On the Rôle of Carbon Dioxide in the Metabolism of Clostridium Thermoaceticum

Abstract

C. thermoaceticum ferments glucose anaerobically with the pro- duction of 2.5 moles of acetic acid per mole of glucose decomposed. It is argued that the high yield of acetic acid and lack of CO2 is ascribable to production of CO2 which is then converted to acetic acid, rather than to a primary cleavage of glucose into 3 C2 fragments. As the strains of C. thermoaceticum available do not attack more reduced substrates (the polyalcohols) and pending the use of CO2 labeled with a carbon isotope, only indirect evidence is available: the pentose l-xylose produces virtually no CO2 though in splitting it should yield C1 fragments (unless 2 Cs fragments combine into a C6 compound); also pyruvate decomposition yields less CO2 and more acetic acid than would be expected in the absence of CO2 reduction and the synthesis of C6 compounds.