Role of Carbon Dioxide and Acetate in Biosynthesis by Sulphate-reducing Bacteria

Abstract

SULPHATE reduction by bacteria is one of the most important biogeochemical processes for which microorganisms are responsible. Sulphate-reducing bacteria obtain energy for biosynthesis from the very small amount released in the reduction of SO₄-ions with the participation of easily activated hydrogen of certain organic compounds and with hydrogen gas. Previous work^1,2 and my recent experiments have shown that the principal sulphate reducer, Desulphovibrio desulphuricans, in pure culture, can only use for this purpose the hydrogen of formate, isobutanol, lactate, pyruvate and ethanol, which are oxidized during the reduction of sulphate to carbon dioxide, butyrate and acetate as the case may be. Among these substances, only the last-mentioned three suffice as sole sources of both energy and carbon for growth. The others are used merely as sources of energy; carbon for biosynthesis must be supplied in this case by the addition of yeast extract^3,4.