The effects of thiosulphate and oxygen concentration on tetrathionate oxidation by Thiobacillus X and T. thioparus

Abstract

Tetra-thionate was oxidized by Thiobacillus X and T. thioparus only after a lag period which was determined by the age, strain and concentration of the cells. At high cell concentrations, tetrathionate oxidation was "stimulated" by the addition of a trace amount of thiosulfate. At low cell concentrations, thiosulfate did not "stimulate" tetrathionate oxidation; but some tetrathionate was metabolized concurrently with thiosulfate oxidation. The "stimulating" action of thiosulfate was inhibited by 100% O2. Decreased O2 concentrations allowed tetrathionate oxidation to proceed without the addition of thiosulfate. Tetrathionate was metabolized anaerobically with the formation of thiosulfate, which was present in small amounts in reaction mixtures that were actively oxidizing tetrathionate.