Pyruvic Acid and Formic Acid Metabolism in Sarcina ventriculi and the Role of Ferredoxin

Abstract

SUMMARY Sarcina ventriculi produced hydrogen, C02 and acetyl phosphate from pyruvate by a clostridial-type thioclastic reaction which required coenzyme A and ferredoxin for activity. Hydrogen production from formate did not require ferredoxin since crude formate hydrogenlyase preparations functioned when depleted of ferredoxin. With fractionated components of the enzymic system, ferredoxin or viologen dyes restored activity. No evidence for the presence of a coliform-type thioclastic reac- tion (pyruvate-formate lyase) was found. Reduction of NADP by hydrogen or formate was ferredoxin-dependent. Acetaldehyde and COz were produced from pyruvate by a yeast-type decarboxylase which required thiamine pyrophosphate and Mg2+ ions for activity. Extracellular pH influenced the pathways of pyruvate metabolism which were reflected by the molar growth yields for glucose; the thioclastic reaction was predominant at alkaline pH.