• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.340-344
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• 2002

A gene, npl, encoding neopullulanase from Paenibacillus sp. KCTC 8848P was cloned and expressed in Escherichia coli. It consisted of an open reading frame of 1,530 bp for a protein that consisted of 510 amino acids with a molecular weight of 58,075 Da. The deduced amino acid sequence of the neopullulanase gene had $92\%$ identity with the neopullulanase of Bacillus polymyxa. The npl gene was also expressed in Saccharomyces cerevisiae secreting Schwanniomyces occidentalis glucoamylase (GAM1) under the control of the yeast actin gene (ACT1) promoter. Secretion of the neopullulanase was directed by the yeast mating pheromone ${\alpha}$ -factor ($MF{\alpha}1$) prepro region. Enzyme assays confirmed that co-expression of npl and GAM1 enhanced starch and pullulan degradation by S. cerevisiae.

• The Korean Journal of Mycology
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• v.45 no.1
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• pp.31-42
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• 2017

Several yeast strains were isolated from leaves collected from Mt. Daedun and Mt. Chilgap in Korea. A total of 79 strains of 32 species were isolated from 44 leaves obtained from Mt. Daedun. Cryptococcus spp., including Cryptococcus magnus, were found to be dominant, while 16 strains of Aureobasidium pullulans were isolated. Among the strains isolated from Mt. Daedun, Asterotremella humicola JSL502, Barnettozyma californica JSL503, Bullera unica JSL501, Bulleromyces albus JSL505, and Candida vaccinii JSL507 are considered rare yeast species in Korea. All of these rare strains, except for Bulleromyces albus JSL505, formed ascospores. Bullera unica JSL501 was able to grow in yeast extract-peptone-dextrose (YPD) medium containing 10% NaCl. Twenty-five yeast strains of 18 species were isolated from 43 leaves obtained from Mt. Chilgap. Six strains of Pseudozyma spp., including three strains of Pseudozyma aphidis, were isolated in the dormant state. Of these strains, the occurrence of Rhodotorula phylloplana JSL515, Rhodotorula pinicola JSL516, Schwanniomyces vanrijiae JSL517, and Sporisorium loudetiae JSL518 is rare in Korea. Only Sporisorium loudetiae JSL518 formed ascospores, while Rhodotorula pinicola JSL516 and Sporisorium loudetiae JSL518 formed pseudomycelia. The halophilic yeast Schwanniomyces vanrijiae JSL517 was isolated and observed to grow in YPD medium containing 5% NaCl.

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.323.2-323
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• 1998

No Abstract, See Full Text

• 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 ℃.

• Applied Biological Chemistry
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• v.32 no.4
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• pp.408-415
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• 1989

Twenty-seven strains of starch utilizing yeasts were isolated from 30 samples of ‘Nuruk’, a traditional starter in Korea. These strains were identified as ten species belonging to four genera; Hansenula anomaly (six strains), Hansenula sydowiorum (two strains), Saccharomycopsis fibuligera (four strains), Schwanniomyces occidentalis (two strains), Candida fabianii(two strains), Candida famata(one strain), Candida hydrocarbofumarica (three strains), Candida silvicola (one strain), Candida steatolytica (four strains) and Candida tropicalis (two strains). Saccharomycopsis fibuligera Nu-01, Nu-08, Nu-12 and Nu-27 produced much amylase, and one of these, Saccharomycopsis fibuligera Nu-12 showed the highest amylase activity (16.9 IU/ml). Among the isolates, the strains of Hansenula anomala were exhibited relatively high specific growth rate in the medium used starch as a carbon source, and ethanol fermentation by the strains of Candida hydrocarbofumarica was not observed.

• Journal of Microbiology and Biotechnology
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• v.3 no.4
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• pp.232-237
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• 1993

A strain of yeast which can convert starch directly to ethanol was developed by the intergeneric protoplast fusion between Schwanniomyces alluvius possessing $\alpha$ amylase as well as glucoamylase with debranching activity and FSC-14-75 which previously had been formed from a heterologous transformation and subsequent intergeneric protoplast fusion. Fusants were selected on minimal medium after protoplasts of auxotrophic mutant of S. alluvius fused with heat-treated protoplasts of FSC-14-75 in the presence of 30%(w/v) PEG and 20 mM $CaCl_2$. The fusion frequency was in the range of $10^{-6}$ order. All fusants tested were intermediate types of parental strains for carbon compound assimilation, and their cell volumes were approximately 1.1 times larger than FSC-14-75 and 1.8 times larger than S. alluvius. The fusants were unable to sporulate like FSC-14-75, while S. alluvius could sporulate. In flask scale the most promising fusant, FSCSa-R10-6, produced 7.83%(v/v) and 10.17%(v/v) ethanol from 15% and 20% of liquefied potato starch, respectively, indicating that the fermetation efficiency of each case increased 1.2 times and 1.6 times than that of FSC-14-75. The elution pattern on DEAE-cellulose chromatography showed that FSCSa-R10-6 has four distinct amylase peaks of which two peaks originated from S. alluvius and the other two from FSC-14-75. These results suggest that the enhanced fermentation efficiency of the fusant might be due to almost-complemented parental amylases.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.386-393
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• 1999

Ethanol is considered as one of the most suitable substitutes for the petroleum, since it offers attractive functional features at an economical cost. Glucoamylase producing yeasts were isolated and characterized. Based on the morphological character, carbon fermentations, assimilation of carbon and nitrate, growth on vitamine-free medicine, and urease activity, five isolates of Saccharomyces diastaticus, two isolates of Saccharomycopsis fibuligera, and two of Schwanniomyces occidentalis, and each isolate of Ambrosiozyma monospora and Lipomyces kononenkoae were identified. Among 12 isolates, one of the S. diastaticus, E3 showed the highest activity of glucoamylase and identified as Saccharomyces diastaticus. The hydrolysis of starch by the E3 strain showed the release of considerable amount of reducing sugar, along with the reduction in iodine staining capacity. The product of action of glucoamylase, glucose was determined by thin-layer chromatography. The enzyme activity was found to be stable in broad pH range of $5.0{\sim}7.0$ with optimal activity at pH $5.0{\sim}6.0$. The enzyme showed optimal antivity at $50^{\circ}C{\sim}60^{\circ}C$. Soluble starch and glucose were better carbon sources for the enzyme production than xylose and glycerol. $Na^+\;and\;Mg^{2+}$ increased the glucoamylase activity, however $Hg^{2+}\;and\;Ag^{2+}$ inhibited the activity. Soluble starch was the best substrate for the enzyme activity.

• Korean Journal of Microbiology
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• v.29 no.2
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• pp.136-142
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• 1991

The selection of ethanol-tolerant strains was applied to enrichment culture of YPD broth medium containing various concentrations of ethanol. Isolates were identified to be Saccharomyces cerevisiae, the others as S. dairensis, S. exiguus, S. telluris, Saccharomycodes ludwigii, Schwanniomyces occidentalis var. occidentalis and Zygosaccharomyces florentinus. Among isolates S. cerevisiae YO-1 was screened as having the highest ethanol tolerance and produced 18% (v/v) ethanol after 4 days fermentation. The change of fatty-acyl residues represents that a progressive decrease in fatty-acyl unsaturation and a proportional increase in saturation in phospholipids of yeast cells during fermentation affected the yeast viability. Supplementation ethanol to the cultures led to an increase of unsaturated fatty-acyl residues, especially $C_{16}$ or $C_{18}$ residues, along with a decrease in the proportion of saturated residues in cellular phospholipids. Increasing the amount of soy flour led to an increase in the maximum number of viable yeast cells and ethanol production. It was possible in 4 days to reach 21% (v/v) ethanol by adding 4% soy flour as source of unsaturated fatty-acyl residues to the fermentation medium. Soy flour not only increased yeast population but also enhanced the physiological properties of yeast cells to be ethanol tolerant in the anaerobic culture.