• KSBB Journal
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• 제15권3호
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• pp.318-322
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• 2000

An oxygen-sensitive fumarate reductase has been purified from the cytosol fraction of the Enterococcus faecalis RKY1 grown anaerobically on a defined medium containing glycerol and fumarate. A major portion of the purification was performed with employing Triton X-100 and reducing agents by Phenyl-sepharose CL-4B DEAE-sepharose and Dephadex G-150 The final activity was 0.42 unit/mg. The deduced molecular mass of active band was 66 kDa. The optimal pH and temperature for the activity were 7.0 and 38$^{\circ}C$ respectively. The enzyme activity was not affected by 1mM metal ions such as bacl2 $.$2H2O HgCl2 MnCl2$.$4H2O ZnCl2 CuCl2$.$2H2O Mgcl2$.$6H2O FeSo4$.$7H2O and by EDTA. Partially purified enzyme ws yellow in color ; spectroscopic study indicated the presence of flavins as a cofactor.

• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.558-566
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• 2016

Biotic agents such as fumarate-reducing bacteria can be used for controlling methane (CH₄) production in the rumen. Fumarate-reducing bacteria convert fumarate to succinate by fumarate reductase, ultimately leading to the production of propionate. Fumarate-reducing bacteria in the genus Enterococcus were isolated from rumen fluid samples from slaughtered Korean native goats. The enterococci were identified as Enterococcus faecalis SROD5 and E. faecium SROD by phylogenetic analyses of 16S rRNA gene sequences. The fumarate reductase activities of the SROD5 and SROD strains were 42.13 and 37.05 mM NADH oxidized/min/mg of cellular nitrogen (N), respectively. Supplementation of rumen fermentation in vitro with the SROD5 and SROD strains produced significantly higher propionate, butyrate, and total volatile fatty acid (VFA) concentrations than controls at 12 h; VFA concentrations tended to increase after 24 h of incubation. The generated CH₄ concentration was significantly lower in the SROD5 and SROD treatment groups after 24 h of incubation. These findings indicate that E. faecium SROD has potential as a direct-fed microbial additive for increasing total VFAs while decreasing CH₄ production in rumen fermentation in vitro.

• Journal of Microbiology and Biotechnology
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• 제17권2호
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• pp.218-225
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• 2007

A lactic acid bacterium capable of anaerobic respiration was isolated from soil with ferric iron-containing glucose basal medium and identified as L. garvieae by using 16S rDNA sequence homology. The isolate reduced ferric iron, nitrate, and fumarate to ferrous iron, nitrite, and succinate, respectively, under anaerobic $N_2$ atmosphere. Growth of the isolate was increased about 30-39% in glucose basal medium containing nitrate and fumarate, but not in the medium containing ferric iron. Specifically, metabolic reduction of nitrate and fumarate is thought to be controlled by the specific genes fnr, encoding FNR-like protein, and nir, regulating fumarate-nitrate reductase. Reduction activity of ferric iron by the isolate was estimated physiologically, enzymologically, and electrochemically. The results obtained led us to propose that the isolate metabolized nitrate and fumarate as an electron acceptor and has specific enzymes capable of reducing ferric iron in coupling with anaerobic respiration.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.870-879
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• 2006

The present study describes the formation of succinic acid by a nonvirulent, highly osmotolerant Klebsiella pneumoniae strain SAP (succinic acid producer), its profile of metabolites, and enzymes of the succinate production pathway. The strain produced succinate along with other metabolites such as lactate, acetate, and ethanol under aerobic as well as anaerobic growth conditions. The yield of succinate was higher in the presence of $MgCO_3$ under $N_2$ atmosphere as compared with that under $CO_2$ atmosphere. Analysis of intracellular metabolites showed the presence of a smaller PEP pool than that of pyruvate. Oxaloacetate, citrate, and $\alpha$-ketoglutarate pools were considerably larger than those of isocitrate and fumarate. In order to understand the synthesis of succinate, the enzymes involved in end-product formation were studied. Levels of phosphoenolpyruvate carboxykinase, fumarate reductase, pyruvate kinase, and acetate kinase were higher under anaerobic growth conditions. Based on the profiles of the metabolites and enzymes, it was concluded that the synthesis of succinate took place via oxaloacetate, malate, and fumarate in the strain under anaerobic growth conditions. The strain SAP showed potential for the bioconversion of fumarate to succinate under $N_2$ atmosphere in the presence of $MgCO_3$. At an initial fumarate concentration of 10 g/l, 7.1 g/l fumarate was converted to 7 g/l succinate with a molar conversion efficiency of 97.3%. The conversion efficiency and succinate yield were increased in the presence of glucose. Cells grown on fumarate contained an 18-fold higher fumarate reductase activity as compared with the activity obtained when grown on glucose.

• 생명과학회지
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• 제34권7호
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• pp.465-475
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• 2024

Lactiplantibacillus plantarum K9은 굼벵이에서 분리된 다양한 생리활성물질에 기인하여 프로바이오틱스 균주로 활용 가능한 유산균이다. L. plantarum K9 유전체 분석결과로써 박테리아 염색체와 3 plasmid가 존재하는 것으로 나타났다. L. plantarum K9의 핵심 대사경로 분석 결과 해당과정, 오탄당대사(pentose phosphate pathway)는 정상적으로 수행되는 것으로 나타났다. 그러나 포도당신생합성과 ED pathway의 핵심 효소인 fructose-1,6-bisphosphatase (EC: 3.1.3.11)와 6-phosphogluconate dehydratase (EC: 4.2.1.12) / 2-keto-de- oxy-6-phosphogluconate (KDPG) aldolase (EC: 4.2.1.55)가 각각 결여되어 있기 때문에 포도당신생합성과 ED pathway는 수행하지 못하는 것으로 제의된다. 또한, TCA 회로에서 fumarate 및 malate를 형성하는 일부 효소만 존재하는 반면에 나머지 TCA 회로에 연관되는 효소들이 모두 결여되어 있었기 때문에 TCA 회로는 진행되지 못하는 것으로 추정되었다. 산화적 전자전달계는 NADH dehydrogenase complex I과 cytochrome reductase complex IV에 해당하는 요소들을 보유하고 있기 때문에 class IIB 타입(bd-type)의 전자전달시스템을 수행할 것으로 예측되었다. 종합적으로, L. plantarum K9은 lactic acid 동형발효를 수행하며, 포도당신생합성 및 오탄당대사가 가능하며, class IIB 타입(bd-type) 산화적 전자전달시스템에 의해 에너지 대사를 수행하는 것으로 제의된다. 따라서, L. plantarum K9은 다른 유산균주에 비교하여 lactic acid 생성량이 비교적 높아 생리활성도가 우수할 것으로 제의된다. 다른 한편으로, L. plantarum K9은 산화적 전자전달이 가능한 것으로 추정되어 산소에 대한 내성이 높아서 배양 특성이 양호하여 프로바이틱스로써 활용가능성이 높은 것으로 제의된다.