• KSBB Journal
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• 제13권5호
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• pp.483-490
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• 1998

Two unidentified methanotrophic strains (MM-white and MM-red) secreting soluble methane monooxygenase (sMMO) involved in thrichloroethylene biodegradation have been isolated from mixed methanotrophic consortium (MM) around Taejon area. Subsequently four methanotrophic strains were isolated from MM and named according to their color; white (MS-white), yellow (MS-yellow), pink (MS-pink) and reddish brown (MS-rbrown). All strains except MS-yellow which can take glucose as well as methane, metabolized methane as a sole carbon source. They all showed symbiotic behavior when methane was used as the sole carbon source. Optimum conditions of cell growth for MM were pH of 6.8 - 7.2, temperature of 29 - 32$^{\circ}C$, and gas flow rate of 6 (for methane), 40 (for air), and 4 ml/min (for carbon dioxide). The sMMO activity was expressed as naphthalene oxidation rate (${\mu}$mol/ mg protein/ hr). The sMMO activity for MM grown in flask culture with 1 ${\mu}$M of CuSO4 was 36, while it was 61 without copper. The activity for MM grown in the fermentor without CuSO4 was 1077, but is was 197 after reaction with 5 ppm of TCE. The methanotrophs showed significantly high sMMO activity despite the presence of 1 ${\mu}$M of CuSO4, although most of other strains already known could not express sMMO activity under this condition.

• 한국환경과학회지
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• 제23권9호
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• pp.1635-1642
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• 2014

Haloacetic acids (HAAs) concentrations have been observed to decreased at drinking water distribution system extremities. This decrease is associated with microbiological degradation by pipe wall biofilm. The objective of this study was to evaluate HAAs degradation in a drinking water system in the presence of a biofilm and to identify the factors that influence this degradation. Degradation of monochloroacetic acid (MCAA), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) was observed in a simulated distribution system. The results obtained showed that different parameters came into play simultaneously in the degradation of HAAs, including retention time, water temperature, biomass, and composition of organic matter. Seasonal variations had a major effect on HAAs degradation and biomass quantity (ATP concentration) was lower by 25% in the winter compared with the summer.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권5호
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• pp.9-17
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• 2014

This paper reported the use of real-time polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and the culture-based method in the intrinsic bioremediation study at a petroleum contaminated site. The study showed that phenol hydroxylase gene was detected in groundwater contaminated with benzene, toluene, ethylbenzene, xylene isomers (BTEX) and methyl tert-butyl ether (MTBE). This indicated that intrinsic bioremediation occurred at the site. DGGE analyses revealed that the petroleum-hydrocarbon plume caused the variation in microbial communities. MTBE degraders including Pseudomonas sp. NKNU01, Bacillus sp. NKNU01, Klebsiella sp. NKNU01, Enterobacter sp. NKNU01, and Enterobacter sp. NKNU02 were isolated from the contaminated groundwater using the cultured-based method. Among these five strains, Enterobacter sp. NKNU02 is the most effective stain at degrading MTBE without the addition of pentane. The MTBE biodegradation experiment indicated that the isolated bacteria were affected by propane. Biodegradation of MTBE was decreased but not totally inhibited in the mixtures of BTEX. Enterobacter sp. NKNU02 degraded about 60% of MTBE in the bioreactor study. Tert-butyl alcohol (TBA), acetic acid, 2-propanol, and propenoic acid were detected using gas chromatography/mass spectrometry during MTBE degraded by the rest cells of Enterobacter sp. NKNU02. The effectiveness of bioremediation of MTBE was assessed for potential field-scale application.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권3호
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• pp.1-10
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• 2013

This study was performed to summarize application of ${\delta}^{13}C$, ${\delta}^{37}Cl$ and ${\delta}D$ of trichloroethylene (TCE) to studies on environmental forensic field regarding identification of TCE sources and evaluation of contribution of TCE to groundwater using data collected from literatures. ${\delta}^{13}C$, ${\delta}^{37}Cl$ and ${\delta}D$ of TCE give some information regarding sources of TCE because they show specific value according to manufacturing method. Also, TCE do not show a significant isotopic fractionation owing to adsorption and dilution. The isotopic fractionation mainly occurs by biodegradation. In addition, isotopic fractionation factor for TCE is different according to a kind of microorganism participated in biodegradation. However, the isotopic data of TCE have to be applied with chemical compositions of TCE and other hydrogeologic factors because isotopic fractionation of TCE is influenced by various factors.

• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.1001-1007
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• 2003

Metal ions contamination may inhibit microorganisms involved in the biodegradation of organic compounds and affect biodegradation rates. Therefore, it is likely that bioremediation of xenobiotics-contaminated soils and waste will require inoculation with efficient biodegrading microbial communities, with capabilities of being resistant to heavy metals as well. Two different transconjugants (Pseudomonas sp. KMl2TC and P. aeruginosa TC) were constructed by conjugation experiments. Results on MIC, induction and growth inhibition strongly indicated that arsenic-resistant plasmid, pKM20, could be mobilized, and the newly acquired phenotype of pKM20 was not only expressed but also well regulated, resulting in newly acquired resistances to $As^{5+},\;As^{3+},\;and\;Sb^{3+} in\;addition\;to\;Cd^{2+},\;Zn^{2+},\;and\;Hg^{2+}$. The phenol- degradation efficiencies of Pseudomonas sp. KMl2TC were maintained significantly even at high heavy metal concentrations at which these efficiencies of P. aeruginosa TC were completely impaired. The results in this study on the effects of heavy metals on phenol degradation, especially after conjugation, are the first ever reported. All the results described in this study encourage to establish a goal of making "designer biocatalysts" which could degrade certain xenobiotics in the area contaminated with multiple heavy metals.

• Journal of Microbiology and Biotechnology
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• 제26권10호
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• pp.1765-1773
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• 2016

Wastewater containing kraft lignin (KL) discharged from pulp and paper industries could cause serious environmental contamination. Appropriate effluent treatment is required to reduce the pollution. Investigations on anaerobic bacteria capable of degrading KL are beneficial to both lignin removal and biofuel regeneration from the effluent. In this paper, an anaerobic strain capable of degrading KL was isolated from the sludge of a pulp and paper mill and identified as Dysgonomonas sp. WJDL-Y1 by 16S rRNA analysis. Optimum conditions for KL degradation by strain WJDL-Y1 were obtained at initial pH of 6.8, C:N ratio of 6 and temperature of 33℃, based on statistical analyses by response surface methodology. For a 1.2 g/l KL solution, a COD removal rate of 20.7% concomitant with biomass increase of 17.6% was achieved after 4 days of incubation under the optimum conditions. After the treatment by strain WJDL-Y1, KL was modified and degraded.

• Environmental Engineering Research
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• 제23권2호
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• pp.223-227
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• 2018

This study reports a cyanide resistant and/or tolerant fungus, isolated from the rhizosphere of Zea mays contaminated with cyanide-based pesticides. The isolate was characterised using molecular biology. The effect of free cyanide and heavy metals on the growth of isolate in a synthetic gold mine wastewater was examined. The molecular analyses identified the isolate as Fusarium oxysporum EKT01/02 (KU985430/KU985431). The isolate had a free cyanide degradation efficiency of 77.6%. The results indicated greater growth impairment in culture containing Arsenic (optical density 1.28 and 1.458) and cyanide (optical density 1.315 and 1.385). Higher growth was observed in all cultures supplemented with extracellular polymeric substance. This study showed that the isolate possesses wide substrate utilisation mechanism that could be deployed in environmental engineering applications.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.1135-1139
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• 2005

Psychrotrophic phenanthrene-degrading bacteria were identified in the sediment samples collected from Lake Baikal, Russia. Among 70 phenanthrene-degrading isolates, the seven that had the highest phenanthrene-degradation rates were identified by 16S rDNA sequencing. Isolate P25, identified as the Gram-positive rod-shaped organism Rhodococcus erythropolis, had the highest growth and degradation rate at $15^{\circ}C$. It could remove $26.0\%$ of 100 mg $1^{-1}$ phenanthrene in 20 days at $15^{\circ}C$, and degradation was less at $5^{\circ}C\;and\;25^{\circ}C$. The addition of surfactants to enhance degradation was tested. Brij 30 and Triton X-100 inhibited degradation at all surfactant concentrations tested, but Tween 80 stimulated phenanthrene degradation, especially at low concentrations. When $20{\times}$ CMC (critical micelle concentration) of Tween 80 was added, $38.0\%$ of 100 mg $1^{-1}$ phenanthrene was degraded in 12 days at $15^{\circ}C$. This psychrotrophic phenanthrene-degrading bacterium is a candidate for use in bioremediation of polycyclic hydrocarbon contamination in low temperature environments.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.946-951
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• 2005

Biodegradation of the endocrine-disrupting chemical di-n-butyl phthalate (DBP) was investigated using a bacterium, Pseudomonas fluorescens B-1, isolated from mangrove sediment. The effects of temperature, pH, salinity, and oxygen availability on DBP degradation were studied. Degradation of DBP was monitored by solid-phase extraction using reversed-phase HPLC and UV detection. The major metabolites of DBP degradation were identified as mono-n-butyl phthalate and phthalic acid by gas chromatography-mass spectrometry (GC-MS) and a pathway of degradation was proposed. Degradation by P. fluorescens B-1 conformed to first-order kinetics. Degradation of DBP was also tested in seawater by inoculating P. fluorescens B-1, and complete degradation of an initial concentration of $100{\mu}g/l$ was achieved in 144 h. These results suggest that DBP is readily degraded by bacteria in natural environments.

• 대한의용생체공학회:의공학회지
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• 제15권1호
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• pp.89-96
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• 1994

키틴의 글루코사민 단위에 클로로프로판, 산화프로필렌 그리고 클로로프로판 디올을 반응시켜 프로필 키틴(PPC), 히드록시프로필 키틴(HPC), 디히드록시프로필 키틴(DHPC)등의 에테르 형태의 키틴 유도체를 합성하였고, 이들을 99% 포름산에 용해시켜 고분자 농도 30 wt%이상에서 콜레스테릭한 유방성 액정을 형성하였다. 액정이 형성된 용액으로부터 필름을 제조하여 라이소자임이 포함된 유사 체액, pH 1.2, pH 6.7 그리고 pH 8.2 용액에서 in vitro 분해정도를 관찰한 결과 처음 1주일에서 급격하게 분해되었으며 중성 영역에서 큰 무게 감소와 기계적 강도가 감소하였다. 세가지 시료들 중 DHPC가 가장 좋은 생분해 정도를 나타냈다.