The assimilation of carbon by Chloropseudomonas ethylicum

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Abstract
The enzymes in ultrasonically prepared extracts of C. ethylicum were studied to elucidate how this organism assimilates acetate and CO2 and why it cannot grow with either of these 2 compounds alone. Such extracts can convert acetate and oxaloacetate into a-oxoglu-tarate and, oxaloacetate into succinyl-CoA, convert phosphopyruvate into 3-phosphoglyceraldehyde and interconvert phosphopyruvate and pyruvate via oxaloacetate. Pyruvate kinase, [alpha]-axoglutarate dehydro-genase, ribulose diphosphate carboxylase, isocitrate lyase and malate synthase were not detected. It is difficult to detect aconitate hydratase, fumarate hydratase and citrate synthase in extracts of the organism ultrasonically treated in tris buffer; extracts should be prepared in phosphate buffer containing 2-mercaptoethanol to demonstrate these enzymes. Provided that this organism can synthesize pyruvate from acetate and CO2, the enzymes detected are sufficient to account for the nutritional requirements of this organism.