• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.211-214
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• 2004

MTBE로 오염된 토양에서 생태독성학적 접근 방법으로 3가지 토양 효소의 활성도를 측정해 보았다. MTBE의 잠재적 위험성으로 인한 논란은 계속되고 있으나 토양 오염에 대한 지표로써 토양 효소 활성도의 사용타당성 여부에 대한 실험은 이전에 행해지지 않았다. 따라서 중금속 오염 토양에 대해 좋은 지표로 사용되고 있는 토양 미생물 효소의 활성도를 MTBE에 적용하여 실험해 보았다. 사용한 토양 효소는 Acid Phosphotase, $\beta$-Glucosidase 그리고 Arysulfatase였다. 그러나 실험 결과 MTBE로 오염된 토양의 경우 중금속으로 오염된 토양에 비해 토양 미생물 활성도의 감소가 매우 적었다. 따라서 MTBE의 오염 토양의 경우 본 연구에서 측정된 효소의 활성도는 좋은 지표로 적합하지 않다는 것을 확인했다.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.53-59
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• 1995

A protease isolated and purified 51 fold from the culture filtrate of a soil bacterium, Bacillus sp. KUN-17, which was appeared to be a monomeric protein with molecular weight of 38, 000 daltons, was suggested to be involved in the serine (-alkaline) protease (E.C 3.4.21.14) since its activity was selectively inhibited by phenylmethylsulfonyl fluoride (PMSF) and required 40$\circ$C and pH 10.5 for optimal condition. The half-life of the enzyme activity was 1 hr at 55$\circ$C, and the activity was maintained even under high concentrations of SDS or urea. The enzyme was indicated to perform random proteolysis from the fact that most of the chromogenic substrates employed were hydrolyzed by the enzyme. The affinity of the enzyme for natural proteins was approximately 10-times higher than ester compounds, and both substrates showed mutual inhibitory effect competitively for the enzyme activity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.3
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• pp.341-347
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• 2007

Chinese milk vetch (CMV) is a winter legume that is commonly used as cover crop in Korea. Kill date of cover crop for addition into soil affects N content in cover crop and N availability in soil. This study was conducted to evaluate the effect of CMV as green manure cover crop according to kill dates before growing corn without artificial fertilizer. Top of CMV cut three times on 13 April, 27 April, and 11 May were added into soil at a rate of 600 kg per 10a. Sugar content in CMV litter was persistently decreased from mid-April to late-May. The decrease of sugar content might be due to the transformation into starch and/or other storage or structural constituents. The decreased amount of sugars was greater than 12% and the increased amount of starch was less than 0.2%. Concentration of $NH_4^+$ in soil treated by CMV litter cut on May 11 was slightly higher than that in the treatment with early-cut (April 13) CMV, the concentration at 28 and 49 DAT (days after treatment) was higher in the treatment with late-cut CMV litter. Regardless of cut (kill) date of CMV, the phosphatase activity in the treatment of CMV litter was higher compared to the untreated control. Soil dehydrogenase activity was increased steadily by addition of CMV litter implying total microbial activities in the soil were increased. Our results demonstrate that the status of cover crop species at kill date is an important factor influencing soil enzyme activities derived from microorganisms. Therefore, the optimal kill date of cover crop should be examined to improve the efficiency of cover crop as green manure crop regarding the practical sequence in cropping system.

• Korean Journal of Environment and Ecology
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• v.26 no.6
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• pp.902-910
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• 2012

This study has been carried out to determine the effects of disturbances from wild boar grubbing on the functions of ecosystem. The experiments was performed in Mt. Jumbong of Long-term Ecological Research Sites of the Ministry of Environment. We measured soil physical properties, soil respiration($CO_2$), microbial biomass C, and soil enzyme activities from both disturbed and control plots. The disturbance sites were divided into two parts, mounds and pits. Soil organic matter contents were highest value at the control plots and lowest at the pit plots, respectively at 20.22% and 15.52%. The soil bulk densities were highest at the pit plots. Soil microbial biomass C and $CO_2$ evolution were significantly higher at the control plots compared to the disturbed plots. The results were positively correlated with soil organic matter contents. The cellulase activity and invertase activity in the soil showed similar pattern as the microbial biomass C and $CO_2$ evolution results. The cellulase activity and invertase activity in the soil were positively correlated with soil microbial biomass C. Soil organic matter contents seemed to affect the soil enzyme activities. The nitrate reductase activities were highest at the pit plots, which showed positive correlation with soil bulk density. The study results showed that the grubbing disturbances by wild boars induced the changes in soil properties, which affected soil microbial activities.

• The Korean Journal of Mycology
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• v.1 no.1
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• pp.23-28
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• 1973

The soil of Kwangneung area(Kyeunggi-Do) was inoculated directly into wheat-bran-media and after $3{\sim}4$ days of incubation, a Penicillium species whose cellulase activity was 1011u/g was isolated. With the treatment of mutagenic agents an improved strain(cellulase activity: 1303u/g) was obtained. This strain was screened again by mono-spore isolation method. Finally a strain C8-14 (cellulase activity: 2351u/g) which had lesser spores than the wild strain was obtained.

• Journal of Plant Biotechnology
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• v.44 no.2
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• pp.156-163
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• 2017

A greenhouse experiment was conducted for evaluation of ecological effects of transgenic melon plants in the rhizospheric soil in terms of soil properties, enzyme activities and microbial communities. Organic matter content of soil under transgenic melon plants was significantly higher than that of soil with non-transgenic melon plants. Significant variations were observed in organic matter, total P and K in soil cultivation with transgenic melon plants. There were also significant variations in the total numbers of colony forming units of fungi, actinomycetes and bacteria between soils treated with transgenic and non-transgenic melon plants. Transgenic and non-transgenic melon significantly enhanced several enzymes activities including urease, acid phosphatase, alkalin phosphatase, arysulphtase, ${\beta}$ glucosidase, dehydrogenase, protease and catalase. Soil polyphenoloxidase activity of $T_1$ transgenic melon was lower than that of $T_0$ transgenic melon and a non-melon plant during the same period. The first generation transgenic melon plants ($T_0$) showed significantly greater (p<0.05) effect on the activitiy of arylsulfatase, which increased from $2.540{\times}10^6CFU\;g^{-1}$ (control) to $19.860{\times}10^6CFU\;g^{-1}$ ($T_0$). These results clearly indicated that transgenic melon might change microbial communities, enzyme activities and soil chemical properties.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.304-310
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• 1995

A thermophilic bacterium producing the extracellular cellulase-free xylanase was isolated from soil and has been identified as Bacillus sp. The optimal growth temperature was 50$\circ$C and the optimal pH, 7.0. Under the optimal growth condition, maximal xylanase production was 2.2 units/ml in the flask culture. The enzyme production was induced by xylan and xylose, but was repressed by sucrose or trehalose. The partially purified xylanase was most active at 70$\circ$C. It was found that the enzyme was stable at 65$\circ$C for 10 hours with over 75% of the activity. The enzyme was most active at pH 7.0 and retained 90% of its maximum activity between pH 5.0 and pH 9.0 though Bacillus sp. was not grown on alkaline conditions (>pH 8.0). In addition, the activity of xylanase was over 60% at pH 10.0. At the ambient temperature, the enzyme was stable over a pH range of 5.0 to 9.0 for 10 h, indicating that the enzyme is thermostable and alkalotolerant. The activity of xylanase was completely inhibited by metal ions including Hg$^{2+}$ and Fe$^{2+}$, while EDTA, phenylmethylsulfonyl fluoride (PMSF), $\beta$-mercaptoethanol and SDS didn't affect its activity. The enzyme was also identified to exert no activity on carboxymethylcellulose, laminarin, galactomannan, and soluble starch.

• Korean Journal of Plant Resources
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• v.21 no.4
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• pp.324-328
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• 2008

One hundred-eighty extracts of soil collected from ginseng (Panax ginseng C.A. Meyer) fields were subjected to lettuce germination test, electrolyte leakage, cell viability and antioxidant enzyme activity test. Regardless of various cultivation periods, there was no significant difference in soil pH, the content of organic matter and available phosphate in ginseng fields. Based on lettuce seed germination test, six soil extracts showing inhibition of germination and/or seedling growth were selected for further study. Selected soil extracts markedly inhibited cell viability of ginseng cultured cells but leakage of electrolytes were not affected by the treatment. Enzyme activity of superoxide dimutase in ginseng cultured cells was not affected by the treatment with the soil extracts. However, those of peroxidase and catalase were significantly inhibited by the treatment with soil extracts which showed inhibition of lettuce seed germination and seedling growth.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.25-33
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• 1980

Pyrocatechase as a phenolytic dioxygenase was extracted from the benzoate-induced cells of a soil bacterium, a member of Pseudomonadaceae, and purified partially by DEAE-cellulose ion-exchange chromatography and Sephadex G-75 gel filtration. Final preparation of the enzyme yielding 200 fold purification over the crude extracts showed a specific activity of about 40 ${\mu}moles$ per minute per mg protein based on catechol as the substrate. The enzyme showed a very limited substrate specificity towards catechol for its catalytic activity. Based on the inhibition study with the substrate analogues, it was assumed that ortho dihydroxy groups on the aromatic ring may participate in the enzyme-substrate binding. The $K_m$ value for catechol was obtained as $1.9{\times}10^{-6}M$, and the optimum activity of the enzyme was obtained at the pH range of 7∼10 and $35^{\circ}C$. With SH-group blocking agents the enzyme was inhibited seriously. The activity of enzyme was also inhibited by the addition of some heavy metals, $Ag^+$ and $Cu^{2+}$, but was not affected by EDTA. General property of the enzyme was characterized and the possible nature of the enzyme active center was also discussed.

• Journal of Life Science
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• v.9 no.1
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• pp.64-68
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• 1999

The properties of purified intracellular adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) of Nocardioides sp. J-326TK isolated from soil have been studied. The enzyme deaminated adenosine and 2`-deoxyadenosine and the respective {TEX}$K_{M}${/TEX} values were 4.0×{TEX}$10^{-4}${/TEX} M and 5.0× {TEX}$10^{-4}${/TEX} M, but the enzyme was not active on 8-bromoadenosine, 6-methylaminopurine riboside, ATP, ADP, 2`-AMP, 3`-AMP, 5`-AMP, dAMP, cAMP, NAD, FAD, NADP and adenine. The enzyme activity was strongly inhibited by the addition of {TEX}$Hg^{2+}${/TEX} and {TEX}$Ag^{+}${/TEX}, {TEX}$Cu^{2+}${/TEX}, {TEX}$Co^{2+}${/TEX} and {TEX}$Mn^{2+}${/TEX} also inhibited the activity but much less extent. The effect of alkyl reagents, metal chelating reagents and certain other compounds on the enzyme activity were also examined. No reagent activated the enzyme. On the contrary, the enzyme reaction was slightly inhibited by o-phenanthroline and 6-benzyladenosine.