DNA barcoding analysis of more than 9 000 yeast isolates contributes to quantitative thresholds for yeast species and genera delimitation

Case report of respiratory aspergillosis and candidiasis in wild Magellanic penguins (Spheniscus magellanicus), Brazil

Magellanic penguins (Spheniscus magellanicus) migrate to the continental shelf of southern-southeastern Brazil during austral winter. Stranded penguins are directed to rehabilitation centers, where they occasionally develop fungal diseases. Aspergillosis, a mycosis caused by Aspergillus spp., is one of the most important diseases of captive penguins, while Candida sp. has been detected in penguins undergoing rehabilitation. Nevertheless, their occurrence in the wild is poorly understood. This study surveyed the occurrence of mycoses in free-ranging Magellanic penguins wintering in southeastern Brazil. These penguins were either found dead or stranded alive and died during transport to a rehabilitation center. Overall, 61 fresh to moderate autolyzed carcasses were necropsied. Upon necropsy, three juvenile males (4.9%) presented mycotic-consistent gross lesions. Histopathology and panfungal PCRs confirmed the mycoses. Major microscopic findings were marked chronic necrotizing multifocal to coalescent pneumonia, airsacculitis, and esophageal/gastric serositis with two types of intralesional fungal structures: (a) septated acute-angled branching hyphae (n = 2) and (b) yeast structures (n = 1), both PAS- and Grocott-positive. Sequences identical to Aspergillus sp. were retrieved in two cases, while the third had sequences identical to Candida palmioleophila. This study describes two cases of aspergillosis and one of candidiasis in free-ranging Magellanic penguins, confirming the species' susceptibility in the wild. These mycoses could be associated with the animals' poor body condition, and/or impaired immunity, and natural and anthropogenic challenges related to migration. To the authors' knowledge, this is the first report of aspergillosis in free-ranging Magellanic penguins in the Atlantic Ocean and of candidiasis in penguins worldwide.

What Is the Best Lens? Comparing the Resolution Power of Genome-Derived Markers and Standard Barcodes

Fungal species delimitation was traditionally carried out with multicopy ribosomal RNA (rRNA) genes, principally for their ease of amplification. Since the efficacy of these markers has been questioned, single-copy protein-encoding genes have been proposed alone or in combination for Multi-Locus Sequence Typing (MLST). In this context, the role of the many sequences obtained with Next-Generation Sequencing (NGS) techniques, in both genomics and metagenomics, further pushes toward an analysis of the efficacy of NGS-derived markers and of the metrics to evaluate the marker efficacy in discriminating fungal species. This paper aims at proposing MeTRe (Mean Taxonomic Resolution), a novel index that could be used both for measuring marker efficacy and for assessing the actual resolution (i.e., the level of separation) between species obtained with different markers or their combinations. In this paper, we described and then employed this index to compare the efficacy of two rRNAs and four single-copy markers obtained from public databases as both an amplicon-based approach and genome-derived sequences. Two different groups of species were used, one with a pathogenic species of Candida that was characterized by relatively well-separated taxa, whereas the other, comprising some relevant species of the sensu stricto group of the genus Saccharomyces, included close species and interspecific hybrids. The results showed the ability of MeTRe to evaluate marker efficacy in general and genome-derived markers specifically.

Single Strain High-Depth NGS Reveals High rDNA (ITS-LSU) Variability in the Four Prevalent Pathogenic Species of the Genus Candida

Ribosomal RNA in fungi is encoded by a series of genes and spacers included in a large operon present in 100 tandem repeats, normally in a single locus. The multigene nature of this locus was somehow masked by Sanger sequencing, which produces a single sequence reporting the prevalent nucleotide of each site. The introduction of next generation sequencing led to deeper knowledge of the individual sequences (reads) and therefore of the variants between the same DNA sequences located in different tandem repeats. In this framework, NGS sequencing of the rDNA region was used to elucidate the extent of intra- and inter-genomic variation at both the strain and species level. Specifically, the use of an innovative NGS technique allowed the high-throughput high-depth sequencing of the ITS1-LSU D1/D2 amplicons of 252 strains belonging to four opportunistic yeast species of the genus Candida. Results showed the presence of a large extent of variability among strains and species. These variants were differently distributed throughout the analyzed regions with a higher concentration within the Internally Transcribed Spacer (ITS) region, suggesting that concerted evolution was not able to totally homogenize these sequences. Both the internal variability and the SNPs between strain can be used for a deep typing of the strains and to study their ecology.

Homoplasy as an Auxiliary Criterion for Species Delimitation

Homoplasy is a sort of noise in phylogenetic reconstructions, due to the accumulation of backmutations, convergent evolution and horizontal gene transfer (HGT), which is considered the major trigger of homoplasy in microorganism for its massive presence. It is also known that homoplasy increases with the complexity of the tree with both real and simulated data. In this paper, we analyzed the variation of homoplasy with the two widely used taxonomic markers ITS and LSU in four taxonomic models characterized by differences in the intra-specific distances. An algorithm (HomoDist) was developed to analyze the homoplasy index (HI) variation upon addition of a single element (strain or species) in increasing distance from a starting element. This algorithm allows to follow changes of the consistency index (CI), complementary to the HI, with the increase of the number of taxa and with the increase of the distance among elements. Results show that homoplasy increases-as expected-with the number of taxa, but also as a function of the overall distance among species, often with an almost linear relationship between distance and HI. No HI change was observed in trees with few taxa spanning through short distances, indicating that this noise is not prohibitive in this context, although the analysis of the ratio between HI and distance can be recommended as a criterion for tree acceptance. The absence of large changes of the HI within the species, and its increase when new species are added by HomoDist, suggest that homoplasy variation can be used as an auxiliary test in distance-based species delimitation with any type of marker.

Clavispora santaluciae f.a., sp. nov., a novel ascomycetous yeast species isolated from grapes

During a study of yeast diversity in Azorean vineyards, four strains were isolated which were found to represent a novel yeast species based on the sequences of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) and of the D1/D2 domain of the large subunit (LSU) rRNA gene, together with their physiological characteristics. An additional strain isolated from Drosophila suzukii in Italy had identical D1/D2 sequences and very similar ITS regions (five nucleotide substitutions) to the Azorean strains. Phylogenetic analysis using sequences of the ITS region and D1/D2 domain showed that the five strains are closely related to Clavispora lusitaniae, although with 56 nucleotide differences in the D2 domain. Intraspecies variation revealed between two and five nucleotide differences, considering the five strains of Clavispora santaluciae. Some phenotypic discrepancies support the separation of the new species from their closely related ones, such as the inability to grow at temperatures above 35 °C, to produce acetic acid and the capacity to assimilate starch. Neither conjugations nor ascospore formation were observed in any of the strains. The name Clavispora santaluciae f.a., sp. nov., is proposed to accommodate the above noted five strains (holotype, CBS 16465^T; MycoBank no., MB 835794).

External ear canal mycobiome of some rabbit breeds

The genus Malassezia is part of the normal skin mycobiota of a wide range of warm-blooded animals. In this genus, M. cuniculi is the only species described from rabbits. However, Malassezia species are rarely studied in lagomorphs. In the present study, the presence of Malassezia was assessed in samples from the external ear canal of healthy rabbits of different breeds. Cytological and culture techniques, Sanger sequencing, and Next-generation sequencing (NGS) were used to describe the ear mycobiota in the samples. Although no growth was observed in the cultured plates, cytological examination revealed the presence of round cells similar to those of Malassezia yeasts. For metagenomics analysis, the D1/D2 domain of the large subunit of the ribosomal DNA (LSU rDNA) was PCR amplified and the resulting reads were mapped against a custom-made cured database of 26S fungal sequences. NGS analysis revealed that Basidiomycota was the most abundant phylum in all the samples followed by Ascomycota. Malassezia was the most common genus presenting the highest abundance in the external ear canal. Malassezia phylotype 131 and M. cuniculi were the main sequences detected in the external auditory canal of rabbits. The study included both lop-eared and erect-eared rabbits and no differences were observed in the results when comparing both groups. This is the first attempt to study the external ear canal mycobiome of rabbits of different breeds using NGS.

LAY SUMMARY

In the present study, the presence of Malassezia was assessed in samples from the external ear canal of healthy rabbits of different breeds. Cytological and culture techniques, Sanger sequencing, and Next-generation sequencing (NGS) were used to describe the ear mycobiota in the samples.

Yeast Biodiversity in Fermented Doughs and Raw Cereal Matrices and the Study of Technological Traits of Selected Strains Isolated in Spain

Bakers use pure microorganisms and/or traditional sourdoughs as the leavening agent for making bread. The performance of each starter and the substances produced by the microorganisms greatly affect the dough rheology and features of breads. Modern sourdoughs inoculated with selected lactic acid bacteria and yeasts are microbiologically stable, safer than traditional sourdoughs, and easy to use. However, the commercial repertoire of baker’s yeasts is still limited. Therefore, there is a demand for new strains of yeast species, capable of conferring distinctive traits to breads made from a variety of agri-food matrices, in the design of innovative starters. In this context, we report the first comprehensive study on yeasts isolated from a wide range of fermented doughs, cereal flours, and grains of Spain. Nine yeast species were identified from 433 isolates, which were distributed among separate clades. Moreover, phenotypic traits of potential technological relevance were identified in selected yeast strains. Mother doughs (MDs) showed the greatest yeast biodiversity, whereas commercial Saccharomyces starters or related and wild strains often dominated the bakery doughs. A metataxonomic analysis of wheat and tritordeum MDs revealed a greater richness of yeast species and percentage variations related to the consistency, flour type, and fermentation time of MDs.

Teunia rosae sp. nov. and Teunia rudbeckiae sp. nov. (Cryptococcaceae, Tremellales), two novel basidiomycetous yeast species isolated from flowers

Three yeast strains isolated from three flower samples were identified as representing two novel species of Teunia based on molecular phylogenetic analysis and phenotypic comparisons. Strains 12A8 and 21S4 with pink cream colonies and subglobose to globose cells had identical sequences in the ITS and LSU D1/D2 regions, which differed from strain X54 with cream colonies and ovoid to ellipsoidal cells by 6 nt substitutions (1 %) and 9 nt mismatches (1.5 %) in the D1/D2 domains and ITS region, respectively. They could also be distinguished from each other in assimilation of glucitol and salicin, growth at 28 °C and cell fibrillar appendages under scanning electron microscopy. The three strains differed from known species of Teunia by more than 8 nt (1.3 %) and 30 nt (5 %) in the D1/D2 domains and ITS region, respectively. Therefore, the names Teunia rudbeckiae sp. nov. (Holotype CGMCC 2.5840, Mycobank MB 835892) and Teunia rosae sp. nov. (Holotype CGMCC 2.5830, MycoBank MB 835891) are proposed to accommodate strain X54, and strains 12A8 and 21S4, respectively.

Draft Genome Sequence of Oleaginous Yeast Saitozyma sp. Strain JCM 24511, Isolated from Soil on Iriomote Island, Okinawa, Japan

Here, we report draft genome sequences of oleaginous yeast strain Saitozyma sp. JCM 24511, which is phylogenetically closely related to Saitozyma podzolica. These data will have implications not only for the study of the oleaginous activities of yeasts but also for the study of the plant-microorganism microbiome.

Here, we report draft genome sequence of oleaginous yeast strain Saitozyma sp. JCM 24511, which is phylogenetically closely related to Saitozyma podzolica. These data will have implications not only for the study of the oleaginous activities of yeasts but also for the study of the plant-microorganism microbiome.

Five new additions to the genus Spathaspora (Saccharomycetales, Debaryomycetaceae) from southwest China

Spathaspora is an important genus of d-xylose-fermenting yeasts that are poorly studied in China. During recent yeast collections in Yunnan Province in China, 13 isolates of Spathaspora were obtained from rotting wood and all represent undescribed taxa. Based on morphological and phylogenetic analyses (ITS and nuc 28S), five new species are proposed: Spathaspora elongata, Sp. mengyangensis, Sp. jiuxiensis, Sp. parajiuxiensis and Sp. rosae. Our results indicate a high species diversity of Spathaspora waiting to be discovered in rotting wood from tropical and subtropical southwest China. In addition, the two Candida species, C. jeffriesii and C. materiae, which are members of the Spathaspora clade based on phylogeny, are transferred to Spathaspora as new combinations.

Isolation and molecular identification of industrially important enzyme producer yeasts from tree barks and fruits

This study aimed to identify the yeast strains associated with the tree bark samples collected from the Aegean and Marmara regions and from rotten fruit samples. Fifty-one yeast strains were successfully isolated and screened for their abilities to produce industrially important extracellular enzymes. Thirty isolates demonstrated ability to produce at least two different enzymes and were selected for subsequent molecular identification using sequence analysis of ITS region and D1/D2 domain of the 26S rDNA. The most prevalent strains belonged to Papiliotrema laurentii (%23), Papiliotrema terrestris (%13) and Candida membranifaciens (%10). Papiliotrema laurentii and Papiliotrema terrestris recorded the highest enzymatic activities for all the screened enzymes. To the best of our knowledge, this is the first report that identifies the yeast strains associated with the tree barks of Turkey and among the limited comprehensive studies that screened considerable number of isolates for their ability to produce several industrially important enzymes.

Fast Recognition of Lecanicillium spp., and Its Virulence Against Frankliniella occidentalis

BACKGROUND

Frankliniella occidentalis (Thysanoptera: Thripidae) is a highly rasping-sucking pest of numerous crops. The entomogenous fungi of Lecanicillium spp. are important pathogens of insect pests, and some species have been developed as commercial biopesticides. To explore Lecanicillium spp. resources in the development of more effective F. occidentalis controls, efficient barcode combinations for strain identification were screened from internal transcribed spacers (ITS), SSU, LSU, TEF, RPB1, and RPB2 genes.

RESULTS

Six genes were used to reconstruct Lecanicillium genus phylogeny. The results showed that ITS, TEF, RPB1, and RPB2 could be used to identify the strains. All phylogenetic trees reconstructed by free combination of these four genes exhibited almost the same topology. Bioassay studies of a purified conidial suspension further confirmed the infection of second-instar nymphs and adult female F. occidentalis by seven Lecanicillium strains. L. attenuatum strain GZUIFR-lun1405 was the most virulent, killing approximately 91.67% F. occidentalis adults and 76.67% nymphs after a 7-day exposure. L. attenuatum strain GZUIFR-lun1405 and L. cauligalbarum strain GZUIFR-ZHJ01 were selected to compare the fungal effects on the number of eggs laid by F. occidentalis. The number of F. occidentalis nymphs significantly decreased when F. occidentalis adults were treated with L. cauligalbarum strain GZUIFR-ZHJ01.

CONCLUSIONS

The combination of ITS and RPB1 could be used for fast recognition of Lecanicillium spp. This is the first report of the pathogenicity of L. attenuatum, L. cauligalbarum, L araneogenum, and L. aphanocladii against F. occidentalis. Additionally, L. cauligalbarum strain GZUIFR-ZHJ01 caused high F. occidentalis mortality and inhibited the fecundity of the pest.

Candida metrosideri pro tempore sp. nov. and Candida ohialehuae pro tempore sp. nov., two antifungal-resistant yeasts associated with Metrosideros polymorpha flowers in Hawaii

Flowers produce an array of nutrient-rich exudates in which microbes can thrive, making them hotspots for microbial abundance and diversity. During a diversity study of yeasts inhabiting the flowers of Metrosideros polymorpha (Myrtaceae) in the Hawai’i Volcanoes National Park (HI, USA), five isolates were found to represent two novel species. Morphological and physiological characterization, and sequence analysis of the small subunit ribosomal RNA (rRNA) genes, the D1/D2 domains of the large subunit rRNA genes, the internal transcribed spacer (ITS) regions, and the genes encoding the largest and second largest subunits of the RNA polymerase II (RPB1 and RPB2, respectively), classified both species in the family Metschnikowiaceae, and we propose the names Candida metrosideri pro tempore sp. nov. (JK22^T = CBS 16091 = MUCL 57821) and Candida ohialehuae pro tempore sp. nov. (JK58.2^T = CBS 16092 = MUCL 57822) for such new taxa. Both novel Candida species form a well-supported subclade in the Metschnikowiaceae containing species associated with insects, flowers, and a few species of clinical importance. The ascosporic state of the novel species was not observed. The two novel yeast species showed elevated minimum inhibitory concentrations to the antifungal drug amphotericin B (>4 μg/mL). The ecology and phylogenetic relationships of C. metrosideri and C. ohialehuae are also discussed.

Savitreea pentosicarens gen. nov., sp. nov., a yeast species in the family Saccharomycetaceae isolated from a grease trap

Two strains (DMKU-GTCP10-8 and CLIB 1740) representing a novel anamorphic yeast species were isolated from a grease sample collected from a grease trap in Thailand and from an unidentified fungus collected in French Guiana, respectively. On the basis of phylogenetic analysis based on the combined D1/D2 domain of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, Lachancea fermentati CBS 707^T was the closely related species with 12.8 % sequence divergence (70 nucleotide substitutions and three gaps in 571 nucleotides) and 28.1 % sequence divergence (93 nucleotide substitutions and 90 gaps in 651 nucleotides) in the D1/D2 domain of the LSU rRNA gene and the ITS region, respectively. Phylogenetic analysis based on the concatenated sequences of the five genes including the small subunit rRNA gene, the D1/D2 domain of the LSU rRNA gene, the ITS region, translation elongation factor-1 alpha (TEF1) and RNA polymerase II subunit 2 (RPB2) genes confirmed that the two strains (DMKU-GTCP10-8 and CLIB 1740) were well-separated from other described yeast genera in Saccharomycetaceae. Hence, Savitreea pentosicarens gen. nov., sp. nov. is proposed to accommodate these two strains as members of the family Saccharomycetaceae. The holotype is S. pentosicarens DMKU-GTCP10-8^T (ex-type strain TBRC 12159=PYCC 8490; MycoBank number 835044).

Isolation of a new Papiliotrema laurentii strain that displays capacity to achieve high lipid content from xylose

In this work, we isolated and selected oleaginous yeasts from rock field soils from two National Parks in Brazil (Caparaó and Serra dos Órgãos) with the potential to accumulate oil from xylose, the main pentose sugar found in lignocellulosic biomass. From the 126 isolates, two were selected based on their lipid contents. They were taxonomically identified as Papiliotrema laurentii (UFV-1 and UFV-2). Of the two, P. laurentii UFV-1 was selected as the best lipid producer. Under unoptimized conditions, lipid production by P. laurentii UFV-1 was higher in glucose than in xylose. To improve its lipid production from xylose, we applied response surface methodology (RSM) with a face-centered central composite design (CCF). We evaluated the effects of agitation rate, initial cell biomass (OD₆₀₀), carbon/nitrogen ratio (C/N ratio) and pH on lipid production. P. laurentii UFV-1 recorded the highest lipid content, 63.5% (w/w) of the cell dry mass, under the following conditions: C/N ratio = 100:1, pH value = 7.0, initial OD₆₀₀ = 0.8 and agitation = 300 rpm. Under these optimized conditions, biomass, lipid titer and volumetric lipid productivity were 9.31 g/L, 5.90 g/L and 0.082 g/L.h, respectively. Additionally, we determined the fatty acid composition of P. laurentii UFV-1 as follows: C14:0 (0.5%), C16:0 (28.4-29.4%), C16:1 (0.2%), C18:0 (9.5-11%), C18:1 (58.6-60.5%), and C20:0 (0.7-0.8%). Based on this composition, the predicted properties of biodiesel showed that P. laurentii UFV-1 oil is suitable for use as feedstock in biodiesel production.

Convolutional neural networks improve fungal classification

Sequence classification plays an important role in metagenomics studies. We assess the deep neural network approach for fungal sequence classification as it has emerged as a successful paradigm for big data classification and clustering. Two deep learning-based classifiers, a convolutional neural network (CNN) and a deep belief network (DBN) were trained using our recently released barcode datasets. Experimental results show that CNN outperformed the traditional BLAST classification and the most accurate machine learning based Ribosomal Database Project (RDP) classifier on datasets that had many of the labels present in the training datasets. When classifying an independent dataset namely the "Top 50 Most Wanted Fungi", CNN and DBN assigned less sequences than BLAST. However, they could assign much more sequences than the RDP classifier. In terms of efficiency, it took the machine learning classifiers up to two seconds to classify a test dataset while it was 53 s for BLAST. The result of the current study will enable us to speed up the taxonomic assignments for the fungal barcode sequences generated at our institute as ~ 70% of them still need to be validated for public release. In addition, it will help to quickly provide a taxonomic profile for metagenomics samples.

Towards yeast taxogenomics: lessons from novel species descriptions based on complete genome sequences

In recent years, ‘multi-omic’ sciences have affected all aspects of fundamental and applied biological research. Yeast taxonomists, though somewhat timidly, have begun to incorporate complete genomic sequences into the description of novel taxa, taking advantage of these powerful data to calculate more reliable genetic distances, construct more robust phylogenies, correlate genotype with phenotype and even reveal cryptic sexual behaviors. However, the use of genomic data in formal yeast species descriptions is far from widespread. The present review examines published examples of genome-based species descriptions of yeasts, highlights relevant bioinformatic approaches, provides recommendations for new users and discusses some of the challenges facing the genome-based systematics of yeasts.

Description of four Apiotrichum and two Cutaneotrichosporon species isolated from guano samples from bat-inhabited caves in Japan

Four new yeast species belonging to the genus Apiotrichum and two new yeast species belonging to Cutaneotrichosporon are described for strains isolated from guano samples from bat-inhabited caves in Japan. In 2005, we reported these isolates as Trichosporon species based on sequence analyses of the D1/D2 domain of large subunit (LSU) rRNA genes according to available basidiomycetous yeast classification criteria; however, to date, they have not been officially published as new species with descriptions. Their phylogenetic positions have been reanalysed based on comparison of internal transcribed spacer (ITS) region sequences (including the 5.8S rRNA gene) and the D1/D2 domain of the LSU rRNA gene with those of known species; we confirmed clear separation from previously described species. Physiological and biochemical properties of the isolates also suggest their distinctiveness. Therefore, we describe Apiotrichum akiyoshidainum (holotype JCM 12595^T), Apiotrichum chiropterorum (JCM 12594^T), Apiotrichum coprophilum (JCM 12596^T), Apiotrichum otae (JCM 12593^T), Cutaneotrichosporon cavernicola (JCM 12590^T) and Cutaneotrichosporon middelhovenii (JCM 12592^T) as new species. C. cavernicola showed particularly distinctive morphology including large inflated anomalous cells on the hyphae and germination from the cells, although clear clamp connections on the hyphae were not confirmed. Further study is needed to elucidate the morph of this species.

Metschnikowia pulcherrima and Related Pulcherrimin-Producing Yeasts: Fuzzy Species Boundaries and Complex Antimicrobial Antagonism

Yeasts affiliated with the Metschnikowia pulcherrima clade (subclade) of the large ascomycetous genus Metschnikowia frequently turn out to produce the characteristic maroon-red pulcherrimin when tested for pigment production and prove to exert antagonistic effects on many types of microorganisms. The determination of the exact taxonomic position of the strains is hampered by the shortage of distinctive morphological and physiological properties of the species of the clade and the lack of rDNA barcode gaps. The rDNA repeats of the type strains of the species are not homogenized and are assumed to evolve by a birth-and-death mechanism combined with reticulation. The taxonomic division is further hampered by the incomplete biological (reproductive) isolation of the species: certain type strains can be hybridized and genome sequencing revealed chimeric genome structures in certain strains that might have evolved from interspecies hybrids (alloploid genome duplication). Various mechanisms have been proposed for the antimicrobial antagonism. One is related to pulcherrimin production. The diffusible precursor of pulcherrimin, the pulcherriminic acid is secreted by the cells into the environment where it forms the insoluble pulcherrimin with the ferric ions. The lack of free iron caused by the immobilization of ferric ions inhibits the growth of many microorganisms. Recent results of research into the complexity of the taxonomic division of the pulcherrimin-producing Metschnikowia yeasts and the mechanism(s) underlying their antimicrobial antagonism are discussed in this review.

Unambiguous identification of fungi: where do we stand and how accurate and precise is fungal DNA barcoding?

True fungi (Fungi) and fungus-like organisms (e.g. Mycetozoa, Oomycota) constitute the second largest group of organisms based on global richness estimates, with around 3 million predicted species. Compared to plants and animals, fungi have simple body plans with often morphologically and ecologically obscure structures. This poses challenges for accurate and precise identifications. Here we provide a conceptual framework for the identification of fungi, encouraging the approach of integrative (polyphasic) taxonomy for species delimitation, i.e. the combination of genealogy (phylogeny), phenotype (including autecology), and reproductive biology (when feasible). This allows objective evaluation of diagnostic characters, either phenotypic or molecular or both. Verification of identifications is crucial but often neglected. Because of clade-specific evolutionary histories, there is currently no single tool for the identification of fungi, although DNA barcoding using the internal transcribed spacer (ITS) remains a first diagnosis, particularly in metabarcoding studies. Secondary DNA barcodes are increasingly implemented for groups where ITS does not provide sufficient precision. Issues of pairwise sequence similarity-based identifications and OTU clustering are discussed, and multiple sequence alignment-based phylogenetic approaches with subsequent verification are recommended as more accurate alternatives. In metabarcoding approaches, the trade-off between speed and accuracy and precision of molecular identifications must be carefully considered. Intragenomic variation of the ITS and other barcoding markers should be properly documented, as phylotype diversity is not necessarily a proxy of species richness. Important strategies to improve molecular identification of fungi are: (1) broadly document intraspecific and intragenomic variation of barcoding markers; (2) substantially expand sequence repositories, focusing on undersampled clades and missing taxa; (3) improve curation of sequence labels in primary repositories and substantially increase the number of sequences based on verified material; (4) link sequence data to digital information of voucher specimens including imagery. In parallel, technological improvements to genome sequencing offer promising alternatives to DNA barcoding in the future. Despite the prevalence of DNA-based fungal taxonomy, phenotype-based approaches remain an important strategy to catalog the global diversity of fungi and establish initial species hypotheses.

Diversity and distribution of yeasts in indigenous fermented foods and beverages of Ethiopia

BACKGROUND

As one of the origin centers of domesticated plants in the world, Ethiopia is rich in diversified fermented foods and beverages, in which yeasts are usually among the essential functional microorganisms. This study aims to investigate yeast species diversity and distribution in indigenous fermented products in Ethiopia using conventional isolation and molecular identification methods.

RESULT

Yeast cell counts in 221 samples of various Ethiopian traditional fermented products, including fermented staple foods, alcoholic beverages, dairy products, and condiments, were compared using the typical dilution plating method. A total of 475 yeast isolates were recovered from these samples and 41 yeast species belonging to 25 genera were identified from yeast isolates using the sequence analysis of the D1/D2 domain of the large subunit of rRNA gene. Candida humilis, Wickerhamomyces anomalus, Meyerozyma guilliermondii, Pichia kudriavzevii, and Saccharomyces cerevisiae were the most dominant species that were widely distributed among the majority of the fermented products analyzed in the current study.

CONCLUSION

Significant variations were encountered both in yeast cell counts, diversity, and distribution of yeast species among different types of fermented products and even among different samples of the same types of fermented products. It calls for a more extensive and systematic microbiological study of Ethiopian indigenous fermented foods, beverages and other related products that can be helpful for standardization and large-scale production of these foods in Ethiopia. © 2020 Society of Chemical Industry.

Blastobotrys baotianmanensis sp. nov. and Blastobotrys xishuangbannaensis f.a., sp. nov., two novel yeast species associated with insects and rotting wood

Five yeast strains were isolated from the gut of the groundbeetle Pterostichus gebleri and rotting wood, which were collected from two different localities in China. These strains were identified as representing two novel species of the genus Blastobotrys through comparison of sequences in the D1/D2 domains of the LSU rRNA gene and other taxonomic characteristics. Blastobotrys baotianmanensis sp. nov. produces two to three spherical ascospores per ascus, and is most closely related to the type strains of B. elegans, B. capitulata, B. arbuscula, and an undescribed species represented by strain BG02-7-20-006A-3-1. Blastobotrys baotianmanensis sp. nov. differed from these strains by 3.6-8.4 % divergence (21-46 substitutions and 0-4 gaps) in the D1/D2 sequences. Blastobotrys xishuangbannaensis f.a., sp. nov. is closely related to B. nivea, B. elegans and B. aristata but the formation of ascospores was not observed on various sporulation media, and it differed from its relatives by 6.2-8.5 % divergence (34-43 substitutions and 2-6 gaps) in the D1/D2 sequences. The holotype of Blastobotrys baotianmanensis sp. nov. is NYNU 1581 and the holotype of Blastobotrys xishuangbannaensis f.a., sp. nov. is NYNU 181030.

Takashi Nakase's last tweet: what is the current direction of microbial taxonomy research?

During the last few decades, type strains of most yeast species have been barcoded using the D1/D2 domain of their LSU rRNA gene and internal transcribed spacer (ITS) region. Species identification using DNA sequences regarding conspecificity in yeasts has also been studied. Most yeast species can be identified according to the sequence divergence of their ITS region or a combination of the D1/D2 and ITS regions. Studies that have examined intraspecific diversity have used multilocus sequence analyses, whereas the marker regions used in this analysis vary depending upon taxa. D1/D2 domain and ITS region sequences have been used as barcodes to develop primers suitable for the detection of the biological diversity of environmental DNA and the microbiome. Using these barcode sequences, it is possible to identify relative lineages and infer their gene products and function, and how they adapt to their environment. If barcode sequence was not variable enough to identify a described species, one could investigate the other biological traits of these yeasts, considering geological distance, environmental circumstances and isolation of reproduction. This article is dedicated to late Dr Takashi Nakase (1939-2018).

Brazilian fungal diversity represented by DNA markers generated over 20 years

Molecular techniques using fungal DNA barcoding (ITS) and other markers have been key to identifying the biodiversity of different geographic areas, mainly in megadiverse countries. Here, we provide an overview of the fungal diversity in Brazil based on DNA markers of phylogenetic importance generated since 1996. We retrieved fungal sequences of ITS, LSU, SSU, tef1-α, β-tubulin, rpb1, rpb2, actin, chitin synthase, and ATP6 from GenBank using different field keywords that indicated their origin in Brazil. A total of 19,440 sequences were recovered. ITS is the most representative marker (11,209 sequences), with 70.1% belonging to Ascomycota, 18.6% Basidiomycota, 10.2% unidentified, 1.1% Mucoromycota, two sequences of Olpidium bornovanus (Fungi incertae sedis), one sequence of Blastocladiomycota (Allomyces arbusculus), and one sequence of Chytridiomycota (Batrachochytrium dendrobatidis). Considering the sequences of all selected markers, only the phyla Cryptomycota and Entorrhizomycota were not represented. Based on ITS, using a cutoff of 98%, all sequences comprise 3047 OTUs, with the majority being Ascomycota (2088 OTUs) and Basidiomycota (681 OTUs). Previous numbers based mainly on morphological and bibliographical data revealed 5264 fungal species from Brazil, with a predominance of Basidiomycota (2741 spp.) and Ascomycota (1881 spp.). The unidentified ITS sequences not assigned to a higher taxonomic level represent 1.61% of all ITS sequences sampled and correspond to 38 unknown class-level lineages (75% cutoff). A maximum likelihood phylogeny based on LSU illustrates the fungal classes occurring in Brazil.

Yamadazyma cocois f.a., sp. nov., an ascomycetous yeast isolated from coconuts

During studies on the endophytic yeast communities associated with fruits from Vietnam, three fermenting yeast strains were isolated from fruits of the coconut palm (Cocos nucifera). Phylogenetic analysis based on the sequences of the ITS regions and D1/D2 domains of the large subunit rRNA gene showed that these strains represented a single species of the Yamadazyma clade that was distinct from the other related species. The new species represented a basal branch of the clade formed by the Yamadazyma species i.e. Y. insecticola and Y. takamatsuzukensis. Based on the phylogenetic analysis and phenotypic characteristics, the studied strains were assigned to a novel species of the genus Yamadazyma, for which the name Yamadazyma cocois f.a., sp. nov. is proposed. The holotype is VCIM 4241, with the ex-type cultures VTCC 920004=VKM Y-3049=KBP Y-6091 code 17-68. The MycoBank number is MB 834435.

CCMetagen: comprehensive and accurate identification of eukaryotes and prokaryotes in metagenomic data

There is an increasing demand for accurate and fast metagenome classifiers that can not only identify bacteria, but all members of a microbial community. We used a recently developed concept in read mapping to develop a highly accurate metagenomic classification pipeline named CCMetagen. The pipeline substantially outperforms other commonly used software in identifying bacteria and fungi and can efficiently use the entire NCBI nucleotide collection as a reference to detect species with incomplete genome data from all biological kingdoms. CCMetagen is user-friendly, and the results can be easily integrated into microbial community analysis software for streamlined and automated microbiome studies.

Wickerhamiella osmotolerans sp. nov. and Wickerhamiella tropicalis sp. nov., novel ascomycetous yeast in the family Wickerhamiellaceae

Seven yeast strains, DMKU VGT1-14T, DMKU VGT1-19T, DMKU-JMGT1-28, DMKU-JMGT1-32, DMKU VGT2-06, DMKU VGT2-19 and DMKU VGT6-14, were isolated from a grease trap in Thailand and two strains, SJ-1 and SN-102 were isolated from the sea surface microlayer in Taiwan. On the basis of phenotypic characteristics and sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, these strains represented two novel yeast species of the genus Wickerhamiella. In terms of pairwise sequence similarity, four strains, DMKU VGT1-14, DMKU-JMGT1-32, DMKU VGT6-14 and SN-102, were closely related to Wickerhamiella infanticola NRRL Y-17858T but differed by 13 nucleotide substitutions with one gap (2.46 %) in the D1/D2 domain of the LSU rRNA gene and 15 nucleotide substitutions with 23 gaps (4.2 %) in the ITS region. The strains DMKU VGT1-19T, DMKU-JMGT1-28, DMKU VGT2-06, DMKU VGT2-19 and SJ-1, differed from the type strain of the most closely related species, Wickerhamiella sorbophila NRRL Y-7921T, by nine nucleotide substitutions with one gap (1.66 %) in the D1/D2 domain of the LSU rRNA gene and nine nucleotide substitutions with 17 gaps (2.52%) in the ITS region. Hence, the names Wickerhamiella osmotolerans sp. nov. and Wickerhamiella tropicalis sp. nov. are proposed to accommodate these species in the genus Wickerhamiella. The holotypes are W. osmotolerans DMKU VGT1-14T (ex-type strain TBRC 11425=PYCC 8359=CGMCC 2.6179; Mycobank number 833394) and W. tropicalis DMKU VGT1-19T (ex-type strain TBRC 11426=PYCC 8360=CGMCC 2.6180; Mycobank number 833393).

Species Identification in Plant-Associated Prokaryotes and Fungi Using DNA

Species names are fundamental to managing biological information. The surge of interest in microbial diversity has resulted in an increase in the number of microbes that need to be identified and assigned a species name. This article provides an introduction to the principles of DNA-based identification of Archaea and Bacteria traditionally known as prokaryotes, and Fungi, the Oomycetes and other protists, collectively referred to as fungi. The prokaryotes and fungi are the most commonly studied microbes from plants, and we introduce the most relevant concepts of prokaryote and fungal taxonomy and nomenclature. We first explain how prokaryote and fungal species are defined, delimited, and named, and then summarize the criteria and methods used to identify prokaryote and fungal organisms to species.

Hyphopichia lachancei, f.a., sp. nov., a yeast species from diverse origins

Three strains originating from insect frass in South Africa, yellow foxglove in Hungary and soil in France, were characterised phenotypically and by sequencing of the D1/D2 domain of the large subunit and the ITS1-5.8S-ITS2 (ITS)-region of the rRNA gene. The strains have identical D1/D2 domain sequences and only one strain shows a 1 bp indel in a 9 bp homopolymer A/T repeat within the ITS-region. Based on sequence analysis Hyphopichia burtonii is the closest related species. The investigated strains differ from the type strain of H. burtonii by 1.9% (9 substitutions and an indel) in the D1/D2 domain and by 23 substitutions and 21-22 indels in the ITS-region. Since the sequence variability is very low among the three strains and the sequence divergence with the closely related H. burtonii exceeds the level generally encountered between species we propose the new species Hyphopichia lachancei f.a., sp. nov. to accommodate the three novel strains. From H. burtonii the new species can be distinguished phenotypically by its inability to ferment cellobiose and by the formation of endospores (Holotype: CBS 5999^T; Isotype: NCAIM Y.02228^T; MycoBank no.: MB833616).

Diversity and phylogeny of basidiomycetous yeasts from plant leaves and soil: Proposal of two new orders, three new families, eight new genera and one hundred and seven new species

Nearly 500 basidiomycetous yeast species were accepted in the latest edition of The Yeasts: A Taxonomic Study published in 2011. However, this number presents only the tip of the iceberg of yeast species diversity in nature. Possibly more than 99 % of yeast species, as is true for many groups of fungi, are yet unknown and await discovery. Over the past two decades nearly 200 unidentified isolates were obtained during a series of environmental surveys of yeasts in phyllosphere and soils, mainly from China. Among these isolates, 107 new species were identified based on the phylogenetic analyses of nuclear ribosomal DNA (rDNA) [D1/D2 domains of the large subunit (LSU), the small subunit (SSU), and the internal transcribed spacer region including the 5.8S rDNA (ITS)] and protein-coding genes [both subunits of DNA polymerase II (RPB1 and RPB2), the translation elongation factor 1-α (TEF1) and the mitochondrial gene cytochrome b (CYTB)], and physiological comparisons. Forty-six of these belong to 16 genera in the Tremellomycetes (Agaricomycotina). The other 61 are distributed in 26 genera in the Pucciniomycotina. Here we circumscribe eight new genera, three new families and two new orders based on the multi-locus phylogenetic analyses combined with the clustering optimisation analysis and the predicted similarity thresholds for yeasts and filamentous fungal delimitation at genus and higher ranks. Additionally, as a result of these analyses, three new combinations are proposed and 66 taxa are validated.

Taxonomy of the yeast genus Vanderwaltozyma and proposal of Vanderwaltozyma meishanica sp. nov., Vanderwaltozyma huisunica sp. nov., and Vanderwaltozyma molinica sp. nov

Using electrophoretic karyotyping, RAPD fingerprinting and phylogenetic analysis of ribosomal RNA gene sequences, twenty-six Vanderwaltozyma strains were studied. Out of 19 strains isolated in mountainous areas of Taiwan, eighteen strains were isolated from soil and one strain was isolated from the fruiting body of mushroom, six were identified as V. polyspora and three as V. verrucispora. Based on the results of a multigene sequence analysis (D1/D2, ITS and mitochondrial COX II gene) and DNA-DNA reassociation, three new ascosporic members of the genus Vanderwaltozyma are formally described: V. huisunica sp. nov. (GA1S06^T = CBS 12250^T = BCRC 23260^T), V. meishanica sp. nov. (EN4S02^T = CBS 12249^T = BCRC 23255^T) and V. molinica sp. nov. (GJ8S05^T = CBS 12251^T = BCRC 23264^T), and the holotypes of these novel species are assigned as BCRC 23260^T, BCRC 23255^T and BCRC 23264^T, respectively.

Grease Waste as a Reservoir of Lipase-Producing Yeast and Description of Limtongella siamensis gen. nov., sp. nov

A total of 175 yeast isolates were obtained from grease samples. Based on the D1/D2 region of the large subunit (LSU) ribosomal RNA (rRNA) gene analysis, 150 yeast isolates were identified as belonging to 36 described yeast species, whereas 25 isolates required more analysis. Among the described species, Rhodotorula mucilaginosa was the only Basidiomycetous yeast, whereas 149 isolates were identified as belonging to 35 described species of 15 genera in the phylum Ascomycota, and Candida tropicalis was the most abundant species. A study of lipase production indicated that strain DMKU-JMGT1-45 showed volumetric activity of 38.89 ± 9.62 and 155.56 ± 14.70 U/mL when grown in yeast extract malt extract (YM) and YM supplemented with 1% olive oil, respectively. In addition, this strain intracellularly accumulated lipid, of which the fatty acid profile revealed the major fatty acids to be 39.9% oleic acid (C18:1), 27.61% palmitoleic acid (C16:1) and 14.97% palmitic acid (C16:0). A phylogenetic analysis of the combined multi-locus gene sequences showed that the strains DMKU-JMGT1-45^T and DMKU-JMGT4-14 formed a well-separated lineage and could not be assigned to any of the currently recognized genera of the Saccharomycetales. Limtongella siamensis gen. nov., sp. nov. is therefore proposed to accommodate these two strains as members of the order Saccharomycetales.

Red yeasts from leaf surfaces and other habitats: three new species and a new combination of Symmetrospora (Pucciniomycotina, Cystobasidiomycetes)

Our understanding of the systematics of red yeasts has greatly improved with the availability of sequence data and it is now clear that the majority of these fungi belong to three different classes of Pucciniomycotina (Basidiomycota): Agaricostilbomycetes, Cystobasidiomycetes, and Microbotryomycetes. Despite improvements in phylogenetic placement, the taxonomy of these fungi has long been in need of revision and still has not been entirely resolved, partly due to missing taxa. In the present study, we present data of culture-based environmental yeast isolation, revealing several undescribed species of Symmetrospora, which was recently introduced to accommodate six species previously placed in the asexual genera Sporobolomyces and Rhodotorula in the gracilis/marina clade of Cystobasidiomycetes. Based on molecular phylogenetic analyses of three rDNA loci, morphology, and biochemical studies, we formally describe the following new species: Symmetrospora clarorosea sp. nov. from leaf surfaces in Portugal and the USA; S. pseudomarina sp. nov. from leaf surfaces in Brazil, and the USA and decaying wood in the USA; and S. suhii sp. nov. from a beetle gut in the USA, leaf surfaces in Brazil and marine water in the Taiwan and Thailand. Finally, we propose a new combination for Sporobolomyces oryzicola based on our molecular phylogenetic data, Symmetrospora oryzicola comb. nov.

Dominant yeasts associated to mango (Mangifera indica) and rose apple (Syzygium malaccense) fruit pulps investigated by culture-based methods

The biotechnological potential of yeasts associated to different habitats in Colombia has been poorly studied, especially the yeasts associated with different plant structures. Fruit pulps are interesting substrates mainly for the growth of yeast species, that can positively affect the productivity and quality of some bioeconomic species. Therefore, the objective of this study was to identify the dominant yeast species associated with mango and rose apple fruit pulps in Cali, Colombia. A total of 90 isolates were obtained, which were grouped considering their colony morphology. The D1/D2 domain of the large ribosomal RNA gene (LSU rRNA gene) or internal transcribed spacer (ITS) 1, ribosomal gene 5.8S and ITS 2 (ITS) regions of one to several representative isolates from each group was sequenced and compared with type strains for identification. The species Hanseniaspora thailandica, H. opuntiae and Clavispora lusitaniae were reported as shared by both fruits, specific for rose apple (H. uvarum, Pichia terricola, Rhodosporidiobolus ruineniae and Candida albicans), or for Mango (Meyerozyma caribbica, M. guilliermondii, C. natalensis, Aureobasidium pullulans, Pichia sp., Saturnispora diversa and C. jaroonii). Two morphotypes were not identified at the taxonomic level of species and were reported as candidates for new species, belonging to the genera Wickerhamomyces and Pichia.

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.

Dynamics of the microbial community during growth of the house dust mite Dermatophagoides farinae in culture

The variation in house dust mite microbial communities is important because various microorganisms modulate the production of allergens by their mite hosts and/or contaminate immunotherapeutic extracts. Temporal changes in mite microbiomes and the mite culture environment occurring at different stages of mite culture development are particularly understudied in this system. Here, we analyzed the dynamics of microbial communities during the culture growth of Dermatophagoides farinae. Changes in microbiomes were related to three key variables: the mite population density, microbial microcosm respiration and concentration of guanine (the mite nitrogenous waste metabolite). Mite populations exhibited the following phases: exponential growth, plateau and exponential decline. The intracellular bacterium Cardinium and the yeast Saccharomyces cerevisiae prevailed in the internal mite microbiomes, and the bacterium Lactobacillus fermentum was prevalent in the mite diet. The reduction in the mite population size during the late phases of culture development was related to the changes in their microbial profiles: the intracellular bacterium Cardinium was replaced by Staphylococcus, Oceanobacillus and Virgibacillus, and S. cerevisiae was replaced by the antagonistic fungi Aspergillus penicillioides and Candida. Increases in the guanine content were positively correlated with increases in the Staphylococcus and A. penicillioides profiles in the culture environment. Our results show that the mite microbiome exhibits strong, dynamic alterations in its profiles across different mite culture growth stages.

Candida yunnanensis sp. nov. and Candida parablackwelliae sp. nov., two yeast species in the Candida albicans/Lodderomyces clade

During studies on the yeast communities associated with rotting wood in the Xishuangbanna Tropical Rainforest in PR China, four novel yeast strains were found. Phylogenetic analysis based on the concatenated sequences of the D1/D2 domains of the large subunit rRNA gene and the ITS regions showed that these strains represented two novel species in the Candida albicans/Lodderomyces clade. The novel species, represented by strains NYNU 17948 and NYNU 17981, formed a clade with Candida maltosa and Candida baotianmanensis, with 1-1.8% sequence divergence in the D1/D2 domains and 8.9-10% sequence divergence in the ITS regions. The other novel species, represented by NYNU 17105 and NYNU 17763, is most closely related to Candida blackwelliae with 0.7 % sequence divergence in the D1/D2 domains and 6.9 % sequence divergence in the ITS regions. The two novel species could be distinguished from their closest described species in terms of physiological traits. The two novel species are described as Candida yunnanensis sp. nov. (holotype NYNU 17948) and Candida parablackwelliae sp. nov. (holotype NYNU 17763).

Fungal biological resources to support international development: challenges and opportunities

Exploitation of microbes, especially fungi, has the potential to help humankind meet the UN's sustainable development goals, help feed the worlds growing population and improve bioeconomies of poorer nations. The majority of the world's fungal genetic resources are held in collections in developed countries, primarily within the USA, Europe and Japan. Very little capacity exists in low to middle income countries, which are often rich in biodiversity but lack resources to be able to conserve and exploit their own microbial resources. In this paper we review the current challenges facing culture collections and the challenges of integrating new approaches, the worth of collaborative networks, and the importance of technology, taxonomy and data handling. We address the need to underpin research and development in developing countries through the need to build 'in country' infrastructure to address these challenges, whilst tackling the global challenges to meet the requirements of the research community through the impacts of legislation and the Nagoya protocol on access to biological resources.

Wickerhamiella shivajii sp. nov., a thermotolerant yeast isolated from distillery effluent

Ethanol production at high temperatures has garnered much interest in recent years and a key factor is the availability of thermotolerant yeasts. During an investigation on the diversity of thermotolerant yeasts from different habitats, a novel yeast species from the spent wash of a distillery unit associated with a sugar factory was isolated. Phylogenetic analysis of D1/D2 large subunit and ITS rRNA genes placed this species in the ascomycetous genus Wickerhamiella. The novel species can be distinguished from the closely related species Wickerhamiella pararugosa using these rRNA gene regions. The cells of the new species are ovoid to ellipsoid with a diameter of 3.5-6.0×2.4-3.10 µm, while W. pararugosa cells are cylindrical with a cell diameter of 1.5-3.0×6-23 µm. This novel species represents, together with Wickerhamiella cacticola, one of the two most thermotolerant yeast species in the genus Wickerhamiella, able to grow at 42 °C. Wickerhamiella shivajii sp. nov. is proposed during this study.

Metschnikowia baotianmanensis f.a., sp. nov., a new yeast species isolated from the gut of the rhinoceros beetle Allomyrina dichotoma

Four strains, NYNU 15610, NYNU 15612, NYNU 15613 and NYNU 15615, of a novel ascomycetous yeast were isolated from the gut of Allomyrina dichotoma (Coleoptera: Scarabeidae) collected from two different localities in Henan Province, Central PR China. The four strains shared identical sequences in both of the D1/D2 domains of the large subunit rRNA gene and the internal transcribed spacer regions. Sequence analyses revealed that this novel species represents a member of the genus Metschnikowia. It differed from its closest known species Metschnikowia zobellii, Metschnikowiaaustralis and Metschnikowia bicuspidata, by 8.4-9.2 % sequence divergence (33-40 nt substitutions and 7-12 gaps over 509 bases) in the D1/D2 sequences. The formation of ascospores was not observed on various sporulation media. In contrast to M. zobellii, M. australis and M. bicuspidata, the novel yeast species was unable to assimilate succinate, ethanol, ethylamine, cadaverine and 10 % NaCl plus 5 % glucose, but was able to grow in vitamin-free medium. The name Metschnikowia baotianmanensis f.a., sp. nov. is proposed to accommodate these strains, with NYNU 15613 as the holotype.

Saturnispora galanensis sp. nov., a yeast species isolated from rotting wood

Three strains of a novel yeast species were isolated from rotting wood in the Xishuangbanna Tropical Rainforest, Yunnan Province, PR China. Sequence analysis of the D1/D2 domains of the large subunit rRNA gene and the internal transcribed spacer (ITS) regions showed that the novel species represents a member of the genus Saturnispora. It differed from its closest known species, Saturnispora sekii CBS 10931^T, by 1.3 % nucleotide substitutions in the D1/D2 domains and by 2.2 % nucleotide substitutions in the ITS regions, respectively. In contrast to Saturnispora sekii, the novel yeast species was unable to assimilate glycerol, dl-lactate, succinate and citrate, and grow at 37 °C. The name Saturnispora galanensis sp. nov. is proposed to accommodate these strains, with NYNU 1797 as the holotype.