The assimilation of carbon by Chloropseudomonas ethylicum

Abstract

1. The enzymes in ultrasonically prepared extracts of Chloropseudomonas ethylicum were studied to elucidate how this organism assimilates acetate and carbon dioxide and why it cannot grow with either of these two compounds alone. 2. Such extracts can (i) convert acetate and oxaloacetate into α-oxoglutarate, (ii) convert oxaloacetate into succinyl-CoA, (iii) convert phosphopyruvate into 3-phosphoglyceraldehyde and (iv) interconvert phosphopyruvate and pyruvate via oxaloacetate. 3. Pyruvate kinase, α-oxoglutarate dehydrogenase, ribulose diphosphate carboxylase, isocitrate lyase and malate synthase were not detected. 4. It is difficult to detect aconitate hydratase, fumarate hydratase and citrate synthase in extracts of the organism ultrasonically treated in tris buffer; to demonstrate these enzymes extracts should be prepared in phosphate buffer containing 2-mercaptoethanol. 5. Provided that this organism can synthesize pyruvate from acetate and carbon dioxide, the enzymes detected are sufficient to account for the nutritional requirements of this organism.