Succinic Acid Production by Rumen Bacteria. III. Enzymic Studies on the Formation of Succinate by Ruminococcus Flavefaciens

Enzymes involved in succinic acid production by strain C of R. ftavefacien8 were investigated in cell-free extracts. The results indicate that phosphoenolpyruvate is carboxylated by a phosphoenolpyruvate carboxykinase which uses GDP as phosphate acceptor, and that the oxaloacetate so formed is converted to succinate via a DPNH-dependent malate dehydrogenase, a fumarate hydratase, and a DPNH-dependent fumarate reductase. Succinate dehydrogenase activity was also observed which differed markedly from fumarate reductase in that DPN+ was not reduced and in inhibition characteristics.

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Succinic Acid Production by Rumen Bacteria II. Radioisotope Studies on Succinate Production by Ruminococcus Flavefaciens

Australian Journal of Biological Sciences ◽

10.1071/bi9670183 ◽

1967 ◽

Vol 20 (1) ◽

pp. 183 ◽

Cited By ~ 5

Author(s):

MF Hopgood ◽

DJ Walker

Keyword(s):

Formic Acid ◽

Succinic Acid ◽

Acid Production ◽

Specific Activity ◽

Carboxyl Group ◽

Rumen Bacteria ◽

Ruminococcus Flavefaciens ◽

Succinate Production ◽

Succinic Acid Production ◽

Acetic Acids

Strain C of R. flavejaciens ferments [1_14C]glucose with the production of methyl-labelled succinic and acetic acids, and the specific activity of the succinic acid produced is one-half that of the substrate. Fermentation of glucose in the presence of [14C]bicarbonate gives rise to carboxyl-labelled succinic acid. Formic acid is also labelled, either by direct exchange with 14C02 or by exchange of 14C02 with the carboxyl group of pyruvate. These results are compatible with the formation of succinate from glucose via the Embden-Meyerhof pathway and carboxylation of pyruvate or phosphoenolpyruvate.

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Genetic Characterization of a Single Bifunctional Enzyme for Fumarate Reduction and Succinate Oxidation in Geobacter sulfurreducens and Engineering of Fumarate Reduction in Geobacter metallireducens

Journal of Bacteriology ◽

10.1128/jb.188.2.450-455.2006 ◽

2006 ◽

Vol 188 (2) ◽

pp. 450-455 ◽

Cited By ~ 48

Author(s):

Jessica E. Butler ◽

Richard H. Glaven ◽

Abraham Esteve-Núñez ◽

Cinthia Núñez ◽

Evgenya S. Shelobolina ◽

...

Keyword(s):

Succinate Dehydrogenase ◽

Dehydrogenase Activity ◽

Mutant Strain ◽

Electron Acceptor ◽

Geobacter Sulfurreducens ◽

Fumarate Reductase ◽

Succinate Dehydrogenase Activity ◽

Geobacter Metallireducens ◽

Terminal Electron Acceptor ◽

Fumarate Reduction

ABSTRACT The mechanism of fumarate reduction in Geobacter sulfurreducens was investigated. The genome contained genes encoding a heterotrimeric fumarate reductase, FrdCAB, with homology to the fumarate reductase of Wolinella succinogenes and the succinate dehydrogenase of Bacillus subtilis. Mutation of the putative catalytic subunit of the enzyme resulted in a strain that lacked fumarate reductase activity and was unable to grow with fumarate as the terminal electron acceptor. The mutant strain also lacked succinate dehydrogenase activity and did not grow with acetate as the electron donor and Fe(III) as the electron acceptor. The mutant strain could grow with acetate as the electron donor and Fe(III) as the electron acceptor if fumarate was provided to alleviate the need for succinate dehydrogenase activity in the tricarboxylic acid cycle. The growth rate of the mutant strain under these conditions was faster and the cell yields were higher than for wild type grown under conditions requiring succinate dehydrogenase activity, suggesting that the succinate dehydrogenase reaction consumes energy. An orthologous frdCAB operon was present in Geobacter metallireducens, which cannot grow with fumarate as the terminal electron acceptor. When a putative dicarboxylic acid transporter from G. sulfurreducens was expressed in G. metallireducens, growth with fumarate as the sole electron acceptor was possible. These results demonstrate that, unlike previously described organisms, G. sulfurreducens and possibly G. metallireducens use the same enzyme for both fumarate reduction and succinate oxidation in vivo.

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