• Korean Journal of Microbiology
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• v.51 no.2
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• pp.97-107
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• 2015

Wetlands constitute a transitional zone between terrestrial and aquatic ecosystems and have unique characteristics such as frequent inundation, inflow of nutrients from terrestrial ecosystems, presence of plants adapted to grow in water, and soil that is occasionally oxygen deficient due to saturation. These characteristics and the presence of vegetation determine physical and chemical properties that affect decomposition rates of organic matter (OM). Decomposition of OM is associated with activities of various extracellular enzymes (EE) produced by bacteria and fungi. Extracellular enzymes convert macromolecules to simple compounds such as labile organic carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) that can be easily taken up by microbes and plants. Therefore, the enzymatic approach is helpful to understand the decomposition rates of OM and nutrient cycling in wetland soils. This paper reviews the physical and biogeochemical factors that regulate extracellular enzyme activities (EEa) in wetland soils, including those of ${\beta}$-glucosidase, ${\beta}$-N-acetylglucosaminidase, phosphatase, arylsulfatase, and phenol oxidase that decompose organic matter and release C, N, P, and S nutrients for microbial and plant growths. Effects of pH, water table, and particle size of OM on EEa were not significantly different among sites, whereas the influence of temperature on EEa varied depending on microbial acclimation to extreme temperatures. Addition of C, N, or P affected EEa differently depending on the nutrient state, C:N ratio, limiting factors, and types of enzymes of wetland soils. Substrate quality influenced EEa more significantly than did other factors. Also, drainage of wetland and increased temperature due to global climate change can stimulate phenol oxidase activity, and anthropogenic N deposition can enhance the hydrolytic EEa; these effects increase OM decomposition rates and emissions of $CO_2$ and $CH_4$ from wetland systems. The researches on the relationship between microbial structures and EE functions, and environmental factors controlling EEa can be helpful to manipulate wetland ecosystems for treating pollutants and to monitor wetland ecosystem services.

• Journal of Wetlands Research
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• v.14 no.1
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• pp.47-57
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• 2012

We have measured soil enzyme activities, which represent the rates of organic matter decomposition, in four riparian ecosystems in Korea. ${\beta}$-glucosidase, N-acetylglucosaminidase, phosphatase and arylsulfatase activities were determined in five occasions over a year period in soils of control plots and plots with invasive plants, namely Sicyos angulatus and Humulus japonicus. Significantly higher enzyme activities were found in soils with invasive plant in barren land, but the difference was season and enzyme-specific. Although it was not universal changes, the invasive plants appeared to accelerate organic matter decomposition in some disturbed riparian ecosystems.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2132-2137
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• 2009

갈대(Phragmites communis Trin.)란 염분이 있는 곳에서 자라는 염생식물로서 우리나라 전역에 분포하고 있다. 지난 50년 동안 우리나라의 여러 습지에 걸쳐서 갈대는 우점종으로 자라왔고, 육지와 수중서식지에서 갈대의 확산범위는 증가하고 있다. 갈대의 확산은 다른 습지 식물의 서식지를 파괴하고, 갈대가 번식하면 동 식물들의 번식 자체가 어려울 뿐 아니라 갈대숲에 포식자가 늘어나 살아가기 어려운 환경으로 변하기때문에 갈대를 체계적으로 관리할 수 있는 방안이 마련되어야 한다. 본 연구는 우점종이 다른 두 습지에서 갈대군집의 성장률을 관찰하고, 토양의 화학적 분석과 식물의 생리적 분석을 통해 갈대군집 성장에 미치는 영양염류의 영향을 규명하였다. 연구 대상지는 한강하구에 위치한 장항습지와 성동습지로서 동일하게 갈대가 분포하며, 장항습지에는 줄 군락이 성동습지에는 새섬매자기 군락이 우점하고 있다. 분석 항목은 이화학적 항목을 비롯하여 용존유기탄소(DOC, dissolved organic carbon), 체외미생물효소활성도(Extracellular enzyme activities), 암모니아성 질소($NH_4^+$), 질산성 질소($NO_3^-$)을 분석하였다. 실험결과, 두 습지 갈대의 성장은 7월부터 9월에 증가하였고 성동습지의 토양성분이 점토질로 형성되어 높은 수분함량과 유기물함량을 유지하고 있기 때문에 갈대의 밀도가 높고 성장률이 활발한 것으로 나타났다. 또한 미생물활성과 환경인자간 양의 상관관계를 보아 환경인자들이 미생물 활성을 자극하고 미생물들은 식물의 성장을 촉진하여 영향을 주며, 반면 식물 뿌리는 enzyme을 생성하는 미생물에게 C 삼출물을 공급해 enzyme 활성에 영향을 미칠 것으로 사료된다.

• The Microorganisms and Industry
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• v.19 no.3
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• pp.38-40
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• 1993

효소는 일반적으로 건전한 생체에서는 원형질에서 충분히 생성되어진다. 또한 미생물의 배양조건을 달리하던가 씨앗의 발아 시기와 같이 생체가 특수한 상황일 때에는 급격히 증가하기도 한다. 이러한 효소는 주로 단백질로 구성되어 있으며, 그 대부분의 아미노산이 peptide 결합을 하고 있는 고분자 화합물로서 효소의 종류에 따라 특정한 반응에만 특이적으로 작용하는 기질특이성을 가지고 있다. 효소를 이용한 건강식품으로는 체내 과산화지질의 분해를 촉진하는 SOD(superoxide dismutase), 활성 산소나 과산화수소 등의 체외 배출을 돕는 글루타치온 생성효소를 이용한 제품 외에 야채의 미생물 발효를 통하여 미생물 자체나 효소를 이용하는 과채발효 음료 등이 있지만, 여기에서는 특별히 미생물 유래의 효소를 이용한 분말형 효소 제품을 소개하고자 한다.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.229-235
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• 1990

A rapid and sensitive method to detect the extracellular enzymatic activity of bacteria colonies grown on agar plates is described. Selective agar media supplemented with protein, starch, chitin, Tween-80, etc. are conventionally used to detect biochemical properties of bacteria. It has been experimentally demonstrated with bacteria pure cultures that fluorogenic Methylumbelliferyl (MUF)-substrates are excellent substrate analogues for normally occurring polymers. Based on MUF-substrate hydrolysis the new method provides reliable qualitative estimates of extracellular enzymatic properties of bacteria within minutes using pure cultures as well as agar p;ates prepared for colony counts. Extracellular enzyme activities of heterotrophic bacteria from freshwater ecosystems and marine sediment using this method are discussed.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.75-80
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• 2015

Pseudoalteromonas donghaensis HJ51, isolated from the East Sea, has been reported as a novel strain to produce extracellular protease. Crude supernatant was used to determine optimal activity and optimal production conditions for the enzyme. It was found that the optimal temperature and pH of the protease were $40^{\circ}C$ and pH 7.5-10.5, respectively. The enzyme activity was kept to 88% at the pH 11. In metal requirement analysis, the enzyme exhibited the highest activity when 10 mM $Fe^{3+}$ was supplied. While supplementation of additional carbon sources used in study showed no positive effect on cell growth and enzyme activity, the addition of beef extract, tryptone, or casamino acids instead of peptone of PY-ASW containing 1% glucose increased enzyme production to 21, 7, 4%, respectively. Taken together these properties, the enzyme produced from P. donghaensis HJ51 can be applied to the industries that require protease activity under alkaline pH and low temperature.

• Korean Journal of Ecology and Environment
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• v.35 no.4 s.100
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• pp.326-330
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• 2002

A wetland soil was sterilised by two methods and changes in microbial enzyme activities were assessed. The short-term effects were determined by toluene addition, while the longer-term effects of elimination was monitored by ${\gamma}$-radiation. The changes in ${\beta}$- glucosidase, ${\beta}$-xylosidase, cellobiohydrolase, phosphatase, arylsulphatase, and N-acetylglucosaminidase activities were determined by using methylumbelliferyl model substrates and comparing with the activities of control samples. Toluene addition induced different responses of enzymes. For example, phosphatase activity increased by the treatment while ${\beta}$-glucosidase and arylsulphatase activities decreased. In contrast, ${\gamma}$-radiation decreased all enzyme activities compared to control by 40-80%. The overall results of the toluene and ${\gamma}$-radiation experiments indicate that the large amounts of enzymes are stabilised outside of living cells, at least in the short term, but that the persistence of enzymes is maintained by de-novo synthesis of microbes.

• Korean Journal of Microbiology
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• v.45 no.1
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• pp.69-73
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• 2009

Proteases are degradative enzymes which hydrolyze a peptide bond between amino acids and they are abundantly applied to commercial field. In order to investigate optimal medium compositions of carbon and nitrogen source for enzyme production, modified STY medium containing 0.15% yeast extract were used as basal medium. When galactose was used as carbon source, enzyme activity showed 1.3 higher than that of glucose. For nitrogen source addition of casamino acids to basal medium in place of tryptone showed lowest activity, whereas addition of malt extract showed maximal activity. The optimum temperature and pH of extracellular protease were found to be $35^{\circ}C$ an pH 8.5.

• Korean Journal of Microbiology
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• v.36 no.2
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• pp.130-135
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• 2000

Decomposition rate of organic matiter in the mud flat of Sunchon Bay was estimated. Physicochemical parameters, cellulose degradation rate. distribution of heterotrophic bacteria, and extracellular enzymatic activities were measured from August 1997 to July 1998. Soil temperatures, water contents, concentration of $PO_4$-P and organic matter were -1-~$30^{\circ}C$, 42.1-53.1%, 0.0779-0.1961 mgig and 1.99-7.64%, respectively. Decomposition rate of cellulose film ranged from 7.7 to 100%imonth, high in summer and low in winter. The number of heterotrophic bacteria ranged from $0.87{\times}10^6 to 3.6{\times}10^7 $CUFsIg dq soil. Enzymatic activities of phosphatase, $\alpha$-D-gluEosidase, $\beta$-D-glucosidase and cellobiohydrolase, which were measured as decomposition rate of methylumbelliferyl(MLiF)-substrate, were 152.23-1779.80 nMIhr, 2.67-202.18 nM/hr, 5.03-258.26 M h r and 3.42-63.07 nM/hr, respectively Cellulose degradaaon rate and extracellular extracellular enzymatic activities were conelated with each other, and showed high correlation coefticiency with soil temperature.

• Microbiology and Biotechnology Letters
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• v.17 no.1
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• pp.69-73
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• 1989

Cellular autolytic enzyme was isolated from the supernatant fluid of exponentially growing cuiture of Cl. butyricum ID-113. The autolysin was partially pruified by ammonium sulfate fractionation, chromatography on DEAE-Sephadex A-50 and gel filtration through Sephadex G-200. This autolytic enzyme lysed SDS-treated cell wall fractions of Cl. butyricum ID, but not whole cells at all. Its optimum pH and temperature were 5.0 and 37$^{\circ}C$, respectively. This enzyme was relatively stable at neutral pH, but sensitive to heat treatment. Enzyme activity was not influenced by the addition of various divalent cation, but inhibited by Cu$^{++}$.