• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.28-38
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• 2004

This study presents the result of uncertainty and sensitivity analysis of a pharmacokinetic model which describes the distribution and removal of benzene at each organ when an indivisual inhales indoor contaminated air with benzene originated from groundwater. The pharmacokinetic model simulates the distribution of benzene deposited in organs of human body through inhalation of contaminated indoor air as well as degradation-metabolism in liver. This study focused on the uncertainty problem induced from the use of the single values for blood flow, partition coefficient, degradation constant, volume, etc. of each organ which was due to a lack of knowledge about these parameters or their measurements. To solve this problem, uncertainty analysis on the pharmacokinetic model was conducted simultaneously which would help understanding the risk assessment associated with VOCs.

• Research in Plant Disease
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• v.16 no.2
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• pp.170-175
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• 2010

A monoterpenoid benzylideneacetone (BZA) is a bacterial metabolite isolated from culture broth of an entomopathogenic bacterium, Xenorhabdus nematophila K1. It was tested in this study the control efficacy of the metabolite against two major fungal diseases occurring in red-pepper plants. BZA exhibited significant antifungal activities against Phytophthora capsici and Colletotrichum acutatum. Under natural light conditions, the antifungal activity of BZA was maintained for more than sixty days. The antifungal activity of BZA was not lost even in soil because the incidence of Phytophthora blight against red-pepper plants was significantly reduced when the suspensions of P. capsici were poured to the rhizosphere soils mixed with BZA. Application of the BZA suspension spray to the fruit surface infected with C. acutatum significantly suppressed the disease occurrence of anthracnose on the red-pepper plants. These results suggest that BZA can be used to develop a promising agrochemical to control phytophthora blight and anthracnose of redpepper plants.

• The Korean Journal of Mycology
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• v.22 no.1
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• pp.50-61
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• 1994

From soil samples, 380 antagonistic microorgnisms were isolated. Among the isolates, 42 strains had mycelia growing inhibition ability against Fusariun solani, ginseng root rot causing pathogen. Isolates CHA 1 and S-PFHR 6 were proposed as antagonists for this study and they were identified as Promicromonospora sp. and Pseudomonas pseudoalcaligenes respectively. As an antagonism against hyphae of F. solani in dual culture test, CHA 1 and S-PFHR 6 inhibited linear growing, caused abnormal branching, and the membrane projection which formed by cell wall destruction. The secondary metabolites contained in the culture filtrates which prepared from PD broth and Nutrient broth inhibited the spore germination to 14.3%. The culture filtrate of S-PFHR 6 which prepared by a little amount of soil extract addition to nutrient rich medium had more strongly. inhibited the spore germination and spore germination decreased to less than 4.0% in it. The soil used in this study had fungistasis and the germination rate of macroconidia and chlamydospore of F.solani was 19.4% and 17.7% respectively. The steam sterilized soil lost fungistasis and germination rate of conidia increased to more than 97.9%. The soils amended with the propagule of CHA 1 and S-PFHR 6 increased fungistasis and the germination rate of macroconidia decreased to 14.7% and 11.7% respectively in each treatments. But the soil ammended with glucose and asparagine annulled fungistatic ability and the germination rate of macroconidia increased to more than 48.0%. As an antagonistic activity of the secondary metabolites of two antagonistic isolates in soil, the germination rate of macroconidia of F. solani was 9.3% in the soil amended with the culture filtrate of CHA 1 but the culture filtrate of S-PFHR 6 had no such activity. In the soil which treated with antagonist propagule or culture filtrate, the chlamydospore germination rate was lower than that in natural soil. The addition of glucose and asparagine to antagonist propagule treated soil did not enhanced the chlamydospore germination.

• The Korean Journal of Pesticide Science
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• v.10 no.2
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• pp.76-83
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• 2006

In order to investigate the impacts of non-selective herbicide, glufosinate-ammonium (ammonium 4-[hydroxy(methyl)phosphinoyl] -DL-homoalaninate, GLA) to the non-target organisms, earthworm was exposed to GLA in the field soil for a month, and microbial populations in the soil were investigated after application of GLA. Simultaneously, the residues of GLA and its metabolite, 3-MPP were analyzed in the same soil. Meanwhile, to elucidate the influence of GLA to the growth of non-target crops incase of inter-furrow application, the amounts of carotenoid, chlorophyll, amino acid, proteins and sugars in the leaves of potato and chinese cabbage grown in the same field were investigated. In result, the dead earthworm was not observed during the test period, and the increasing rates of bodyweight were $9.410{\sim}11.603%$ in GLA-treated plots and 5.645% in GLA-untreated plots. The populations of fungi, bacteria and actinomycetes in the GLA-treated soils were $6.2{\times}10^4$, $1.5{\times}10^6$ and $5.7{\times}10^4$, respectively. They maintained relatively similar levels to the control which were $3.7{\times}10^4$, $3.7{\times}10^5$ and $3.7{\times}10^4$, respectively. In residue analysis, the limit of detection of GLA was 0.02 mg $kg^{-1}$, that of 3-MPP was the same level, and the half-life of GLA was 15 days in sandy clay loam soil. This result indicates that GLA was degraded very quickly in field soil. On the other hand, the amounts of physiological, biochemical components such as carotenoid, amino acid, chlorophyll, protein and sugar were ranged from 90.0 to 104.3% in potato and from 99.0 to 112.7% in chinese cabbage. Comparing with hand-weeded plots, it is indicated that GLA had not affected to the growth of non-target crops when applied at inter-furrow in crops-growing field.

• Microbiology and Biotechnology Letters
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• v.25 no.4
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• pp.396-402
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• 1997

Biocontrol of plant pathogens provides an alternative means of reducing the incidence of plant diseases without the negative aspects of chemical pesticides. Nowdays, as the resistant fungi about the chemical fungicides have revealed and the concern of environment has increased, the biological control of phytopathogenic fungi by the antagonistic microorganisms is very much indispensable. For the selection of strong antagonistic bacterium for biological control agent of rice leafblast and cucumber gray mold rot, the antifungal strain KL-3 strain was selected among 120 strains isolated from the rhizosphere soils. And the strain was identified to be a species of Bacillus subtilis or closely related strain. In several biochemical and in vitro antibiosis tests, antifungal substances of Bacillus sp. KL-3 were presumed heat stable, micromolecular antibiotic substances. In vivo test and vinyl house field test, the antifungal substances of Bacillus sp. KL-3 represented excellent biocontrol ability aganist Alternaria mali, Phyricularia oryzae, and Alternaria kikuchiana as well as broad spectrum of other fungi. In particular, Bacillus sp. KL-3 strain showed more predominant activity than some chemical fungicides against fungi shown to resist chemcal fungicides.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.68-68
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• 1995

청주 근처 토양에서 분리한 에너지 대사 저해제인 2,4-dinitrophenol (DNP)에 내성을 보이는 Streptomyces CM 001 균주가 생산하는 항진균성 물질(CUA)을 순수하게 분리 정제하고 화학분석을 통한 구조의 규명, 항진균활성 연구 및 유전적 변이원성(mutagenicity)등을 살펴보았다. CM 001 균주를 베네트 배지와 같이 영양성이 좋은 배지에서 배양시 항진균 활성이 동반 생성되는 색소와 비례적으로 증가했다. 배양 상등액 속의 항진균성 물질들을 염산처리, 유기용매처리 후 Amberlite XAD-4 column chromatography, silica gel adsorption-Sephadex LH-20 chromatography 과정을 통해 색소가 제거된 부분 정제 백색분말로 얻었다 이로부터 Prep. HPLC과정을 통하여 8종의 화합물을 각기 분리하였는데 이 화합물들은 동일한 UV spectrum과 216, 260nm에서 최대 흡수파장을 보였다.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1978.04a
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• pp.98.5-99
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• 1978

항생물질과 RNA 분해효소를 동시에 생산하는 방선균의 한 균주를 토양으로부터 분리하여 이 균주가 생산하는 RNA 분해효소의 물리화학적 성질 및 분해산물에 대해 검토하였다. 효소반응의 최적 pH 및 온도는 명명 pH 5.6과 $50^{\circ}C이었다.$ $37^{\circ}C$ 에서 90분간 열처리 시켰을 때, 이 효소의 활성은 비교적 안정하였지마는 $50^{\circ}C$ 에서 90분간 열처리 시켰을 때는 효소활성이 심하게 저하되었다. 이 효소의 활성은 $Ba^{2+}$ 에 의하여 50% 정도의 저해 작용을 나타내었지만 EDTA에 의해서는 저해되지 않았다. 이 효소에 의한 RNA분해로 이 효소가 대사산물로서 guanosine, adenosine과 밝혀지지 않은 두 가지의 핵산관연물질을 생산함을 알 수 있었다. 제2보에서는 ENase의 효소학적 성질을 검토하였으며 이후 항생물질 측면에서 검토할 예정이다.

• The Korean Journal of Pesticide Science
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• v.7 no.3
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• pp.176-181
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• 2003

The leaching behaviour of [aniline-$^{14}C$]mefenacet in soil was investigated using glass columns (5 cm I.D. $\times$ 30 cm. H) packed with two types of soils with different physicochemical properties. $^{14}C$-Mefenacet (8.33 kBq) and mefenacet (in total, 1.05 mg/kg) were treated onto soil columns and rice plants (Oryza sativa L.) were grown for 17 weeks on these columns. Leachates from the columns were collected at the rate of 122.5 mL per week. $^{14}C$-Activities leached from soil A (OM, 3.1%; CEC, 86 mmol(+)/kg; texture, loam) columns with and without rice plants were 1.95 and 4.19% of the originally applied, whereas those from soil B (OM, 1.3%; CEC, 71 mmol(+)/kg; texture, loam) were 2.69 and 7.05%, respectively. These results indicated that larger amounts of $^{14}C$ were percolated from soil B with less organic matter and from the columns without vegetation. $^{14}C$-Activities absorbed by rice plants from soil A and B were 8.95 and 8.47%, respectively, most of which remained in the root and shoot excluding unhulled grains and ears without grains. $62\sim73%$ of the originally applied $^{14}C$ remained in the depth of $0\sim5cm$ in soil. The mass balance indicated that the losses by volatilization and/or mineralization amounted to $3.4\sim9.2%$ of the originally applied. $^{14}C$-Radioactivities in the aqueous phase of the leachates ranged from 59.4 to 97.7% of the radioactivities in leachates, showing the fast transformation of mefenacet to the polar metabolites.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.5
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• pp.290-303
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• 2003

Modern agriculture has been heavily dependent on chemical fertilizers to meet the food demands of ever increasing population. Progressive depletion of major plant nutrients in soil due to intensive cultivation practices has also necessitated the use of higher dose of chemical fertilizers particularly in soils where the organic matter content is very low. Indiscriminate use of chemical fertilizers and pressure on agriculturists to enhance per area crop yields has led to fast depletion of fossil fuel resources with concomitant increase in the prices of chemical fertilizers and also led to environmental pollution. Hence, the current trend throughout the world is to explore the possibility of using alternate nutrient sources or increasing the efficiency of chemical fertilizers by supplementing them with organic fertilizers and bioinoculants comprising largely microbes like, bacteria, fungi, algae etc to enhance nitrogen and phosphates in the soil thus creating a sustainable agricultural environment. Among the different microbial inoculants or biofertilizers, Azospirillum could be a potential candidate due to its non specific host root colonization. It had the capability to fix $N_2$ in wide pH regimes and even in presence of combined nitrogen. Azospirillum inoculation can increase the crop yield to 10-25% and substitute 25% of recommended doses of nitrogenous fertilizers. Apart from nitrogen fixation, Azospirillum is also involved in the root improvement, the activity which was attributed to an increase in the rate of water and mineral uptake by roots. The ability of Azospirillum to produce phytohormones was reported to enhance the root respiration rate, metabolism and root proliferation. They have also been reported to produce polyhydroxybutyrate, that can be used as a biodegradable thermosplastic. A lot of studies have addressed improvements in enhancing its efficiency to fix nitrogen fixation and hormone production.

• Microbiology and Biotechnology Letters
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• v.35 no.1
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• pp.26-29
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• 2007

Tautomycetin (TMC), which is produced by Streptomyces sp. CK4412, is a novel activated T cell-specific immunosuppressive compound with an ester bond linkage between a terminal cyclic anhydride moiety and a linear polyketide chain bearing an unusual terminal alkene. Antifungal activity against Aspergillus niger and TMC productivity assayed by HPLC using culture extracts from Streptomyces sp. CK4412 grown on solid medium adjusted at various pH were measured. The cells cultured at acidic pH (pH 4-5) medium exhibited much stronger antifungal activity as well as higher TMC productivity than those cultured at neutral pH medium, implying that the acidic pH-shock should be an efficient strategy to induce the productivity of secondary metabolites in Streptomyces culture.