• Korean journal of applied entomology
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• v.52 no.2
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• pp.115-123
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• 2013

A microbial insecticide "Bt-Plus" has been developed to enhance an insecticidal efficacy of an entomopathogenic bacterium, Bacillus thuringiensis (Bt). However, its wettable powder formulation is not preferred by farmers and industry producers due to relatively high cost. This study aimed to develop a soluble concentrate formulation of Bt-Plus. To this end, an optimal mixture ratio of two bacterial culture broths was determined to be 5:4 (v/v) of Bt and Xenorhabdus nematophila (Xn) along with 10% ethanol preservative. In addition, Bt broth was concentrated by 10 times to apply the mixture at 1,000 times fold dilution. The resulting liquid formulation was sprayed on cabbage crop field infested by late instar larvae of the diamondback moth, Plutella xylostella. The field assay showed about 77% control efficacy at 7 days after treatment, which was comparable to those of current commercial biopesticides targeting P. xylostella. For storage test in both low and room temperatures, the liquid formation showed a relatively stable control efficacy at least for a month. To develop a quality control technique to exhibit a stable control efficacy of Bt-Plus, Bt spore density ($5{\times}10^{11}$ spores/mL) and eight active component concentrations of Xn bacterial metabolites in the formulation products have been proposed in this study.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.7
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• pp.501-510
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• 2011

In this study, water pollution sources of 14 major tributaries of Han river and characteristics of water quality for each target streams were evaluated based on water quality data in 2007.1-2009.12 (14 data sets) using a statistical package, SPSS-17.0. Cluster analysis over time and space for each stream resulted in 4 groups for the spatial variations in which type and density of pollution sources in the basins showed the greatest impact on grouping. Moreover, cluster analysis for the time variation in which rainfall, temperature and eutrophication were shown to contribute to the clustering, produced 2 groups, from summer to fall (July-Oct.) and from winter to early summer (Nov.-June). Four factors were found as responsible for the data structure explaining 71-90% of the total variance of the data set depending on the streams and they were organic matter, nutrients, bacterial contamination. Factor analysis showed main factors (water pollutants) changed according to the season with different pattern for each stream. This study demonstrated that water quality of each stream could produce useful outcomes when factor and pollution source of basin were evaluated together.

• Microbiology and Biotechnology Letters
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• v.35 no.4
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• pp.298-303
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• 2007

A halophilic bacterium, H. subglaciescola DH-1, grew at 2.0 M salinity, but did not grow at 0.8 M salinity when cultivated at higher temperature ($40^{\circ}C$) than optimum ($30^{\circ}C$). When the cell extract of strain DH-1 was heated at $50^{\circ}C$ for 60 min in the absence of NaCl, isocitrate dehydrogenase and malate dehydrogenase lost their activities, but when it was heated in the presence of 2.0 M NaCl, the activity was maintained. Meanwhile, the cell extract of E. coli did not catalyze the reduction of $NAD^+$ to NADH coupled with the oxidation of isocitrate and malate at higher salinities than 1.0 M. The pH range for DH-1 was 7 to 10, and that for E. coli was 5 to 9. DH-1 was not grown in conditions with sodium salts other than NaCl.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.249-249
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• 1996

Gentamicin은 임상에서 많이 사용되는 aminoglycoside계 항생물질로서 세균의 세포막 단백질 합성을 억제하여 살균작용을 나타낸다. 최근 Gentamicin이 동물사료에 포함되거나 동물약품으로 많이 사용되어, 이를 복용한 식용가축에서의 잔류 량에 대한 인체유해성이 WHO/FAO 식품첨가물 전문가 협의회에서 논의되고 있다. Gentamicin의 육가공류의 잔류허용량 기준설정을 위한 독성 재평가의 일환으로 in vivo. in vitro 염색체이상시험을 실시하여 다음과 같은 결론을 얻었다. 1. 체외 염색체이상시험에서는 포유동물 배양세포인 chinese hamster lung cell을 배양하여 gentamicin sulfate 및 gentamicin을 최고 처리농도 5mg/$m\ell$부터 세포독성시험을 실시한 결과, 세포독성을 나타내지 않았다. 본 시험에서는 5mg/$m\ell$를 최고농도로 2.5, 1.25mg/$m\ell$의 3농도를 직접법 및 대사활성화법으로 각 농도당 2매의 플레이트씩 슬라이드를 제작, 결과를 판독한 결과, 직접법 및 대사활성화법 모두에서 전 농도 군에서 음성대조군과 같은 정도의 염색체이상을 유발하여 유전독성이 없음을 나타내었다. 2. 체내 염색체 이상시험에서는 ddY마우스를 이용하여 gentamicin sulfate의 LD$_{50}$의 1/2에 해당하는 200mg/kg을 최고농도로 gentamicin 과 gentamicin sulfate를 암수 각각 3마리씩 공비 2의 3농도로 투여한 후, 24시간째 골수세포의 염색체 표본을 제작하여 관찰한 결과, 세포독성 및 염색체 이상을 유발하지 않았다. 또한 동물약품으로 사용되는 치료용량 및 투약방법에 근거하여 10mg/kg 및 5, 2.5mg/kg을 1일 1회씩 4회 투여한 군에서도 암수에 상관없이 전 농도 군에서 염색체이상을 나타내지 않아 유전독성을 나타내지 않음을 관찰하였다.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.374-382
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• 2011

We investigated the mutagenicity of methiozolin, newly developed herbicide, in vitro reverse mutation test using Salmonella typhimurium and Escherichia coli, chromosome aberration test using chinese hamster lung (CHL) cells and in vivo micronucleus test of mice. In the reverse mutation test, the methiozolin did not induce mutagenicity in Salmonella typhimurium TA98, TA100, TA1535, TA1537, Escherichia coli WP2uvrA with and without metabolic activation at $5,000{\mu}g$/plate. In the chromosome aberration test, the results showed no incidence of increased structural and numerical chromosome abberrations at any doses tested (80, 40, $20{\mu}g$/mL). In micronucleous test, the ratio of micronuclei was measured in polychromatic erythrocytes with treated methiozolin for ICR mice. No incidence of increased micronuclei were observed in polychromatic erythrocytes (1,500, 1,000, 500 mg/kg). Based on these results, we concluded that methiozolin has no mutagenic toxicity in vitro and in vivo systems.

• Korean journal of applied entomology
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• v.51 no.3
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• pp.245-253
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• 2012

Benzylinedeneacetone (BZA) is a bacterial metabolite which is synthesized by at least two entomopathogenic bacteria, namely Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata. It has been shown to possess inhibitory effects on insect cellular and humoral immune responses as well as antimicrobial activities against various species of bacteria and fungi. However, its relatively high phytotoxicity, and nonsystematic effect have thus far prevented its development into an optimal pesticide. This study screened five different BZA derivatives in order to select an optimal compound, which would have relatively high solubility and low phytotoxicity while retaining sufficient degrees of the immunosuppressive and antimicrobial activities associated with BZA. Hydroxylation of the benzene ring of BZA was found to significantly suppress its immunosuppressive and antimicrobial activities. Transformation of the ketone of BZA by carboxylation also suppressed the inhibitory activities. However, a shortening of the aliphatic chain of BZA into acetate form (4-hydroxyphenylacetic acid: HPA) did not decrease the inhibitory activity. HPA also showed much less phytotoxicity against the hot pepper plant Capsicum annuum, when compared to BZA. This study identified an optimal BZA derivative, which exhibited relatively little phytotoxicity, but retained a high degree of inhibitory activity to suppress insect immune responses and antimicrobial activities against plant pathogens.

• Journal of Life Science
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• v.25 no.2
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• pp.237-242
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• 2015

The use of calcite-forming bacteria (CFB) in crack remediation and durability improvements in construction materials creates a permanent and environmentally-friendly material. Therefore, research into this type of application is stimulating interdisciplinary studies between microbiology and architectural engineering. However, the mechanisms giving rise to these materials are dependent on calcite precipitation by the metabolism of the CFB, which raises concerns about possible hazards to cement-based construction due to microbial metabolic acid production. The aim of this study was to determine target microorganisms that possibly can have bio-corrosive effects on cement mortar and to assess multi-functional CFBs for their safe application to cement structures. The chalky test was first used to evaluate the $CaCO_3$ solubilization feature of construction sites by fungi, yeast, bacterial strains. Not all bacterial strains are able to solubilize $CaCO_3$, but C. sphaerospermum KNUC253 or P. prolifica KNUC263 showed $CaCO_3$ solubilization activity. Therefore, these two strains were identified as target microorganisms that require control in cement structures. The registered patented strains Bacillus aryabhatti KNUC205, Arthrobacter nicotianae KNUC2100, B. thuringiensis KNUC2103 and Stenotrophomonas maltophilia KNUC2106, reported as multifunctional CFB (fungal growth inhibition, crack remediation, and water permeability reduction of cement surfaces) and isolated from Dokdo or construction site were unable to solubilize $CaCO_3$. Notably, B. aryabhatti KNUC205 and A. nicotianae KNUC2100 could not hydrolyze cellulose or protein, which can be the major constituent macromolecules of internal materials for buildings. These results show that several reported multi-functional CFB can be applied to cement structures or diverse building environments without corrosive or bio-deteriorative risks.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.83-93
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• 2006

In heavily industrialized areas, soil sites are contaminated with high concentrations of heavy metals. These pollutants are highly accumulated to the human body through the food web and cause serious diseases. To remove heavy metals from the soil, a potential strategy is the environmental friendly and cost effective phytoremediation. For the enhancement of remediation efficiency, the symbiotic interaction between the plant and plant growth-promoting rhizobacteria (PGPR) has been attended. In this review, the interaction of the plant and PGPR in the heavy metal-contaminated soil has been reviewed. The physicochemical and biological characteristics of the rhlzosphere can influence directly or indirectly on the biomass, activity and population structure of the rhizobacteria. The root exudates are offered to the soil microbes as useful carbon sources and growth factors, so the growth and metabolism of rhizobacteria can be promoted. PGPR have many roles to lower the level of growth-inhibiting stress ethylene within the plant, and also to provide iron and phosphorus from the soil to plant, and to produce phytohormone such as indole acetic acid. The plant with PGPR can grow better in the heavy metal contaminated soil. Therefore higher efficiency of the phytoremediation will be expected by the application of the PGPR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.437-443
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• 2019

This study examined the productivity, blood characteristics, and cecal microorganisms with the addition of mixed enzymes in broiler chickens. Three hundred chickens (Ross 308) were assigned randomly to five treatment groups (control, 0.5 MXG, 1.0 MXG, 2.0 MXG, and 1.0 G) with three replications. Based on the results, the weight, feed intake, feed efficiency, and daily gain increased slightly by the treatment assignment. Carcass, stomach, and heart weights increased slightly in all treatment groups compared to the control. On the other hand, liver weight was significantly low by enzyme addition compared to the control group (p<0.05). The total number of appendix bacteria decreased significantly in all treatment groups compared to the control group (p<0.05). The total protein, blood urea nitrogen (BUN), and glucose level did not differ after treatment. On the other hand, the IgG level was significantly higher in the 1.0 MXG and 2.0 MXG groups than in the control group (p<0.05). In conclusion, the addition of a mixed enzyme (MXG) will improve the feed efficiency and IgG, as well as reduce the liver weight and total bacteria in broiler chickens.

• KSBB Journal
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• v.19 no.4
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• pp.315-320
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• 2004

We examined the culture conditions and degrading characteristics of styrene dimer (endocrine disrupter) using microorganism. The isolated microbe were consisted of 3 kinds of strain. The strains were identified to Pseudomonas sp. and Klebsiella pneumoniae by API 20E kit, but one was not identified. Single strain was not grown on the C-medium containing styrene dimer. However the complex strain YH3 could grow and we confirmed it by the broth color and O.D$_{660nm}$ (optical density 660 nm). The optimal culture conditions of complex strain YH3 were 35$^{\circ}C$, 1,000 ppm (v/v) of styrene dimer and pH 7.0, respectively. In tolerance test against the organic solvents, the complex strain YH3 could grow above log P=3.1, and could degrade ethyl benzene and 2,4-D, one kind of herbicide. As a result of TLC (Thin Layer Chromatography) analysis, we confirmed that the metabolite of styrene dimer was created by YH3 after 5th day, but not at control samples.