• 한국토양비료학회지
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• 제44권1호
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• pp.84-90
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• 2011

It is imperative to study the hydrolysis of urea in high saline-sodic condition of a newly reclaimed tidal land in order to overcome the problems associated with use of urea fertilizer. The methodology adopted in this study tried to get a convenient way of estimating rate for N transformation needed in N fate and transport studies by reviewing pH and salt contents which can affect the microbial activity which is closely related to the rate of urea hydrolysis. The hydrolysis of urea over time follows first-order kinetics and soil urease activity in reclaimed soils will be represented by Michaelis-Menten-type kinetics. However, high pH and less microorganisms may delay the hydrolysis of urea due to decrease in urease activity with increasing pH. Therefore, the rate of urea hydrolysis should adopt $V_{max}$ referring enzyme activity ($E_0$) accounting for urease concentration which is indicative for urea hydrolysis, especially in a high saline and sodic soils.

• 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.

• 생약학회지
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• 제15권1호
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• pp.15-23
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• 1984

To find antimicrobial strains of the soil microorganisms in Korea, they were isolated from the soil samples of different locations and screened for antibiotic activity against several standard microbes. An isolate among them had an antibacterial activity against gram-positive bacteria. The examination of its morphological and biochemical characteristics according to the International Streptomyces Project methods showed that it belongs to the genus Streptomyces. The strain was named DMC-72. The strain appears to be a new strain when it was compared with the species within the genus which have been so far reported. The antibiotic metabolite of the strain was produced in submerged culture method. It was found to be a quinone compound and was named soulomycin. This strain was also found to produce an ${\alpha}-amylase$ inhibitor in the submerged culture.

• 대한환경공학회지
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• 제39권5호
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• pp.265-276
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• 2017

폐광산은 방치된 광미 등으로 인하여 주변환경에 복합적인 중금속 오염을 야기한다. 이를 방지하기 위하여 국내에서는 1990년대 중반부터 석회석 등의 안정화제와 복토를 이용한 안정화 공법을 기반으로 토양개량사업이 시행 중이다. 복원된 토양의 상부에서는 작물의 재배로 인해 중금속이 고정된 안정화 층이 지화학적 변화를 겪게 되며 이에 따른 중금속의 용출 및 이동이 가능하므로 토양개량사업을 마친 토양에 대한 질 평가 등의 사후 관리는 반드시 필요하다. 토양의 질 평가를 하기 위해서는 이화학적 분석 또는 생물학적인 분석을 개별적으로 하기보다는 이들을 결합한 종합적인 분석이 필요하며 이를 통해 토양의 생태기능상태(ecological functional state)를 평가할 수 있다. 본 연구에서는 대상시료로 경상북도 봉화군 풍정 광산, 전라남도 광양시 점동 광산, 충청남도 서산시 서성 광산 인근 안정화 처리 토양과 안정화 처리가 되지 않은 오염, 비오염 토양을 선정하였다. 토양의 이화학적 성질인 pH, CEC, LOI와 중금속 농도를 측정하였고, 미생물 효소활성도와 비소환원유전자를 정량하였다. 다변량 통계분석을 바탕으로 모든 데이터를 분석하여 토양 생태기능상태를 평가하였다. 안정화 심도 토양과 상부복토, 하부오염토 간의 상관관계를 확인한 결과, 안정화 심도 토양에서 중금속의 농도가 높게 측정되었다. 그리고 풍정광산에서는 안정화 처리 심도 토양이 하부오염토와 유사한 특성을, 점동, 서성 광산에서는 안정화 심도 토양이 상부복토와 유사한 특성을 나타내었는데 이는 점동, 서성 광산 주변 상부복토의 생태기능상태가 좋지 않을 수 있음을 시사한다.

• Journal of Microbiology and Biotechnology
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• 제32권10호
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• pp.1292-1298
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• 2022

Soil autotrophic bacterial communities play a significant role in the soil carbon (C) cycle in paddy fields, but little is known about how rhizosphere soil microorganisms respond to different long-term (35 years) fertilization practices under double rice cropping ecosystems in southern China. Here, we investigated the variation characteristics of rhizosphere soil RubisCO gene cbbL in the double rice ecosystems of in southern China where such fertilization practices are used. For this experiment we set up the following fertilizer regime: without any fertilizer input as a control (CK), inorganic fertilizer (MF), straw returning (RF), and organic and inorganic fertilizer (OM). We found that abundances of cbbL, 16S rRNA genes and RubisCO activity in rhizosphere soil with OM, RF and MF treatments were significantly higher than that of CK treatment. The abundances of cbbL and 16S rRNA genes in rhizosphere soil with OM treatment were 5.46 and 3.64 times higher than that of CK treatment, respectively. Rhizosphere soil RubisCO activity with OM and RF treatments increased by 50.56 and 45.22%, compared to CK treatment. Shannon and Chao1 indices for rhizosphere soil cbbL libraries with RF and OM treatments increased by 44.28, 28.56, 29.60, and 23.13% compared to CK treatment. Rhizosphere soil cbbL sequences with MF, RF and OM treatments mainly belonged to Variovorax paradoxus, uncultured proteobacterium, Ralstonia pickettii, Thermononospora curvata, and Azoarcus sp.KH33C. Meanwhile, cbbL-carrying bacterial composition was obviously influenced by soil bulk density, rhizosphere soil dissolved organic C, soil organic C, and microbial biomass C contents. Fertilizer practices were the principal factor influencing rhizosphere soil cbbL-carrying bacterial communities. These results showed that rhizosphere soil autotrophic bacterial communities were significantly changed under conditions of different long-term fertilization practices Therefore, increasing rhizosphere soil autotrophic bacteria community with crop residue and organic manure practices was found to be beneficial for management of double rice ecosystems in southern China.

• Journal of Microbiology and Biotechnology
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• 제23권5호
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• pp.644-651
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• 2013

The fermented manure derivative known as Preparation 500 is traditionally used as a field spray in biodynamic agriculture for maintaining and increasing soil fertility. This work aimed at characterizing the product from a microbiological standpoint and at assaying its bioactive properties. The approach involved molecular taxonomical characterization of the culturable microbial community; ARISA fingerprints of the total bacteria and fungal communities; chemical elemental macronutrient analysis via a combustion analyzer; activity assays for six key enzymes; bioassays for bacterial quorum sensing and chitolipooligosaccharide production; and plant hormone-like activity. The material was found to harbor a bacterial community of $2.38{\times}10^8$ CFU/g dw dominated by Gram-positives with minor instances of Actinobacteria and Gammaproteobacteria. ARISA showed a coherence of bacterial assemblages in different preparation lots of the same year in spite of geographic origin. Enzymatic activities showed elevated values of ${\beta}$-glucosidase, alkaline phosphatase, chitinase, and esterase. The preparation had no quorum sensing-detectable signal, and no rhizobial nod gene-inducing properties, but displayed a strong auxin-like effect on plants. Enzymatic analyses indicated a bioactive potential in the fertility and nutrient cycling contexts. The IAA activity and microbial degradation products qualify for a possible activity as soil biostimulants. Quantitative details and possible modes of action are discussed.

• 한국작물학회지
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• 제52권3호
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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.

• 환경위생공학
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• 제17권1호
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• pp.52-56
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• 2002

The study was carried out to evaluate the characteristics of biodegradation by Pseudomonas putida G7 in soil column. The reactor system was used to investigate mass transfer of VOCs as Toluene in a column of unsaturated soil. Determination of the fate of VOCs in unsaturated soil is necessary to evaluate the feasibility of natural attenuation as a VOCs remediation strategy. The objective of this study was to develop a mechanistically based mathematical model that would consider the interdependence of VOC transport, microbial activity, and sorptive interactions in a moist, unsaturated soil. Because the focus of the model was on description of natural attenuation, the advective VOCs transport that is induced in engineered remediation processes such as vapor extraction was not considered. It can be concluded that the coefficient for gas liquid mass-transfer was found to be a key parameter controlling the ability of bacteria to VOCs. Finally, it appeared that bioremediation technology of VOCs which are difficult to be decomposed by chemical methods.

• 한국토양비료학회지
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• 제43권5호
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• pp.650-658
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• 2010

시설재배지의 경우 휴작기간 동안 녹비작물의 활용가능성이 높을 것으로 판단된다. 본 연구는 녹비작물이 시설재배지에서의 양분공급 및 토양질 개선에 미치는 영향을 평가하고자 두과 (헤어리베치, 크림손클로버) 및 화본과 (호밀, 수수, 수단그라스) 녹비작물을 재배 후 토양과 혼합하였으며, 무기질소 공급능과 생물적 지표로써 토양 탄수화물, 미생물활성 및 부식함량의 경시적 변화를 측정하였다. 관행구의 무기태 질소함량은 전 기간 비슷한 수준을 유지하였으나 녹비작물을 처리한 토양에서는 토양처리 후 4주까지 무기태질소 함량이 지속적으로 증가하였고, 특히 수단그라스에서 무기태질소 함량이 두드러지게 증가하였다. 녹비작물 처리 후 토양 중 수용성 당은 두과 녹비작물 처리 후 서서히 증가하기 시작하여 7주 경에 가장 높았으며 이후 서서히 감소하는 경향이 나타났다. 반면 화본과 녹비작물 처리 후 수용성 당이 빠르게 증가하여 처리 후 4주 경에 최대치에 도달한 후 감소하는 양상이 나타났다. 토양 내의 부식산 (humicacid)은 아무것도 첨가하지 않은 관행구와 녹비처리 초기에는 비슷한 수준으로 낮았으나 녹비처리 후 4주 정도 시간이 경과하면서 녹비작물의 부숙에 의해 형성된 부식산이 점점 증가하는 것을 확인할 수 있었다. 또한 양이온과 결합하여 물에 잘 용해되는 염을 만드는 fulvic 산에서도 작물 간 차이는 있었지만 부식산의 함량 변화와 비슷한 경향이었다.

• 한국환경농학회지
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• 제30권1호
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• pp.16-23
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• 2011

본 연구는 유기농 배 과원에서 2년간 시용한 여러 종류의 유기질 퇴비와 화학비료에 따른 시기별 토양 물리화학성 및 미생물성에 미치는 영향을 구명하고자 수행하였다. 대조구는 NPK 화학비료를 시용한 처리구를 선정하였고 유기질 비료는 유박과 휴믹산 그리고 키틴퇴비를 포함하였다. 모든 처리구는 질소성분량 200 g/나무 양으로 동일시해서 2008년부터 2009년까지 2년간 매해 3월 30일에 수관주위에 산포 처리하였다. 토양 물리성은 처리구간에 별다른 영향이 없었다. 5월과 8월에 조사된 토양 유기물과 전질소 그리고 칼륨, 칼슘, 마그네슘 농도는 유기질 비료 처리구에서 일반적으로 대조구보다 높게 나타났고 유기질 비료간에 일관성 있는 효과가 나타나지 않았다. ${\beta}$-glucosidase를 제외하고 미생물 생체량 탄소와 질소, dehydrogenase, acid-phosphatase, 그리고 chitinase활성은 시기별로 증가하는 경향을 보였다. 8월 조사에서 유기질 비료인 유박과 키틴퇴비는 대조구보다 높은 미생물 활성이 나타났다.