Reinstatement of the fission yeast species Schizosaccharomyces versatilis Wickerham et Duprat, a sibling species of Schizosaccharomyces japonicus.

Schizosaccharomyces japonicus Yukawa et Maki (1931) and Schizosaccharomyces versatilis Wickerham et Duprat (1945) have been treated as varieties of S. japonicus or as conspecific, based on various approaches including mating trials and nDNA/nDNA optical reassociation studies. However, the type strains of S. japonicus and S. versatilis differ by five substitutions (99.15% identity) and one 1-bp indel in the sequences of the D1/D2 domain of the 26S rRNA gene, and 23 substitutions (96.3% identity) and 31-bp indels in the sequences of internal transcribed spacer (ITS) of rRNA, suggesting that they may not be conspecific. To reassess their taxonomic status, we conducted mating trials and whole-genome analyses. Mating trials using the type strains showed a strong but incomplete prezygotic sterility barrier, yielding interspecies mating products at two orders of magnitude lower efficiency than intraspecies matings. These mating products, which were exclusively allodiploid hybrids, were unable to undergo the haplontic life cycle of the parents. We generated chromosome-level gap-less genome assemblies for both type strains. Whole genome sequences yielded an average nucleotide identity (ANI) of 86.4%, indicating clear separation of S. japonicus and S. versatilis. Based on these findings, we propose the reinstatement of S. versatilis as a distinct species (holotype strain: CBS 103T and ex-types: NRRL Y-1026, NBRC 1607, ATCC 9987, PYCC 7100; Mycobank no.: 847838).

Schizosaccharomyces lindneri sp. nov., a fission yeast occurring in honey.

Two strains of fission yeast were isolated from honey. They differ from the type strain of Schizosaccharomyces octosporus by three substitutions in the D1/D2 domain of the nuclear 26S large subunit ribosomal RNA (rRNA) gene sequence, resulting in a 99.5% identity. In the internal transcribed spacer (ITS) region (consisting of ITS1, 5.8S rDNA, and ITS2), the strains differ from S. octosporus by 16 gaps and 91 substitutions, which is equivalent to an identity of 88.1%. Genome sequencing on one of the new strains revealed that the average nucleotide identity (ANI) between its genome and the reference genome of S. octosporus is 90.43% and there exist major genome rearrangements between the two genomes. Mating analysis revealed that S. octosporus and one of the new strains are completely reproductively separated. A strong prezygotic barrier exists and the few mating products consist of diploid hybrids that do not form recombinant ascospores. In the new strains, asci are either zygotic, arising from conjugation, or they develop without conjugation from asexual cells (azygotic). Compared to the currently recognized Schizosaccharomyces species, the spectrum of nutrients that are assimilated by the new strains is restricted. Of the 43 carbohydrates that were included in the physiological standard tests, only 7 were assimilated. According to the results of the genome sequence analysis, the mating trials, and the phenotypic characterization, the new species Schizosaccharomyces lindneri is described to accommodate the two strains (holotype: CBS 18203T  and ex-type: MUCL 58363; MycoBank no.: MB 847838).

MAT heterozygosity and the second sterility barrier in the reproductive isolation of Saccharomyces species.

The genetic analysis of large numbers of Saccharomyces cerevisiae × S. uvarum ("cevarum") and S. kudriavzevii × S. uvarum ("kudvarum") hybrids in our previous studies revealed that these species are isolated by a postzygotic double-sterility barrier. We proposed a model in which the first barrier is due to the abruption of the meiotic process by the failure of the chromosomes of the subgenomes to pair (and recombine) in meiosis and the second barrier is assumed to be the result of the suppression of mating by allospecific MAT heterozygosity. While the former is analogous to the major mechanism of postzygotic reproductive isolation in plants and animals, the latter seems to be Saccharomyces specific. To bolster the assumed involvement of MAT in the second sterility barrier, we produced synthetic alloploid two-species cevarum and kudvarum hybrids with homo- and heterothallic backgrounds as well as three-species S. cerevisiae × S. kudvarum × S. uvarum ("cekudvarum") hybrids by mass-mating and examined their MAT loci using species- and cassette-specific primer pairs. We found that the allospecific MAT heterozygosity repressed MAT switching and mating in the hybrids and in the viable but sterile spores produced by the cevarum hybrids that had increased (allotetraploid) genomes. The loss of heterozygosity by meiotic malsegregation of MAT-carrying chromosomes in the latter hybrids broke down the sterility barrier. The resulting spores nullisomic for the S. uvarum chromosome produced vegetative cells capable of MAT switching and conjugation, opening the way for GARMe (Genome Autoreduction in Meiosis), the process that leads to chimeric genomes.

Assaying the effect of yeasts on growth of fungi associated with disease.

BACKGROUND: Pathogenic fungi often cause serious infections mainly in immunocompromised persons. The number of infections caused by the non-albicans Candida or other species has significantly increased over the last years. These infections present a major challenge in the health sector because these pathogenic fungi have strong virulence and often show resistance to the commonly used antifungal treatments. To solve the problems caused by the drug resistant pathogenic fungi, it is necessary to find new antifungal agents and their sources. The aim of this study was to give evidence that yeasts can effectively fight against strains which belong to pathogenic fungi and reveal those yeasts which are able to inhibit growth of Kodamaea ohmeri, Pichia kudriavzevii, Naganishia albida or Candida tropicalis. Furthermore, we wanted to determine the effects of certain culturing factors on the growth inhibition. RESULTS: Our screening revealed that although the strains belonging to pathogenic species were much more tolerant to the yeast-produced bioactive agents than the non-disease-associated yeasts, growth of Kodamaea ohmeri and Candida tropicalis could be inhibited by Metschnikowia andauensis, while Naganishia albida could be controlled by Pichia anomala or Candida tropicalis. Our data proved that the experimental circumstances could have a serious impact on the inhibitory capacity of the yeasts. Appearance of inhibition strongly depended on media, pH and temperature. Our data also shed some light on the fact that Pichia kudriavzevii must have high natural resistance to the yeast-produced agents, while other species, such as Saccharomycopsis crataegensis belonged to the easily inhibitable species. CONCLUSIONS: Our study suggests that yeast-produced bioactive agents could be potential growth inhibitory agents against the disease-associated fungi and yeasts can also contribute to alternative approaches to combat against pathogenic fungi. Our data revealed an important role of the culturing factors in inhibition and pointed to the complex nature of antagonism.

Mycosarcoma aegyptiacum sp. nov., an antagonistic polymorphic basidiomycetous yeast related to smut fungi.

Six polymorphic yeast strains with strong antifungal activities isolated from dicot plants in an alkaline-lake desert region were subjected to taxonomic examination. The phylogenetic trees reconstructed by using neighbour-joining, maximum-likelihood and Bayesian methods from concatenated D1/D2 and ITS-5.8S-ITS2 sequences revealed phylogenetic affinity to Ustilaginaceae, but the large phylogenetic distance separating the isolates from the most closely related groups of species indicates that they represent a separate species. The sequences of the genes coding for the LSU rDNA, act1, rpb2 and a protein of unknown function corroborate this position. The isolates can easily be distinguished from their closest relatives by physiological tests (utilisation of carbon and nitrogen sources). Based on these results, a new species, Mycosarcoma aegyptiacum sp. nov., is proposed to accommodate the isolates. All isolates are polymorphic. Transitions between budding-yeast and pseudohyphal morphologies which take place during colony formation result in morphologically different colony sectors and invasive growth into the medium. Neither sexual mating nor sporulation was observed in cultures growing on laboratory media.

Starmerella vitis f.a., sp. nov., a yeast species isolated from flowers and grapes.

A novel yeast species of Starmerella vitis f.a. sp. nov. is proposed to accommodate five strains isolated from flowers, grapes and an insect in the Azores, Canada, Hungary, Palau and Taiwan. As the strains were genetically distinct, we used parsimony network analysis based on ITS-D1/D2 sequences to delineate the species in a statistically objective manner. According to sequence comparisons and phylogenetic analysis, the novel species is most closely related to Starmerella lactis-condensi. The two species cannot be distinguished by conventional physiological tests. The type strain of Starmerella vitis f.a., sp. nov. is CBS 16418T; Mycobank number MB 835251.

Antagonistic yeasts from a salt-lake region in Egypt: identification of a taxonomically distinct group of phylloplane strains related to Sporisorium.

Non-pathogenic yeasts antagonising microorganisms that cause pre- and postharvest diseases of plants have been found in diverse habitats. Their practical applicability as biocontrol agents (BCAs) depends on the strength of their antagonistic activity and/or spectrum of sensitive target microorganisms. In this study, yeasts were isolated from the phylloplane and fruits of plants growing in the alkaline water lake region Wadi El-Natrun, Egypt, and tested for antifungal and antibacterial activity. All phylloplane yeast isolates belonged to the Basidiomycota and most of them could antagonise at least certain test organisms. One group of isolates showing strong antagonism against almost all fungi and yeasts appears to represent a hitherto undescribed species distantly related to the smut genus Sporisorium. This is the first report of antagonistic activity in Sporisorium. The isolates assigned to Naganishia and Papiliotrema were more effective against bacteria. The broadest range and intensity of antagonism was observed in the fruit-associated strains belonging to the ascomycetous species Wickerhamomyces subpelliculosus. The Wickerhamomyces strains are good broad-spectrum BCA candidates, the Sporisorium strains could be used as efficient antifungal BCAs, whereas the Papiliotrema isolate can be exploited as an antibacterial biocontrol agent.

Application of different markers and data-analysis tools to the examination of biodiversity can lead to different results: a case study with Starmerella bacillaris (synonym Candida zemplinina) strains.

Starmerella bacillaris (Candida zemplinina) is a genetically heterogeneous species. In this work, the diversity of 41 strains of various origins is examined and compared by the analysis of the length polymorphism of nuclear microsatellites and the RFLP of mitochondrial genomes. The band patterns are analysed with UPGMA, neighbor joining, neighbor net, minimum spanning tree and non-metric MDS algorithms. The results and their comparison to previous analyses demonstrate that different markers and different clustering methods can result in very different groupings of the same strains. The observed differences between the topologies of the dendrograms also indicate that the positions of the strains do not necessarily reflect their real genetic relationships and origins. The possibilities that the differences might be partially due to different sensitivity of the markers to environmental factors (selection pressure) and partially to the different grouping criteria of the algorithms are also discussed.

Expression pattern and phenotypic characterization of the mutant strain reveals target genes and processes regulated by pka1 in the dimorphic fission yeast Schizosaccharomyces japonicus.

The cAMP cascade plays an important role in several biological processes. Thus, study of its molecular details can contribute to a better understanding of these processes, treatment of diseases, or even finding antifungal drug targets. To gain further information about the PKA pathway, and its evolutionarily conserved and species-specific features, the central regulator pka1 gene, which encodes the cAMP-dependent protein kinase catalytic subunit, was studied in the less known haplontic, dimorphic fission yeast Schizosaccharomyces japonicus. Namely, this species belongs to a highly divergent phylogenetic branch of fungi. Furthermore, S. japonicus had only a single copy pka1 gene in contrast to the budding yeasts. Therefore, the pka1 deleted mutant was created, whose RNA sequencing and phenotypic studies revealed that the Pka1 regulated at least 373 genes, among them further kinases, phosphatases and transcriptional regulators. It regulated elongation of hyphae, cell size, aging and stress response. Furthermore, half of the pka1 target genes seemed to be conserved in Schizosaccharomyces pombe and S. japonicus. However, there were oppositely regulated genes in the two closely related species. The target genes suggest that this single gene must be able to fulfill all the functions of TPK1-3 of Saccharomyces cerevisiae. Thus, our results shed light on certain similarities and differences of the PKA pathway of S. japonicus compared to the budding yeasts and confirmed the multifunctionality of the pka1 gene, but further experiments are needed to prove its involvement in the metabolic processes and transport.

fhl1 gene of the fission yeast regulates transcription of meiotic genes and nitrogen starvation response, downstream of the TORC1 pathway.

Environmental changes, such as nutrient limitation or starvation induce different signal transducing pathways, which require coordinated cooperation of several genes. Our previous data revealed that the fhl1 fork-head type transcription factor of the fission yeast could be involved in sporulation, which was typically induced under poor conditions. Since the exact role of Fhl1 in this process was not known, we wanted to identify its downstream targets and to investigate its possible cooperation with another known regulator of sporulation. Gene expression and Northern blot analysis of the fhl1∆ mutant strain revealed the target genes involved in mating and sporulation. Our results also showed that Fhl1 could regulate nutrient sensing, the transporter and permease genes. Since the majority of these genes belonged to the nitrogen starvation response, the possible cooperation of fhl1 and tor2 was also investigated. Comparison of their microarray data and the expression of fhl1 + from a strong promoter in the tor2-ts mutant cells suggested that one part of the target genes are commonly regulated by Fhl1 and Tor2. Since the expression of fhl1 + from a strong promoter could rescue rapamycin and temperature sensitivity and suppressed the hyper-sporulation defect of the tor2-ts mutant cells, we believe that Fhl1 acts in TOR signaling, downstream of Tor2. Thus, this work shed light on certain novel details of the regulation of the sexual processes and a new member of the TOR pathway, but further experiments are needed to confirm the involvement of Fhl1 in nutrient sensing.

Schizosaccharomyces pombe rsv1 Transcription Factor and its Putative Homologues Preserved their Functional Homology and are Evolutionarily Conserved.

Environmental glucose is an important regulator of biological processes, as it can launch different cell processes depending on its concentration. Thus, low glucose concentration can induce entry into quiescence, which ensures long-term viability for the cells or in other cases mycelial growth in the dimorphic species, which, in turn, provides the cells with fresh nutrients. Several genes, such as the genes of cAMP cascade, are involved in glucose sensing and response. Since this signal transduction pathway seemed to be an evolutionarily conserved process, we assumed that its genes were also conserved and preserved their functional homology. To obtain evidence, Schizosaccharomyces pombe rsv1 and its orthologous genes were investigated using in silico and experimental approaches. Our results supported that the Rsv1 zinc-finger transcription factors of Schizosaccharomyces japonicus and Schizosaccharomyces octosporus and the Candida albicans cas5p were really functional homologues of the S. pombe Rsv1. Namely, the homologous proteins were able to restore mutant phenotype of the S. pombe rsv1-deleted cells. Bioinformatic anaysis revealed that the most conserved parts of the proteins always contained the C2H2 domains and the complementation abilities of the counterpart genes were not uniform regarding the investigated features, which can be in connection with the conserved regions outside C2H2.

Complete genome sequence and transcriptome regulation of the pentose utilizing yeast Sugiyamaella lignohabitans.

Efficient conversion of hexoses and pentoses into value-added chemicals represents one core step for establishing economically feasible biorefineries from lignocellulosic material. While extensive research efforts have recently provided advances in the overall process performance, the quest for new microbial cell factories and novel enzymes sources is still open. As demonstrated recently the yeast Sugiyamaella lignohabitans (formerly Candida lignohabitans) represents a promising microbial cell factory for the production of organic acids from lignocellulosic hydrolysates. We report here the de novo genome assembly of S. lignohabitans using the Single Molecule Real-Time platform, with gene prediction refined by using RNA-seq. The sequencing revealed a 15.98 Mb genome, subdivided into four chromosomes. By phylogenetic analysis, Blastobotrys (Arxula) adeninivorans and Yarrowia lipolytica were found to be close relatives of S. lignohabitans Differential gene expression was evaluated in typical growth conditions on glucose and xylose and allowed a first insight into the transcriptional response of S. lignohabitans to different carbon sources and different oxygenation conditions. Novel sequences for enzymes and transporters involved in the central carbon metabolism, and therefore of potential biotechnological interest, were identified. These data open the way for a better understanding of the metabolism of S. lignohabitans and provide resources for further metabolic engineering.

Candida vulturna pro tempore sp. nov., a dimorphic yeast species related to the Candida haemulonis species complex isolated from flowers and clinical sample.

In a taxonomic study of yeasts isolated from flowers in Cagayan de Oro, Mindenao Island, The Philippines, strains were identified as representing Kabatiella microsticta, Metschnikowia koreensis and a hitherto undescribed dimorphic species. Sequences of the D1/D2 domains of the LSU 26S rRNA genes, the internal transcribed spacer (ITS) regions and the SSU 18S rRNA genes were identical in the strains of the last-named group and differed from the corresponding sequences of the type strain of the closest related species, Candida duobushaemulonii, by 4 % (D1/D2), 7 % (ITS) and 1 % (SSU). In an independent study, a strain with D1/D2 and ITS sequences very similar to those of the Philippine strains was isolated in Malaysia from the blood of a patient dying of aspiration pneumonia. Both groups of isolates were moderately sensitive to anidulafungin, caspofungin, fluconazole, itraconazole and voriconazole but resistant to amphotericin B. Molecular phylogenetic analysis of the sequences placed the Philippine and Malaysian isolates close to the Candida haemulonis complex of Candida species. To reflect the geographical location of the sites of sample collection, the novel species name Candida vulturna pro tempore sp. nov. is proposed to accommodate these strains. The type strain is 11-1170T (=CBS 14366T=CCY 094-001-001T=NCAIM-Y02177T) isolated in Cagayan de Oro, The Philippines. Mycobank: MB 817222.

Wickerhamomyces orientalis f.a., sp. nov.: an ascomycetous yeast species belonging to the Wickerhamomyces clade.

Five closely related yeast strains were isolated from soil in Kharg Island, Persian Gulf, Iran, and from fallen fruits in Galle, Sri Lanka, during separate projects. Morphologically, the strains produced white-coloured yeast colonies, with cells that were ovoid to ellipsoidal, making branched, true hyphae and pseudohyphae. Ascospore formation was not observed. Biochemically, the strains were able to ferment d-glucose and weakly ferment d-galactose. The strains could use a wide variety of carbon sources except methanol and hexadecane. Phylogenetic analyses using combined sequences of the small ribosomal subunit and the D1/D2 domains of the LSU, as well as the internal transcribed spacer regions, suggested that these strains belong to the Wickerhamomyces clade and that together they form one strongly supported phylogenetic clade. Differences in their sequences, biochemistry and morphology suggest they are representatives of distinct species of the genus Wickerhamomyces. Therefore, the name Wickerhamomyces orientalis f.a., sp. nov. is proposed to accommodate these novel strains; the type strain is IBRC-M 30103T (=CBS 13306T). The MycoBank number is MB 807323.

Metahyphopichia laotica gen. nov., sp. nov., a polymorphic yeast related to Hyphopichia.

Four strains alternating between yeast and filamentous growth morphologies were isolated from flowers in two regions of Laos. In liquid environment the isolates propagated by budding and developed irregularly shaped pseudohyphae. On solid media, their yeast cells switched to hyphal growth which could return to the yeast phase by developing lateral blastoconidia. The sequences of the D1/D2 domains of the large subunit (LSU) 26S rRNA genes, the internal transcribed spacer (ITS) regions and the small subunit (SSU) 18S rRNA genes were identical in the four strains and differed from the corresponding sequences of other yeast species available in databases by at least 11 % (D1/D2), 13 % (ITS) and 7 % (SSU). In an independent project, two strains with D1/D2 and ITS sequences very similar to those of the Laotian strains were found in bark samples collected in Brazil. The six strains also differed from the closest yeast species in physiological properties, indicating that they represented a hitherto undescribed species. Phylogenetic analysis of the D1/D2 sequences, and the concatenated sequences of the SSU rRNA genes, D1/D2 domains of LSU rRNA genes as well as the protein-encoding genes ACT1 and TEF1 placed thestrains close to Hyphopichia. To reflect this position, the novel genus name Metahyphopichia gen. nov. and the novel species name Metahyphopichia laotica gen. nov., sp. nov. are proposed for them. The type strain of the type species is 11-1006T(=CBS 13022T=CCY 092-001-001T=NCAIM Y.02126T) and was isolated in Luang Prabang (Laos). MycoBank registration numbers are MB 808253 (Metahyphopichia) and MB 808254 (Metahyphopichia laotica).

Genotypic and phenotypic evolution of yeast interspecies hybrids during high-sugar fermentation.

The yeasts of the Saccharomyces genus exhibit a low pre-zygotic barrier and readily form interspecies hybrids. Following the hybridization event, the parental genomes undergo gross chromosomal rearrangements and genome modifications that may markedly influence the metabolic activity of descendants. In the present study, two artificially constructed hybrid yeasts (Saccharomyces cerevisiae x Saccharomyces uvarum and S. cerevisiae x Saccharomyces kudriavzevii) were used in order to evaluate the influence of high-sugar wine fermentation on the evolution of their genotypic and phenotypic properties. It was demonstrated that the extent of genomic modifications differs among the hybrids and their progeny, but that stress should not always be a generator of large genomic disturbances. The major genome changes were observed after meiosis in the F1 segregants in the form of the loss of different non-S. cerevisiae chromosomes. Under fermentation condition, each spore clone from a tetrad developed a mixed population characterized by different genotypic and phenotypic properties. The S. cerevisiae x S. uvarum spore clones revealed large modifications at the sequence level of the S. cerevisiae sub-genome, and some of the clones lost a few additional S. cerevisiae and S. uvarum chromosomes. The S. cerevisiae x S. kudriavzevii segregants were subjected to consecutive loss of the S. kudriavzevii markers and chromosomes. Both the hybrid types showed increased ethanol and glycerol production as well as better sugar consumption than their parental strains. The hybrid segregants responded differently to stress and a correlation was found between the observed genotypes and fermentation performances.

First isolation of Candida wangnamkhiaoensis from the blood of immunocompromised paediatric patient.

Candida wangnamkhiaoensis is a species clustered under the Hyphopichia clade has not ever been isolated from any clinical specimens. To the best of our knowledge, this is the first report of C. wangnamkhiaoensis associated with fungaemia in immunocompromised paediatric patient. The isolate was assigned a strain name as UZ1679/14, in which the identification was confirmed by a polymerase chain reaction-sequencing of the internal transcribed spacer (ITS) and large subunit (LSU) regions of the rRNA gene. Antifungal susceptibility pattern showed that the isolate was sensitive to anidulafungin, caspofungin, fluconazole and voriconazole. The patient clinically improved after the antifungal treatment with caspofungin.

The yeast Starmerella bacillaris (synonym Candida zemplinina) shows high genetic diversity in winemaking environments.

The yeast Candida zemplinina (Starmerella bacillaris) is frequently isolated from grape and wine environments. Its enological use in mixed fermentation with Saccharomyces cerevisiae has been extensively investigated these last few years, and several interesting features including low ethanol production, fructophily, glycerol and other metabolites production, have been described. In addition, molecular tools allowing the characterization of yeast populations have been developed, both at the inter- and intraspecific levels. However, most of these fingerprinting methods are not compatible with population genetics or ecological studies. In this work, we developed 10 microsatellite markers for the C. zemplinina species that were used for the genotyping of 163 strains from nature or various enological regions (28 vineyards/wineries from seven countries). We show that the genetic diversity of C. zemplinina is shaped by geographical localization. Populations isolated from winemaking environments are quite diverse at the genetic level: neither clonal-like behaviour nor specific genetic signature were associated with the different vineyards/wineries. Altogether, these results suggest that C. zemplinina is not under selective pressure in winemaking environments.

Hannaella siamensis sp. nov. and Hannaella phetchabunensis sp. nov., two new anamorphic basidiomycetous yeast species isolated from plants.

Eight strains, representing two novel anamorphic yeast species, consisted of five strains isolated from the external surfaces of rice leaves (DMKU-RP72(T), DMKU-RP109, DMKU-RP119, YE-124 and YE-156) and one from a corn leaf (DMKU-CP430(T))4 collected in Thailand, and one strain isolated from each of a composite flower (11-1114) and a fallen dead leaf (12-301); the latter two were collected in Belize. On the basis of sequence analysis of the D1/D2 region of the large subunit rRNA gene and the internal transcribed spacer (ITS) region, they were suggested to be two novel species of the genus Hannaella. Seven strains (DMKU-RP72(T), DMKU-RP109, DMKU-RP119, YE-124, YE-156, 11-1114 and 12-301) differed from each other by 0-3 nt substitutions in the D1/D2 region and by 0-1 nt substitutions in the ITS region. In terms of pairwise sequence similarities of the D1/D2 region these seven strains were closest to Hannaella zeae, but with 1.2-1.7% (7-9) nucleotide substitutions. The sequences of the ITS region of these seven strains differed from H. zeae by 3.7-3.9% (16-17) nucleotide substitutions. Therefore, they were assigned to a single novel species and the name Hannaella siamensis sp. nov. has been proposed. The type strain is DMKU-RP72(T) ( = BCC 69493(T) = NBRC 110425(T) = CBS 13533(T)). Strain DMKU-CP430(T) represents the second novel species and was also most closely related to H. zeae, but with 1.0% (6) nucleotide substitutions in the D1/D2 region and 3.2% (14) nucleotide substitutions in the ITS region. It was assigned to the proposed novel species, Hannaella phetchabunensis sp. nov. (type strain DMKU-CP430(T) = BCC 69492(T) = NBRC 110424(T) = CBS 13386(T)).

Starmerella syriaca f.a., sp. nov., an osmotolerant yeast species isolated from flowers in Syria.

Four strains of a novel asexual ascomycetous yeast species were isolated from Malva sp. flowers in Syria. Sequencing of the regions spanning the small subunit, 5.8S, and the D1/D2 domains of the large subunit ribosomal RNA genes showed that the isolates were conspecific. Comparative analysis of these sequences and the corresponding sequences of the type strains of ascomycetous yeasts revealed that the novel species is phylogenetically related to members of the Starmerella clade. Its closest relative is Candida vaccinii. For the new species the name Starmerella syriaca is proposed. Its strains are osmotolerant and produce pseudohypha-like structures capable of penetrating agar media. The type strain is 2-1362(T) (=CBS 13909(T) = NCAIM Y.02138(T) = CCY 090-003-001(T)). The GenBank accession numbers for its nucleotide sequences are: JX515986 (D1/D2 LSU), JX515987 (ITS1-5.8S-ITS2) and JX515988 (SSU). Mycobank: MB 810090.