• YAKHAK HOEJI
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• v.45 no.3
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• pp.245-250
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• 2001

Aminoacyl tRNA synthetases of bacteria are known as potential targets for new anti-microbial agents. To isolate new inhibitors of bacterial methionyl-tRNA synthetases from natural sources, a new target-oriented screening system using whole cells which are over-expressing a target enzyme was developed. Approximately 8,000 culture broths of microorganisms from soils were tested by this screening system. Among them, ten culture broths was found to contain inhibitory activity against methionyl -tRNA synthetases of Escherichia coli. For the validation of the screening system, this new method was compared with in vitro enzymatic method. Seven out of 10 culture broths showed inhibitory activity against methionyl-tRNA synthetases of E. coli. This result showed that the new screening system was comparable to the enzyme assay. Thus we believe that our screening system as a new method can be applied for the screening of new antibiotics inhibiting bacterial methionyl-tRNA synthetases from natural products.

• Korean Journal of Microbiology
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• v.26 no.2
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• pp.122-128
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• 1988

The enzymatic properties of soil cellobiohydrolase were examined and compared with those of cellobiohydrolase-active extracts from soil in the forms of enzyme-humic complex and humicfree enzyme, and cellobiohydrolase partially pruified from Aspergillus niger. The pH optima of soil cellobiohydrolase and cellobiohydrolase-humic complex were greater by 1.5-3.0 pH units than those of cellobiohydrolase in humic-free extract and from A. niger. Soil cellobiohydrolase and cellobiohydrolase-humic complex were remarkably resistant to thermal denaturation and proteolysis. These results confirm that cellobiohydrolase in soil is atable in conditions which rapidly inactivate microbial cellobiohydrolase and that its stability is due to the immobilization of this enzyme by association with humic substances. The Michaelis-Menten constants (Km) for soil, cellobiohydrolase-humic complex, humic free extract and cellobiohydrolase from A. niger were 22.1mg/ml, 11.3mg/ml, 10.6mg/ml and 4.5 mg/ml of Avicel, respectively.

• Korean Journal of Pharmacognosy
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• v.50 no.3
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• pp.159-164
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• 2019

Zanthoxylum Peel is widely used as a common spice for a variety of foods. In the orient, it has also been used as traditional agents for treating diseases such as indigestion. Recently, Zanthoxylum Peel has been reported to have anti-cancer activity, anti-microbial activity, and anti-inflammatory activity. Chemical components are known sanshool compounds and xanthoxylin. In this study, we were carried out to investigate the constituents of inhibiting a drug metabolizing enzyme CYP3A4 from Zanthoxylum Peel. CYP3A4 is known as an enzyme involved in drug metabolism as monooxygenase containing the heme. As a result of experiment, we found that bergapten ($IC_{50}=18.21{\mu}M$) and quercetin ($IC_{50}=17.27{\mu}M$) isolated from EtOAc extract of Zanthoxylum Peel showed remarkable CYP3A4-inhibiting activities. Structures of the isolated active compounds were established by chemical and spectroscopic means.

• Mycobiology
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• v.33 no.1
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• pp.41-50
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• 2005

Results from an innovative approach to improve remediation in the rhizosphere by encouraging healthy plant growth and thus enhancing microbial activity are reported. The effect of arbuscular mycorrhizal fungi (Am) on remediation efficacy of wheat, mungbean and eggplant grown in soil spiked with polyaromatic hydrocarbons (PAH) was assessed in a pot experiment. The results of this study showed that Am inoculation enhanced dissipation amount of PAHs in planted soil, plant uptake PAHs, dissipation amount of PAHs in planted versus unplanted spiked soil and loss of PAHs by the plant-promoted biodegradation. A number of parameters were monitored including plant shoot and root dry weight, plant tissue water content, plant chlorophyll, root lipid content, oxido-reductase enzyme activities in plant and soil rhizosphere and total microbial count in the rhizospheric soil. The observed physiological data indicate that plant growth and tolerance increased with Am, but reduced by PAH. This was reflected by levels of mycorrhizal root colonization which were higher for mungbean, moderate for wheat and low for eggplant. Levels of Am colonization increased on mungbean > wheat > eggplant. This is consistent with the efficacy of plant in dissipation of PAHs in spiked soil. Highly significant positive correlations were shown between of arbuscular formation in root segments (A)) and plant water content, root lipids, peroxidase, catalase polyphenol oxidase and total microbial count in soil rhizosphere as well as PAH dissipation in spiked soil. As consequence of the treatment with Am, the plants provide a greater sink for the contaminants since they are better able to survive and grow.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.358-365
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• 2020

An organic solvent- and bleach-stable protease-producing strain was isolated from a polluted river water sample and identified as Aeromonas veronii OB3 on the basis of biochemical properties (API 20E) and 16S rRNA sequence analysis. The strain was found to hyper-produce alkaline protease when cultivated on fish waste powder-based medium (HVSP, 4080 U/ml). The biochemical properties and compatibility of OB3 with several detergents and additives were studied. Maximum activity was observed at pH 9.0 and 60℃. The crude protease displayed outstanding stability to the investigated surfactants and oxidants, such as Tween 80, Triton X-100, and H₂O₂, and almost 36% residual activity when incubated with 1% SDS. Remarkably, the enzyme demonstrated considerable compatibility with commercial detergents, retaining more than 100% of its activity with Ariel and Tide (1 h, 40℃). Moreover, washing performance of Tide significantly improved by the supplementation of small amounts of OB3 crude protease. These properties suggest the potential use of this alkaline protease as a bio-additive in the detergent industry and other biotechnological processes such as peptide synthesis.

• BMB Reports
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• v.28 no.1
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• pp.83-86
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• 1995

In the course of screening for new aminopeptidase M inhibitors which were expected to be analgesic, immunopotentiating, or anti-metastatic agents, the novel synthetic substance MR-387C[(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl-L-valyl-L-prolyl-L-leucine] (M.W. 504 daltons) was obtained. It was competitive with the substrate and had an $IC_{50}$ value of $0.04\;{\mu}m/ml$ ($7.9{\times}10^{-8}\;M$) and an inhibition constant ($K_i$) of $3.8{\times}10^{-8}\;M$. This novel MR-387C was compared with various known inhibitors of aminopeptidase M. It inhibited the enzyme more strongly than any other microorganism-originated inhibitor, except probestin.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.1
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• pp.57-60
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• 2000

$(R)-\beta-acetylmercaptoisobutyric$ acid (RAM), a chiral compound, is an important intermediate for the chemical synthesis of various antihypertensive and congestive heart failure drugs. Microorganisms capable of converting $(R,S)-\beta-acetylmercaptoisobutyric$ acid ((R,S)-ester) to RAM were screened from soil microorganisms. A strain of Pseudomonas sp. 1001 screened from a soil sample was selected to be the best. Cells showed an activity of 540 U/mL from culture broth and the enzyme was thermostable up to $70^{\circ}C$. This strain could produce RAM asymmetrically from (R,S)-ester.

• Korean Journal of Microbiology
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• v.35 no.1
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• pp.72-77
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• 1999

To investigate soil bacterial diversity according to vegelalioo types, utilizing ability of sole carbon sources and restriction enzyme patterns of 16s rDNA were analyzed. From the both results; five kinds of soil microbial communities were grouped as forest soil (Quercus mongolica and Pinus densi&ra vegetation), grass-agricultured soil and microbial communities of naked soil. But, both soil microbial communities of directily exlracted from ths soil and indirectly extracted from heterotrophic bacteria that cultured soil in LB medium showed very different similarity.

• Preventive Nutrition and Food Science
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• v.17 no.2
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• pp.172-176
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• 2012

Doenjang is a traditional Korean fermented soybean product that provides a major source of protein. In this study, a total of 18 different home-made doenjang samples were examined for the presence of foodborne pathogens and the total aflatoxin levels. Using an enzyme-linked immunosorbent assay to assess microbial quality and potential public health risk, we showed that total coliform levels in the doenjang samples ranged from 0 to $4.43{\pm}2.32{\times}10^6\;CFU/g$, and the maximum limit of Bacillus cereus was $4.67{\pm}2.0{\times}10^5\;CFU/g$. However, other foodborne pathogens, such as Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella spp., were not detected among the tested samples. One of the samples (S3) showed a maximum limit of $42.2{\pm}9.1\;{\mu}g/kg$ for aflatoxin levels, which was above the safety limit allowed by the Codex Alimentarius Commission (CAC) regulatory agency. Further research is necessary to determine whether and how doenjang safety can be improved via elimination/reduction of microbial contamination during fermentation and storage or using microbial starter cultures for its fermentation.

• Journal of Microbiology and Biotechnology
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• v.32 no.4
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• pp.437-446
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• 2022

In this study, to obtain icaritin with high pharmacological activities from icariin, which has a content ratio of over 58% in the total flavonoids of Epimedium herb, a special Epimedium flavonoid-glycosidase was produced, purified and characterized from Aspergillus sp.y848 strain. The optimal enzyme production was gained in a medium containing 5% (w/v) wheat bran extract and 0.7% (w/v) Epimedium leaf powder as the enzyme inducer, and strain culture at 30℃ for 6-7 days. The molecular weight of the enzyme was approximately 73.2 kDa; the optimal pH and temperature were 5.0 and 40℃. The enzyme Km and Vmax values for icariin were 15.63 mM and 55.56 mM/h. Moreover, the enzyme hydrolyzed the 7-O-glucosides of icariin into icariside II, and finally hydrolyzed 3-Orhamnoside of icariside II into icaritin. The enzyme also hydrolyzed 7-O-glucosides of epimedin B to sagittatoside B, and then further hydrolyzed terminal 3-O-xyloside of sagittatoside B to icarisiede II, before finally hydrolyzing 3-O-rhamnoside of icarisiede II into icaritin. The enzyme only hydrolyzed 7-O-glucoside of epimedin A or epimedin C into sagittatoside A or sagittatoside C. It is possible to prepare icaritin from the high-content icariin in Epimedium herb using this enzyme. When 2.5% icariin was reacted at 40℃ for 18-20 h by the low-cost crude enzyme, 5.04 g icaritin with 98% purity was obtained from 10 g icariin. Also, the icaritin molar yield was 92.5%. Our results showed icaritin was successfully produced via cost-effective and relatively simple methods from icariin by crude enzyme. Our results should be very useful for the development of medicines from Epimedium herb.