Carbon metabolism inChloroflexus aurantiacus

Abstract

The metabolism of organic compounds in Chloroflexus aurantiacus under light-anaerobic and dark-aerobic conditions is bound up with the tricarboxylic acid cycle and the glyoxylate shunt. According to the enzyme activities detected, sugars are degraded mainly via the Embden-Meyer-hof-Parnas pathway. Glycerol is oxidized with participation of glycerokinase and pyridine-independent glycerophosphate dehydrogenase. The determination of labelled products in short-term experiments, assays of enzyme activities, and the effect of some inhibitors suggest that C. auratiacus fixes CO₂ autotrophically via a novel cycle. The key enzyme of this cycle is malate lyase. The cycle involves pyruvate synthase, pyruvate phosphate dikinase, phosphoenolpyruvate carboxylase and malate dehydrogenase.