• Food Science and Preservation
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• v.3 no.2
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• pp.171-178
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• 1996

This study was carried out for the purpose of improving the persimmon vinegar. The acetic acid bacteria strain JST-3, using acetic acid fermentation was isolated from the traditional persimmon vinegar. The optimum conditions for high yield of acetic acid were studied in the shaking bath. Acetic acid bacteria was cultured at 3$0^{\circ}C$ for 4 days and transferred to persimmon alcoholic juice for acetic acid fermentation. The optimum initial acidity for acetic acrid fermentation was 1%(w/v) and the addition of glucose or yeast extract was observed to produce relatively low yield of acetic acid. Succinic and acetic acid were major organic acid in the persimmon vinegar, The contents of lactic acid which was known to increase off-flavor were very low. Sensory evaluation revealed that the persimmon vinegar prepared in this study was superior to two commercial ones in the aroma and taste.

• KSBB Journal
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• v.9 no.2
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• pp.147-156
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• 1994

A study was carried out for production of a pigment : bluish purple, using a mutant Streptomyces californicus KS-89-7. The mutant was induced from Streptomyces californicus KS-89 with N-methyl-N-nitro-N-nitrosoquanidin(MNNG). It was immobilized on an inert substance made of colloidal sillica and 3.5% sodium alginate with 1 to 10 ratio. The diameter of inert bead was 2mm, and number of immobilized mutant spore was approximately $1.0{\times}10^7$/ml. It was packed in a column reactor and fermentation was conducted with a substrate made of soluble starch 1%, glycerol 1.0%, sodium glutamate 0.1%, sodium nitrate 0.05%, L-prolin 0.025% and with some trace elements. The aeration for production of the pigment was 2.5m1/min with semi-continuous fermentation. The pigment production reached at peak on 8 days of fermentation, and the mutant produced the pigment 1.8 times more than its parent strain with the maximum pigment production of $1.72g/\ell$. The pigment production continued for 24 hours of fermentation, and at the end of the fermentation the mutant produced the pigment $1.52g/\ell$.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.363-366
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• 2004

In order to obtain an industrial strain with higher L(+)-lactic acid yield, the wild type strain Rhizopus oryzae PW352 was mutated by means of Nitrogen ions implantation (l5 Kev, $7.8 \times 10^{14} - 2.08 \times 10^{15} ions/Cm^2$ and two mutants RE3303 and RF9052 were isolated. After 36 h shake-flask cultivation, the concentration of L(+)-lactic acid reached 131-136 g/l, the conversion rate of glucose was as high as 86%-90% and the productivity was 3.61 g/l.h. It was almost a 75% increase in lactic acid production compared with the wild type strain. Maximum fermentation temperature of RF9052 was increased to $45^{\circ}C$ from original $36^{\circ}C$. At the same time, the preferred range of fermentation temperature of RF9052 was broadened compared with PW352.

• Restorative Dentistry and Endodontics
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• v.6 no.1
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• pp.93-103
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• 1980

Streptococcus mutans were isolated from dental plaques of carious lesions of 4 patients on mitis-salivarius agar medium. Three patients known to harbor S. mutans in their dental plaques. Identification of the isolated S. mutans was established by colonial morphology on mitis-salivarius agar medium, the fermentation of mannitol and sorbitol, and confirmed by agglutinating reaction with home made anti-S. mutans NCTC 10449 (serotype c) antiserum. Of the isolated S. mutans, one strain (P2-1) showed strong agglutinating reaction with antiserum, another strain (P1-2) showed weak agglutinating reaction. P2-1 strongly adhered to the wall of the test tube containing 5% sucrose broth, while p1-2 weakly colonized on the wall of the test tube. Biotyping of the isolated S. mutans based on the fermentation of mannitol, sorbitol, raffinose and melibiose, and the production of ammonia from L-arginine, and the inhibition of acid production by bacitracin. Biochemical characteristics of P2-1 strain correlated with the recognized biotype c, pl-2 strain resembled biotype d of S. mutans.

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.568-577
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• 2015

To protect skin problems, new natural material alternative to synthetic antioxidants has been extensively selected from natural sources such as plants, animals, and microorganisms. Poncirus trifoliata of those has been widely used as treatment of allergy, chronic inflammatory diseases, and natural antioxidant. In recent days, microbial fermentation to natural products has been reported to increase feasibly their bioavailability. Accordingly, we performed the fermentation using hot water extract of Poncirus trifoliata by isolated Leuconostocs sp. strain JYK and investigated the change of antioxidative activity. Antioxidative material such as hesperidine naringine, imperatorin, and luteolin was found in hot water extract of Poncirus trifoliata. Total phenolics compounds and flavoniods in hot water extract were $71.2{\pm}4.58GAE(mg/g)$ and $25.1{\pm}4.12$ hesperidine(mg/g), respectively. After fermentation, their values were $89.2{\pm}13.47GAE(mg/g)$ and $31.0{\pm}4.06$ hesperidine(mg/g), respectively. After fermentation, ABTS[2,2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid)] and DPPH(1,1-diphenyl-2-picrylhydrazyl) radical were highly enhanced from $70.2{\pm}9.01$ to $86.2{\pm}3.72$ and $18.7{\pm}1.81$ to $26.6{\pm}4.06$, respectively. Thus microbial fermentation offers a tool to further increase the bioactive potential of Poncirus trifoliata.

• The Korean Journal of Food And Nutrition
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• v.27 no.5
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• pp.785-795
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• 2014

This study was conducted to develop low-salinity Kimchi with acetic acid, starters and fruits added for health and taste. The quality characteristics of the developed Kimchi by storage period and salt concentrations were investigated herein. The effects of salinity and fermentation temperature ($0^{\circ}C$, $5^{\circ}C$) on the quality characteristics of low-salinity Kimchi were investigated through physicochemical and microbiological analysis. The sensory characteristics are shown in the results below. The pH and acidity were quickly changed by higher temperature over longer storage periods, with gradual decrease in the pH accompanied with an increase in acidity. The microbiological analysis revealed increase in the total cell number regardless of the concentration and strain added during the storage period. Finally, test of the overall acceptability with regard to sensory characteristics according to the different strain sets in low-salinity Kimchi showed the average score for smell, salty taste and overall acceptability were highest in the hetero-fermentation strain group.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.767-774
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• 2010

In this study, the problems of high caloric content, increased maturation time, and off-flavors in commercial beer manufacture arising from residual sugar, diacetyl, and acetaldehyde levels were addressed. A recombinant industrial brewing yeast strain (TQ1) was generated from T1 [Lipomyces starkeyi dextranase gene (LSD1) introduced, ${\alpha}$-acetohydroxyacid synthase gene (ILV2) disrupted] by introducing Saccharomyces cerevisiae glucoamylase (SGA1) and a strong promoter (PGK1), while disrupting the gene coding alcohol dehydrogenase (ADH2). The highest glucoamylase activity for TQ1 was 93.26 U/ml compared with host strain T1 (12.36 U/ml) and wild-type industrial yeast strain YSF5 (10.39 U/ml), respectively. European Brewery Convention (EBC) tube fermentation tests comparing the fermentation broths of TQ1 with T1 and YSF5 showed that the real extracts were reduced by 15.79% and 22.47%; the main residual maltotriose concentrations were reduced by 13.75% and 18.82%; the caloric contents were reduced by 27.18 and 35.39 calories per 12 oz. Owing to the disruption of the ADH2 gene in TQ1, the off-flavor acetaldehyde concentrations in the fermentation broth were 9.43% and 13.28%, respectively, lower than that of T1 and YSF5. No heterologous DNA sequences or drug resistance genes were introduced into TQ1. Hence, the gene manipulations in this work properly solved the addressed problems in commercial beer manufacture.

• Journal of Microbiology and Biotechnology
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• v.23 no.11
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• pp.1577-1585
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• 2013

Bioethanol production from lignocellulose is considered as a sustainable biofuel supply. However, the low cellulose hydrolysis efficiency limits the cellulosic ethanol production. The cellulase is strongly inhibited by the major end product cellobiose, which can be relieved by the addition of ${\beta}$-glucosidase. In this study, three ${\beta}$-glucosidases from different organisms were respectively expressed in Saccharomyces cerevisiae and the ${\beta}$-glucosidase from Saccharomycopsis fibuligera showed the best activity (5.2 U/ml). The recombinant strain with S. fibuligera ${\beta}$-glucosidase could metabolize cellobiose with a specific growth rate similar to the control strain in glucose. This recombinant strain showed higher hydrolysis efficiency in the cellulose simultaneous saccharification and fermentation, when using the Trichoderma reesei cellulase, which is short of the ${\beta}$-glucosidase activity. The final ethanol concentration was 110% (using Avicel) and 89% (using acid-pretreated corncob) higher than the control strain. These results demonstrated the effect of ${\beta}$-glucosidase secretion in the recombinant S. cerevisiae for enhancing cellulosic ethanol conversion.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1529-1533
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• 2010

The inulinase gene (INU1) from Kluyveromyces marxianus NCYC2887 was overexpressed by using the GAL10 promotor in a ${\Delta}ga180$ strain of Saccharomyces cerevisiae. The inulinase gene lacking the original signal sequence was fused in-frame to a mating factor ${\alpha}$ signal sequence for secretory expression. Use of the ${\Delta}ga180$ strain allowed for the galactose-free induction of inulinase expression using a glucose-only medium. Shake-flask cultivation in YPD medium produced 34.6 U/ml of the recombinant inulinase, which was approximately 13-fold higher than that produced by K. marxianus NCYC2887. It was found that the use of the ${\Delta}ga180$ strain improved the expression of inulinase in the recombinant S. cerevisiae in both aerobic and anaerobic conditions by about 2.9- and 1.7-fold, respectively. A 5-l fed-batch fermentation using YPD medium was performed under aerobic condition with glucose feeding, which resulted in the inulinase production of 31.7 U/ml at the $OD_{600}$ of 67. Ethanol fermentation of dried powder of Jerusalem artichoke, an inulin-rich biomass, was also performed using the recombinant S. cerevisiae expressing INU1 and K. marxianus NCYC2887. Fermentation in a 5-l scale fermentor was carried out at an aeration rate of 0.2 vvm, an agitation rate of 300 rpm, and with the pH controlled at 5.0. The temperature was maintained at $30^{\circ}C$ and $37^{\circ}C$, respectively, for the recombinant S. cerevisiae and K. marxianus. The maximum productivities of ethanol were 59.0 and 53.5 g/l, respectively.

• Korean Journal of Microbiology
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• v.52 no.2
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• pp.220-225
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• 2016

To improve antioxidant glutathione (GSH) content and saccharification ability in sake yeasts of Saccharomyces cerevisiae, the ${\gamma}$-glutamylcysteine synthetase gene (GSH1) from S. cerevisiae, glucoamylase gene (GAM1) and ${\alpha}$-amylase gene (AMY) from Debaryomyces occidentalis were co-expressed in sake yeasts for manufacturing a refreshing alcoholic beverage abundant in GSH from rice starch. The extracellular GSH content of the recombinant sake yeasts increased 1.5-fold relative to the parental wide-type strain. The saccharification ability by glucoamylase of the new yeast strain expressing both GAM1 and AMY genes was 2-fold higher than that of the yeast strain expressing only GAM1 gene when grown in the culture medium containing 2% (w/v) rice starch. It generated 11% (v/v) ethanol from 20% (w/v) rice starch and consumed up to 90% of the starch content after 7 days of fermentation.