• 미생물학회지
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• 제51권2호
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• pp.97-107
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• 2015

육상과 수계의 전이지대에 위치한 습지는 빈번한 침수, 육상생태계로부터의 영양염류의 유입, 수계와 토양에 적절하게 적응된 식생의 존재 및 토양 내 산소 결핍과 같은 독특한 특징을 가지고 있다. 이러한 생지화학적 특성과 독특한 식생의 존재는 유기물의 분해과정에 물리적 화학적 영향을 미치고 있는데, 특히 미생물에서 생산되는 체외효소 활성도는 유기물의 분해 과정과 관련을 맺고 있다. 체외효소는 고분자 유기물을 간단한 형태의 유기탄소, 무기 질소, 인, 황으로 분해하여 미생물과 식물이 용이하게 이들 영양물질을 흡수할 수 있도록 도움을 주기 때문에, 체외효소에 대한 연구는 습지 토양 내에서의 유기물 분해와 물질순환의 기작을 이해하는 데 필수적인 요소이다. 본 연구는 습지 토양 내 ${\beta}$-glucosidase, ${\beta}$-N-acetylglucosaminidase, phosphatase, arylsulfatase, phenol oxidase와 같은 체외 효소활성도에 영향을 미치는 물리적 생지화학적 요소가 무엇인지 문헌연구를 통하여 고찰하였다. 물리적 요소로써, pH와 유기물의 입자 크기는 체외효소 활성도에 크게 영향을 미치지 않았으나, 온도에 대한 영향은 미생물의 극한 온도에서의 적응성 정도에 따라 다양하게 나타났다. 화학적 요소로써, 탄소, 질소, 인의 첨가는 습지 토양의 영양상태, C:N 비율과 제한 요소, 및 체외효소의 종류에 따라 그 영향이 다양하게 발현되었다. 특히, 유기물의 기질 특성(Substrate quality)은 다른 어떤 요소보다도 체외효소 활성도에 큰 영향을 미치는 것으로 나타났다. 향후 연구 과제로써는 기후 변화와 질소 침적의 증가에 따른 효소 활성도의 변화 및 분자생물학적 접근을 통한 미생물 군집과 체외효소 기능간의 관계를 규명하는 연구가 필요하다. 또한, 습지 토양내 체외효소 활성도를 극대화 할 수 있는 환경을 조성함으로써, 앞으로 습지 토양이 오염물질을 제거하고 습지의 생태학적 기능을 최대화 할 수 있는 연구가 요구된다.

• 지질공학
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• 제33권1호
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• pp.15-25
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• 2023

화성암과 퇴적암으로 이루어진 국내 산림토양 중 표토와 심토에서 채취된 시료의 미생물군집 활성도에 미치는 산불의 영향을 알아보았다. 베타글루코시다아제의 분석결과, 화성암보다 퇴적암의 미생물군집에서 높게 나타났다. 산불 발생 초기에 효소 활성이 관찰되지 않았으나, 시간이 경과됨에 따라 활성이 회복되었다. 또한, 토양의 훼손여부와 상관없이 심토는 표토에 비해 활성이 33~46% 저해되었다. EcoPlate를 이용하여 산불이 미생물 기질이용성에 미친 영향을 알아보았다. 정상토와 훼손토의 평균반응구발색도 값 백분율은 표토에서 각각 52.7~56.8% 및 62.3~83.6%로 나타났다. 산불 발생은 토양 유기물의 분해를 촉진함으로 심토미생물군집의 다양성 및 기질이용성에 영향을 준 것으로 보여진다. 미생물군집의 종다양성지수인 샤논 인덱스(Shanon index, H)는 모든 시료의 표토에서 높게 나타났다. 샤논 풍부도는 퇴적암 토양미생물이 화성암에 비하여 높게 나타났으며, 표토가 심토보다 높게 나타났다.

• Ecology and Resilient Infrastructure
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• 제4권2호
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• pp.93-96
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• 2017

Spatial variations of physicochemical and microbiological variables were examined to understand spatial heterogeneity of those variables in intertidal flat. Variograms were constructed for understanding spatial autocorrelations of variables by a geostatistical analysis and spatial correlations between two variables were evaluated by applications of a Cross-Mantel test with a Monte Carlo procedure (with 999 permutations). Water content, organic matter content, pH, nitrate, sulfate, chloride, dissolved organic carbon (DOC), four extracellular enzyme activities (${\beta}-glucosidase$, N-acetyl-glucosaminidase, phosphatase, arylsulfatase), and bacterial diversity in soil were measured along a transect perpendicular to shore line. Most variables showed strong spatial autocorrelation or no spatial structure except for DOC. It was suggested that complex interactions between physicochemical and microbiological properties in sediment might controls DOC. Intertidal flat sediment appeared to be spatially heterogeneous. Bacterial diversity was found to be spatially correlated with enzyme activities. Chloride and sulfate were spatially correlated with microbial properties indicating that salinity in coastal environment would influence spatial distributions of decomposition capacities mediated by microorganisms. Overall, it was suggested that considerations on the spatial distributions of physicochemical and microbiological properties in intertidal flat sediment should be included when sampling scheme is designed for decomposition processes in intertidal flat sediment.

• The Korean Journal of Ecology
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• 제9권4호
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• pp.231-241
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• 1986

The annual decomposition of cellulose and hemicellulose by microorganism and distribution of soil microbial flora were investigated in the humus horizon of a Pinus rigida stand in Mt. Kwanak. The cellulase activity was the lowest, 142$\mu$g glucose/g/hr from Dec. 1985 to Mar. 1986 and the highest, 760~1, 072$\mu$g glucose/g/hr in Jul. and Aug. 1985. The xylanase activity was 47% higher than the cellulase activity and was the lowest, 211~275$\mu$g xylose /g/hr from Feb. to Mar. 1986 and the highest as 799~1, 322$\mu$g xylose/g/hr from Jun. to Aug. 1986. The vertical distribution of the enzyme activity was decreased with the order of F, H, L, and A1 in both enzymes and the activities were exponentially decreased below L horizon, which suggests that most decomposition be done in F and H horizons with lots of organic matters. The SEM study slowed that the main decomposers of litters were fungi and initial attack into litters was also made by them. The enzyme activities of soil had strong correlations with the temperature and the precipitation. The correlation coefficients were 0.813 and 0.886 in the cellulase, and 0.673 and 0.626 in the xylanase for the temperature and the precipitation, respectively.

• Journal of Microbiology and Biotechnology
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• 제20권6호
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• pp.1032-1041
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• 2010

The comparative influence of two nanoparticles [viz., superparamagnetic iron oxide nanoparticles (SPION) and nanobarium titanate (NBT)] upon the in vitro and in situ low-density polyethylene (LDPE) biodegradation efficiency of a potential polymer-degrading microbial consortium was studied. Supplementation of 0.01% concentration (w/v) of the nanoparticles in minimal broth significantly increased the bacterial growth, along with early onset of the exponential phase. Under in vitro conditions, ${\lambda}$-max shifts were quicker with nanoparticles and Fourier transform infrared spectroscopy (FTIR) illustrated significant changes in CH/$CH_2$ vibrations, along with introduction of hydroxyl residues in the polymer backbone. Moreover, simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) reported multiple-step decomposition of LDPE degraded in the presence of nanoparticles. These findings were supported by scanning electron micrographs (SEM), which revealed greater dissolution of the film surface in the presence of nanoparticles. Furthermore, progressive degradation of the film was greatly enhanced when it was incubated under soil conditions for 3 months with the nanoparticles. The study highlights the significance of bacteria-nanoparticle interactions, which can dramatically influence key metabolic processes like biodegradation. The authors also propose the exploration of nanoparticles to influence various other microbial processes for commercial viabilities.

• 자원환경지질
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• 제32권1호
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• pp.101-111
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• 1999

Sedimentary organic matter, exposed to continental surficial environment, reacts with oxygen supplied from the atmosphee and forms carbon-containing oxidation products. Knowledge of the rate and mechanisms of sedimentary organic matter weathering is important because it is one of the major controls on atmospheric oxygen level through geologic time. Under the abiological conditions, the oxidation rate of coal organic matter by molecular oxygen is enhanced by the increase of oxygen concentration and temperature. At ambient temperature and pressure, aqueous coal oxidation results in the formation of dissolved $CO_2$ dissolved organic carbon and solid oxidation products which are all quantitatively significant reaction products. The effects of pH, ultraviolet light, and microbial activity on the weathering of sedimentary organic matter are poorly contrained. Based on the results of geochmical and environmental studies, it is believed that the photochemical reaction should play an important role in the decomposition and oxidation of sedimentary organic matter removed from the weathering profile. At higher pH conditions, the production rate of DOC can be accelerated due to base catalysis. These high molecular weight oranic matter can react with man-made pollutants such as heavy metal ions via adsorption/desorption or ion exchange reactions. The effect of microbial activity on the oxidative weathering of sedimentary organic matter is poorly understood and remains to be studied.

• 한국환경과학회지
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• 제30권6호
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• pp.429-439
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• 2021

Food waste is both an industrial and residential source of pollution, and there has been a great need for food waste reduction. As a preliminary step in this study, waste reduction is quantitatively modeled. This study presents two models based on kinetics: a simple kinetic model and a mass transport-shrinking model. In the simple kinetic model, the smaller is the reaction rate constant ratio k₁, the lower the rate of conversion from the raw material to intermediate products. Accordingly, the total elapsed reaction time becomes shorter. In the mass transport-shrinking model, the smaller is the microbial decomposition resistance versus the liquid mass transfer resistance, the greater is the reduction rate of the radius of spherical waste particles. Results showed that the computed reduction of waste mass in the second model agreed reasonably with that obtained from a few experimantal trials of biodegradation, in which the microbial effect appeared to dominate. All calculations were performed using MATLAB 2020 on PC.

• 유통과학연구
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• 제19권4호
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• pp.53-60
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• 2021

Purpose: This study focuses on exploring ways to improve the distribution method of shrimp farming so that it is eco-friendly and increases the distribution of shrimp. Research design, data and methodology: The experimental device installed in a biofloc shrimp culture in one area tested 10 times. Complex odor, concentration of H2S, water quality improvement effected by decomposition of organic substances, and degree of microbial activation measured. The data of the experimental results verified using the T-test technique, and the p value was determined based on the significance probability of 0.05. Results: This experimental device was effective in reducing odor and hydrogen sulfide in shrimp farms. With the improvement of water quality, dissolved oxygen increased due to the microbubble and cavitation action of air ejector and ultrasonic waves. In addition, the cultured microorganisms in the cultured water treated by the experimental device were remarkably proliferated compared to the raw water. Conclusions: The biofloc distribution method has a significant effect on improving water quality and reducing odor substances and will become a new eco-friendly and efficient distribution method for shrimp farming in the future.

• 농약과학회지
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• 제2권2호
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• pp.39-44
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• 1998

국내에서 많이 사용되고 있는 수도용 농약중 iprobenfos, isoprothiolane 및 diazinon의 수중 분해속도를 구명하기 위하여 수중 농약분해의 주요 요인인 가수분해, 미생물분해 및 광분해에 대해서 실험한 결과는 다음과 같다. Iprobenfos는 주로 미생물에 의해서 분해되었는데 반감기는 $4.0{\sim}5.7$일이었고, 고온일수록 가수분해가, pH가 낮을수록 분분해가 촉진되었다. Isoprothiolane은 미생물과 광에 의해서 주로 분해되었는데 광영향이 더 크게 작용한 것으로 나타났으며, 광분해는 pH 9.0에서 반감기가 91일인 반면 pH 4.0, 7.2에서는 각각 13, 16일로 pH가 낮을수록 분해가 신속하였다. Diazinon은 이 세가지 요인에 의해 분해가 일어났으며 pH가 낮을수록 가수분해가 매우 빠르게 일어났다. 농업환경에서 iprobenfos, isoprothiolane 및 diazinon의 수중분해는 각각 미생물분해, 광분해, 가수분해가 주요인으로 판단되었다. 시험농약을 분해하는 미생물을 동정한 결과 iprobenfos, isoprothiolane 및 diazinon은 각각 Pseudomonas putida, Alcaligenes xylosoxydans, Klebsiella planticola/ornithinllytica었고 유사도는 $54.8{\sim}86.2%$였다.

• Journal of Applied Biological Chemistry
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• 제56권2호
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• pp.95-100
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• 2013

현재 토양 생태에서 토양미생물은 유기물 분해, 질소 순환, 식물의 질소 이용 등 중요한 역할을 하고 있어, 토양 내 미생물 다양성을 분석하기 위한 연구는 지속적으로 진행되어 오고 있다. 본 연구에서는 논 토양의 미생물 생태 다양성을 조사하기 위한 효과적인 방법으로 denaturing gradient gel electrophoresis (DGGE)를 적용하고자 본 연구를 수행하였다. 논 토양 미생물의 DNA를 분리하기 위하여 lysis buffer method, skim milk bead method, sodium phosphate buffer method, Epicentre SoilMaster DNA extraction kit (Epicentre, USA), Mo Bio PowerSoil kit (Mo Bio, USA)를 이용하여 토양 내 gDNA 최적 추출방법을 확인하였다. 그 결과 Mo Bio PowerSoil kit를 사용하였을 때 Shannon 다양성지수가 세균 3.3870, 진균 3.6254으로 미생물 다양성 분석시에 가장 효과적이었다. DGGE 분석을 위한 조건은 세균의 경우 6% polyacylamide gel, 45-60% denaturing gradient였고, 진균의 경우 6% polyacrylamide gel, 45-80% denaturing gradient에서 최적 분석조건을 보였다. 위의 분석법을 적용하여 논 토양내의 미생물 군집의 변화를 살펴보면 시간의 변화 요인에 의해 미생물 변화가 일어나는 것을 알 수 있었다. 본 연구에서 사용된 DGGE 분석법을 통해 논토양 미생물의 분석 가능성을 제시 할 수 있었다.