• Food Science and Biotechnology
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• v.18 no.6
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• pp.1411-1416
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• 2009

The suppressive effects of glutathione-enriched Saccharomyces cerevisiae FF-8 strain (FF-8 GY) on alcoholinduced hepatotoxicity have been studied. FF-8 GY (256 mg/L) from the fermentation at a large scale bioreactor was used. Either of 5% FF-8 GY or 5% commercial glutathione-enriched yeast extract (GYE) with or without 30% alcohol was tested with rats for 4 weeks. FF-8 GY and GYE were found to reduce those alcohol-elevated serum alanine aminotransferase (ALT), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) activities. Blood alcohol and acetaldehyde were also decreased by FF-8 GY and GYE. Interestingly, FF-8 GY drastically increased both hepatic alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) activities in comparison to GYE group, thus FF-8 GY would be more effective in blood alcohol and acetaldehyde reduction. Attenuated lipid droplet accumulation in hepatocytes was observed in both FF-8 GY and GYE when alcohol stimulated the accumulation. Therefore, FF-8 GY may be useful to protect liver from alcohol-induced hepatotoxicity.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.411-416
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• 1990

Microbiological conversion of sterols to 17-ketosteroids has been recongnized as a source for commerical preparation of steroidal drugs. For the purpose of strain development, we isolated microorganisms through enrichment culture method and identified an isolate strain. The strain was closely related to Brevibacterium ergthrogenes. The optimal conditions for 1, 4-androstadiene-3, 17-dione (ADD) formation were as follows; pH 7.4, lactose 0.2%, beef extract 0.2%, bentonite 0.5% in the chlolesterol fermentation medium. Maximum production was obtained with the addition of $\alpha$, $\alpha$'-dipyridyl (1 mM, final conc.) at 17-20 hours after incubation.

• Journal of Life Science
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• v.12 no.3
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• pp.357-362
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• 2002

A bacterial strain showing the fibrinolytic activity was screened from korean traditional soybean products. For the identification, the strain was investigated morphology and biochemical characteristics and it was classified to Bacillus subtilis. The strain had high fibrinolytic activity in Chungkukjang. The optimum fermentation condition of temperature and time were 37$^{\circ}C$ and 24hour. The pH in Chungkukjang was gradually alkalized during fermentation. The fibrinolytic enzyme in Chungkukjang stable at heft treatment; After heating at 6$0^{\circ}C$ and 8$0^{\circ}C$ for 30 min, the fibrinolytic activity remained 75% and 40%, respectively.

• Journal of Microbiology and Biotechnology
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• v.34 no.9
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• pp.1912-1918
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• 2024

Single-cell protein (SCP) derived from microorganisms is widely recognized as a viable alternative protein source for the future. Nevertheless, the commercialization of yeast-based SCP is hampered by its relatively low protein content. Therefore, this study aimed to enhance the protein content of Saccharomyces cerevisiae via random mutagenesis. To achieve this, S. cerevisiae KCCM 51811, which exhibited the highest protein concentration among 20 edible S. cerevisiae strains, was selected as a chassis strain. Subsequently, a KCCM 51811 mutant library was constructed (through UV irradiation) and screened to isolate mutants exhibiting high protein content and/or concentration. Among the 174 mutant strains studied, the #126 mutant exhibited a remarkable 43% and 36% higher protein content and concentration, respectively, compared to the parental strain. Finally, the #126 mutant was cultured in a fed-batch system using molasses and corn-steep liquor, resulting in a protein concentration of 21.6 g/l in 100 h, which was 18% higher than that produced by the parental strain. These findings underscore the potential of our approach for the cost-effective production of food-grade SCP.

• Applied Biological Chemistry
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• v.16 no.2
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• pp.85-93
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• 1973

These experiments were carried out to study influences of the kind of yeasts and of brewing condition on fermentation of Takjoo mash. The results obtained were as follows: 1. Kind of yeasts and the number of yeasts in mash. When the first stage mash was fermented at $20^{\circ}C$ for $1.5{\sim}2.5$ days and at $25^{\circ}C$, $30^{\circ}C$ for $1{\sim}2days$, in the second stage mash that was fermented at high temperature, the number of yeasts was less as compared with the case of fermentation at low temperature, but the living yeasts number of Takjoo yeast strain Dm-1 was more than those of sake yeast, strain No. 7. 2. Kind of yeasts and composition of ripened mash. 1) In the secondstage mash that was fermented at high temperature($30{\sim}35^{\circ}C$), alcohol percentage of ripened mash using the selected Takjoo yeasts (strains: Dm-1, Y-1) was remarkably higher than the case of another yeasts (strains: No.7, No.6, No. 396, No. 1). 2) Acidity of mash had a little differences between strain Dm-1 and strain No. 7. 3) In the second stage mash that was fermented at high temperature ($30{\sim}35^{\circ}C$), the amount of Formol-N using strain Dm-1 was remarkably less than strain No.7. 3. Brewing condition and alcohol percentage of mash. 1) The fit amount of wheat bran Kuk addition per material was 3 percentage and it was adequate to use the mixture of wheat flour Kuk 20 percentage and wheat bran Kuk 1-2 percentage. 2) Though brewing concentration of the first stage mash was duiluted by twice of general brewing concentration, the yeast reproduction was normal. 3) In addition of wheat flour $80{\sim}140g$ per 180ml water, alcohol percentage of the mash increased almost propotionally according to the increase of the amount of wheat flour. 4) It was recognized that three stage brewing was superior in method to two stage brewing at present.

• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1557-1567
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• 2012

Glutathione reductase (GR, E.C. 1.6.4.2) is an important enzyme that reduces glutathione disulfide (GSSG) to a sulfydryl form (GSH) in the presence of an NADPH-dependent system. This is a critical antioxidant mechanism. Owing to the significance of GR, this enzyme has been examined in a number of animals, plants, and microbes. We performed a study to evaluate the molecular properties of GR (OsGR) from rice (Oryza sativa). To determine whether heterologous expression of OsGR can reduce the deleterious effects of unfavorable abiotic conditions, we constructed a transgenic Saccharomyces cerevisiae strain expressing the GR gene cloned into the yeast expression vector p426GPD. OsGR expression was confirmed by a semiquantitative reverse transcriptase polymerase chain reaction (semiquantitative RT-PCR) assay, Western-blotting, and a test for enzyme activity. OsGR expression increased the ability of the yeast cells to adapt and recover from $H_2O_2$-induced oxidative stress and various stimuli including heat shock and exposure to menadione, heavy metals (iron, zinc, copper, and cadmium), sodium dodecyl sulfate (SDS), ethanol, and sulfuric acid. However, augmented OsGR expression did not affect the yeast fermentation capacity owing to reduction of OsGR by multiple factors produced during the fermentation process. These results suggest that ectopic OsGR expression conferred acquired tolerance by improving cellular homeostasis and resistance against different stresses in the genetically modified yeast strain, but did not affect fermentation ability.

• Korean Journal of Microbiology
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• v.50 no.3
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• pp.233-238
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• 2014

For the collection of starters suitable for the brewing of traditional liquor, an alcohol-resistant strain of lactic acid bacteria with low level of acid production was isolated from traditional fermented soybean lumps. The strain named as JBE 30 was identified as Lactobacillus brevis by 16S rRNA sequence analysis and additional biochemical tests. The strain could grow well at a MRS medium containing 8% (v/v) ethanol for 96 h of cultivation at $30^{\circ}C$. The final pH after cultivation was 4.5. It also inhibited the growth of food spoilage and pathogenic bacteria including Escherichia coli, Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Micrococcus luteus, and Pseudomonas aeruginosa. These results showed that Lactobacillus brevis JBE 30 could be used as a promising starter in brewing process of traditional liquor.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.5
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• pp.741-746
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• 1996

Antibacterial activities of the bamboo(Pseudosasa japonin Makino) leaves extract on lactic acid bacteria related to Dongchimi fermentation were investigated. The bamboo leaves were extracted with 70% ethanol, fractionated it with 4 solvents which have a different polarity. Total viable count was very similar to those obtained by lactic acid bacteria during fermentation of Dongchimi. Its maximum counts were (equation omitted) 10$^{7}$ CFU/m1 at 8 days of fermention. Lactic acid bacteria isolated during Dongchimi fermentation were identified as Leuconostoc species(BK-2, BK-07, BK-22), Lactobaillus species (BK-05, BK-08) and Streptococcus species(BK-15) 70% ethanol extract of the bamboo leaves showed antibacterial activity against strain BK-02, BK-07, BK-lS and BK-22. Especially, strain BK-22 was more effective to the extracted substance. Among the each fractions, 70% ethanol and diethyl ether had the strongest antibacterial activity against strain BK-22 and BK-07, respectively. The two fractions also showed similar activities against all of the test strains.

• The Microorganisms and Industry
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• v.19 no.2
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• pp.34-41
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• 1993

Industrial strain improvement is concerned with developing or modifying microorganisms used in production of commercially important fermentation products. The aim is to reduce the production cost by improving productivity of a strain and manipulating specific characteristics such as the ability to utilize cheaper raw materials or resist bacteriophages. The traditional empirical approach to strain improvement is mutation combined with selection and breeding techniques. It is still used by us to improve the productivity of organisms in amino acids, organic acids and enzymes production. The breeding of high L-lysine-producing strain Au112 is one of the outstanding examples of this approach. It is a homoserine auxotroph with AEC, TA double metabolic analogue resistant markers. The yield reaches 100 g/l. Besides, the citric acid-producing organism Aspergillus niger, Co827, its productivity reaches the advanced level in the world, is also the result of a series mutations especially with $^60Co{\gamma}$-radiation. The thermostable .alpha.-amylase producing strain A 4041 is the third example. By combining physical and chemical mutations, the strain A 4041 becomes an asporogenous, catabolite derepressed mutant with rifamycin resistant and methionine, arginine auxotroph markers. The .alpha.-amylase activity reaches 200 units/ml. The fourth successful example of mutation in strain improvement is the glucoamylase-producing strain Aspergillus niger SP56, its enzyme activity is 20,000 units/ml, 4 times of that of the parental strain UV-11. Recently, recombinant DNA approach provides a worthwhile alternative strategy to industrial strain improvement. This technique had been used by us to increase the thermostable .alpha.-amylase production and on some genetic researches.

• Food Science and Preservation
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• v.22 no.1
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• pp.108-118
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• 2015

To raise the added value of the fruits of Cudrania tricuspidata, Cudrania tricuspidata vinegar was produced and examined for its fermentation conditions. Forty nine acetic acid bacteria with resistance against acetic acid, ethanol, and sulfide as high acetic acid producers were isolated from fermented foods and identified as Acetobacter indonesiensis, A. cerevisiae, A. orientalis, A. tropicalis, A. fabarum, A. pasteurianus, and A. syzygii based on the results of the analysis of the 16S rRNA gene sequences. Among them, two GRAS strains, A. pasteurianus SCMA5 and SCMA6, were finally selected for the production of acetic acid. Optimal vinegar productions were obtained from the medium containing 40% (v/v) fruit juice of Cudrania tricuspidata and 5% (v/v) ethanol at $25^{\circ}C$ for 72 hr. The sensory panel preferred the vinegar fermented with the SCMA06 to that with the SCM05 strain. The radical scavenger capacity of DPPH was 53% higher than that of the control in the vinegar fermented with the SCMA06 strain. The ${\alpha}$-glucosidase inhibitor activity as an index of the antidiabetic drug showed 91% inhibition, which is higher than that of acabose. This study will be helpful for the scale-up production of vinegar with the fruit of Cudrania tricuspidata.