• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.273-276
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• 2004

The adhesion of hydrocarbon degrading bacteria(HDB) differing in surface hydrophobicity was investigated. Cell wall hydrophobicity was modified chemically and physiologically. Modified adhesion deficient mutant of HDB was selected in a soil column assay. Physiologically and chemical modification increased cell surface hydrophobicity. Cell surface characteristics including BATH and FTIR were measured. Physiological modification using ampicillin was not stable, but chemical modification was stable. Hydrocarbon degrading efficiency was measured of TPH modified and unmodifed HDB.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.26-33
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• 2006

This study investigated the characteristics of the biofilm removal by free chlorine or monochloramine. The simulated drinking water distribution pipes on which biofilms had been formed were supplied with tap water containing 0.5, 1.0, 2.0 mg/L of free chlorine or monochloramine residuals. The biofilm removal was characterized by measurement of attached HPC and biomass on pipe surfaces. Chlorine was more effective in both inactivation of attached viable heterotrophic bacteria and removal of biofilm biomass compared to monochloramine. Biofilm matrix was not much eliminated from the surfaces by monochloramine disinfection. Free chlorine residual of 2.0 mg/L was found to be effective in biomass removal. However, biofilm level as low as $10CFU/cm^2$ of attached HPC and $5{\mu}g/cm^2$ of biomass still remained on the surfaces at 2.0 mg/L of chlorine residual. The measurement of biomass appeared to be a useful means in evaluating the characteristics of biofilm removal.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.249-254
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• 1995

When mating type A and a cells of heterobasidiomycetous yeast Rhodosporidium toruloides were mix-cultured, both of the mating type cells have shown strong agglutination. But this agglutination was not detactable when the A and a cell were cultured separately. From reagglutination made just after the result of disassembling the agglutination by sonication, we knew that the agglutination was sexual-agglutination, not simple physical cell agglutination. The sexual agglutination was progressed actively on logarithmic phase and, in addition, progressed faster on mating type a cell treated with rhodotorucine A. These sexual agglutination have been inhibited by several protease such as trypsin, pronase, chymotrpysin and thermolysin and inhibited by 5 mM DTT as well.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.28-34
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• 2006

Effects of various surface sterilization and washing methods on sterilization of fresh chicory surface were evaluated. Fresh-cut chicory was washed with tap water for 1 min, 100 ppm chlorinated water, and 3 ppm ozonated water using mechanical washing machine for 3 min, packed with bi-axially oriented polypropylene (OPP 0.04 mm) film, and stored for 3 weeks at 4 and $10^{\circ}C$. Tap water washing resulted in approximately 1 log CFU/g reduction of microbial load, and ozonated water and chlorinated water treatments resulted in additional 2 log CFU/g reduction.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.49-49
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• 2018

라오스의 Houay Pano 유역은 상업적 조림으로 인해 2011년부터 2013년까지 급속한 토지이용 변화를 겪어왔다. 본 연구는 이러한 토지이용변화가 박테리아 거동에 어떠한 영향을 주는지 이해하기 위해 Soil and Water Assessment Tool (SWAT) 모형을 활용한 박테리아 거동 모델링을 수행하였다. SWAT 모형은 수치 표고 모델, 토양 특성, 토지 이용 등의 정보를 종합하여, 유역 내수량 및 수질의 변화를 모의할 수 있는 모형으로, 본 연구는 대표적인 분원성 지표 세균 (Fecal Indicator Bacteria)인 대장균 (Escheichia coli, E. coli)을 대상으로 모델링을 수행하였다. SWAT 모형은 지표면 위 박테리아를 1)식물 위, 2)토양 용액상, 3)토양 입자상으로 구분하여 모의한다. 각 상태로 분할된 박테리아는 소멸 (die-off), 씻김 (wash-off), 침투, 표면 유출을 통한 수계로의 이동 등의 단계를 통하여 유역 내에서 거동한다. 본 연구는 서로 다른 기후의 영향을 배제하기 위해 각 토지이용 시나리오를 (2011, 2012, 2013) 실제 기후 조건과 동일 기후(2011-2013 평균) 조건으로 분류하여 분석하였다. 실제 기후 조건에서 SWAT 모형은 표면 유출, 토사 유출, E. coli 거동에 대해 2011년부터 2012년까지 감소, 2012년부터 2013년까지 증가로 모두 동일한 양상을 모의하였다. 이는 강수량의 양상과 동일한 것으로, 강수량이 표면 유출의 양을 결정하고, 달라진 표면 유출에 따라 토사 유출과 E. coli 거동이 결정되기 때문이다. 하지만 동일 기후 조건에서는, E. coli 거동 동인인 표면 유출과 토사 유출이 비교적 일정해짐에 따라, 각 상태로 분할된 박테리아의 초기 부하량값이 E. coli 거동을 결정하는 주된 요인임을 확인 할 수 있었다. 따라서 초기 부하량 분할에 활용되는 엽면적 지수 (Leaf Area Index)와 분배계수 (BACTKDDB)의 정확도가 요구된다. 추가적으로 본 연구는 박테리아의 유입원인 비료 모델링과, LAI를 활용한 박테리아 초기 부하량 산정, 토양 특성 변수와 토지 이용 변수의 분리, 지하수를 통한 박테리아 거동 등을 중심으로 SWAT 모형의 한계점과 개선점을 제시하였으며, 본 연구 결과는 토지이용변화가 박테리아 거동에 주는 영향을 모형적으로 이해하고, 또한 추후 박테리아 모델링 개발에 도움을 줄 것으로 예상된다.

• Journal of Life Science
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• v.8 no.6
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• pp.648-653
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• 1998

The development of natural food preservatives instead of chemical synthetic food preservatives is world wide inte-rest. Authors already investigated that cinnamon bark extract revealed antimicrobial activity against general spoilage microorganisms of food especially its acitivity was stronger against molds than against bacteria. In this paper, authors examined the mirobial flora from the spoiled fish meat paste products and also checked the possibility of cinnamon bark extract food preservative for prolong the shelf life of the fish paste product and breads. The predominat bacteria was Bacillus sp. as about 98% of the total microorganisms isolated from unpacked or packed spoiled fish meat paste products. While molds and yeast are not detected from the vacuum packed products. The MIC(minimum inhibitory concentration) of cinnamon bark extract against the isolated spoilage bacteria and molds was 160~640$\mu\textrm{g}$/$m\ell$ and 40~80$\mu\textrm{g}$/$m\ell$, respectively. When the diluted cinnamon bark extract (the extract : ethanol=1 : 3) was sprayed on the surface of fried fish meat paste product, molds growth was delayed by 2 days at room temperature. The shelf lifes of sandwich and glutinousrice bread which surface sprayed with the diluted extract(1 : 1) was extended by 5 and 7 days, respectively.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.342-347
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• 2003

Clumping of cells is one of the major obstacles to culture wild myxobacterial strains in liquid media. In an effort to solve this problem, we tried a method isolating spontaneous mutants that grow dispersed in liquid media from a wild myxobacterial strain. Myxococcus stipitatus KYC1001, a newly isolated strain from Gyearyongsan National Park in Korea, clumps and sticks to the surface of culture vessels as other wild myxobacteria behave in liquid media. Taking an advantage of the characteristics that dispersed mutant cells would grow dispersed while most other wild type cells would clump and stick to the surface of culture vessels, spontaneous dispersed mutants were enriched by repeated subculturing of culture supernatant. A resultant mutant, KYC2001, did not form any clumps nor stick to the surface of culture flasks, but grew completely dispersed in liquid. Meanwhile, three other spontaneous mutants, KYC2002, KYC2003, and KYC2004, shelved partially dispersed phenotype. A major portion of the cells grew dispersed in liquid but they still formed some clumps.

• Journal of Korea Soil Environment Society
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• v.4 no.3
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• pp.95-104
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• 1999

Comparative biodegradation studies of liquid and solid alkanes and of two different solid alkanes were conducted by an isolated Acinetobacter sp., which degraded crude oil alkanes simultaneously. for the determination of degradation mechanism of hydrophobic crude oil constituents. Also a model oil experimental system composed of a solid alkane. heneicosane, as a substrate and a non-degradable non-aqueous phase liquid. pristane, as an oil matrix was established and studied. It was proposed that the Acinefobacter sp. utilized hydrophobic substrates directly on the surface of them with no difference in the degradation rates between the liquid and solid alkanes. On the basis of the results from the heneicosane/pristane system which imitates crude oil matrix containing solid constituents. the crude oil matrix was considered to reduce the bioavailability of contained substrates by reducing the specific surface area of substrates to contact with microorganisms.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.427-434
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• 2009

Indigenous bacterium which shows a tolerance to high metal toxicity was isolated from soil concomitantly contaminated with oil and heavy metals. The characteristics of the bacterium for Pb and Cd biosorption was investigated under the various experimental conditions such as bacterial growth phase, the initial metal concentration, the input biomass amount, temperature and pH. The Langmuir adsorption isotherm modeling was described to know the capacity and intensity of biosorption. The low initial concentration of heavy metals and high biomass has a maximum heavy metal removal efficiency, but biosorption capacity of Pb and Cd has different values. Biosorption efficiency was highest in the end of the microbial growth stage and under pH 5~9 condition, but was less affected by temperature variation of 25~$35^{\circ}C$. The maximum biosorption capacity for Pb and Cd was 62.11 and 192.31 mg/g, respectively and each $R^2$ was calculated as 0.71 and 0.98 by applying Langmuir isothermal adsorption equation. Biosorption for Cd was considered as monomolecular adsorption to single layer on the surface of cells, whereas biosorption for Pb was considered as accumulation process into the cell by the microbial metabolism and precipitation reaction with anion of bacteria.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.286-293
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• 2006

Three hundred thirty two bacterial colonies which were able to degrade crude oil were isolated from soil samples that were contaminated with oil in Daejon area. Among them, one bacterial strain was selected for this study based on its low surface tension ability, and this selected bacterial strain was identified as Pseudomonas sp. G314 through physiological-biochemical tests and analysis of its 16S rRNA sequence. Pseudomonas sp. G314 showed a high resistance to antibiotics such as ampicillin, chloramphenicol, spectinomycin, and streptomycin, and heavy metals such as Li, Cr, and Mn. It was found that the optimal pH and temperature for biosurfactant production of Pseudomonas sp. G314 were pH 7.0 and $30^{\circ}C$, respectively. After seven hours of inoculated, the biosurfactant activity reached the maximum, and surface tension of the culture broth was decreased from 72 to 25 dyne/cm. The crude biosurfactant was obtained from the culture broth by acid precipitation, followed by solvent extraction, evaporation and then freeze drying. The CMC (critical micelle concentration) value of the crude biosurfactant was 20 mg/L.