sources

Three genetically distinct groups of Candida parapsilosis were detected among clinical isolates. These were distinguishable on the basis of isoenzyme profiles and DNA sequences of internally transcribed spacer (ITS) sequences flanking the 5.8S RNA gene. In an investigation of 45 strains, including 32 clinical isolates from Texas, C. parapsilosis group I composed the majority of the common clinical isolates. The type strain of C. parapsilosis was a member of this group. The 10 group II isolates were indistinguishable from group I strains when tested with the API 20C kit. The two group III isolates differed from those in groups I and II by being D-xylitol positive by the API 20C kit; however, isolates in all groups assimilated D-xylitol from broth. Isoenzyme profiles excluded the close relationship of any of these groups to Lodderomyces elongisporus, which is a teleomorphic yeast that has a physiological profile similar to that of C. parapsilosis. Although there were insignificant differences in the ITS2 rDNA sequences, comparisons of the ITS1 sequences revealed several differences. A sequence analysis of ITS1 in which missing bases were counted as mismatches showed the following similarities: group I versus group II, 87.7%; group I versus group III, 82.1%; group II versus group III, 84.5%. Also, the activity of secreted proteinase showed differences among the three groups, with many group I isolates having moderate to high activity. The degree of susceptibility to antifungal agents, amphotericin B, ketoconazole, and 5-fluorocytosine, could not be used to determine an isolate's group.

Resolutive Candida utilis fungemia in a nonneutropenic patient

We report here the second case of Candida utilis infection in humans. The patient was apparently immunocompetent, had no central catheter, and survived an 8-day fungemia. Genomic analysis confirmed the conspecificity of medical and industrial strains of C. utilis and that of the anamorphic yeast C. utilis with the teleomorphic yeast Pichia jadinii.

The molecular phylogeny of the Q10-equipped species of the heterobasidiomycetous yeast genus Rhodosporidium Banno based on the partial sequences of 18S and 26S ribosomal ribonucleic acids.

Twelve strains of the Q10-equipped species of the teleomorphic yeast genus Rhodosporidium and the anamorphic yeast genus Rhodotorula were examined for the partial sequences of 18S and 26S rRNAs. In the positions 492 through 625 of 26S rRNA, the strains of R. kratochvilovae, R. paludigenum, R. diobovatum, R. sphaerocarpum, and Rh. graminis were linked at 71% or more maximum homologies to the type species of the genus Rhodosporidium (R. toruloides). Rhodosporidium dacryoidum constituted its own separate cluster (66% maximum homology). In the positions 1451 through 1618 of 18S rRNA, the strains of the above-mentioned species were divided into two clusters. The first cluster included R. kratochvilovae, R. paludigenum, R. diobovatum, R. sphaerocarpum, and Rh. graminis (within 0 or 2 base differences), and the second cluster included the only species, R. dacryoidum (11 base differences). These results indicate that R. dacryoidum should be classified in a separate new genus.

Significance of the coenzyme Q system in the classification of yeasts and yeast-like organisms. Part XXXIII. The phylogenetic relationship of the conidium-forming anamorphic yeast genera Sterigmatomyces, Kurtzmanomyces, Tsuchiyaea and Fellomyces, and the teleomorphic yeast genus Sterigmatosporidium on the basis of the partial sequences of 18S and 26S ribosomal ribonucleic acids.

The eleven strains of conidium-forming yeasts classified in the basidiomycetous anamorphic genera Sterigmatomyces, Kurtzmanomyces, Tsuchiyaea and Fellomyces, and the teleomorphic genus Sterigmatosporidium were examined as to the partial sequences of 18S rRNA and 26S rRNA. The positions determined (in Saccharomyces cerevisiae) were 1451 through 1618 of 18S rRNA, and 1618 through 1835 and 470 through 626 of 26S rRNA. The partial sequence determination of positions 470 through 626 of 26S rRNA indicated that T. wingfieldii should be included in the group comprised of Fellomyces and Sterigmatosporidium species. However, the genera Sterigmatomyces, Kurtzmanomyces, Tsuchiyaea and Fellomyces constituted their own separate clusters as to the partial sequences of positions 1451 through 1618 of 18S rRNA and 1618 through 1835 of 26S rRNA. The classification of the conidium-forming yeasts in the four basidiomycetous anamorphic genera mentioned above was proved to be reasonable from the phylogenetic point of view.

The electrophoretic comparison of enzymes in strains of species in the anamorphic yeast genera Sterigmatomyces and fellomyces and in the teleomorphic yeast genus Sterigmatosporidium.

A taxonomic study below the generic or at the specific level was made of the electrophoretic pattern of seven enzymes in Sterigmatomyces, Fellomyces, and Sterigmatosporidium species. The seven enzymes were glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase, hexokinase, phosphoglucomutase, and catalase. All examined strains of S. elviae, S. halophilus (≡S. indicus), and S. polymorphum gave a uniform electrophoretic enzyme pattern within the respective species. Four strains of S. halophilus and three strains of S. halophilus (≡S. indicus) were linked to each other with a similarity value of 43%. The similarity value between S. elviae and S. halophilus was calculated to be only 14%. The three Fellomyces species, F. nectairei, F. penicillatus, and F. polyborus and S. tursiopsis had quite different electrophoretic enzyme patterns. Their similarity values were all 0%. Between F. nectairei and S. polymorphum, the similarity value was only 14%. These data are discussed from the taxonomic point of view.