• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.219-224
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• 2014

In order to develop a new anti-diabetic ${\alpha}$-glucosidase inhibitor, we compared the ${\alpha}$-glucosidase inhibitory activity of the cell-free extracts of 48 strains of yeasts isolated from Korean fermented foods, and found that Pichia burtonii Y257-7 exhibited the highest ${\alpha}$-glucosidase inhibitory activity of 55.6%. The ${\alpha}$-glucosidase inhibitor was maximally produced when Pichia burtonii Y257-7 was cultured in LB broth (initial pH of 6.0) at $28^{\circ}C$ for 24 h. The ${\alpha}$-glucosidase inhibitor, partially purified by Sephadex G-50 gel permeation chromatography and systematic solvents extraction, revealed potent hypoglycemic effects in normal rats and streptozotocin-induced diabetic rats after the oral administration of starch.

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.241-248
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• 2006

Conditions for extraction of antimicrobial materials from licorice root, Glycyrrhiza glabra, were optimized. Among solvents tested, 95% ethanol gave highest antimicrobial activity, and was chosen as optimal extracting solvent. Extraction temperature and time were optimal at room temperature and for 12 hr, respectively. Minimal inhibitory concentration (MIC) of 95% ethanol extracts was determined against 14 microorganisms. Reference microorganisms included 6 Gram(-) bacteria, 4 Gram(+) bacteria, and 4 yeast strains. Ethanol extract exerted very strong growth inhibition on Gram(+) bacteria, while was moderately effective for Gram(-) bacteria and yeasts. Treatment at $180^{\circ}C$ for 30 min or extreme pHs merely destroyed antimicrobial activity of ethanol extract. These findings suggest ethanol extract of G glabra may be useful as natural preservative.

• Journal of Life Science
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• v.20 no.5
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• pp.683-690
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• 2010

The yeast strains of Saccharomyces diastaticus produce one of three isozymes of an extracellular glucoamylase I, II or III, a type of exo-enzyme which can hydrolyse starch to generate glucose molecules from non-reducing ends. These enzymes are encoded by the STA1, STA2 and STA3 genes. Another gene, sporulation-specific glucoamylase (SGA), also exists in the genus Saccharomyces which is very homologous to the STA genes. The SGA has been known to be produced in the cytosol during sporulation. However, we hypothesized that the SGA is capable of being secreted to the extracellular region because of about 20 hydrophobic amino acid residues at the N-terminus which can function as a signal peptide. We expressed the cloned SGA gene in S. diastaticus YIY345. In order to compare the biochemical properties of the extracellular glucoamylase and the SGA, the SGA was purified from the culture supernatant through ammonium sulfate precipitation, DEAE-Sephadex A-50, CM-Sephadex C-50 and Sephadex G-200 chromatography. The molecular weight of the intact SGA was estimated to be about 130 kDa by gel filtration chromatography with high performance liquid chromatography (HPLC) column. Sodium dedecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed it was composed of two heterogeneous subunits, 63 kDa and 68 kDa. The deglycosylation of the SGA generated a new 59 kDa band on the SDS-PAGE analysis, indicating that two subunits are glycosylated but the extent of glycosylation is different between them. The optimum pH and temperature of the SGA were 5.5 and $45^{\circ}C$, respectively, whereas those for the extracellular glucoamylase were 5.0 and $50^{\circ}C$. The SGA were more sensitive to heat and SDS than the extracellular glucoamylase.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.360-367
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• 2014

Candida albicans is an opportunistic and the most prevalent fungal pathogen that can cause superficial and systemic infections in immunocompromised patients. C. albicans can promote the transition from budding yeast to filamentous form, generating biofilms. Infections associated with C. albicans biofilms are frequently resistant to conventional antifungal therapy. Therefore, the development of more effective antifungal drugs related with biofilm formation is required urgently. The roots of Rheum undulatum have been used for medicinal purposes in Korea and China traditionally. The aim of present study was to evaluate the effect of R. undulatum extract upon preformed biofilms of 12 clinical C. albicans isolates and the antifungal activities. Its effect on preformed biofilms was evaluated using XTT reduction assay, and metabolic activity of all tested strains was reduced significantly ($49.4{\pm}6.0%$) at 0.098 mg/ml R. undulatum. The R. undulatum extract blocked the adhesion of C. albicans biofilms to polystyrene surfaces, and damaged the cell membrane integrity of C. albicans which was analyzed by CFDA, AM, and propidium iodide double staining. It caused cell lysis which was observed by Confocal laser scanning and phase contrast microscope after propidium iodide and neutral red staining, respectively. Membrane permeability was changed as evidenced by crystal violet uptake. The data suggest that R. undulatum inhibits biofilm formation by C. albicans, which can be associated with the damage of the cell membrane integrity, the changes in the membrane permeability and the cell lysis of C. albicans.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.5
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• pp.743-752
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• 2013

The objective of this study was to investigate the quality characteristics of spirits derived from fruit using copper distillation equipment. First, optimal yeast strains were chosen through a fermentation test on raw materials (apples, mandarins and rowanberries). The normal fermentation condition for rowanberries observed at a rowanberry concentration of 8% during mashing included chaptalization with sugar to increase the alcohol content. During the mashing, fruits were fermented and distilled through one of three different types of distillation apparatuses (pot distiller, vacuum distiller, or multistage distiller made of copper). The results revealed that the type of apparatus used affects the content of alcohol and flavor components. The distilled spirits prepared through a copper multistage distiller had a much higher tendency to retain components of fruit aromas such as ethyl acetate and provided higher yields than spirits prepared with a pot distiller or vacuum distiller. Thus, the copper multistage distiller apparatus can be applied to positively influence the taste and flavor of fruit distilled spirits by enhancing fruit aromas, removing impurities such as sulfur components and enhancing yields.

• Applied Biological Chemistry
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• v.51 no.1
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• pp.24-37
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• 2008

Yeast with excellent ferment ability was isolated and selected from wild grape to manufacture wild grape wine. Wild grape wine by SMR-3 isolated from wild grape was better than other strains in quality, such as high alcohol content and low acidity, residual sugar, organic acid and fusel oil content. Fermentation condition was optimized to manufacture wild grape wine with response surface methodology using isolated SMR-3 as an alcohol fermentation strain. As a result of culture conditions, 10.61% of alcohol content was expected under the conditions of $21.91^{\circ}C$ fermenting temperature, $21.48^{\circ}brix$ of initial sugar content, and 14.65 day of fermentation time. Residual sugar content showed the lowest value at $24.48^{\circ}C$ fermentation temperature, $12.78^{\circ}brix$ of initial sugar content, and 9.02 day fermentation time. The highest level of sensory evaluation was found at $20.23^{\circ}C$ fermentation temperature, $25.30^{\circ}brix$ of initial sugar content, and 5.94 day fermentation time. Ethyl alcohol was the main alcohol component in wild grape wine and fusel oil in wild grape wine was hardly detected; thus, the quality of wild grape wine was considered excellent. The optimal fermentation conditions of wild grape wine was superimposed by deriving a regression equation for alcohol content, fusel oil, ethyl alcohol content, and overall palatability for each variable of wild grape wine. Hence, the optimal fermentation conditions are estimated to be: fermentation temperature $24{\sim}28^{\circ}C$, initial sugar content $20{\sim}24^{\circ}brix$, and fermenting time $12{\sim}14$ days.

• The Korean Journal of Mycology
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• v.38 no.2
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• pp.146-151
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• 2010

A total of 167,955 microorganisms were isolated from 366,661 clinical specimens. Among them, 6,517 strains of the Candida spp. were isolated from the department of laboratory medicine in "C" hospital from Jan. 1, 2005 to Dec. 31, 2009. All clinical specimens were reviewed by the medical records of patients with Candida by the method of retrospectiveness. From this, we got the some isolated pure cultured yeasts. We identified these yeast by the identification kit system of VITEKII and VITEKII-ID-YST card. The isolation frequencies of Candida spp. were as follows. 56.4%,of C. albicans, 17.7% C tropicalis, 10.7% C glabrata and 9.5% C parapsilosis. The isolated frequency of Candida spp. in 2009 was 1.9 times higher than that in 2005. The clinical materials showing over 10.0% isolation rate were in sputum (30.1%), random urine (25.0%), 15.8% blood (15.8%) and catheterized urine (13.5%) in Candida spp.. The clinical department of showing over 7.0% isolation rate were in pulmonary medicine (20.5%), renal medicine (11.0%), infection disease medicine (10.4%), critical care medicine (10.0%), hematooncology (9.6%), general surgery (7.5%) and gastrointestinal medicine (7.4%) in Candida spp.. In monthly analysis, Candida spp. were most friquency isolated in July (10.6%), but lowest one in February (6.1%). Candida spp. were most frequently isolated in patient of over 50 years old (16.7-40.1%) than those isolated from the patients under the age of 0-49 (1.3-7.5%).

• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1350-1357
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• 2000

Traditional Kochujang was prepared adding horseradish or mustard powder to repress the gas formation which used to cause swelling problem during distribution. The koji for Kochujang was prepared by the strains which had high amylase and protease activities with superior flavor. The gas production from Kochujang during fermentation at $25^{\circ}C$ was ceased after stopping yeast growth completely by bactericidal components from $0.6{\sim}1.2%(w/w)$ of horseradish or mustard addition. Total viable bacterial count was not affected by adding horseradish or mustard. The amino type nitrogen content in Kochujang, which was one of the most important parameters in quality of Kochujang, increased continually during fermentation. The Kochujang fermented by P-2 isolate and added with mustard was significantly higher in amino type nitrogen content than other treatments after 120 days' fermentation. ${\alpha}-Amylase$ activity was very low while ${\beta}-amylase$ activity was high in Kochujang fermented by adding horseradish and mustard powder. The protease(acid and neutral) activities gradually increased by fermentation with no difference between treatments. The color and flavor were not different, but overall palatability of the Kochujang evaluated by sensory test showed significantly high rank in Kochujang fermented by P-2 isolate and with horseradish.

• Journal of Life Science
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• v.31 no.2
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• pp.175-182
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• 2021

Saccharomyces lysate has the well-known function of soothing the skin in various ways: it is an anti-irritant and can treat skin care conditions, such as skin whitening and antioxidative activity. However, data on the safety for use of Saccharomyces lysate in cosmetics and skin care products are still limited. To design a new cosmetic material with antioxidant and skin-whitening effects, 80 yeast strains were isolated from berries grown in Sunchang. Among the isolates, the FT4-4 strain, which exhibited superior biological activities, was selected for further experiments. The FT4-4 strain was identified as Saccharomyces cerevisiae by 18S rRNA gene sequencing analysis. S. cerevisiae FT4-4 showed higher DPPH radical-scavenging (51.41%), superoxide dismutase (62.23%), and tyrosinase inhibition (64.75%) activities. The highest yield of biomass (3.16 g/l) and maximum growth rate of S. cerevisiae FT4-4 were observed within 16 h. Furthermore, the cytotoxicity potential of S. cerevisiae FT4-4 on B16F10 melanoma cells was measured by an MTT assay, and the results indicated that S. cerevisiae FT4-4 had a capacity to inhibit melanin up to 72.02% at an initial 10 mg/ml concentration. These results suggest that S. cerevisiae FT4-4 could be a promising candidate as a multi-functional material for application in the cosmetic industry, especially because of its antioxidant and skin-whitening effects.

• Food Science and Preservation
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• v.30 no.4
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• pp.691-702
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• 2023

This study aimed to develop high value-added mulberry (Morus alba) vinegar by fermenting mulberry with yeast and acetic acid bacteria, for using it in various foods. To select the optimal strain for mulberry fermentation, different strains were tested and Saccharomyces cerevisiae SRCM101756 and Acetobacter pasteurianus SRCM102419, exhibiting excellent alcohol and acetic acid production ability during mulberry fermentation, were selected for fermentation. Mulberry vinegar was prepared using mulberry wine and the selected acetic acid bacteria, and the physicochemical properties and physiological effects were measured. The pH was 2.98 and total acidity was 4.70% by day 9 of fermentation, establishing the possibility of developing them into vinegars for industrial use. The angiotensin-glucosidase inhibition activity of mulberry vinegar increased from 13.22% to 19.19% in the 100-fold dilution, and from 42.35% to 46.11% in the 50-fold dilution, from before fermentation to after fermentation, respectively. The angiotensin-converting enzyme inhibition activity of mulberry vinegar was found to significantly increase from 44.82% before fermentation to 63.88% after fermentation in the 25-fold dilution. Moreover, a significant increase in pancreatic lipase inhibition activity after fermentation was observed. Thus, mulberry vinegar can be used as a functional material in vinegar and other foods.