The occurrence of polythionates as intermediates in the metabolism of thiosulphate by the thiobacilli.

Further evidence for the inclusion of polythionates in the pathway of thiosulphate oxidation by members of the genus Thiobacillus is presented. Manometric experiments showed tetrathionate oxidation to be a stage in thiosulphate oxidation by suspensions of T. thioparus and T. thiocyanoxidans. Thiobltcillus thioparus accumulated a sufficient concentration of polythionate in the medium to allow chromatograms to be prepared, and the type of polythionate accumulated was influenced by the ratio between the sodium and potassium ions in the medium. The restriction of the oxidation of tetrathionate at the lower concentrations of K+ may be due to a restriction in the entry of phosphate into the cell during growth; this is discussed.