• 한국미생물·생명공학회지
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• 제26권4호
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• pp.303-308
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• 1998

충북 청주시의 공단폐수 유입지로부티 탈질화에 의한 페놀분해 세균이 분리되었다. 분리된 균의 형태적, 생화학적 및 생리학적 특성을 분석한 결과 Pseudomonas sp.로 판명되었고 HL100으로 명명하였다. 분리된 균은 nitrate가 최종전자 수용체로서 공급되는 경우 페놀을 단일 탄소 및 에너지원으로 이용하였다. 배지에 첨가된 nitrate가 nitrite로 환원되면서 3mM의 페놀을 약 110시간만에 완전히 분해하였으며 관찰된 최대 doubling time은 20시간이었다. 적절한 조건에서 nitrate로부터 $N_2$를 생성하는 능력을 보여 분리된 균의 경우 탈질작용의 전과정을 수행할 수 있는 것으로 확인되었다. 최적 생장온도와 pH는 각각 37$^{\circ}C$와 7.0으로 판명되었으며 탈질화에 의한 생장시 toluene을 탄소원으로 이용하였지만 Xylene과 benzene은 이용하지 못하였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.77-82
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• 2004

Quantifying rates of microbial processes under subsurface conditions is difficult, and is most commonly approximated by laboratory studies using aquifer materials. In this study a single-well, 'push-pull' test method is adapted for the in situ determination of denitrification rates in groundwater aquifers. The rates of stepwise reduction of nitrate to nitrite, nitrous oxide, and molecular nitrogen were determined by performing a series of push-pull tests at an experimental well field of Korea University. A single Transport Test, one Biostimulation Test, and four Activity Tests were conducted for this study. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide (a conservative tracer), fumarate (a carbon and/or source), and nitrate (an electron acceptor). At this site, extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the solutes prior to biostimulation. Biostimulation tests were conducted to stimulate the activity of indigenous heterotrophic denitrifyinc microorganisms. Biostimulation was detected by the simultaneous production of carbon dioxide and nitrite after each injection. Activity tests were conducted to quantify rates of nitrate, nitrite, and nitrous oxide reduction. Estimated zero-order degradation rates decreased in the order nitrate '||'&'||'gt; nitrite '||'&'||'gt; nitrous oxide. The series of push-pull tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibi1ity assessments for in situ denitrification in nitrate-contaminated aquifers.

• 상하수도학회지
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• 제28권4호
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• pp.419-429
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• 2014

Recent studies have been reported the presence of Endocrine Disrupting Compounds, Pharmaceuticals and Personal Care Products (EDC/PPCPs) in surface and wastewater, which could potentially affect to the complicate behavior in coupled presence of nano-colloid particles and surfactants (adsorption, dispersion, and partitioning). In this study, the adsorption of EDC/PPCPs by Single Walled Carbon Nanotubes (SWNTs) as a representative of nano-particles in cationic surfactant solutions were investigated. Hydrophobic interactions (${\pi}-{\pi}$ Electron Donor-Acceptor) have been reported as a potential adsorption mechanisms for EDC/PPCPs onto SWNTs. Generally, the adsorptive capacity of the relatively hydrophobic EDC/PPCPs onto SWNTs decreased in the presence of cationic surfactant (Cetyltrimethyl Ammonium Bromide, CTAB). This study revealed that the competitive adsorption occurred between CTAB cations and EDC/PPCPs by occupying the available SWNT surface (CTAB adsorption onto SWNTs shows five-regime and maximum adsorption capacity of 370.4 mg/g by applying the BET isotherm). The adsorption capacity of $17{\alpha}$-ethinyl estradiol (EE2) on SWNT showed the decrease of 48% in the presence of CTAB. However, the adsorbed naproxen (NAP) surely increased by forming hemimicelles and resulted in a favorable media formation for NAP partition to increase SWNTs adsorption capacity. The adsorbed NAP increased from 24 to 82.9 mg/g after the interaction of CTAB with NAP. The competitive adsorption for EDC/PPCPs onto SWNTs is likely to be a key factor in the presence of cationic surfactant, however, NAP adsorption showed a slight competition through $CH_3-CH_3$ interaction by forming hemimicelles on SWNT surface.

• 미생물학회지
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• 제37권3호
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• pp.177-181
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• 2001

Bacillus licheniformis Bl을 이용하여 청국장발효를 거쳐 보존성이 높은 분말청국장을 제조하였다. 분말청국장의 다양한 생리활성 물질 중에서도 항산화물질의 존재여부와 그 효괴를 결정하였다. 분말청국장을 증류수로 추출하여, Sephadex G-75 Bel filtration chromatography 작업을 수행한 후, 390 nm에서 광범위한 분자량의 갈변물질을 검출 할 수 있었다. 1,1 diphenyl-2-picrylhydrazyl (DPPH)를 이용하여 갈변물질의 항산화도를 결정하였다. 분자량이 큰 갈변물질의 항산화도는 매우 약하였으나, 분자량이 작은 갈변물질에서는 10-20%의 항산화능이 결정되었다. 체내에서는 분자량이 작은 갈변물질의 흡수가 더 유리할 수 있다. 분말청국장의 항산화물질 추출에 ethanol을 이용했을때는 60.1%, methanol을 이용했을 때는 58.97%의 높은 항산화능을 보여주어, 증류수로 추출했을 때에 비해 휠씬 효 율적이었다. 또한 분말컹국장을 ethanol 5%이상 되게끔 녹였을 때 항산화도가 가장 컸다. 본 분말청국장에 존재하는 항산화물질은 항산화능이 우수하였는 데, 앞으로 안정성이 확보된다면, 식용류, 주류에 첨가하는 천연 항산화물질로 개발할 수 있을 것이다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권6호
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• pp.192-203
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• 2016

A field investigation was conducted on an aquifer contaminated with trichloroethylene (TCE) for application of in situ reactive zone treatment using nanosized zero-valent iron (NZVI). The aquifer was an unconfined aquifer with a mean hydraulic conductivity of $5.14{\times}10^{-4}cm/sec$, which would be favorable for NZVI injection. Seasonal monitoring of TCE concentration revealed a presence of non-aqueous phase liquid form of TCE near IW (injection well). The hydrochemical data characterized the site groundwater to be a $Ca-HCO_3$ type. The average value of Langelier Saturation Index of the groundwater was -1.33, which implied that the site was favorable for corrosion of NZVI. Dissolved oxygen (DO) concentration varied between 2.5~11.5 mg/L, which indicated that DO would greatly compete with TCE as an electron acceptor. The hydrogeological and hydrochemical characterization reveals that the time around November would be appropriate for NZVI injection when water level and temperature are relatively high and DO concentration is low.

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.138-145
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• 2007

Anabaena sensory rhodopsin is a seven transmembrane protein that uses all-trans/13-cis retinal as a chromophore. About 22 residues in the retinal-binding pocket of microbial rhodopsins are conserved and important to control the quality of absorbing light and the function of ion transport or sensory transduction. The absorption maximum is 550 nm in the presence of all-trans retinal at dark. Here, we mutated Pro206 to Glu or Asp, of which the residue is conserved as Asp among all other microbial rhodopsins, and the absorption maximum and pKa of the proton acceptor group were measured by absorption spectroscopy at various pHs. Anabaena rhodopsin was expressed best in Escherichia coli in the absence of extra leader sequence when exogenous all-trans retinal was added. The wild-type Anabaena rhodopsin showed small absorption maximum changes between pH4 and 11. In addition, Pro206Asp showed 46 nm blue-shift at pH7.0. Pro206Glu or Asp may change the contribution to the electron distribution of the retinal that is involved in the major role of color tuning for this pigment. The critical residue Ser86 (Asp 96 position in bacteriorhodopsin: proton donor) for the pumping activity was replaced with Asp, but it did not change the proton pumping activity of Anabaena rhodopsin.

• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.627-636
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• 2016

The causative agent of pandemic cholera, Vibrio cholerae, infects the anaerobic environment of the human intestine. Production of cholera toxin (CT), a major virulence factor of V. cholerae, is highly induced during anaerobic respiration with trimethylamine N-oxide (TMAO) as an alternative electron acceptor. However, the molecular mechanism of TMAO-stimulated CT production is not fully understood. Herein, we reveal that CT production during anaerobic TMAO respiration is affected by glucose fermentation. When the seventh pandemic V. cholerae O1 strain N16961 was grown with TMAO and additional glucose, CT production was markedly reduced. Furthermore, an N16961 Δcrp mutant, devoid of cyclic AMP receptor protein (CRP), was defective in CT production during growth by anaerobic TMAO respiration, further suggesting a role of glucose metabolism in regulating TMAO-mediated CT production. TMAO reductase activity was noticeably decreased when grown together with glucose or by mutation of the crp gene. A CRP binding region was identified in the promoter region of the torD gene, which encodes a structural subunit of the TMAO reductase. Gel shift assays further confirmed the binding of purified CRP to the torD promoter sequence. Together, our results suggest that the bacterial ability to respire using TMAO is controlled by CRP, whose activity is dependent on glucose availability. Our results reveal a novel mechanism for the regulation of major virulence factor production by V. cholerae under anaerobic growth conditions.

• 한국결정학회지
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• 제11권4호
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• pp.212-223
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• 2000

A stochiometric mix of CuInTe₂ polycrystal was prepared in a honizonatal furnace. To obtain the single crystal thin films, CuInTe₂ mixed crystal was deposited on throughly etched GaAs(100) by the HWE system. The source and substrate temperatures were 610℃ and 450℃ respectively, and the thickness of the deposited single crystal thin film was 2.4㎛. CuInTe₂ single crystal thin film was proved to be the optimal growth condition when the excition emission spectrum was the strongest at 1085.3 nm(1.1424 eV) of photoluminescence spectrum at 10 K, and also FWHM of Double Crystal X-ray Rocking Curve (DCRC) was the smallest, 129 arcsec. The Hall effect on this sample was measured by the method of Van der Pauw, and the carrier density and mobility dependent on temperature were 9.57x10/sup 22/ electron/㎥, 1.31x10/sup -2/㎡/V·s at 293 K, respectively. The ΔCr(Crystal field splitting) and the ΔSo (spin orbit coupling splitting( measured at f10K from the photocurrent peaks in the short wavelength of the CuInTe₂ single crystal thin film were about 0.1200 eV, 0.2833 eV respectively. From the PL spectra of CuInTe₂ single crystal thin film at 10 K, the free exciton (E/sub x/) was determined to be 1064.5 nm(1.1647 eV) and the donor-bound exciton(D/sup 0/, X) and acceptor-bound exciton (A/sup 0/, X) were determined to be 1085.3 nm(1.1424 eV) and 1096.8 nm(1.1304 eV0 respectively. And also, the donor-acciptor pair (DAP)P/sub 0/, DAP-replica P₁, DAP-replica P₂ and self-activated (SA) were determined to be 1131 nm (1.0962 eV), 1164 nm(1.0651 eV), 1191.1 nm(1.0340 eV) and 1618.1 nm (0.7662 eV), respectively.

• 한국물환경학회지
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• 제21권6호
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• pp.624-629
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• 2005

The purpose of this study is to investigate the performance of nitrogen removal using autotrophic microorganism in the Membrane-Attached Biofilm Reactor (MABR). The treatment system consists of an aerobic MABR (R1) for nitrification and an anaerobic MABR (R2) for hydrogenotrophic denitrification. Oxygen and hydrogen were supplied through the lumen of hollow-fiber membranes as electron acceptor and donor, respectively. In phase Ι, simultaneous organic carbon removal and nitrification were carried out successfully in R1. In phase II, to develop the biofilm on the hollow-fiber membrane surface and to acclimate the microbial community to autotrophic condition, R1 and R2 were operated independently. The MABRs, R1 and R2 were connected in series continuously in phase III and operated at HRT of 8 hr or 4 hr with $NH_4{^+}-N$ concentration of influent, from 150 to 200 mgN/L. The total nitrogen removal efficiency reached the maximum value of 99% at the volumetric nitrogen loading rate of $1.20kgN/m^3{\cdot}d$ in the combined MABR system with R1 and R2. The results in this study demonstrated that the combined MABR system could operate effectively for the removal of nitrogen in wastewater not containing organic materials and can be used stably as a high rate nitrogen removal technology.

• Preventive Nutrition and Food Science
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• 제10권4호
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• pp.340-343
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• 2005

Induction of NAD(P)H:(quinone-acceptor) oxidoreductase (QR) which promotes obligatory two electron reduction of quinones and prevents their participation in oxidative cycling and thereby the depletion of intracellular glutathione, has been used as a marker for chemopreventive agents. Induction of phase II enzyme is considered to be an important mechanism of cancer prevention. In our previous study, we assessed the quinone reductase QR-inducing activities of 216 kinds of medicinal herb extracts in cultured murine hepatoma cells, BPRc1 and hepalc1c7 cells. Among the 216 herbal extracts tested in that study, extracts from Chrysanthemum zawadskii showed significant induction of QR. In this study, we examined QR-inducing activity of solvent fractions of the herbal extract. The dichloromethane fraction of the herb showed the highest QR induction among the samples fractionated with four kinds of solvents with different polarity. The fraction also significantly induced the activity of glutathione S-transferase (GST), one of the major detoxifying enzymes, at $4{\mu}g/mL\;and\;2{\mu}g/mL$ in hepalc1c7 and BPRc1 cells, respectively. In conclusion, dichloromethane-soluble fraction of Chrysanthemum zawadskii which showed relatively strong induction of detoxifying enzymes merits further study to identify active components and evaluate their potential as cancer preventive agents.