Membrane-associated Sulfur Oxidation by the Autotroph Thiobacillus thiooxidans

Adair, Frank W. (Rutgers, The State University, New Brunswick, N. J.). Membrane-associated sulfur oxidation by the autotrophThiobacillus thiooxidans . J. Bacteriol.92: 899–904. 1966.—Washed cell wall-membrane fragments derived from sulfur-grown cells of the strictly autotrophic bacterium,Thiobacillus thiooxidans , oxidized elemental sulfur to sulfate without the addition of cofactors. The oxidation was optimal atp H 7.0 and was increased by the presence of wetting agents. Oxygen uptake was inhibited by cyanide, azide, and thiol-binding agents. Sulfite was also oxidized, and both the sulfur- and sulfite-oxidizing systems were heat-labile. Neither thiosulfate nor tetrathionate was oxidized by soluble or membrane preparations. The fragments fixed C14 O2 in the presence of ribose-5-phosphate, Mg++ , and adenosine triphosphate. Sulfur oxidation did not provide energy for C14 O2 fixation in this system.