• The Korean Journal of Mycology
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• v.48 no.4
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• pp.523-531
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• 2020

This study focused on the isolation and characterization of wild yeasts in Korea. The yeasts were identified by phylogenetically analyzing the D1/D2 domains of the 26S rDNA regions. Consequently, we identified seven strains, NNIBRFG856, NNIBRFG3732, NNIBRFG3734, NNIBRFG3738, NNIBRFG3739, NNIBRFG5497, and NNIBRFG6049, which were confirmed to be Kabatiella microsticta, Pichia membranifaciens, Candida vartiovaarae, Candida sake, Debaryomyces hansenii, Candida railenensis, and Schwanniomyces polymorphus, respectively, all of them being new in Korea. Morphological and cultural characteristics of these yeast species were investigated. None of the strains formed ascospores or pseudomycelia. Moreover, these yeasts grew in a pH range of 4-8. NNIBRFG3732, NNIBRFG3738, NNIBRFG3739, NNIBRFG5497, and NNIBRFG6049 were halotolerant or halophilic, and NNIBRFG3732, NNIBRFG3734, and NNIBRFG6049 grew in vitamin-free medium. NNIBRFG3732, NIBRFG3739, and NNIBRFG6049 grew at 35 ℃, but not at 40 ℃.

• Journal of Species Research
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• v.10 no.4
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• pp.350-355
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• 2021

In 2020, 11 Basidiomycetous yeast strains were isolated from soil samples collected from the forests of Namhansanseong in Korea. Among them, seven species were reported, but four species were unreported in Korea. To identify wild yeasts, pairwise sequence comparisons of D1/D2 domain of the 26S rRNA were performed using Basic Local Alignment Search Tool (BLAST). The cell morphologies and assimilation test are observed by phase contrast microscope and API 20C AUX kit, respectively. The 11 strains were assigned to the genera Rhodotorula (4 strains) of the order Sporidiobolales of the class Microbotryomycetes; and Cryptococcus(2 strains), Goffeauzyma (1 strains), Naganishia (2 strains) of the order Filobasidiales and Saitozyma (2 strains) of the order Tremellales of the class Tremellomycetes in the phylum Basidiomycota. The unreported yeast strains Cryptococcus gastricus 20n5-2, Goffeauzyma gilvescens 20n2-7, Naganishia adeliensis 20n8-1, and Naganishia friedmannii 20n24-1 belong to the family Filobasidiaceae. All strains had oval shaped cells and cream-colored colonies cultured on on YM agar for 3 days. In this study, we focus on the description of four unreported yeast species in Korea.

• Mycobiology
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• v.40 no.4
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• pp.255-257
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• 2012

Among 80 types of yeast isolated from wild flowers in Daejeon, Korea, two species that have not yet been identified by phylogenetic analysis of the internal transcribed spacer-2 (ITS2) genes and 26S rDNA sequences were identified as Candida sp. 44-C-1 and Cryptococcus sp. 9-D-1. Neither of the newly identified species formed ascospores, while Candida sp. 44-C-1 formed pseudomycelium and Cryptococcus sp. 9-D-1 did not.

• The Plant Pathology Journal
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• v.16 no.5
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• pp.247-251
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• 2000

Latent infections of healthy-appearing oaks of Hypoxylon atropunctatum complicates field studies by interfering with inoculation experiments to follow pathogenesis, fungal development and reproduction of this canker rot fungus. Mutants with unique and easily scorable phenotypes would be useful for inoculation studies. There is a broad range in the capacity of wild-type isolates to utilize nitrate as a sole nitrogen sources. Several types of nitrate-nonutilization mutants (nit1, Nit3, NitM) were selected from nitrate-utilizing wild-type isolates. Also, a few mutants of Hypoxylon atropunctatum were selected that could only grow poorly on basal medium supplemented with various nitrogen sources and even on yeast extract agar. These unknown mutants need to be characterized further. Nit mutants of Hypoxylon atropunctatum were readily selected, grew well and were recovered after inoculation into oak stems. These results suggest that nit mutants could be useful for inoculation studies in trees that contain latent infections.

• Journal of Radiation Industry
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• v.6 no.2
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• pp.181-188
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• 2012

A mushroom mutant with increased cellulolytic activity was developed through radiation mutagenesis. The homogenized hypha suspension of Pleurotus florida was exposed to gamma radiation ($^{60}Co$, AECL) at the dose of $LD_{99}$ (0.51 kGy, $D_{10}$; 0.26 kGy). Among 16 mutants, Pf CM4 showed 17.24% more cellulolytic activity than the wild type (p<0.05). It was observed that Pf CM4 can utilize all kinds of carbon sources tested for their mycelia growth. Starch, xylan, and glucose favourably supported the radial mycelia extension. Yeast extract and $NH_4NO_3$ have been recorded as the best organic and inorganic nitrogen sources, respectively. Pf CM4 was found to grow significantly faster, even at high temperature ($30^{\circ}C$), than wild type (p<0.05), and the optimal pH was 5.5~6.5. This study reveals that the mutant Pf CM4 could be employed for the effective recycling of cellulosic wastes, in addition to mushroom farming.

• BMB Reports
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• v.29 no.4
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• pp.359-364
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• 1996

By both in vitro hydroxylamine mutagenesis of the wild type 3-phosphoglycerate kinase gene (PGK) promoter DNA and insertion of the leu2-d gene, we have created yeast expression vectors potentially useful for production of eukaryotic genes in yeast. The guanine (G) to adenine (A) change at the -3 position from the ATG start codon of the PGK promoter-based vector rendered a 6~7 times elevated expression of the adjacent eukaryotic gene, and insertion of the leu2-d gene in the vector containing the mutated PGK promoter further enhanced the expression of the gene. When expression of the AIDS virus HIV1-gagP17 gene in a lacZ fusion form was examined with this new vector, a 15 times higher level of expression than that from the original PGK promoter was observed. Northern and Southern analysis showed that this elevated expression is due to the production of a high copy number of mRNA by leu2-d gene functioning and by efficient translation of the produced mRNA. Thus, the vector that contained the A at the -3 position from the ATG start codon in the promoter region and the leu2-d gene shows increased expression capability and will be potentially useful for production of eukaryotic genes in yeast.

• IMMUNE NETWORK
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• v.2 no.3
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• pp.137-141
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• 2002

Among the members of the inhibitor of apoptosis (IAP) protein family, only Livin and survivin have been reported to have variant forms. We have found a variant form of c-IAP2 through the interaction with the X protein of HBV using the yeast two-hybrid system. In contrast to the wild-type c-IAP2, the variant form has two stretches of sequence in the RING domain that are repeated in the C-terminus that would disrupt the RING domain. We demonstrate that the variant form has an inhibitory effect on TNF-mediated $NF-{\kappa}B$ activation unlike the wild-type c-IAP2, which increases TNFmediated $NF-{\kappa}B$ activation. These results suggest that this variant form has different activities from the wild-type and the RING domain may be involved in the regulation of TNF-induced $NF-{\kappa}B$ activation.

• The Korean Journal of Mycology
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• v.42 no.2
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• pp.170-173
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• 2014

Two unrecorded yeasts, Meyerozyma caribbica UL5-1 and Pichia silvicola UL6-1 were screened from 58 yeasts which were isolated from wild flowers in Ulleungdo in Gyeongsangbuk-do, Korea. The morphological and cultural characteristics of these unrecorded yeasts were investigated. Both yeasts were oval in shape and formed pseudomycelia. P. silvicola UL6-1 formed ascospore, but M. UL5-1 did not. P. silvicola UL6-1 and M. caribbica UL5-1 also grew in vitamin-free medium and 5% NaCl-containing yeast extract-peptone-dextrose medium. The two unrecorded yeasts assimilated glucose, galactose, xylose, cellobiose, trehalose, glycerol and sorbitol, and also fermented glucose, fructose and mannose. The supernatant of both M. caribbica UL5-1 and P. silvicola UL6-1 showed high antihypertensive angiotensin I-converting enzyme inhibitory activity of 84.2% and 82.6%, respectively. Cell-free extract of P. silvicola UL6-1 also showed very high anti-diabetic ${\alpha}$-glucosidase inhibitory activity (85.8%).

• KSBB Journal
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• v.17 no.3
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• pp.290-294
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• 2002

The present work describes the improvement of an erythritol-producing strain to lower the formation of glycerol, which is a characteristic by-product of the strain and could cause difficulties in the recovery and purification of the final product. The yeast-like fungi Moniliella suaveolens var. nigra, isolated previously in the same laboratory from beehives, was mutated by exposing it to a 4 g/L NTG solution. From a total of 2000 mutated strains, Em6j30-14 was selected as the one having the most desirable properties. Cultivating the strain for seven days in 300 mL flasks containing 30 mL of a 400 g/L glucose medium resulted in an erythritol yield of 43%. The glycerol yield was 5%, which is a value 50% lower as compared with the wild type. However, attempts to reproduce the above results in a 5L-fermenter failed, resulting in a similar erythritol concentration but a much higher formation of glycerol. Possible reasons for such a different behaviour could be oxygen limitation or the aggregation of cells, but the exact mechanism could not yet be identified. Foam formation, which is another major problem in large-scale fermentation, tended to be much lower for the mutant strain.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.4
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• pp.234-241
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• 2000

The Saccharomyces cerevisiae PMR1 gene encodes a Ca2+-ATPase localized in the Golgi. We have investigated the effects of PMR1 disruption in S. cerevisiae on the glycosylation and secretion of three heterologous glycoproteins, human ${\alpha}$1-antitrypsin (${\alpha}$1-AT), human antithrombin III (ATHIII), and Aspergillus niger glucose oxidase (GOD). The pmr1 null mutant strain secreted larger amounts of ATHIII and GOD proteins per a unit cell mass than the wild type strain. Despite a lower growth rate of the pmr1 mutant, two-fold higher level of human ATHIII was detected in the culture supernatant from the pmr1 mutant compared to that of the wild-type strain. The pmr1 mutant strain secreted ${\alpha}$1-AT and the GOD proteins mostly as core-glycosylated forms, in contrast to the hyperglycosylated proteins secreted in the wild-type strain. Furthermore, the core-glycosylated forms secreted in the pmr1 mutant migrated slightly faster on SDS-PAGE than those secreted in the mnn9 deletion mutant and the wild type strains. Analysis of the recombinant GOD with anti-${\alpha}$1,3-mannose antibody revealed that GOD secreted in the pmr1 mutant did not have terminal ${\alpha}$1,3-linked mannose unlike those secreted in the mnn9 mutant and the wild type strains. The present results indicate that the pmr1 mutant, with the super-secretion phenotype, is useful as a host system to produce recombinant glycoproteins lacking high-mannose outer chains.