Rungluk Kaewwichian

Wickerhamomyces xylosica sp. nov. and Candida phayaonensis sp. nov., two xylose-assimilating yeast species from soil.

Two strains (NT29(T) and NT31(T)) of xylose-assimilating yeasts were obtained from soils collected in northern Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and sequence analysis of the D1/D2 domain of the large subunit rRNA gene and the internal transcribed spacer region, the two strains were found to represent two novel ascomycete yeast species. Strain NT29(T) was assigned to the genus Candida belonging to the Pichia clade as a representative of Candida phayaonensis sp. nov.; the type strain is NT29(T) (=BCC 47634(T)=NBRC 108868(T)=CBS 12319(T)). Strain NT31(T) represented a novel Wickerhamomyces species, which was named Wickerhamomyces xylosica sp. nov.; the type strain is NT31(T) (=BCC 47635(T)=NBRC 108869(T)=CBS 12320(T)).

Candida wangnamkhiaoensis sp. nov., an anamorphic yeast species in the Hyphopichia clade isolated in Thailand

Two strains representing a single novel yeast species were isolated from a flower of Calycoopteris floribunda Lame (SK170T) and insect frass (ST-122) collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and the sequence analysis of the D1/D2 domain of the large subunit rRNA gene and the internal transcribed spacer region, the two strains were assigned as a single novel Candida species in the Hyphopichia clade for which the name Candidawangnamkhiaoensis sp. nov. is proposed. The type strain is SK170T=BCC 39604T=NBRC 106724T=CBS 11695T).

Nakazawaea siamensis f.a., sp. nov., a yeast species isolated from phylloplane

Strain DMKU-RK467(T), representing a novel yeast species, was isolated from the external surface of sugar cane leaves collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and sequence analysis of the D1/D2 region of the LSU rRNA gene and the internal transcribed spacer (ITS) region, strain DMKU-RK467(T) was assigned to a novel species of the genus Nakazawaea. The novel species was related most closely to the type strain of Candida wickerhamii but they differed by 1.9 % nucleotide substitutions in the D1/D2 region of the LSU rRNA gene and by 5.2 % nucleotide substitutions in the ITS region. The name Nakazawaea siamensis f.a., sp. nov. is proposed (type strain DMKU-RK467(T) = BCC 50734(T) = NBRC 108903(T) = CBS 12569(T)).

Wickerhamomyces siamensis sp. nov., a novel yeast species isolated from the phylloplane in Thailand.

Strain DMKU-RK359(T), representing a novel yeast species, was isolated from the external surface of a sugar-cane leaf collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, sequence analysis of the D1/D2 region of the large-subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, strain DMKU-RK359(T) was assigned to a novel Wickerhamomyces species. The novel species was closest to Wickerhamomyces ciferrii, but differed from it by 0.7 % nucleotide substitutions in the D1/D2 region of the LSU rRNA gene and 6 % nucleotide substitutions in the ITS region. The name Wickerhamomyces siamensis sp. nov. is proposed (type strain DMKU-RK359(T)  = BCC 50732(T)  = NBRC 108900(T)  = CBS 12570(T)).

Geotrichum siamensis sp. nov. and Geotrichum phurueaensis sp. nov., two asexual arthroconidial yeast species isolated in Thailand.

Two asexual arthroconidial yeast strains, TM3-44(T) and LYSM5(T), were isolated, respectively, from estuarine water in a mangrove forest and soil in a terrestrial forest in Thailand. Analysis of the D1/D2 domains of the large-subunit rRNA gene sequences revealed that strain TM3-44(T) differed from the closest species in terms of pairwise sequence similarity, Dipodascus albidus, by 11.7% nucleotide substitutions, while strain LYSM5(T) was closest to Galactomyces geotrichum with only 2.9% nucleotide substitutions. The phylogenetic tree further demonstrated that strain TM3-44(T) was at a distant position from the closest species, D. albidus, and other related species in the Dipodascus clade, while strain LYSM5(T) clustered with G. geotrichum, it closest relative in the Galactomyces clade. The phenotypic characteristics of the two strains were typical of the genus Geotrichum. On the basis of the above findings, strain TM3-44(T) was assigned as a novel species of Geotrichum, for which the name Geotrichum siamensis sp. nov. is proposed. The type strain is TM3-44(T) (BCC 29903(T)=NBRC 104880(T)=CBS 10929(T)). Strain LYSM5(T) represented another novel species of Geotrichum, which was named Geotrichum phurueaensis sp. nov. The type strain is LYSM5(T) (BCC 34756(T)=NBRC 105674(T)=CBS 11418(T)).

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)).

Candida gosingica sp. nov., an anamorphic ascomycetous yeast closely related to Scheffersomyces spartinae

During surveys on yeast diversity in forest soils from Taiwan and Thailand, ten yeast strains isolated from different samples were found to have similar molecular and physiological characteristics. Sequence analysis of small subunit (SSU) rDNA, the D1/D2 domain of large subunit (LSU) rDNA and internal transcribed spacer (ITS)-5.8S rDNA demonstrated that these strains were closely related to Scheffersomyces spartinae. The novel strains could be differentiated from S. spartinae by a 0.9  % sequence divergence (5 substitutions, 0 gaps) in the D1/D2 domain of LSU rDNA, a 1.5  % divergence (8 substitutions, 0 gaps) in the ITS-5.8S rDNA and a 0.7  % divergence (12 substitutions, 2 gaps) in the SSU rDNA. The novel strains also showed specific patterns of electrophoretic karyotypes that differed from that of S. spartinae. Therefore, a novel yeast species, Candida gosingica sp. nov., is proposed to accommodate these strains. The type strain SJ7S11(T) (=BCRC 23194(T)=CBS 11433(T)) was assigned and deposited in the Bioresource Collection and Research Center (BCRC), Food Industry Development and Research Institute, Hsinchu, Taiwan, and Centraalbureau voor Schimmelcultures (CBS), Utrecht, The Netherlands.

Yamadazyma insecticola f.a., sp. nov. and Yamadazyma epiphylla f.a., sp. nov., two novel yeast species.

Two yeast strains representing two novel yeast species were isolated from frass of an unidentified insect (ST-78(T)) and the external surfaces of rice leaves (YE170(T)) collected in Thailand. The two strains were genetically, morphologically and phenotypically distinct from recognized species and were found to represent two novel species of the genus Yamadazyma although formation of ascospores was not observed. In terms of pairwise sequence similarity of the D1/D2 region of the large subunit rRNA gene, the closest relative of strain ST-78(T) was Candida lessepsii CBS 9941(T) but with 3.8% nucleotide substitutions, while the closest relative of strain YE170(T) was strain ST-78(T) but with 4.3% nucleotide substitutions. Analysis of the sequences of the internal transcribed spacer 1 and 2 (ITS1-2) regions revealed that strain ST-78 differed from C. lessepsii CBS 9941(T) by 8.8% nucleotide substitutions and from strain YE170(T) by 9.4% nucleotide substitutions. The result of pairwise sequence similarity of the D1/D2 and ITS1-2 regions together with phylogenetic analysis indicated that strains ST-78(T) and YE170(T) represented two novel species within the Yamadazyma clade. The names Yamadazyma insecticola f.a., sp. nov. (type strain ST-78(T) = BCC 8314(T) = NBRC 110421(T) = CBS 13382(T); MycoBank no. MB810546) and Yamadazyma epiphylla f.a., sp. nov. (type strain YE170(T) = BCC 63466(T) = NBRC 110423(T) = CBS 13384(T); MycoBank no. MB810547) are proposed for the two novel yeast species.

Cryptotrichosporon siamense sp. nov., a ballistoconidium-forming yeast species in Trichosporonales isolated in Thailand

Two strains, which formed pink colonies and produced ballistoconidia and represented a novel anamorphic yeast species, were isolated from peat (DMKU-SPS1-2) and fern leaf (ST-145) 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 were identical to the sequences of the D1/D2 domains of the LSU rRNA gene and differed by two nucleotide substitutions in the ITS regions. Phylogenetic analysis based on the combined sequences of the ITS and the D1/D2 regions confirmed that the two strains represented a single species in the genus Cryptotrichosporon that was distinct from the other known species of the genus. Cryptotrichosporon argae (CBS 14376T) was the most closely related species, but with 2.2 % nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene, and 6.8-8.0 % nucleotide substitutions in the ITS regions. Therefore, the two strains were assigned as a novel species, for which we propose the name Cryptotrichosporon siamense sp. nov. The type is DMKU-SPS1-2T. The MycoBank number of the novel species is MB82336.