• 한국식물병리학회지
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• 제13권2호
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• pp.100-104
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• 1997

Influence of the moisture content in soils was examined on population variations of soil microbes, including Cylindrocarpon destructans causing root rot of ginseng, in vivo and under the field condition. Fungal populations decreased in soils treated with various moisture contents in vivo as days after the treatment in creased, but there was not a significant difference in the population among other treatments except 135% moisture content (flooding) at 15 weeks after the treatment. In flooded soils populations of total fungi and C. destructans were reduced to 1/10 and 1/50 of initial populations, respectively. There was, however, a little difference in the population of total bacteria or Actinomycetes between before and at 15 weeks after flooding. On the other hand, population variations of bacteria and Actinomycetes were much greater than those of fungi at different intervals after the moisture treatment. Variations of microbial populations in flooded soils under the field condition were similar to those in vivo. Especially, populations of Fusarium and pectolytic bacteria in flooded soils were reduced to 1/100 of populations in nonflooded soils at 170 days after treatment.

• Journal of Ginseng Research
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• 제33권2호
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• pp.139-142
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• 2009

석회질소의 인삼포 예정지 훈증제로서의 적량을 구하기 위하여 실내시험을 하였다. 중국제 석회질소는 추천량 (60Kg/10a)의 배량에서도 인삼 입고병균인 라이족토니아 (Rhizoctonia solani)와 피지움 (Pythium sp.)에 대한 멸균효과가 없었다. 멸균 유효수준은 10,000 ppm이였다. 토양 미생물에 대하여서는 250 ppm에서 토양곰팡이의 밀도를 50% 감소 시켰으며 방선균 50%이상 증가시키고 세균에는 변화가 없었다. 살균력에서 분제가 입제보다 우수하였다. 무씨의 발아억제는 9,000 ppm 이상에서 확인되었다.

• Journal of Ginseng Research
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• 제25권1호
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• pp.53-58
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• 2001

적변삼과 건전삼 그리고 이들의 근권토양으로부터 분리한 토양세균과 적변현상과의 관계를 구명하고자 pH 변화와 철 이온에 따른 토양세균의 생장 특성을 조사한 결과, 분리된 모든 토양세균은 pH 3.0에서는 생장하지 못하였다. 그러나 RCG와 RCS는 2 mM Fe$^{3+}$ 가 포함된 배지에서는 pH 3.0에서도 생장하였다. 특히, RCG의 경우는 철이 포함된 배지에서는 철이 없는 배지보다 생장이 2배 정도 높았다. 적변삼의 뿌리에서 분리된 토양세균(RCG)은 pH 5.0에서 pH 9.0사이에서는 생장에 큰 차이가 없었으나, 건전삼의 근권토양에서 분리된 토양세균(HES)은 다른 곳에서 분리된 세균에 비해 생장이 낮았다. 적변삼의 근권토양에서 분리한 토양세균(RCS)과 표토에서 분리한 토양세균(SUS)의 생장은 pH5.0에서 pH 7.0과 pH 9.0에 비해 다소 낮았다. 분리된 모든 토양세균의 cellulase효소활성은 철이온이 포함된 배지에서 철이온이 없는 배지보다 2배 이상 높게 나타났다. 세포 외효소 활성은 세포 내 효소 활성보다 약 10 이상 높았고, pH5.0에서 RCS의 효소활성은 pH 7.0 보다 2배 이상 높았다. 특히, 2 mM Fe$^{3+}$ 가 포함된 배지에서 RCS의 세포 내 효소활성은 철이온이 없는 배지보다 6~7배 높았고 세포 외 효소의 경우에는 11~12배가 증가되었다. 이러한 결과는 인삼의 적변현상과 관련된 토양세균은 철이온의 산화환원과cellulase분비에 의한 세포벽 분해 그리고 인삼 표피세포에 철이온과 강력한 리간드를 형성하는 것으로 판단된다.

• Applied Biological Chemistry
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• 제27권
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• pp.56-67
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• 1984

As in many other country, the use of organic matter in Korea has long history. Farmers understand the value of organic matter as the source of plant nutrient and soil improving agent in general. Since 50 years ago, the sources of organic matter in paddy soils were compost, rice and barly straw, green manure, animal waste, fish and beancake, etc.. Application of green manures such as vetch and chinese milk vetch showed no significant effect on the yield of brown rice in paddy soil. On the other hand, the effects of compost and rice straw showed more significant on the yield of brown rice in paddy soil. Application of rice straw in rice cultivation is commonly made at different times between harvest, early spring and several weeks before transplanting. Considering the suitable paddy soil for application of rice straw under well to moderately well drained soil, the yield was pronounced more than poorly drained soil. Based on laboratory and field experimants, application of rice straw promoted the decrease of oxidation-reduction potential in well to moderately well drained soil. This results to be enhanced the release of some mineral nutrients,. such as potassium, calcium, silicon, and increase of availability of soil phosphorus. In the field experiments, results obtained from nitrogen fraction on the immobilization-mineralization of the tracer nitrogen applied in paddy soil,the amount and index of organic nitrogen incoporated in soil was more pronounced in rice straw application than control. Rice straw and its transformation products incoporated in the soil, provided the inflow of energy necessary to maintain heterotrophic microbes activities. Rice straw and its transformation products, especially soluble carbohydrate, enhanced the population of free-living heterotrophic $N_2$ - fixing microbes. Moreover, rice straw and its transformation products in paddy soil, enhanced the activities of soil enzymes such as dehydrogenase and urease.

• 한국지반공학회논문집
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• 제29권2호
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• pp.23-34
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• 2013

식물의 추출물로 제조할 수 있는 유기산 재료는 포설 시 지중 속에서 미생물의 증식을 유도하며, 미생물에 의해 지반에서 압밀을 가속화시키고 빠르게 간극수압을 소산시킨다. 추가적으로 일부 미생물에 의해 탄산칼슘을 생성시켜 공극을 채워 강도를 증대시키거나 투수성을 감소시킬 수 있다. 따라서, 본 연구에서는 유기산 재료의 지반개량 메커니즘 규명을 위하여 화강풍화토, 라테라이트성 적토에 유기산 재료 혼합 전 후의 강도와 투수시험을 실시하였으며, SEM, XRD로부터 원인을 규명하였다. 유기산 재료 혼합 후 재령 96일에서 강도는 약 1.5~2.5배 증가하였으며, 투수계수는 72.9~93.1%의 감소율을 보였다. SEM으로부터 흙 입자의 구조가 변하거나 공극이 감소한 것을 관찰하여 강도증대, 투수감소의 원인을 규명할 수 있었으며, XRD로부터 탄산칼슘의 생성도 고결화의 주된 요인이라고 결론내릴 수 있었다. 이에 본 유기산 재료는 친환경적으로 지반을 개량할 수 있는 공법으로 활용될 수 있을 것으로 보인다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권6호
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• pp.37-45
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• 2015

This study was conducted to determine the toxic effect of TNT and RDX on indigenous soil microbes by measuring enzymatic activity. Denitrification activity, dehydrogenase activity, phosphatase activity, and fluorescein diacetate hydrolytic activity were determined for military firing range, field, and paddy soils exposed to TNT, and RDX from 0 to 1,000 mg/kg and 0 to 4,000 mg/kg, respectively, for 2, 4, and 8 weeks. Soil microbial enzymatic activities decreased with higher TNT and RDX concentration and longer exposure time. Microbial enzymatic activities of firing range soil were higher than field and paddy soils, indicating that indigenous microbes in firing range might have been adapted to TNT and RDX due to pre-exposure of the explosives. In addition, the toxicity of TNT and RDX decreased with higher organic matter because TNT and RDX tend to absorb to soil organic matter. No Observable Effect Concentration (NOEC) values of each microbial enzymatic activity were derived by the geometric mean of NOECs from exposure times (2, 4, and 8 weeks) and soil types (firing range, field, paddy soil). The derived NOECs ranged from 45.3 to 55.2 mg/kg for TNT and 286 to 309 mg/kg for RDX.

• 한국토양환경학회지
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• 제4권2호
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• pp.193-201
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• 1999

유류 오염토양의 생물학적 복원에 있어 동절기의 급격한 온도 저하에 따른 적용 한계성을 극복하기 위한 composting기술의 현장 적용 가능성을 검토하고, 온도 변화에 따른 분해 특성을 검토하였다. 또한 생물학적 복원에 필요한 영양원(N, P source)과 유류 분해 미생물의 첨가에 따른 분해효율을 검토하기 위한 기초 실험을 실시하였으며, 동절기 낮은 온도로 인한 미생물의 활성도 저하를 막기 위해서 발효가 진행중인 퇴비를 주입하였다. 주입된 퇴비의 영향으로 토양 pile내부의 온도는 30∼40일 동안 중온 상태를 유지하였으며, 초기 2,340mg TPH/kg dry soil에서 시작된 생물학적 반응은 약 40일 경과 후 216mg TPH/kg dry soil 으로 감소되어 제거효율이 약 91%를 나타냈다. 총균수, 유효균수, TPH간의 상관 관계를 관찰해 본 결과, TPH가 급격한 감소를 나타내는 10∼30일 사이에 유효균수가 급격히 상승하는 것으로 관찰되었다. 따라서 landfarming site에서 유류 오염토양을 복원함에 있어 별도의 시설투자 없이 동절기에도 저온의 영향을 받지 않고 유류를 분해시킬 수 있는 composting기술의 적용 가능성을 확인하였으며, 이는 기타 난분해성 물질의 생물학적 분해에 대해서도 확대 적용될 수 있을 것으로 판단된다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.28-30
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• 2005

Because of high population diversity in soil microbial communities, it is difficult to accurately assess the capability of biodegradation of toxicant by microbes in soil and sediment. Identifying biodegradative microorganisms is an important step in designing and analyzing soil bioremediation. To remove non-important noise information, it is necessary to selectively enrich genomes of biodegradative microorganisms fromnon-biodegradative populations. For this purpose, a stable isotope probing (SIP) technique was applied in selectively harvesting the genomes of biphenyl-utilizing bacteria from soil microbial communities. Since many biphenyl-using microorganisms are responsible for aerobic PCB degradation In soil and sediments, biphenyl-utilizing bacteria were chosen as the target organisms. In soil microcosms, 13C-biphenyl was added as a selective carbon source for biphenyl users, According to $13C-CO_2$ analysis by GC-MS, 13C-biphenyl mineralization was detected after a 7-day of incubation. The heavy portion of DNA(13C-DNA) was separated from the light portion of DNA (12C-DNA) using equilibrium density gradient ultracentrifuge. Bacterial community structure in the 13C-DNAsample was analyzed by t-RFLP (terminal restriction fragment length polymorphism) method. The t-RFLP result demonstates that the use of SIP efficiently and selectively enriched the genomes of biphenyl degrading bacteria from non-degradative microbes. Furthermore, the bacterial diversity of biphenyl degrading populations was small enough for environmental genomes tools (metagenomics and DNA microarrays) to be used to detect functional (biphenyl degradation) genes from soil microbial communities, which may provide a significant progress in assessing microbial capability of PCB bioremediation in soil and groundwater.

• Journal of Microbiology and Biotechnology
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• 제34권7호
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• pp.1530-1543
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• 2024

With an increase in the commercialization of bioplastics, the importance of screening for plastic-degrading strains and microbes has emerged. Conventional methods for screening such strains are time-consuming and labor-intensive. Therefore, we suggest a method for quickly and effectively screening plastic-degrading microbial strains through dual esterase assays for soil and isolated strains, using p-nitrophenyl alkanoates as substrates. To select microbe-abundant soil, the total amount of phospholipid fatty acids (PLFAs) included in each soil sample was analyzed, and esterase assays were performed for each soil sample to compare the esterase activity of each soil. In addition, by analyzing the correlation coefficients and sensitivity between the amount of PLFAs and the degree of esterase activity according to the substrate, it was confirmed that substrate pNP-C2 is the most useful index for soil containing several microbes having esterase activity. In addition, esterase assays of the isolated strains allowed us to select the most active strain as the degrading strain, and 16S rRNA results confirmed that it was Bacillus sp. N04 showed the highest degradation activity for polybutylene succinate (PBS) as measured in liquid culture for 7 days, with a degradation yield of 99%. Furthermore, Bacillus sp. N04 showed degradation activity against various bioplastics. We propose the dual application of p-nitrophenyl alkanoates as an efficient method to first select the appropriate soil and then to screen for plastic-degrading strains in it, and conclude that pNP-C2 in particular, is a useful indicator.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.137-140
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• 2003

This study presents a mathematical model for simulating the fate and transport of a reactive organic contaminant degraded through cometabolism in dual-porosity soils during the in situ bioaugmentations. To investigate the effect of dual-porosity on transport and biodegradation of organic hydrocarbons, a bimodal approach was incorporated into the model. Modified Monod kinetics and a microcolony concept [Molz et at., 1986〕 were employed to represent the effects of biodegrading microbes on the transport and biodegradation of an organic contaminant. The effect of permeability reduction due to biomass accumulation on the flow field were examined in the simulation of a hypothetical field-scale in situ bioaugmentation. Simulation results indicate that the presence of the immobile region can decrease the bioavailablity of biodegradable contaminants and that the placement of microbes and nutrients injection wells should be considered for an effective in situ bioaugmentation scheme.