Open AccessKeto Acid Metabolism in Desulfovibrio
Author(s) -
Andrew Lewis,
Jonathan D. Miller
Publication year - 1975
Publication title -
journal of general microbiology/journal of general microbiology
Language(s) - Uncategorized
Resource type - Journals
eISSN - 2059-9323
pISSN - 0022-1287
DOI - 10.1099/00221287-90-2-286
Subject(s) - citric acid cycle , biochemistry , malate dehydrogenase , desulfovibrio , pyruvate decarboxylation , fumarate reductase , chemistry , pyruvate dehydrogenase complex , metabolism , bacteria , biology , succinate dehydrogenase , enzyme , genetics
Four strains of Desulfovibrio each excreted pyruvate to a constant level during growth; it was re-absorbed when the substrate (lactate) was exhausted. Malate, succinate, fumarate and malonate also accumulated during growth. One of the strains (Hildenborough) excreted alpha-ketoglutarate as well as pyruvate when incubated in nitrogen-free medium; the former was re-absorbed on addition of NH4Cl. In a low-lactate nitrogen-free medium, strain Hildenborough rapidly re-absorbed the pyruvate initially excreted, but did not re-absorb the alpha-ketoglutarate. Arsenite (I mM) prevented the accumulation of alpha-ketoglutarate; I mM-malonate did not affect the accumulation of keto acids. Isocitrate dehydrogenase activity (NAD-specific) in all strains was lower than NADP-specific glutamate dehydrogenase activity. Alpha-Ketoglutarate dehydrogenase could not be detected in any strain. NADPH oxidase activity was demonstrated. This and previous work indicate that a tricarboxylic acid pathway from citrate to alpha-ketoglutarate exists in Desulfovibrio spp., and that succinate can be synthesized via malate and fumarate; however, an intact tricarboxylic acid cycle is evidently not present. The findings are compared with observations on biosynthetic pathways in clostridia, obligate lithotrophs, phototrophs, and methylotrophs, and various facultative bacteria.