ABSTRACT
The thiobacilli, well-known chemoautotrophic or chemolithotropic bacteria, have a unique mode of life among living organisms in that they have the capacity to derive their energy and reducing power for growth from the oxidation of inorganic sulfur compounds and to synthesize all the cellular carbon by assimilation of atmospheric carbon-di-oxide. The sulfur-oxidizing enzyme has also been isolated and characterized in T. thioparus, T. novellus, and T. ferrooxidans and the enzymes properties appear to be similar to that of T. thiooxidans. A sulfur-oxidizing system which requires both soluble and membrane fractions has been prepared by sonication of T. thiooxidans cells under a nitrogen atmosphere. More recently the sulfur-oxidizing enzyme has been reinvestigted in our laboratory by measuring the oxygen uptake polarographically with a Clark oxygen electrode. Thiosulfate has been widely used as a preferred growth substrate in the routine cultivation of many thiobacilli that grow at neutral pH conditions.
