Exophiala amphawaensis sp. nov., a novel black yeast isolated from the gut of amphipods in Thailand.

The genus Exophiala is polymorphic, able to transition between yeast, hyphal and pseudohyphal forms. Species of the genus Exophiala are ubiquitous fungi that are distributed in various environments around the world. During a survey of fungal diversity in the gut of amphipods (Floresorchestia amphawaensis and undescribed Dogielinotid amphipods) from the Amphawa estuary, Samut Songkhram province, Thailand, five black yeast strains (DMKU-MG01, DMKU-MG07, DMKU-MG08, DMKU-HG10 and DMKU-FG04) were identified as representing a novel taxon on the basis of a combination of morphological and molecular phylogenetic features. The five strains did not produce filamentous hyphae or pseudohyphae. Only budding yeast cells were observed. On the basis of the phenotypic characteristics and the results of molecular analyses of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, the five strains were identified as representing a novel species via applied nucleotide pairwise analysis. They differed from the most closely related species Exophiala alcalophiala by 3.54 % nucleotide substitutions (20 nucleotide substitutions in 572 bp) in the D1/D2 domains of the LSU rRNA gene. Moreover, the sequences of the ITS region of the five strains differed from those of the most closely related species E. alcalophiala, by 7.44-9.62 % nucleotide substitutions, and Exophiala halophiala, by 7.2-7.53 % nucleotide substitutions. The results of phylogenetic analyses based on the concatenated sequences of the ITS regions and the D1/D2 domains of the LSU rRNA gene confirmed that the five black yeast strains represented a single novel species of the genus Exophiala. In this study, Exophiala amphawaensis sp. nov. is proposed to accommodate these strains. The holotype is TBRC 15626T and the isotype is PYCC9020. The MycoBank accession number of the novel species is MB 851477.

Savitreea siamensis sp. nov., an ascomycetous yeast species in the family Saccharomycetaceae discovered in Thailand.

Four yeast strains, representing a novel anamorphic species, were isolated in Thailand. The two strains (ST-3660T and ST-3647) were obtained from two different estuarine water samples in a mangrove forest. Strain DMKU-FW1-37 was derived from a grease sample, and another strain (TSU57) was isolated from a fruiting body of Phallus sp. Pairwise sequence analysis showed that the four strains had identical or differed by only one nucleotide substitution in the D1/D2 domains of the large subunit (LSU) rRNA gene, and differed by one to three nucleotide substitutions in the internal transcribed spacer (ITS) regions. Savitreea pentosicarens is the most closely related species to the four strains, but with 9-10 (1.57-1.72 %) nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and 29-31 (4.22-4.45 %) nucleotide substitutions in the ITS regions. Phylogenetic analyses based on the concatenated sequences of the ITS regions and the D1/D2 domains of the LSU rRNA gene showed that the four strains form a well-separated lineage from S. pentosicarens with high bootstrap support, confirming that they represent a distinct species. Therefore, the four strains are assigned as representives of a novel species of the genus Savitreea, for which the name Savitreea siamensis sp. nov. is proposed. The holotype is TBRC 4481T and the ex-type is PYCC 9794T (=ST-3660T). The MycoBank number of the novel species is MB 851951.

Phylogenomic delineation of two new species of ascomycetous yeasts, Wickerhamiella koratensis sp. nov. and Wickerhamiella limtongiae sp. nov., and proposal of two synonyms, Wickerhamiella infanticola and Wickerhamiella tropicalis.

Two novel ascomycetous yeast species of the genus Wickerhamiella are proposed based on isolates obtained in Thailand from food waste and the fruiting body of a polypore fungus, and on a combination of conventional DNA-barcode sequence analyses and whole-genome phylogenies. We focus on a particular subclade of the genus Wickerhamiella that contains species found in anthropic environments and describe Wickerhamiella limtongiae sp. nov. (DMKU-FW31-5T=PYCC 9022T=TBRC 15055T), found on food waste samples. In an adjacent clade, we describe Wickerhamiella koratensis sp. nov. (DMKU-KO16T=PYCC 8908T=TBRC 14869T), which represents the closest relative of Wickerhamiella slavikovae and was isolated from the fruiting body of Bjerkandera sp. In the subclade of W. limtongiae sp. nov., we propose that Wickerhamiella infanticola should be regarded as a synonym of Wickerhamiella sorbophila and that Wickerhamiella tropicalis should be regarded as a synonym of Wickerhamiella verensis.

Yamadazyma sisaketensis f.a., sp. nov. and Yamadazyma koratensis f.a., sp. nov., two novel ascomycetous yeast species from mushrooms and cocoa leaves in Thailand, and reassignment of Candida andamanensis, Candida jaroonii and Candida songkhlaensis to the genus Yamadazyma.

Six strains representing two novel ascomycetous yeast species were isolated from mushroom fruiting bodies and cocoa leaves collected in Thailand. Analysis of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit rRNA gene sequences showed that the six strains were divided into two groups. The first group consisted of four strains (DMKU-SSK46, DMKU-SK1, SCCL3-5 and SCCL19-3), that were closely related to the type strains of Candida conglobata, Candida insectorum, Yamadazyma dushanensis, Yamadazyma mexicana and Yamadazyma riverae, but with 12-14 (2.5-2.9 %) and 28-50 (5.4-8.8 %) nucleotide substitutions in the D1/D2 domains and the ITS regions, respectively. However, two strains (DMKU-KMY40 and DMKU-KO18) of the second group differed from a group of described species, Candida diddensiae, Candida dendronema, Candida germanica, Candida kanchanaburiensis, Candida naeodendra, Candida vaughaniae and Yamadazyma siamensis by 8-15 (1.5-2.8 %) and 45-53 (8.2-9.6 %) nucleotide substitutions in the D1/D2 domains and the ITS regions, respectively. Phylogenetic analysis based on the concatenated sequences of the ITS regions and D1/D2 domains showed that these strains represented two species of the Yamadazyma clade that were distinct from the other related species. Based on the phylogenetic analysis and phenotypic characteristics, these six strains were assigned to two novel species of the genus Yamadazyma, although formation of ascospores was not observed. Yamadazyma sisaketensis f.a., sp. nov., is proposed for the first group (four strains). The holotype is TBRC 17139T (ex-type culture: PYCC 9797). The MycoBank number is MB 849637. Yamadazyma koratensis f.a., sp. nov. is proposed for the second group (two strains). The holotype is TBRC 14868T (ex-type culture: PYCC 8907). The MycoBank number is MB 849638. In addition, it is proposed that Candida andamanensis, Candida jaroonii and Candida songkhlaensis are reassigned to the genus Yamadazyma as Yamadazyma andamanensis comb. nov., Y. jaroonii comb. nov. and Y. songkhlaensis comb. nov., respectively.

Diversity of duckweed (Lemnaceae) associated yeasts and their plant growth promoting characteristics.

The diversity of duckweed (Lemnaceae) associated yeasts was studied using a culture-dependent method. A total of 252 yeast strains were isolated from 53 duckweed samples out of the 72 samples collected from 16 provinces in Thailand. Yeast identification was conducted based on the D1/D2 region of the large subunit (LSU) rRNA gene sequence analysis. It revealed that 55.2% and 44.8% yeast species were Ascomycota and Basidiomycota duckweed associated yeasts, respectively. Among all, Papiliotrema laurentii, a basidiomycetous yeast, was found as the most prevalent species showing a relative of frequency and frequency of occurrence of 21.8% and 25%, respectively. In this study, high diversity index values were shown, indicated by the Shannon-Wiener index (H'), Shannon equitability index (EH) and Simpson diversity index (1-D) values of 3.48, 0.86 and 0.96, respectively. The present results revealed that the yeast community on duckweed had increased species diversity, with evenness among species. Principal coordinate analysis (PCoA) revealed no marked differences in yeast communities among duckweed genera. The species accumulation curve showed that the observed species richness was lower than expected. Investigation of the plant growth promoting traits of the isolated yeast on duckweed revealed that 178 yeast strains produced indole-3-acetic acid (IAA) at levels ranging from 0.08-688.93 mg/L. Moreover, siderophore production and phosphate solubilization were also studied. One hundred and seventy-three yeast strains produced siderophores and exhibited siderophores that showed 0.94-2.55 activity units (AU). One hundred six yeast strains showed phosphate solubilization activity, expressed as solubilization efficiency (SE) units, in the range of 0.32-2.13 SE. This work indicates that duckweed associated yeast is a potential microbial resource that can be used for plant growth promotion.

Kodamaea samutsakhonensis f.a., sp. nov., a novel ascomycetous yeast species isolated from wild mushrooms in Thailand.

Two strains of genus Kodamaea, representing a novel anamorphic yeast species, were isolated from two samples of Marasmiellus sp. collected in Thailand. Analysis of the sequences of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit (LSU) rRNA gene showed that the two strains differed by 27-42 nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and 7-34 nucleotide substitutions in the ITS region of a group of related species, Kodamaea smagusa CBS 11430T, Kodamaea fungicola JCM 10142T, Kodamaea plutei ATCC MYA-4329T, Kodamaea lidongshanica SD5S01T and Kodamaea jinghongensis NYNU 167162T. Phylogenetic analysis based on the concatenated sequences of the ITS and the D1/D2 domains of the LSU rRNA gene showed that the two strains were placed in the Kodamaea clade and clearly separated from other recognized species of the genus. Therefore, the two strains were assigned as a novel species of the genus Kodamaea, for which we propose the name Kodamaea samutsakhonensis f.a., sp. nov. The holotype is TBRC 16043T (=DMKU-BP19T) and the isotype is PYCC 9354. The MycoBank number of the novel species is MB 846490.

Three new yeast species from flowers of Camellia sinensis var. assamica collected in Northern Thailand and their tannin tolerance characterization.

Our recent research study focused on Miang fermentation revealed that tannin-tolerant yeasts and bacteria play vital roles in the Miang production process. A high proportion of yeast species are associated with plants, insects, or both, and nectar is one of the unexplored sources of yeast biodiversity. Therefore, this study aimed to isolate and identify yeasts of tea flowers of Camellia sinensis var. assamica and to investigate their tannin tolerance, which is a property essential to Miang production processes. A total of 82 yeasts were recovered from a total of 53 flower samples in Northern Thailand. It was found that two and eight yeast strains were distinct from all other known species within the genera Metschnikowia and Wickerhamiella, respectively. These yeast strains were described as three new species, namely, Metschnikowia lannaensis, Wickerhamiella camelliae, and W. thailandensis. The identification of these species was based on phenotypic (morphological, biochemical, and physiological characteristics) and phylogenetic analyses of a combination of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit (LSU) ribosomal RNA gene. The yeast diversity in tea flowers acquired from Chiang Mai, Lampang, and Nan provinces had a positive correlation with those acquired from Phayao, Chiang Rai, and Phrae, respectively. Wickerhamiella azyma, Candida leandrae, and W. thailandensis were the species uniquely found in tea flowers collected from Nan and Phrae, Chiang Mai, and Lampang provinces, respectively. Some of the tannin-tolerant and/or tannase-producing yeasts were associated with yeasts in the commercial Miang process and those found during Miang production, i.e., C. tropicalis, Hyphopichia burtonii, Meyerozyma caribbica, Pichia manshurica, C. orthopsilosis, Cyberlindnera fabianii, Hanseniaspora uvarum, and Wickerhamomyces anomalus. In conclusion, these studies suggest that floral nectar could support the formation of yeast communities that are beneficial for Miang production.

Distribution of Kazachstania Yeast in Thai Traditional Fermented Fish (Plaa-Som) in Northeastern Thailand.

Thai traditional fermented fish products (Plaa-som) from four provinces (Ubon Ratchathani, Surin, Sisaket, and Khon Kaen) in the northeast part of Thailand were collected and analyzed to determine their salt content, total acidity, and pH. Yeasts in all samples were isolated and identified to the genus and species level based on sequence analysis of the D1/D2 of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region. The results revealed that the salt content, total acidity, and pH values are in the range of 2.01-6.9%, 0.62-1.9%, and 4.4-6.57%, respectively. Moreover, 35 strains of yeast were isolated and identified as eight genera, namely Candida, Diutina, Filobasidium, Kazachstania, Pichia, Saccharomyces, Torulaspora, and Yarrowia with 17 species. The ascosporogenous yeast, Kazachstania, was the most dominant genus found and was widely distributed among the fermented food samples. In addition, a new strain of yeast, Kazachstania surinensis, was also discovered in Plaa-som samples. Thus, this study is the first to report the presence and wide distribution of these yeasts in fish fermentation products.

Kazachstania surinensis f.a., sp. nov., a novel yeast species isolated from Thai traditional fermented food.

Seven yeast strains (UBIF12-1, UBFB13-1, SRFS56-3, SRFS57-2, SKFS62-1, SKFS66-1 and SKFS67-1) representing a single anamorphic novel yeast species were isolated from traditional Thai fermented foods in Ubon Ratchathani, Surin and Sisaket in the northeast part of Thailand. The results of analysis of the sequences of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region indicated that the seven strains showed zero to one nucleotide substitutions in the sequences of the D1/D2 region of the LSU rRNA gene, and zero to four nucleotide substitutions in the ITS region. Kazachstania humilis CBS 5658T was the most closely-related species, but with 0.7-0.9% nucleotide substitutions in the D1/D2 region of the LSU rRNA gene, and 2.0-2.2% nucleotide substitution in the ITS region. The results of a phylogenetic analysis based on the concatenated ITS and D1/D2 regions confirmed that the seven strains represented a single species of the genus Kazachstania distinct from the other recognized species of the genus. Furthermore, the morphological, biochemical and physiological properties of the seven strains not only indicated that they represented members of the genus Kazachstania, but that they were separated from K. humilis and K. pseudohumilis, the two most closely related species in the phylogenetic tree. Therefore, the seven strains were identified as representing a novel species, for which we propose the name Kazachstania surinensis f.a., sp. nov. The holotype is TBRC 15053T (isotype: SRFS57-2 and PYCC 9021). The MycoBank number of the novel species is 841892.

A Novel Yeast Genus and Two Novel Species Isolated from Pineapple Leaves in Thailand: Savitreella phatthalungensis gen. nov., sp. nov. and Goffeauzyma siamensis sp. nov.

Four yeast strains, representing one genus and two novel anamorphic yeast species, were isolated from pineapple leaves collected in Thailand. Analysis of the sequences of the D1/D2 domains of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) regions showed the two strains (DMKU-PAL186 and DMKU-PAL178) were closely related to the type strains of the Protomyces and Taphrina species, but with high nucleotide divergence. Two strains (DMKU-PAL39 and DMKU-PAL18) were found to be closely related to the type strains of Goffeauzyma iberica, but with eight nucleotide substitutions in the D1/D2 domains and 26 nucleotide substitutions in the ITS regions. In phylogenetic analyses, the strains DMKU-PAL186 and DMKU-PAL178 formed a well-separated lineage from Protomyces and Taphrina genera, confirming that they represented a distinct genus, while the strains DMKU-PAL39 and DMKU-PAL18 represented a species in the genus Goffeauzyma, which was phylogenetically distinct from other recognized species of the genus. Based on molecular analyses and phenotypic characteristics, the names Savitreella gen. nov. (Taphrinomycetes, Ascomycota) and Savitreella phatthalungensis sp. nov. are proposed to accommodate the strains DMKU-PAL186 and DMKU-PAL178, and the name Goffeauzyma siamensis sp. nov. (Tremellomycetes, Basidiomycota) is proposed to accommodate the strains DMKU-PAL39 and DMKU-PAL18.

Wickerhamiella nakhonpathomensis f.a. sp. nov., a novel ascomycetous yeast species isolated from a mushroom and a flower in Thailand.

Strains SU22T (TBRC 14875T) and FLA11.5, representing a novel anamorphic yeast species, were respectively isolated from a fruiting body of a Coprinus species and an inflorescence of a Coffea species collected in Thailand. Analysis of the sequences of the D1/D2 domains of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) regions showed that the two strains differed by two nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and were identical in the ITS regions. Wickerhamiella drosophilae CBS 8459T was the most closely related species, but with 24-26 nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and 24 nucleotide substitutions in the ITS regions. A phylogenetic analysis, based on the sequences of the D1/D2 domains, indicated that the two strains represented a species in the genus Wickerhamiella which was distinct from other recognized species of the genus. Therefore, the two strains were assigned as a novel species, for which we propose the name Wickerhamiella nakhonpathomensis f.a. sp. nov. The holotype is TBRC 14875T (isotype PYCC 8914T). The MycoBank number of the novel species is MB 840833.

Metahyphopichia suwanaadthiae sp. nov., an anamorphic yeast species in the order Saccharomycetales and reassignment of Candida silvanorum to the genus Metahyphopichia.

Seven yeast strains, representing a single novel anamorphic species, were isolated in Thailand. They consisted of five strains (DMKU-MRY16T, DMKU-SK18, DMKU-SK25, DMKU-SK30 and DMKU-SK32) obtained from five different mushrooms, and two strains (ST-224 and 11-14.2) derived from insect frass and soil, respectively. The pairwise sequence analysis indicated that all seven strains had identical sequences in the D1/D2 domains of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region. Metahyphopichia silvanorum was the most closely related species, but with 11.9-12.4% nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and 13.1-13.3% nucleotide substitutions in the ITS region. The phylogenetic analyses based on the concatenated sequences of the ITS region and the D1/D2 domains of the LSU rRNA gene showed that the seven strains form a well-separated subclade in a clade containing M. silvanorum and Metahyphopichia laotica with high bootstrap support. A phylogenetic analysis of a multilocus dataset including the small subunit (SSU) rRNA gene, the ITS region, the D1/D2 domains of the LSU rRNA gene, translation elongation factor 1-alpha gene, actin gene and the RNA polymerase II subunit 2 gene, confirmed the presence of the monophyletic clade that also includes M. silvanorum and M. laotica, and strongly supported the phylogenetic isolation of the seven strains from its neighbouring species. Therefore, the seven strains were assigned as a single novel species of the genus Metahyphopichia, according to their phylogenetic relationships. The name Metahyphopichia suwanaadthiae sp. nov. is proposed to accommodate the seven strains. The holotype is DMKU-MRY16T (TBRC 11775T=NBRC 114386T=PYCC 8655T). The MycoBank number of the novel species is MB 841280. In addition, Candida silvanorum is reassigned to the genus Metahyphopichia. The MycoBank number of M. silvanorum comb. nov. is MB 841279.

Diversity of fermentative yeasts with probiotic potential isolated from Thai fermented food products.

This research aimed to evaluate the diversity of yeasts recovered from fermented foods gathered from some areas of Northeastern Thailand. The fermented food items included Pla-som, Nham-pla, Kem-buknud, Isan-sausage, Pla-ra, Mhum-neu, Mhum-Khai-pla, Nham-neu, Nham-mu, Kung-joom, Som-pla-noi, and Poo-dong. Their probiotic characteristics were also investigated. A total of 103 yeast isolates of nine genera were identified using 28S rDNA sequencing. The yeast genera were Candida (20.3%), Diutina (2.9%), Filobasidium (1.0%), Kazachstania (33.0%), Pichia (3.9%), Saccharomyces (1.0%), Starmerella (28.2%), Torulaspora (2.9%), and Yarrowia (6.8%). Based on probiotic characteristic analysis of ten selected yeast strains, Kazachstania bulderi KKKS4-1 showed the strongest probiotic characteristics in terms of hemolytic activity, antimicrobial activity against pathogenic bacteria, tolerance to low pH and bile salt and hydrophobicity. Isolated yeasts with probiotic characteristics may be useful in fermented food and animal feed production to improve their nutritional values.

Yeasts Associated with the Small-Intestinal Contents and Epithelium of Pon Yang Kham (Charolais Crossbred) Fattening Beef Cattle.

Yeast diversity in the pia and small-intestinal epithelium of Pon Yang Kham fattening cattle in Thailand was studied using a culture-dependent method. A total of 701 yeasts were isolated from the pia of the duodenum, jejunum, and ileum of the small intestine, while 425 isolates were obtained from the epithelium of all three parts of the small intestine. Yeast identification was performed and ascomycetous yeasts were found at levels of 96.9% and 86.8% in the pia and small intestine, respectively, whereas basidiomycetous yeasts were found at levels of 2.3% and 12.7%. Candida parapsilosis was the species with the highest occurrence in the duodenal and jejunal pia, with an 83.3% and 77.8% frequency of occurrence (FO), respectively. Both C. parapsilosis and C. tropicalis were species with the highest occurrence in the ileum, with a 61.1% FO. Moreover, C. parapsilosis was the species with the highest occurrence in the epithelium of the duodenum, jejunum, and ileum, with FOs of 88.2%, 87.5%, and 87.2%, respectively. Principal coordinate analysis revealed no marked differences in yeast communities from either the pia or epithelium of all three parts of the small intestine. An estimation of the expected richness of the species showed that the observed species richness was lower than the predicted richness.

Application of raw starch degrading enzyme from Laceyella sacchari LP175 for development of bacterial cellulose fermentation using colored rice as substrate.

Brown and black rice substrates were applied for sugar syrup production by the hydrolysis of raw starch degrading enzyme (RSDE) from Laceyella sacchari LP175 (300 U/mL) and commercial glucoamylase (GA, 2.0 U/mL) at 50 °C for 12 h using a simplex centroid mixture design. Results indicated that 300 g/L of substrates, consisting of 255 g/L Leum Pua glutinous rice and 45 g/L Black Jasmine rice, gave the highest sugar syrup production at 124.6 ± 2.52 g/L with 2.00 ± 0.05 mg GAE/mL of total phenolic content (TPC), equivalent to 0.42 ± 0.01 g/g rice sample and 6.67 ± 0.15 mg GAE/g rice sample, respectively. The obtained sugar syrup was used as the substrate for production of bacterial cellulose (Nata) by Komagataeibacter xylinus AGR 60 in a plastic tray at room temperature for 9 days. The fermentation medium containing 200 mL of rice syrup (25 g/L), 2.0 g of ammonium sulfate [(NH4)2SO4] and 0.4 mL glacial acetic acid yielded 1.1 ± 0.08 cm thickness with 8.15 ± 0.12 g of dry weight. The obtained bacterial cellulose from colored rice was characterized compared with bacterial cellulose from the conventional coconut juice by scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) which demonstrated that the sugar syrup from colored rice could use as substrate for a novel bacterial cellulose as a healthy product in the future through microbial enzyme technological process. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02673-3.

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 707T 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-GTCP10-8T (ex-type strain TBRC 12159=PYCC 8490; MycoBank number 835044).

Teunia siamensis f.a., sp. nov., a novel tremellaceous yeast species isolated from soil in a secondary peat swamp forest area.

The strain DMKU-XD44, representing an anamorphic novel yeast species, was isolated from soil collected in a peat swamp forest (PSF) area in Rayong Botanical Garden in eastern Thailand. On the basis of sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, Teunia cuniculi CBS 10309T was the most closely related species. The novel species differed from the T. cuniculi type by 2.5 % (14 nucleotide substitutions) in the D1/D2 region of the LSU rRNA gene and by 8.0 % (40 nucleotide substitutions) in the ITS region. The results of a phylogenetic analysis, based on the combined sequences of the ITS region and the D1/D2 region, indicated that DMKU-XD44 represents a member of the Teunia clade in the Cryptococcaceae (Tremellales, Tremellomycetes, Agaricomycotina and Basidiomycota) and is phylogenetically distinct from other species of the genus Teunia in the clade. Therefore, DMKU-XD44 represents a novel species of the genus Teunia. The name Teunia siamensis f.a., sp. nov. is proposed. The holotype is DMKU-XD44, while the MycoBank number is MB 832816.

Yeast communities of secondary peat swamp forests in Thailand and their antagonistic activities against fungal pathogens cause of plant and postharvest fruit diseases.

Secondary peat swamp forest (PSF) arise by degradation of primary PSF as a result of fire and human activities. Yeasts diversity of Kuan Kreng (KK) and Rayong Botanical Garden (RBG) PSF, which are two secondary PSF in southern and in eastern Thailand, respectively, were investigated. Yeasts were isolated from soil and peat soil by the dilution plate and enrichment techniques. From six samples collected from KK PSF, 35 strains were obtained, and they were identified based on the sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene 13 species in 12 genera, and one potential new species of the genus Galactomyces were detected. Thirty-two strains were obtained from six samples collected from RBG PSF and 26 strains were identified as 13 known yeast species in 11 genera, whereas six strains were found to represent two potential new species of the genera Papiliotrema and Moesziomyces. Among yeast strains isolated from KK PSF, the number of strains in the phylum Ascomycota and Basidiomycota were equal, whereas there were slightly fewer strains in Ascomycota than in Basidiomycota among the strains obtained from RBG PSF. The yeast strains were evaluated for their antagonistic activities against fungal pathogens which cause rice diseases (Fusarium moniliforme, Helminthosporium oryzae, Rhizoctonia solani, Curvularia lunata and Pyricularia grisea) and postharvest disease of fruits (Phytophthora palmivora, Lasiodiplodia theobromae and Colletotrichum gloeosporioides). Twelve strains of seven species were found to be antagonistic yeast strains. Starmerella kuoi DMKU-SPS13-6, Hanseniaspora lindneri DMKU ESS10-9 and Piskurozyma taiwanensis DMKU-SPS12-2 capable to inhibit R. solani by 70.1-76.2%, Wickerhamomyces anomalus DMKU SPS6-1 and three Rhodotorula taiwanensis strains (DMKU SPS8-1, DMKU ESS9-3, DMKU SPS9-2) inhibited C. lunata by 69.8-71.9%, Hanseniaspora lindneri DMKU ESS10-9 and Scheffersomyces spartinae DMKU SPS9-3 inhibited P. grisea by 81.9-84.4% and four Papiliotrema laurentii strains (DMKU-SPS15-1, DMKU-ESS11-2, DMKU-ESS8-2, DMKU-ESS6-4) inhibited P. palmivora by 53.2-59.5%.

Yeast Associated with Rice Phylloplane and Their Contribution to Control of Rice Sheath Blight Disease.

The phylloplane is an important habitat for yeasts and these yeasts may have antagonistic activities against pathogens and could be used as biocontrol agents. To investigate rice phylloplane yeasts, 282 strains were isolated from 89 rice leaf samples and identified as 15 known yeast species in the phylum Ascomycota and 35 known and two potential new species in the phylum Basidiomycota. The majority of rice phylloplane yeasts belonged to the phylum Basidiomycota. The evaluation of antagonistic activities of 83 yeast strains against rice pathogenic fungi Pyricularia oryzae, Rhizoctonia solani, Fusarium moniliforme, Helminthosporium oryzae and Curvularia lunata revealed that 14 strains inhibited these pathogens. Among the antagonistic strains, Torulaspora indica DMKU-RP31, T. indica DMKU-RP35 and Wickerhamomyces anomalus DMKU-RP25 inhibited all rice pathogens tested, and the production of volatile organic compounds, fungal cell wall degrading enzymes and biofilm were the possible antagonistic mechanisms against all rice pathogens tested in vitro. These yeast strains were evaluated for controlling rice sheath blight caused by R. solani in rice plants in the greenhouse and were found to suppress the disease by 60.0-70.3%, whereas 3% validamycin suppressed by 83.8%. Therefore, they have potential for being developed to be used as biocontrol agents for rice sheath blight.

Yeast communities of primary and secondary peat swamp forests in southern Thailand.

Khanthuli peat swamp forest (PSF) is one of a few fertile peat swamp forests that remain in Thailand. It is composed of primary PSF and some areas which have been degraded to secondary PSF due to drought, wildfires and land conversion, which have resulted in a decrease in peat layers and change in the species of the plant community. In this study, diversity of yeasts in peat from both primary and secondary PSF areas of the Khanthuli PSF was determined based on culture-dependent approaches, using dilution plate and enrichment techniques. A total of 66 yeast isolates were identified by the analysis of sequence similarity of the D1/D2 region of the large subunit rRNA gene or the combined analysis of sequence of the D1/D2 region and internal transcribed spacer region and confirmed by phylogenetic analysis of the D1/D2 region to belong to 22 known yeast species and six potential new species in the genera Candida (Kurtzmaniella, Lodderomyces, Ogataea, Pichia and Yamadazyma clades), Clavispora, Cyberlindnera, Galactomyces, Hanseniaspora, Metschnikowia, Saturnispora, Schwanniomyces, Cryptotrichosporon, Pichia, Curvibasidium, Papiliotrema, Rhodotorula, and Saitozyma. The most prevalent yeasts in the primary PSF were Cyberlindnera subsufficiens and Galactomyces candidus, while Saitozyma podzolica was the most frequently found in peat from the secondary PSF. Common yeast species in both, primary and secondary PSF, were Cy. subsufficiens, G. candidus and Rhodotorula mucilaginosa.