• Mycobiology
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• v.47 no.3
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• pp.292-300
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• 2019

IAA biosynthetic pathways in a basidiomycetous yeast, Rhodosporidiobolus fluvialis DMKU-CP293, were investigated. The yeast strain showed tryptophan (Trp)-dependent IAA biosynthesis when grown in tryptophan supplemented mineral salt medium. Gas chromatography-mass spectrometry was used to further identify the pathway intermediates of Trpdependent IAA biosynthesis. The results indicated that the main intermediates produced by R. fluvialis DMKU-CP293 were tryptamine (TAM), indole-3-acetic acid (IAA), and tryptophol (TOL), whereas indole-3-pyruvic acid (IPA) was not found. However, supplementation of IPA to the culture medium resulted in IAA peak detection by high-performance liquid chromatography analysis of the culture supernatant. Key enzymes of three IAA biosynthetic routes, i.e., IPA, IAM and TAM were investigated to clarify the IAA biosynthetic pathways of R. fluvialis DMKU-CP293. Results indicated that the activities of tryptophan aminotransferase, tryptophan 2-monooxygenase, and tryptophan decarboxylase were observed in cell crude extract. Overall results suggested that IAA biosynthetic in this yeast strain mainly occurred via the IPA route. Nevertheless, IAM and TAM pathway might be involved in R. fluvialis DMKU-CP293.

• Journal of Species Research
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• v.13 no.1
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• pp.105-110
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• 2024

The purpose of this study was to isolate and identify wild yeasts from soil samples collected in Seoul and Daejeon, Republic of Korea. To identify wild yeast strains, pairwise sequence comparisons of D1/D2 region of the 26S rRNA gene sequence were done using Basic Local Alignment Search Tool (BLAST). The cell morphologies were observed by phase contrast microscope and carbon source assimilation test were done using API 20C AUX kit. Among the 13 isolated strains, 11 strains were previously reported, but two strains have never been reported from Republic of Korea. The 13 strains were assigned to the phylum Basidiomycota. The two unrecorded yeast strains B2UV-201 and DJ1-5-B-10C belong to the genera Rhodotorula and Rhodosporidiobolus, respectively. The two unrecorded yeast strains are oval shaped and polar budding cells. This research focuses on the morphological and biochemical properties of the two unreported yeast species that have not officially been reported in Korea.

• The Korean Journal of Mycology
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• v.48 no.2
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• pp.151-160
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• 2020

The goal of this study was to investigate the diversity present among wild yeasts obtained from soils of spice fields and from mountain soils, and to further, characterize previously unrecorded novel wild yeast strains. In total, 36 strains from 17 different species of wild yeasts were isolated from 35 soil samples obtained from garlic fields of Geumsan, Chungcheongnam-do, Korea. Among these, six yeast strains of Trichosporon moniliiforme, and four strains each of Papiliotrema flavescens and Candida melibiosica species were isolated. Additionally, 22 strains of 18 different species of wild yeasts were isolated from 32 soil samples collected from the ballonflower and ginger fields of Geumsan, Korea. Finally, 46 strains of wild yeasts were isolated from 35 soil samples obtained from Mt. Daedun in Geumsan, Korea. Among the total of 106 isolated wild yeast strains, 10 strains, including Debaryomyces vindobonensis GHY31-3 represented novel yeast strains which were previously unrecorded. All the 10 previously unrecorded yeasts were oval or global in shape, and five strains, including Filobasidium stepposum SFG1-4 formed ascospores. Three strains, including Pseudozyma alboarmeniaca CD 23-5 grew well in vitamin-free medium. Cell-free extract obtained from Filobasidium magnum SFG1-3 indicated 28.6% of xanthine oxidase inhibitory activity.