• Journal of Microbiology and Biotechnology
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• v.2 no.2
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• pp.108-114
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• 1992

The fermentative characteristics in ethanol production from lactose, with increased ethanol tolerance, of a fusant yeast strain constructed by protoplast fusion of Saccharomyces cerevisiae and Kluyveromyces fragilis were studied. The ethanol tolerance of this strain was increased to 8.0%, compared with the parent K. fragilis. During batch ethanol fermentation the optimal cultivation conditions for this fusant yeast were an initial pH of 4.5, a culture temperature $30^\circ{C}$. stirring at 100 rpm without aeration in 10% lactose medium (supplied with 1.0% yeast extract). Using this fusant strain in whey fermentation to ethanol, maximum ethanol production reached 3.41% (w/v) (theoretical yield; 66.7%) after a 48 hour cultivation period.

• Food Science and Preservation
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• v.17 no.2
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• pp.174-181
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• 2010

The yeast strains used for fermentation are known to influence the qualities of wine. We investigated the effects of fermentation using different yeast strains on the properties of wine produced from 'Hayward' kiwifruit (Actinidia deliciosa). The physicochemical characteristics of wine produced using various yeast strains for fermentation were also analyzed. Saccharomyces cerevisiae Gervin No.5 strain (GVN), S. bayanus Lavin strain EC1118 (EC1118), and S. cerevisiae Red star Davis No. 796 (No.796) are commercial dry yeast strains selected for optimization of fermentation. Although the soluble solid contents of samples fermented by all three yeast strains decreased by a similar extent, the levels of alcohol production differed, particularly during the first week of fermentation. Use of the GVN strain resulted in the highest alcohol concentration (13.8%, v/v), whereas fermentation with No.796 and EC1118 strains yielded alcohol contents of 13.0% and 12.5% (both v/v), respectively. Upon sensory evaluation, GVN-fermented wine had a strong taste and bitterness, with high acid and alcohol contents. Wine fermented using No.796 had a chemical profile similar to that of GVN-fermented product, but the taste remained sweet, consistent with the lower alcohol content. EC1118-fermented wine was soft and sweet in taste, high in flavor, and had a low alcohol content. Total phenolic levels and antioxidant activities in wine fermented by EC1118 were significantly higher than in wines prepared using No.796 or GVN. When previously described characteristics were additionally considered, EC1118 was selected as an optimum strain for further study. In conclusion, fermentation of kiwifruit using different yeast strains yielded wines with distinct characteristics. The yeast strain EC1118 had the most desirable properties, and is considered suitable for kiwifruit fermentation. Valuable attributes of wine fermented by this yeast include overall sensory acceptance, an appropriate level of total phenolics, and good antioxidant activity.

• Mycobiology
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• v.40 no.1
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• pp.42-46
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• 2012

This report describes the isolation and identification of a potent acetylcholinesterase (AChE) inhibitor-producing yeasts. Of 731 species of yeast strain, the S-3 strain was selected as a potent producer of AChE inhibitor. The selected S-3 strain was investigated for its microbiological characteristics. The S-3 strain was found to be short-oval yeast that did not form an ascospore. The strain formed a pseudomycelium and grew in yeast malt medium containing 50% glucose and 10% ethanol. Finally, the S-3 strain was identified by its physiological characteristics and 26S ribosomal DNA sequences as $Yarrowia$ $lipolytica$ S-3.

• Mycobiology
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• v.42 no.4
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• pp.361-367
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• 2014

Makgeolli, also known as Takju, is a non-filtered traditional Korean alcoholic beverage that contains various floating matter, including yeast cells, which contributes to its high physiological functionality. In the present study, we assessed the levels of ${\beta}$-glucan and glutathione in various yeast strains isolated from traditional Korean Nuruk and selected a ${\beta}$-glucan- and glutathione-rich yeast strain to add value to Makgeolli by enhancing its physiological functionality through increased levels of these compounds. Yeast ${\beta}$-glucan levels ranged from 6.26% to 32.69% (dry basis) and were strongly species-dependent. Dried Saccharomyces cerevisiae isolated from Nuruk contained $25.53{\mu}g/mg$ glutathione, $0.70{\mu}g/mg$ oxidized glutathione, and $11.69{\mu}g/g$ and $47.85{\mu}g/g$ spermidine and L-ornithine monohydrochloride, respectively. To produce functional Makgeolli, a ${\beta}$-glucan- and glutathione-rich yeast strain was selected in a screening analysis. Makgeolli fermented with the selected yeast strain contained higher ${\beta}$-glucan and glutathione levels than commercial Makgeolli. Using the selected yeast strain to produce Makgeolli with high ${\beta}$-glucan and glutathione content may enable the production of functional Makgeolli.

• Journal of Species Research
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• v.9 no.3
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• pp.204-209
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• 2020

In 2019, as a subset study to discover indigenous yeast species in Korea, a total of 20 yeast species were isolated from soil samples collected in Pochoen-si. Among them, eight strains were unreported species. From the high 26S rRNA gene sequence similarity and formation of a robust phylogenetic clade with the closest species, it was determined that each strain belonged to independent and predefined yeast species. The 20 strains were assigned to the genera Aureobasidium (1 strain) and Meyerozyma (1 strain) of the phylum Ascomycota and Cystofilobasidium (2 strains), Filobasidium (1 strain), Naganishia (2 strains), Bullera (3 strains), Leucosporidium (9 strains) and Sampaiozyma (1 strain) of the phylum Basidiomycota. There is no official report of the following species in Korea: Leucosporidium creatinivorum (4 strains), Leucosporidium escuderoi(2 strains), Leucosporidium golubevii(1 strain) and Leucosporidium intermedium (2 strains). Basic biochemical characteristics, colony and cell morphology are also described in the species description section.

• Applied Biological Chemistry
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• v.20 no.1
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• pp.123-129
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• 1977

A potent lytic strain was selected by an extensive screening test of microorganisms isolated from soils and sewages on the medium containing baker's yeast as a carbon source. This strain (M-10) was identified to a strain of Humicola sp. by the Genera of Fungi (Clements, 1964). The strain was cultured on the basal medium composed of 2% of baker's yeast, 0.3% of $K_2HPO_4$, 0.01% of $MgSO_4{\cdot}7H_2O$, 0.1% of yeast extract in a shaking incubator. Cultural conditions for lytic enzyme production has been studied, and the results obtained were as follows: 1. The Optimal conditions for lytic enzyme production were: initial pH 5.5 to 6.0, temperature $33^{\circ}C$ in shaking culture. 2. Among the various carbon sources, baker's yeast (4%) was the best for lytic enzyme production, increasing the level of activity eight, times higher than when grown on glucose (1%). 3. The most effective concentration of $K_2HPO_4\;and\;MgSO_4{\cdot}7H_2O$ in the basal medium for lytic enzyme production was 0.1% and 0.01% respectively. 4. When the strain was cultured under the optimal conditions, the production of lytic enzyme was maximized in 72 hours.

• Korean Journal of Agricultural Science
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• v.7 no.2
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• pp.176-181
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• 1980

As a part of experiments aimed to reduce the acidic taste of a soured fruit wine, a selected yeast strain was studied on its morphological and physiological properties as well as its fermentative characteristics of apple wine. The results obtained were as follows. 1. The selected yeast strain was identified as a strain of Schizosaccharomyces pombe. 2. The tolerance of the strain to metabisulfite in apple juice was stronger than that of wine yeast. 3. The growth rate of the strain was more rapid than those of wine yeast and Sake yeast when cultured in apple juice at $25^{\circ}C$, but it was decreased below the levels of others when cultured at $15^{\circ}C$. 4. The levels of ethanol production and acid reduction by the strain were high when the apple wine brewed at $25^{\circ}C$, while these were dropped significantly at $15^{\circ}C$.

• Korean journal of food and cookery science
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• v.24 no.1
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• pp.11-15
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• 2008

In searching for yeast to be utilized as biocontrol agents, a single yeast strain was isolated from Camellia sinensis based on its morphological, cultural, physiological, and biochemical properties, as well as by molecular techniques. This single strain was pink to red in color and designated as strain JY-1. The effects of temperature, pH, NaCl concentration, and ethanol concentration on the growth of the JY-l strain were examined for the JY-1. Growth occurred at temperatures ranging from 20 to $35^{\circ}C$, and between pH 3.0 and 12.0, with optimal growth at $25-30^{\circ}C$ and pH 5.0. The yeast also grew in the presence of 0-2% (w/v) NaCl and 0-4% (v/v) EtOH. The isolate was further classified based on biochemical characteristics using the VITEK system. The biochemical data obtained using this system were similar to those of Rhodotorula glutinis/Rhodotorula mucilaginosa (exhibiting a 93% matching level). Molecular phylogenetic analysis based on l8S rDNA sequences indicated that the yeast represented a basidiomycetous species, and its highest degree of sequence similarity was with Rhodosporidium azoricum, strain JCM11251 (99%).

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.129-133
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• 2014

BACKGROUND: This study was performed for selecting yeast mutants with a high tolerance for targeted metals, and determining whether yeasts strains tolerant to multiple heavy metals could be induced by sequential adaptations. METHODS AND RESULTS: A mutant yeast strain tolerant to the heavy metals cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) was selected by sequential elevated exposures to each metal with intermittent mutant isolation steps. A Cd-tolerant mutant was isolated by growing yeast cells in media containing $CdCl_2$ concentrations that were gradually increased to 1 mM. Then the Cd-tolerant mutant was gradually exposed to increasing levels of $CuCl_2$ in growth media until a concentration of 7 mM was reached, thus generating a strain tolerant to both Cd and Cu. In the subsequent steps, this mutant was exposed to $NiCl_2$ (up to 8 mM), and a resultant isolate was further exposed to $ZnCl_2$ (up to 60 mM), allowing the derivation of a yeast mutant that was simultaneously tolerant to Cd, Cu, Ni, and Zn. CONCLUSION: This method of inducing tolerance to multiple targeted heavy metals in yeast will be useful in the bioremediation of heavy metals.

• Journal of Microbiology and Biotechnology
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• v.8 no.2
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• pp.119-123
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• 1998

The feasibility of using combined treatments of electric field and chemical mutagen N-methyl-N'-nitro-N-nitroso-guanidine (NTG) for the strain improvement of Saccharomyces sp. in ethanol production was examined. The treatment of electric field alone resulted in no effect on the lethality of yeast cells under the conditions of this study. However, when the electric field was applied together to the treatment of yeast cells with NTG, the electric field increased the lethal effect and auxotrophic mutation rate of NTG. The combined treatment of electric field and NTG also increased the chances of. obtaining superior yeast strains for the ethanol production from tapioca. A higher number of improved clones was obtained by the combined treatments of electric field and NTG than by the NTG treatment alone. The best clone, NF 30-9, which was also obtained by the combined treatment, produced $11.07\%$ (w/v) ethanol from tapioca slurry containing 25% (w/v) reducing sugar while the parental strain produced 9.77% (w/v).