• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2002년도 춘계 국제 학술대회
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• pp.9-12
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• 2002

Diffusive transport of volatile organic compounds(VOCs) and their degradation by bacteria in unsaturated soils are couple by poorly understood mass transfer kinetics at the gas/water interface. Determination of the fate of VOCs in unsaturated soil is necessary to evaluate the feasibility of natural attenuation as a VOC remediation strategy. The objective of this study was to develop a mechanistically based mathematical model that would consider the interdependence of VOC transport, microbial activity, and sorptive interaction in a moist, unsaturated soil. Because the focus of the model was on description of natural attenuation, the advective VOC transport that is induced in engineered remediation processes such as vapor extraction was not considered. The utility of the model was assessed through its ability to describe experimental observations form diffusion experiments using toluene as a representative VOC in well-defined soil columns that contained a toluene degrading bacterium, Pseudomonas Putida, as the sole active microbial species. The coefficient for gas-liquid mass-transfer, K$\sub$LA/, was found to be a key parameter controlling the ability of bacteria to degrade VOCs. This finding indicates that soil size and geometry are likely to be important parameters in assessing the possible success of natural attenuation of VOCs in contaminated unsaturated soils.

• Journal of Microbiology and Biotechnology
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• 제17권5호
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• pp.812-821
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• 2007

The ecosystems of certain abandoned mines contain arsenic-resistant bacteria capable of performing detoxification when an ars gene is present in the bacterial genome. The ars gene has already been isolated from Pseudomonas putida and identified as a member of the membrane transport regulatory deoxyribonucleic acid family. The arsenite-oxidizing bacterial strains isolated in the present study were found to grow in the presence of 66.7 mM sodium arsenate($V;\;Na_2HAsO_4{\cdot}7H_2O$), yet experienced inhibited growth when the sodium arsenite($III;\;NaAsO_2$) concentration was higher than 26 mM. Batch experiment results showed that Pseudomonas putida strain OS-5 completely oxidized 1 mM of As(III) to As(V) within 35 h. An arsB gene encoding a membrane transport regulatory protein was observed in arsenite-oxidizing Pseudomonas putida strain OS-5, whereas arsB, arsH, and arrA were detected in strain OS-19, arsD and arsB were isolated from strain RW-18, and arsR, arsD, and arsB were found in E. coli strain OS-80. The leader gene of arsR, -arsD, was observed in a weak acid position. Thus, for bacteria exposed to weak acidity, the ars system may cause changes to the ecosystems of As-contaminated mines. Accordingly, the present results suggest that arsR, arsD, arsAB, arsA, arsB, arsC, arsH, arrA, arrB, aoxA, aoxB, aoxC, aoxD, aroA, and aroB may be useful for arsenite-oxidizing bacteria in abandoned arsenic-contaminated mines.

• 대한환경공학회지
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• 제32권11호
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• pp.1017-1023
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• 2010

본 연구에서는 지질매질체내에서 계면활성제(비이온성 계면활성제(Tween 20), 생계면활성제)가 박테리아(Bacillus subtilis ATCC 6633)의 이동 증진에 미치는 영향을 분석하였다. 계면활성제가 존재하는 다양한 실험조건에서 석영모래(입경분포: 0.5~2.0 mm, 평균입경: 1.0 mm)로 충진된 칼럼을 이용하여 박테리아의 이동에 관한 칼럼실험을 수행하였고, 박테리아 파과곡선으로부터 질량회수율과 부착효율 등을 정량화하였다. 실험결과, MSM(박테리아 성장에 필요한 무기물 배지)의 존재 하에서 매질체 표면에 박테리아의 부착이 상당히 증가하였는데(특히, 주입부분에), 이는 MSM으로 인한 이온강도의 증가 때문이다. 계면활성제가 존재할 경우에는, 계면활성제로 인하여 매질체내에서 박테리아 이동이 증진됨을 관찰할 수 있었다. 또한, MSM과 생계면활성제 주입방법에 따른 박테리아의 이동을 비교한 결과, 박테리아의 이동 증진을 위한 주입조건은 박테리아를 함유한 MSM용액보다 계면활성제를 선주입하거나, 또는 MSM용액과 계면활성제를 동시주입하는 것이 효과적임을 알 수 있었다. 본 연구를 통해 계면활성제의 존재와 주입방법이 박테리아의 이동에 영향을 미칠 수 있음을 알 수 있었다.

• 한국물환경학회지
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• 제26권1호
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• pp.111-115
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• 2010

Beaches in estuaries, bays, and harbors are frequently contaminated with indicators of human pathogens such as fecal indicator bacteria. Tracking down the sources of contamination at these enclosed beaches is complicated by the many point and non-point sources that could potentially degrade water quality along the shore. A mathematical framework was developed to test quantitative relationships between fecal indicator bacteria concentration in ankle depth water at enclosed beaches, the loading rate of fecal indicator bacteria from non-point sources located along the shore, physical characteristics of the beach that affect the transport of fecal indicator bacteria across the beach boundary layer, and a background concentration of fecal indicator bacteria attributable to point sources of fecal pollution that impact water quality over a large region of the embayment. Field measurements of fecal indicator bacteria concentrations and water turbulence at an enclosed beach were generally consistent with predictions and assumptions of the mathematical model, and demonstrated its utility for assessing waste load of non-point sources, such as runoff, bather shedding, bird droppings, and tidal washing of contaminated sediments.

• Journal of Microbiology and Biotechnology
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• 제29권1호
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• pp.1-10
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• 2019

Gram-negative pathogens, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, pose a serious threat to public health worldwide, due to high rates of antibiotic resistance and the lack of development of novel antimicrobial agents targeting Gram-negative bacteria. The outer membrane (OM) of Gram-negative bacteria is a unique architecture that acts as a potent permeability barrier against toxic molecules, such as antibiotics. The OM is composed of phospholipids, lipopolysaccharide (LPS), outer membrane ${\beta}-barrel$ proteins (OMP), and lipoproteins. These components are synthesized in the cytoplasm or in the inner membrane, and are then selectively transported to the OM by the specific transport machines, including the Lol, BAM, and Lpt pathways. In this review, we summarize recent studies on the assembly systems of OM components and analyze studies for the development of inhibitors that target these systems. These analyses show that OM assembly machines have the potential to be a novel attractive drug target of Gram-negative bacteria.

• Journal of Microbiology and Biotechnology
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• 제5권6호
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• pp.315-318
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• 1995

Sulfanilic acid (4-aminobenzenesulfonic acid) alone is normally not permeant in bacteria but can be readily delivered via the microbial dipeptide transport system. A dipeptidyl derivative of this compound, L-phenylalanyl-L-2-sulfanilylglycine (PSG), prepared by attachment of its primary amino group to the phenylalanyl $\alpha$-glycine moiety, appeared to have a Km of 0.125 mM and a Vmax of 1.9 nmoles/ml/min ($A_{660}$, 1.0) in Escherichia coli. From competitive spectrophotometric analysis, it was found that the type of amino acids in both of the N- and C-terminals affected the kinetic power of dipeptides. The growth inhibitory effect of PSG was over 7 times more potent than that of the sulfanilic acid against E. coli, suggesting that this potential inhibition was presumably due to the increased hydrophobic nature of the sulfanilyl dipeptide.

• 미생물학회지
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• 제48권2호
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• pp.57-65
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• 2012

인은 인지질, 탄수화물 및 핵산 등의 생분자 합성에 필요한 원소이다. 세균은 외부환경으로부터 인산이나 인산을 포함하는 영양소를 흡수하여 인을 얻고, 세포대사에 사용되고 남은 인산은 polyphosphate 형태로 저장한다. 현재까지 알려진 다섯 개의 인산 수송 시스템 중, 인산에 특이적으로 높은 친화력을 갖는 Pst 시스템이 가장 중요한 역할을 하며, 그 발현은 세포외부 인산 농도에 반응하는 PhoB-PhoR two component 신호전달 시스템에 의해 조절된다. 반응 조절 단백질 PhoB는 인산 대사뿐 아니라 이와 관계없는 유전자들의 전사를 조절하는 것으로 알려졌으며, 따라서 PhoB의 활성이 조절되지 않으면 많은 종류의 다른 표현형이 나타난다. 본 총설은 각 인산 수송 시스템의 기능이 결여된 세균의 표현형에 대한 최근 연구 결과를 토대로 다음과 같은 내용을 기술하였다. 첫째, 세포 내부 인산의 적정 농도 유지를 위한 인산 수송 시스템들의 역할, 둘째, 인산뿐 아니라 여타 환경 신호와 관련된 수송 시스템의 다양한 표현형, 그리고 마지막으로, 수송 시스템들 간 혹은 그 조절자들 간의 표현형 중복을 분류하여 제시하였다. 이러한 내용은 결국 세균의 대사, 적응반응 및 병원성 발현에 미치는 인산 항상성의 중요성을 강조한다.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2003년도 International Meeting of the Microbiological Society of Korea
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• pp.26-33
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• 2003

We isolated and identifed culturable Arctic bacteria that have inhabited around Korean Arctic Research Station Dasan located at Ny-Alsund, Svalbard, Norway $(79^{\circ}N,\;12^{\circ}E)$. The pure colonies were inoculated into nutrient liquid media, genomic DNA was extracted, and phylogenetic analysis was performed on the basis of 16S rDNA sequences. Out of total 227 strains, 198 strains were overlapped or unidentified, and 43 bacteria were finally identified: 31 strains belonged to Pseudomonas, 7 strains Arthrobacter, two Flavobacterium sp., an Achromobacter sp., a Pedobacter sp., and a Psychrobacter sp. For isolation of diverse bacteria, we need more effective transport method than 3M petri-films, which were used for convenience of transportation that was restricted by volume. We also need to use other culture media than nutrient media. We expect these Arctic bacteria can be used for screening to develop new antibiotics or industrial enzymes that are active at low temperature.

• Applied Microscopy
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• 제48권4호
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• pp.96-101
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• 2018

The release of nanoscale membrane-bound vesicles is common in all three domains of life. These vesicles are involved in a variety of biological processes such as cell-to-cell communication, horizontal gene transfer, and substrate transport. Prokaryotes including bacteria and archaea release membrane vesicles (MVs) (20 to 400 nm in diameter) into their extracellular milieu. In spite of structural differences in cell envelope, both Gram-positive and negative bacteria produce MVs that contain the cell membrane of each bacterial species. Archaeal MVs characteristically show surface-layer encircling the vesicles. Filamentous fungi and yeasts as eukaryotic microbes produce bilayered exosomes that have varying electron density. Microbes also form intracellular vesicles and minicells that are similar to MVs and exosomes in shape. Electron and fluorescence microscopy could reveal the presence of DNA in MVs and exosomes. Given the biogenesis of extracellular vesicles from the donor cell, in situ high-resolution microscopy can provide insights on the structural mechanisms underlying the formation and release of microbial extracellular vesicles.

• 대한환경공학회지
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• 제34권7호
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• pp.504-515
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• 2012

지하수는 전 세계적으로 널리 이용되는 음용수원이다. 하지만, 병원성 미생물에 의한 지하수 오염은 매우 심각한 환경문제로써 음용수의 수질을 저하시키고 인류의 건강을 위협한다. 지하수를 오염시키는 병원성 미생물은 바이러스, 세균, 원생동물 등이 있는데, 이중 바이러스는 박테리아나 원생동물보다 크기가 훨씬 작기 때문에 토양을 통과하는 과정에서 잘 제거되지 않고, 지하수 환경에서 이동성이 뛰어나다. 토양과 대수층에서 바이러스 거동 연구는 지하수의 병원성 미생물 오염 취약성을 판단하고 안전한 음용수원을 확보하는데 꼭 필요하다. 또한, 이러한 연구는 공중 보건을 위한 정책 및 규정을 제정하기 위한 중요한 정보를 제공한다. 본 논문에서는 최근까지의 지중 환경에서 바이러스 거동과 관련하여 수행된 연구들을 현장 조건에서 수행된 것과 실험실 조건에서 수행된 것으로 나눠 정리하였다. 또한, 이러한 연구들을 통해 알려진 바이러스의 거동에 영향을 미치는 인자들을 제시하였다. 그리고, 최근 바이러스 거동 연구에 널리 이용되는 박테리오파지의 특성을 정리하였고, 바이러스 거동을 모사하는데 이용되는 수학적 모델과 콜로이드 여과이론을 제시하였다. 지금까지의 연구결과를 바탕으로 향후 연구는 바이러스 오염원으로부터 지하수를 보호한다는 측면에서 바이러스 보호구역의 설정과 관련된 연구들이 활발히 진행되어야 할 것으로 판단된다. 특히, 바이러스 보호구역 설정과 관련하여 이격거리나 이동시간을 계산할 수 있는 수학적 모델을 개발하고 모델과 관련된 파라미터들의 정보를 축적하는데 집중되어야 할 것으로 판단된다.