• 자연과학논문집
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• 제14권1호
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• pp.7-24
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• 2004

Thiol peroxidase인 E.coli AhpC의 아미노산 서열을 database를 이용해 분석하여, TPx와 상동성이 있는 새로운 형태의 Thiol peroxidase를 찾아내었다. 그 중 병원성을 갖는 박테리아인 Haemophilus Influenzae에서 존재하는 TPx와 유사하고, GRX와 함께 fusion 되어있는 새로운 형태의 단백질의 유전자를 클로닝하여 E.coli에서 과발현시켜 분리정제 하였다. 정제된 TPx-GRX는 환원제로 thiol 성분을 갖는 MCO system(Fe, DTT, Oxygen)에 의하여 Glutamine Synthetase(GS)의 불활성화를 방어하는 티올 특이적 향산화활성을 갖고, peroxides를 제거하는 peroxidase 활성을 갖는 것을 밝혔다. 이 결과들로부터 TPx-GRX는 새로운 형태의 Thiol perosidase임을 알 수 있었다. 더 나아가서 이 결과들은 TPx-GRX가 병원성 박테리아에서 oxidative stress를 막는 생리적으로 중요한 역할을 할 것이라는 것을 시사한다.

• 대한화장품학회지
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• 제18권1호
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• pp.42-63
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• 1992

방부제와 계면활성제를 혼합 사용하였을 경우 미생물에 대한 방부력 변화를 검토하고자 Imidazolidinyl urea, Methylparaben, Imidazolidinyl urea와 Methylparaben 혼합체 3종의 농도에 따른 각 농도별 계면활성제 Tween 20, Tween60, Tween 80의 첨가가 S. aureus ATCC E. coli ATCC 10536, P. aeruginosa NCTC 10490에 대한 방부력에 미치는 영향을 실험하였으며, 아울러 제품내에서 Tween 60 계면활성제 농도에 변화를 주었을 때의 방부력 변화를 조사하였다. 1. S. aureus ATCC 6538 Methylparaben과 Imidazolidinyl urea 혼합체에 대해 내성을 전혀 갖지 않았다. 2. E. coli ATCC 10536은 Mithylparaben에 대하여 내성을 전혀 갖지 않았다. 3. Mithlparaben과 Imidazolidinyl urea 혼합체는 Gram 음성균, Gram 양성균에 넓은 향균 spectrum을 나타났다. 즉, 방부제는 단일 사용시보다 혼합 사용시 상승효과를 가졌다. 4. Imidazolidinyl urea는 Polyoxyethylene(20) Sorbitan fatty acid ester류에 의해 전혀 방부력에 영향을 받지 않는 반면에 시험균주 3종에 대해 내성이 잘 되었다. 5. Muthylparaben은 Polyoxyethylene(20) Sorbitan fatty acid ester류에 의해 불활성화가 큰 폭으로 나타났다. 6. 방부제 Methyparaben 0.2%를 함유하는 제품에 비이온 계면활성제 Tween 60의 량을 0.5, 1.0, 2.0%로 달리 첨가하였을시 D-value는 제품내 비이온 계면활성제 Tween 60의 량이 증가할수록 비례하여 커졌다. 즉, 비이온 계면활성제 Polyoxyethylene(20) Sorbitan monostearate에 의해 Methylparaben이 제품내에서도 불활성화 되었다.

• Journal of Microbiology and Biotechnology
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• 제29권9호
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• pp.1401-1411
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• 2019

Mycobacterial cell walls comprise thick and diverse lipids and glycolipids that act as a permeability barrier to antibiotics or other chemical agents. The use of OH radicals from a non-thermal plasma jet (NTPJ) for the inactivation of mycobacteria in aqueous solution was adopted as a novel approach. Addition of water vapor in a nitrogen plasma jet generated OH radicals, which converted to hydrogen peroxide ($H_2O_2$) that inactivated non-pathogenic Mycobacterium smegmatis and pathogenic Mycobacterium tuberculosis H37Rv. A stable plasma plume was obtained from a nitrogen plasma jet with 1.91 W of power, killing Escherichia coli and mycobacteria effectively, whereas addition of catalase decreased the effects of the former. Mycobacteria were more resistant than E. coli to NTPJ treatment. Plasma treatment enhanced intracellular ROS production and upregulation of genes related to ROS stress responses (thiolrelated oxidoreductases, such as SseA and DoxX, and ferric uptake regulator furA). Morphological changes of M. smegmatis and M. tuberculosis H37Rv were observed after 5 min treatment with $N_2+H_2O$ plasma, but not of pre-incubated sample with catalase. This finding indicates that the bactericidal efficacy of NTPJ is related to the toxicity of OH and $H_2O_2$ radicals in cells. Therefore, our study suggests that NTPJ treatment may effectively control pulmonary infections caused by M. tuberculosis and nontuberculous mycobacteria (NTM) such as M. avium or M. abscessus in water.

• 한국식품위생안전성학회지
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• 제35권1호
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• pp.68-74
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• 2020

본 연구는 저온살균(60℃, 5-20분)과 대기압플라즈마(5-20분)를 병용한 고춧가루 중의 E. coli 저감화 및 시너지 효과를 조사하였다. 저온살균 단일처리시 대장균의 불활성화는 최대 2 log₁₀ CFU/g(=99% 감소) 이상 나타내었으며, 대기압플라즈마 5, 10, 15, 및 20분간 단일처리 하였을 때 각각 0.4, 0.8, 0.9 및 1.4 log₁₀ CFU/g 감소되었다. 저온살균 및 대기압플라즈마 단독 처리만으로는 만족할 만한 미생물 저감화효과를 얻을 수 없었기에 저온살균 처리 후, 대기압플라즈마를 병용처리 하여 대장균의 불활성화는 1-6 log₁₀ CFU/g 이상 감소되었다. 그러나, 저온살균과 대기압플라즈마 병용처리에 따른 관능적 품질 (색, 이취, 맛, 조직감 및 전체적인 기호도)에 대한 유의적인 차이는 관찰되지 않았다(P>0.05). 따라서 고춧가루의 미생물학적 안전성 확보를 위해 저온살균과 대기압플라즈마 단독처리보다 이 둘의 병용처리가 E. coli의 확실한 저감화 효과를 유도하고 식품 고유의 품질특성을 유지하는데 효과적이었음을 본 연구를 통해 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.114-120
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• 2002

A 1,989-bp genomic region encoding nickel resistance genes was isolated from Legionella pneumophila, a pathogen for legionellosis. From a sequencing and computer analysis, the region was found to harbor two structural genes, a nreB-like protein gene (1,149 bp) and a nreA-like protein gene (270 bp), in a row. Both genes exhibited a significant degree of similarity to the corresponding genes from Synechocystis sp. PCC6803 ($54\%$ amino acid sequence identity) and Achromobacter xylosoxidans 31A ($76\%$). The gene was successfully expressed in E. coli MG1655 and conferred a nickel resistance of up to 5 mM in an LB medium and 3 mM in a TMS medium including gluconate as the sole carbon source. E. coli harboring the nickel resistance gene also exhibited a substantial resistance to cobalt, yet no resistance to cadmium or zinc. Since the extracellular concentration of nickel remained constant during the whole period of cultivation, it was confirmed that the nickel resistance was provided by an efflux system like the $Ni^2＋$permease (nrsD) of Synechocystis sp. strain PCC6803. Since polyphosphate (poly-P) is known as a global regulator for gene expression as well as a potential virulence factor in E. coli, the nickel resistance of a ppk mutant of E. coli MG 1655 harboring the nickel resistance gene from L. pneumophila was compared with that of its parental strain. The nickel resistance was significantly attenuated by ppk inactivation, which was more pronounced in an LB medium than in a TMS medium.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.270.1-270.1
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• 2013

Zinc oxide (ZnO) is one of the most powerful materials for purifying organic pollutants using photocatalytic activity. In this study, we have introduced a novel method to design highly photoreactive flexible 3 dimensional (3D) ZnO nanocomposite [F-ZnO-m (m: reaction time, min)] by electrospinning and simple-step ZnO growth processing (one-step ZnO seed coating/growth processing). Significantly, the F-ZnO-m could be a new platform (or candidate) as a photocatalytic technology for both morphology control and largearea production. The highest photocatalytic degradation rate ([k]) was observed for F-ZnO-m at 2.552 h-1, which was 8.1 times higher than that of ZnO nanoparticles (NPs; [k] = 0.316 h-1). The enhanced photocatalytic activity of F-ZnO-m may be attributed to factors such as large surface area. The F-ZnO-m is highly recyclable and retained 98.6% of the initial decolorization rate after fifteen cycles. Interestingly, the F-ZnO-m samples show very strong antibacterial properties against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) after exposure to UV-light for 30 min. The antibacterial properties of F-ZnO-m samples are more effective than those of ZnO NPs. More than 96.6% of the E. coli is sterilized after ten cycles. These results indicate that F-ZnO-m samples might have utility in several promising applications such as highly efficient water/air treatment and inactivation of pathogenic microorganisms.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.412-412
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• 2014

Zinc oxide (ZnO) is one of the most powerful materials for purifying organic pollutants using photocatalytic activity. In this study, we have introduced a novel method to design highly photoreactive flexible 3 dimensional (3D) ZnO nanocomposite [F-ZnO-m (m: reaction time, min)] by electrospinning and simple-step ZnO growth processing (one-step ZnO seed coating/growth processing). Significantly, the F-ZnO-m could be a new platform (or candidate) as a photocatalytic technology for both morphology control and large-area production. The highest photocatalytic degradation rate ([k]) was observed for F-ZnO-m at 2.552 h-1, which was 8.1 times higher than that of ZnO nanoparticles (NPs; [k] = 0.316 h-1). The enhanced photocatalytic activity of F-ZnO-m may be attributed to factors such as large surface area. The F-ZnO-m is highly recyclable and retained 98.6% of the initial decolorization rate after fifteen cycles. Interestingly, the F-ZnO-m samples show very strong antibacterial properties against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) after exposure to UV-light for 30 min. The antibacterial properties of F-ZnO-m samples are more effective than those of ZnO NPs. More than 96.6% of the E. coli is sterilized after ten cycles. These results indicate that F-ZnO-m samples might have utility in several promising applications such as highly efficient water/air treatment and inactivation of pathogenic microorganisms.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.219-225
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• 2017

An aqueous chlorine dioxide ($ClO_2$) treatment combined with highly activated calcium oxide (CaO) and mild heat was tested for inactivating naturally existing bacteria and Escherichia coli O157:H7 inoculated on fresh-cut kale. Kale samples were treated with different concentrations of $ClO_2$ (10, 30, and 50 ppm), CaO (0.01%, 0.05%, 0.1%, and 0.2%), and mild heat ($25^{\circ}C$, $45^{\circ}C$, $55^{\circ}C$, and $65^{\circ}C$) as well with combinations of 30 or 50 ppm $ClO_2$ and 0.2% CaO at $55^{\circ}C$ for 3 min. An increasing concentration of $ClO_2$ and CaO significantly reduced the microbial population compared with the control. In addition, mild heating at $55^{\circ}C$ elicited greater microbial reduction than the other temperatures. A combined treatment of 50 ppm $ClO_2$ and 0.2% CaO at $55^{\circ}C$ reduced the population of naturally existing bacteria on kale by 3.10 log colony forming units (CFU)/g, and the counts of E. coli O157:H7 were below the detection limit (1 log CFU/g). In addition, no significant differences in the Hunter color values were evident in any treatment during storage. Therefore, a combined treatment of $ClO_2$ and active CaO at $55^{\circ}C$ can be an effective sanitizing method to improve the microbiological safety of fresh-cut kale without affecting its quality.

• Journal of Microbiology and Biotechnology
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• 제25권4호
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• pp.554-558
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• 2015

Drug delivery systems (DDSs) incorporating bacterial minicells have been evaluated as a very powerful tool in view of biocompatibility. However, limited studies have been carried out on these systems, mainly using minicells from Salmonella sp. and Escherichia coli. Thus, we generated a new minicell-producing strain from an endotoxin-free Corynebacterium glutamicum by the inactivation of genes related to cell division. The two knockout strains, ${\Delta}parA$ and ${\Delta}ncgl1366$, showed distinct abilities to produce minicells. The resulting minicells were purified via sequential antibiotic treatments and centrifugations, which resulted in reproducible yields.

• 한국환경과학회지
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• 제16권11호
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• pp.1295-1300
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• 2007

The antibacterial effects of anodic electrolyzed water against various bacteria were studied in this investigation. Complete inactivation of Gram-positive and Gram-negative bacteria occurred within 15 s after exposure to anodic electrolyzed water. Moreover, 1/2, 1/5 and 1/10 diluted anodic electrolyzed water by adding deionized water showed strong antibacterial effects. However, the inhibitory effect of anodic electrolyzed water on the anaerobe of Propionibacterium acnes was much weaker than that on the aerobes, including Gram-positive and Gram-negative bacteria. The degraded fragments of E. coli cell were observed upon treating anodic electrolyzed water for 1 min by using scanning electron microscopy.