• 한국식품과학회지
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• 제37권6호
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• pp.951-956
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• 2005

Bifidobacteria의 효과적인 이용을 위해서는 산소에 내성을 갖는 균주를 선발하는 연구 외에도 산소 스트레스에 대한 방어 기작에 대한 기초적인 연구가 필요하다. 인체로부터 분리된 산소 내성 bifidobacteria는 산소제거활성을 가지고 있었으며 이는 열처리 및 극단적인 pH(pH 2.0)하에서 산소제거활성이 소실되는 것으로 보아 효소가 관여 할 가능성을 확인하였다. 또한 산소제거활성을 보이는 주된 효소를 탐색해본 결과 NADH를 공급하였을 때만 산소제거활성을 보여 NADH oxidase가 주된 역할을 하는 효소임을 알 수 있었다. 또한 산소 내성 균주는 높은 NADH peroxidase 활성을 보유한 것으로 보아 NADH oxidase의 작용에 의해 생성되는 $H_2O_2$는 NADH peroxidase에 의해 무독화 되는 것으로 판단되었다. 배양 중 산소를 공급하여 산소스트레스를 주었을 경우 NADH oxidase와 NADH peroxidase 활성이 1시간 이내에 급격히 증가하였고 산소 공급 후 2시간 동안 배양액 중 용존 산소가 크게 증가하지 않았다. 산소공급 후 2시간 이상이 경과하면 NADH oxidase와 NADH peroxidase활성이 감소하고 용존 산소가 급격히 증가하였고 산소스트레스에 대한 방어 체계가 붕괴되는 현상이 관찰되었다. 즉, 산소 내성 bifidobacteria는 일정 한계까지는 환경중의 산소를 NADH oxidase로 제거하고 생성되는 $H_2O_2$는 NADH peroxidase에 의해 제거시키는 방어 체계를 갖고 있음을 알 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제7권5호
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• pp.356-359
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• 1997

To study the relationship between oxygen tolerance and enzyme activity in the oxygen metabolism of bifidobacteria, the activities of catalase, superoxide dismutase (SOD), NADH oxidase and NADH peroxidase from six typical bifidobacteria and other bacteria were assayed by spectrophotometry. Catalase activity was hardly detected in any of the bifidobacteria tested. SOD activity was detected in every species including the Clostridium species. In particular SOD activity was notably high in the aerosensitive Bifidobacterium adolescentis. This fact indicates that SOD activity is not a critical factor to ensure aerotolerance. Aerosensitive B. adolescentis showed very low NADH oxidative enzyme activity whereas other aerotolerant bifidobacteria exhibited considerable activity for the enzymes. It seems that detoxification of $H_2O_2$ by NADH oxidative enzymes might be an important factor in improving for aerotolerant bifidobacteria survival rates in an oxygen environment.

• Journal of Microbiology and Biotechnology
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• 제14권5호
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• pp.919-923
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• 2004

The sk10 isolated from kimchi was identified as W. kimchii on the basis of l6s-rDNA sequencing. Studies were made to analyze the metabolic flux shift of the sk10 on glucose under aerobic growth conditions. The sk10 produced 38.2 mM acetate, 16.3 mM ethanol, and 33.2 mM lactate under aerobic conditions, but 2.4 mM acetate, 48.0 mM ethanol, and 44.1 mM lactate under anaerobic conditions. The NADH peroxidase (NADH-dependent hydrogen peroxidase) activity of sk10 grown under aerobic conditions was 11 times higher than that under anaerobic conditions. Under the low ratio of $NADH/NAD^+$, the metabolic flux toward lactate and ethanol was shifted to the flux through acetate kinase without NADH oxidation. The kinds of enzymes and metabolites of sk10 were close to those in the pathway of Leuconostoc sp., but the metabolites produced under aerobic growth conditions were different from those of Leuconostoc sp. The stoichiometric balance calculated using the concentrations of metabolites and substrate was about 97%, coincident with the theoretical values under both aerobic and anaerobic conditions. From these results, it was concluded that the metabolic flux of W. kimchii sk10 was partially shifted from lactate and ethanol to acetate under aerobic conditions only.

• Journal of Microbiology and Biotechnology
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• 제14권5호
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• pp.914-918
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• 2004

This study was carried out to analyze the metabolic flux of W. kimchii sk10 on pyruvate and ethanol as a carbon source. The sk10 grown on ethanol produced acetate under aerobic conditions rather than under anaerobic conditions. The lactate and acetate were produced on ethanol plus pyruvate by the sk10 grown under aerobic and anaerobic conditions, respectively. The resting cell of sk10 produced 99.1 mM acetate and 17.3 mM lactate under aerobic conditions and 51.1 mM acetate and 62.4 mM lactate under anaerobic conditions from ethanol plus pyruvate, respectively. This result is thought to be due to the difference in the $NADH/NAD^+$ ratio depending on the growth conditions. The 11-fold overproduction of NADH peroxidase results in a low $NADH/NAD^+$ratio under aerobic growth conditions. At the low $NADH/NAD^+$ ratio, the metabolic flux of pyruvate toward lactate has to be shifted to a flux toward acetate without NADH oxidation to $NAD^+$, and ethanol oxidation to acetate coupled to $NAD^+$ reduction to NADH has to be activated.

• 대한수의학회지
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• 제31권1호
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• pp.41-47
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• 1991

The protective of influences of sodium selenitc ($Na_2SeO_3$) against the methemoglobinemia with sodium nitrite were investigated on hemoglobin, methemoglobin, glutathione peroxidase and NADH-methemoglobin reductase activity in rabbits which were given 0,1,3 and 9ppm sodium selenite of drinking water for a week. Dietary selenium did not alter total hemoglobin in the blood of rabbits. Selenium was found to decrease nitrite-induced methemoglobin in a dose-dependent manner. The glutathione peroxidase activity was also increased by selenium in all the experimental groups. However, the NADH-methemoglobin reductase activity by selenite did not show significant differences as concerns the methemoglobinemia. These results showed that selenium could inhibit nitrite-induced methemoglobinemia. Its influence of inhibition is suggested that the effect of the reduction of methemoglobin was greatly stimulated by glutathione peroxidase activity.

• 식물조직배양학회지
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• 제25권4호
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• pp.277-282
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• 1998

장미(Rosa sp. cv Paul's Scarlet) 현탁 배양체의 배지에서는 정상적인 성장 조건하에서 cationic peroxidase (POD)만 관찰되었으나, 효모 세포벽으로부터 추출한 숙주 특이성이 낮은 elicitor를 10 mg glucan/L의 농도로 투여하여 24시간 정도 배양하였을 때 기존의 POD와 뚜렷하게 구분되는 anionic POD가 유도됨을 관찰하였다. Elicitor에 의해 유도되는 prominent한 anionic POD (pI 6.1)와 대조구로서 pI 8.4의 cationic isozyme을 분리한 후 효소학적 성질을 비교하였다. Ammonium sulfate농축, ion exchange chromatography, gel filtration chroma tography를 통하여 약 200배로 농축된 두 효소를 분리하였으며, 이 두 효소의 몇몇 기질에 대한 kinetic parameter들은 매우 의미있는 차이를 보여 주었다. 그 중에서 ferulic acid에 대한 Km은 anionic POD의 경우 4.6 mM, cationic POD는 1.38 mM로 측정되었으며, $\textrm{H}_2\textrm{O}_2$에 대한 Km은 각각 anionic POD가 0.72 mM, cationic isozyme이 0.45 mM로 나타났다. 특히 NADH 산화 반응의 활성은 anionic POD가 cationic POD에 비하여 약 2배 높은 것으로 측정되었다. 0.1 mM coniferyl alcohol의 첨가에 의한 NADH 산화 반응의 억제는 anionic POD fraction에서 약 60% 정도 일어난 반면에 cationic POD fraction에서는 약 15% 정도 일어났다.

• 한국동물위생학회지
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• 제30권3호
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• pp.291-304
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• 2007

Mutants of an obligate aerobic bacterium, Vitreoscilla, that have deficiency in heat-labile catalase-peroxidase hydroperoxidase I (HPI) were created by EMS treatment. The catalase-peroxidase HPI-deficient mutant showed substantially lower peroxidase activity in exponential and mid-stationary phase compared with the wild type strain. In late stationary phase, the mutant exhibited no peroxidase activity. Peroxidase deficiency in the mutant was revealed by polyacrylamide gels stained for peroxidase activity. Characteristically, catalase levels in the mutant increased about 14- and 8-fold during growth in the exponential and stationary phases, respectively, compared to those in the wild type, suggesting a compensatory effect for protection from $H_2O_2$ toxicity. The mutant showed differences in physiology from the wild type: retardation in growth rate and decrease in oxygen consumption. Both the wild type and the catalase-peroxidase HPI-deficient mutant of Vitreoscilla had lower growth rates in media containing increasing $H_2O_2$ concentrations. However, the mutant exhibited an additionally decreased growth rate after 6 to 8 h of growth compared to the wild type. The wild type was resistent up to 20 mM $H_2O_2$, whereas the mutant was very sensitive to high concentrations of exogenous $H_2O_2$. Although elevated catalase levels would provide protection of the bacteria from the deleterious effect of $H_2O_2$, it did not appear to be complete. Cell-free extracts of the mutant showed decreased NADH oxidation rates and higher accumulation of $H_2O_2$ during this oxidation. These results may account for the impaired growth and earlier onset of death phase by the catalase-peroxidase HPI-deficient mutant of Vitreoscilla.

• 한국미생물·생명공학회지
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• 제26권1호
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• pp.7-14
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• 1998

Bifidobacterium spp.의 내 산소성기작을 밝히기 위하여, 산소에 민감한 B. adolescentis와 상대적으로 산소에 내성이 있는 B. longum을 선정하여 혐기적 조건, 미호기성 조건,호기성 배양 조건 등에서 그 생육,산화 효소들의 활성, 세포 지방산 조성의 변화 등을 연구하였다. B. adolescentis의 생육은 미 호기성 조건에서 민감하게 저해되었으나, B. longum은 같은 조건에서 혐기배양과 같은 정도의 생육을 유지하였다. 이들 조건에서 두 균주의 catalase는 관찰되지 않은 반면, superoxide dismutase는 B. adolescentis와 B. longum모두에서 관찰되었으며 어느 조건에서든 B. adolescentis은 B. longum보다 높은 활성을 나타내었다. NADH oxidase와 NADH peroxidase의 활성은 B. adolescentis에서는 매우 낮은 반면, B. longum에서는 일정한 수준의 활성을 보였으며, 이 활성은 혐기적 배양조건에서 보다는 미호기성 조건에서 3.7-11.4배 증가하였다. 세포의 지방산 분석 결과 두 균주 모두 $C_{l6:0}$과 $C_{l8:1}$이 전체 methylated성분 중 60-70%를 차지했다. B. longum에는 특히 $C_{l9:0 cyclo 9,10}$가 2-14% 함유되어 있었으며, 이는 lactobacillic acid와는 cylization 위치가 다른 cis 9, 10-methylene octadecanoic acid이었고 미호기적 배양과 정지기 세포에서 증가되는 경향을 보였다. 두 균주 모두 혐기균에서만 확인된 세포막의 plasmalogen의 존재로 인한 dimethyl acetals(DMA)을 함유하고 있었는데 이 중 $C_{l8:1}$ DMA는 호기성 조건에서 현저히 감소되었다. 산소 stress환경의 bifidobacteria의 생육에 있어 NADH oxidative enzymes은 중요한 역할을 하며, 이들 효소체계와는 별도로 환경에 적응하기 위한 세포구조적 변화의 일부로 지방산 $C_{l9:0}$ Cyclo와 plasmalogen의 $C_{l8:1}$ 등이 변화한 것으로 생각된다.

• Toxicological Research
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• 제9권1호
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• pp.23-33
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• 1993

In the present study, the effects of allopurinol on paraquat toxicity were investigated in paraquat-treated rats. The surivals of paraquat-treated rats were increased by allopurinol treatment. The contents of glutathione in liver and kidney were significantly decreased by paraquat, but restored by allopurinol. The activity of xanthine oxidase was significantly reduced but NADH dehydrogenase was not changed by allopurinol teatment. The activities of catalase, SOD and glutathione peroxidase in liver were significantly decreased by paraquat but catalase was restored by allopurinol treatment.

• Journal of Microbiology and Biotechnology
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• 제19권7호
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• pp.666-674
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• 2009

An electrochemical bioreactor (ECB) composed of a cathode compartment and an air anode was used in this study to characterize the ethanol fermentation of Zymomonas mobilis. The cathode and air anode were constructed of modified graphite felt with neutral red (NR) and a modified porous carbon plate with cellulose acetate and porous ceramic membrane, respectively. The air anode operates as a catalyst to generate protons and electrons from water. The growth and ethanol production of Z. mobilis were 50% higher in the ECB than were observed under anoxic nitrogen conditions. Ethanol production by growing cells and the crude enzyme of Z. mobilis were significantly lower under aerobic conditions than under other conditions. The growing cells and crude enzyme of Z. mobilis did not catalyze ethanol production from pyruvate and acetaldehyde. The membrane fraction of crude enzyme catalyzed ethanol production from glucose, but the soluble fraction did not. NADH was oxidized to $NAD^+$in association with $H_2O_2$reduction, via the catalysis of crude enzyme. Our results suggested that NADH/$NAD^+$balance may be a critical factor for ethanol production from glucose in the metabolism of Z. mobilis, and that the metabolic activity of both growing cells and crude enzyme for ethanol fermentation may be induced in the presence of glucose.