• Toxicological Research
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• v.14 no.3
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• pp.385-391
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• 1998

The study was carried out to evaluate the acute toxicity of enrofloxacin-colistin combination via a single oral(p.o.)and intravenous(i.v.) administration in ICR mice. All procedures of the test were performed by the established regulation of Korean National Institute of Safety Research (1994. 4.14). The maximal dose of oral and intravenous routes was 5,000mg/kg and 90mg/kg, consisting with each 6 groups including control of male and female, respectively. As the results, $LD_{50}$m}'s of the combinations showed 3,075mg/kg (f)and 2,564mg/kg(m) after oral administrations, together with 48mg/kg(f) and 40mg/kg(m) after intravenous administration. These facts indicated that acute toxicitiy of enrofloxacin-colistin combination were different depending on the administration routes and sexes in ICR mice. In conclusion, the route of enrofloxacin-colistin combination must not choose as i.v. route administration in terms of acute toxicity based on $LD_{50}$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.5
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• pp.643-649
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• 1993

Soybean composition, which is different from those of other beans and grains, gives from 35 to 40 percent protein, 15 to 20 percent oil, and 20 to 25 percent sugar. Soybean has been extensively used as the raw material for traditional foods such as bean curd, soy sauce, soy paste and so on, since ancient times in Korea. Ultracentrifugal components of the soybean proteins represent four major peaks with sedimentation constants of about 2, 7, 11 and 15S. The two major reserve protein of soybean, 7S and 11S globulins, have been isolated and characterized by many works. The curd made with microbial enzyme exhibited minuter structure than those of the metal ion-and acid-treatment. Thus, the curd obtained by enzymatic operation serves as a material for further development of food items, and the procedure may by widely applicable in food processing.

• Archives of Pharmacal Research
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• v.20 no.6
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• pp.525-528
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• 1997

Steroid $9{\alpha}$.-hydroxylase is a key enzyme system in steroid nucleus degradation in company with ${\Delta}$-dehydrogenase. To examine $9{\alpha}$-hydroxylase activity during microbial transformation of steroids, 9(11)-dehydro-$17{\alpha}$-methyl-testosterone was adopted as a stable substrate for preventing the rupture of steroid nucleus. Using Nocardia restrictus ATCC 14887 capable of introducing a $9{\alpha}$-hydroxyl group into steroids, $9{\alpha}$,$11{\alpha}$-oxido-$17{\beta}$-hydroxy-$17{\alpha}$-methyl-4-androstene-3-one and $9{\alpha}$-hydroxyl group into steroids,$9{\alpha}$,$11{\alpha}$-oxido-$17{\beta}$-hydroxy-$17{\alpha}$-methyl-1,4-androstadiene-3- one were obtained. These microbiologically transformed products could be used as reference compounds in the enzyme assay.

• Journal of Microbiology and Biotechnology
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• v.32 no.5
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• pp.672-679
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• 2022

Microbial lipases are used widely in the synthesis of various compounds due to their substrate specificity and position specificity. 4-Ethyl malate (4-EM) made from diethyl malate (DEM) is an important starting material used to make argon fluoride (ArF) photoresist. We tested several microbial lipases and found that Photobacterium lipolyticum M37 lipase position-specifically hydrolyzed DEM to produce 4-EM. We purified the reaction product through silica gel chromatography and confirmed that it was 4-EM through nuclear magnetic resonance analysis. To mass-produce 4-EM, DEM hydrolysis reaction was performed using an enzyme reactor system that could automatically control the temperature and pH. Effects of temperature and pH on the reaction process were investigated. As a result, 50℃ and pH 4.0 were confirmed as optimal reaction conditions, meaning that M37 was specifically an acid lipase. When the substrate concentration was increased to 6% corresponding to 0.32 M, the reaction yield reached almost 100%. When the substrate concentration was further increased to 12%, the reaction yield was 81%. This enzyme reactor system and position-specific M37 lipase can be used to mass-produce 4-EM, which is required to synthesize ArF photoresist.

• Journal of the Korean Applied Science and Technology
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• v.40 no.5
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• pp.1126-1135
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• 2023

Nine microbial strains were isolated from the byproduct of ginseng processing and field of ginseng cultivation. Two strains among them were confirmed. Phylogenetic analysis of these 𝛽-Glucosidase strains confirmed that strain GYP-1 belongs to the Rhodotorula and strain GYP-3-3 belong to genus Brachybacterium. Rhodotorula sp. GYP-1 was finally selected due to its high biomass production. The 𝛽-Glucosidase activity of Rhodotorula sp. GPY-1 was assessed at 30 ℃, and Higher than 70% of the enzyme activity was maintained at the temperature range of 20-40℃. Although the optimum pH for the highest enzyme activity was pH 5.0, the enzyme was stable throughout the pH range of 5.0-8.0. In addition, Rhodotorula sp. demonstrated antifungal activity against the ginseng root rot disease caused by Botrytis.

• 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.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.7
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• pp.1103-1112
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• 2020

Objective: To measure whether a microbial additive could effectively improve the fermentation quality of delayed-sealing (DS) silage, we studied the effects of inoculants of lactic acid bacteria (LAB) and cellulase enzyme on microbial populations, ensiling characteristics, and spoilage loss of DS silage of Napier grass in Africa. Methods: Quick-sealing (QS) and DS silages were prepared with and without LAB (Lactobacillus plantarum) inoculant, cellulase enzymes, and their combination. The QS material was directly chopped and packed into a bunker silo. The DS material was packed into the silo with a delay of 24 h from harvest. Results: In the QS silage, LAB was dominant in the microbial population and produced large amounts of lactic acid. When the silage was treated with LAB and cellulase, the fermentation quality was improved. In the DS silage, aerobic bacteria and yeasts were the dominant microbes and all the silages were of poor quality. The yeast and mold counts in the DS silage were high, and they increased rapidly during aerobic exposure. As a result, the DS silages spoiled faster than the QS silages upon aerobic exposure. Conclusion: DS results in poor silage fermentation and aerobic deterioration. The microbial additive improved QS silage fermentation but was not effective for DS silage.

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1123-1133
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• 2021

Biodegradation is the key process involved in natural lignocellulose biotransformation and utilization. Microbial consortia represent promising candidates for applications in lignocellulose conversion strategies for biofuel production; however, cooperation among the enzymes and the labor division of microbes in the microbial consortia remains unclear. In this study, metagenomic analysis was performed to reveal the community structure and extremozyme systems of a lignocellulolytic microbial consortium, TMC7. The taxonomic affiliation of TMC7 metagenome included members of the genera Ruminiclostridium (42.85%), Thermoanaerobacterium (18.41%), Geobacillus (10.44%), unclassified_f__Bacillaceae (7.48%), Aeribacillus (2.65%), Symbiobacterium (2.47%), Desulfotomaculum (2.33%), Caldibacillus (1.56%), Clostridium (1.26%), and others (10.55%). The carbohydrate-active enzyme annotation revealed that TMC7 encoded a broad array of enzymes responsible for cellulose and hemicellulose degradation. Ten glycoside hydrolases (GHs) endoglucanase, 4 GHs exoglucanase, and 6 GHs β-glucosidase were identified for cellulose degradation; 6 GHs endo-β-1,4-xylanase, 9 GHs β-xylosidase, and 3 GHs β-mannanase were identified for degradation of the hemicellulose main chain; 6 GHs arabinofuranosidase, 2 GHs α-mannosidase, 11 GHs galactosidase, 3 GHs α-rhamnosidase, and 4 GHs α-fucosidase were identified as xylan debranching enzymes. Furthermore, by introducing a factor named as the contribution coefficient, we found that Ruminiclostridium and Thermoanaerobacterium may be the dominant contributors, whereas Symbiobacterium and Desulfotomaculum may serve as "sugar cheaters" in lignocellulose degradation by TMC7. Our findings provide mechanistic profiles of an array of enzymes that degrade complex lignocellulosic biomass in the microbial consortium TMC7 and provide a promising approach for studying the potential contribution of microbes in microbial consortia.

• Microbiology and Biotechnology Letters
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• v.48 no.1
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• pp.64-71
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• 2020

A total of 262 bacterial strains were isolated from clay minerals, bentonite and zeolite, in Gyeongsangbukdo, Republic of Korea, and their hydrolytic enzyme activities were analyzed. Most of the isolated strains belonged to Micrococcales and Bacillales order. Of strains, 96 strains produced α-amylase activity, 42 strains showed cellulase activity, 111 strains had pectinase activity, and 70 strains showed protease activity. Among them, 177 isolates exhibited one or more of the hydrolytic enzyme activities and in particular Bacillus cereus MBLB1321, B. albus MBLB1326 and KIGAM017, B. mobilis MBLB1328, MBLB1329 and MBLB1330 showed all of the enzyme activities. These results demonstrate the diversity of functional Bacillus species in clay minerals as vital sources for the discovery of industrially valuable hydrolytic enzymes, which have a great commercial prospect in various bio-industrial applications.

• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.242-248
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• 2002

Previously, it was reported that the nonhomologous C-terminal regions of the D-hydantoinases are nonessential for catalysis, but affect the oligomeric structure of the enzyme [3]. In an effort to further confirm the above observation, the C-terminal region-inserted enzyme was constructed by attaching a peptide (22 residues) at the C-terminal of the D-hydantoinase from Bacillus thermocatenulatus GH2, and its structural and biochemical properties were compared with both the wild-type and C-terminal region-truncated enzymes. As a result, native tetrameric D-hydantoinase was dimerized as the truncated enzyme, and the inserted mutant with a new sequence was expressed as a catalytically active form in E. coli. Expression level of the inserted and truncated enzymes were found to be significantly increased compared to the level of the wild-type enzyme, and this appears to be due to the reduced toxic effect of the mutant enzymes on host cells. Dimerized enzymes exhibited increased thermo- and pH stabilities considerably when compared with the corresponding wild-type enzyme. Comparison of the substrate specificity between the mutant and wild-type enzymes suggests that the substrate specificity of the D-hydantoinase is closely linked with the oligomeric structure.