Scientific Reports of the Faculty of Agriculture, Okayama University
Published by the Faculty of Agriculture, Okayama University
ONLINE ISSN : 2186-7755

Mechanism of Oxidation of Reduce Sulfur Compounds by Sulfur-Grown Acidithiobacillus Caldus Strain GO-1

Kamimura, Kazuo Kaken ID researchmap
Sawada, Ryoko
Sugio, Tsuyoshi
Abstract
The oxidation of reduced sulfur compounds was studied by using resting cells of sulfur-grown Acidithiobacillus caldus strain GO-1. The optimum pHs for the oxidation of thiosulfate, tetrathionate, sulfur, sulfite and sulfide were 2, 3, 3-6, 7 and 7, respectively. The highest oxidation rate was observed with sulfite. The oxidation rates of the reduced sulfur compounds were measured in the absence or presence of inhibitors and uncouplers. 2, 4-dinitrophenol (DNP) and carbonyl cyanide-m-chlorophenylhydrazone (CCCP) strongly inhibited the oxidations of sulfur and sulfite. N-Ethylmaleimide (NEM) strongly inhibited the oxidation of tetrathionate and sulfur. 2-heptyl-4-hydroxy-quinoline-N-oxide(HQNO) inhibited the oxidation of sulfur and sulfite. The results suggested that tetrathionate was oxidized in the periplasmic space, and sulfur and sulfite were oxidized in the cytoplasm. Pyridine ferrohemochromes prepared from the membrane of strain GO-1 cell revealed the involvement of cytochromes b and c. Ubiquinol oxidase activity was detected in strain GO-1 cell, but cytochrome c oxidase measured by using mammalian cytochrome c as an electron donor was not detected in the cell. On the basis of the results a model for the metabolism of the reduced sulfur compounds by At. caldus strain GO-1 was proposed.
Keywords
acidithiobacillus caldus
acidophile
moderately thermophilic bacterium
sulfur-oxidizing bacterium
sulfite oxidation
ISSN
0474-0254
NCID
AN00033029