Abstract
Under anaerobic conditions tetl'athionate was metabolized by washed cells of Thiobacillus X to thiosulphat,e, sulphate, and smnll amounts of trithionate and pentathionate. Depending upon the growth history of the cells large amounts of either elementary sulphur or higher polythionates were also former1. Some oxidation of the inner sulphur of tetrathionate occurred during tho metabolism of t·etra· thionate under nitrogen. The quantitative relationships between the amounts of tetrathionate metabolized and the products suggested that a major reaction was hydrolysis according to the equation: