Chlorella pyrenoidosa Chick (Emerson strain 3) utilizes thiosulfate for growth as effectively as sulfate, and more effectively than a variety of organic sulfur compounds containing sulfur in various oxidation states. Thiosulfates, differentially labeled with (35)S in either the SH- or SO(3) - sulfur moieties, were used to follow the incorporation of thiosulfate-sulfur into constituents of the i...