The Effect of Uncoupling Agents on Carbon Dioxide Fixation by a Thiobacillus

Abstract

A newly isolated strain (c) of ThiobaciUus thioparus is described. The organism oxidizes thiosulfate, sulfide, tetrathionate or trithionate to sulfate; carbon dioxide fixation is coupled to the oxidation of each of these compounds. Concentrations of arsenate, 2,4-dinitrophenol and other inhibitors of oxidative phosphorylation, inhibit carbon dioxide fixation without appreciably affecting oxygen uptake. Carbon dioxide fixation coupled to sulfide oxidation is more sensitive to arsenate and 2,4-dinitrophenol inhibition than that coupled to thiosulfate oxidation. This result is consistent with the suggestion that thiosulfate oxidation is linked to a substrate phosphorylation which is relatively insensitive to inhibition by 2,4.dinitrophenol and arsenate.