Acetate oxidation by sulphate was studied with
Desulfobacter postgatei
. Cell extracts of the organism were found to contain high activities of the following enzymes: citrate synthase, aconitase, isocitrate dehydrogenase, a-ketoglutarate dehydrogenase, succinate dehydrogenase, fumarase, malate dehydrogenase and pyruvate synthase. It is concluded that acetate oxidation with sulphate in
D. postgatei
proceeds via the citric acid cycle with the synthesis of pyruvate from acetyl CoA and CO
2
as an anaplerotic reaction. The apparent
K
s
for acetate oxidation by
D. postgatei
as determined
in vivo
was near 0.2 mM. The apparent Ks for acetate fermentation to methane and CO
2
by
Methanosarcina barkeri
was 3 mM. The significantly lower
K
s
for acetate of the sulphate reducer explains why methane formation from acetate in natural habitats is apparently inhibited by sulphate.
Microbial manganese(III) reduction fuelled by anaerobic acetate oxidation