Acidithiobacillus thiooxidans

Bacteria may catalyze and considerably enhance the oxidation of pyrite and Fe(II) in water, especially under acidic conditions (Welch et al., 2000, 597). Many microbial species actually oxidize only specific elements in sulfides. With pyrite, Acidithiobacillus thiooxidans is important in the oxidation of sulfur, whereas Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans (formerly Thiobacillus fer-rooxidans) oxidize Fe(II) (Gleisner and Herbert, 2002, 140). Acidithiobacillus ferrooxidans obtain energy through Reaction 3.45 (Gleisner and Herbert, 2002, 140). The bacteria are most active at about 30 °C and pH 2-3 (Savage, Bird and Ashley, 2000, 407). Acidithiobacillus sp. and Leptospirillum ferrooxidans have the ability to increase the oxidation of sulfide minerals by about five orders of magnitude (Welch et al., 2000, 597). 

Acidithiobacillus thiooxidans, formerly known as Thiobacillus thiooxidans, is an acidophilic bacterium that oxidizes and thiosulfate, but not iron. Due to the rapid kinetics involved in sulfide oxidation by dissolved oxygen, some sulfide-oxidizing bacteria are in continuous competition with the chemical oxidation mechanism. Acidithiobacillus ferrooxidans, formerly known... 

Chandraprabha, M.N. and Natarajan, K.A., Surface chemical and flotation behaviour of chalcopyrite and pyrite in the presence of Acidithiobacillus thiooxidans. Hydrometallurgy, 83, 146. 2006. 

Similar enzymes are known to occur in Paracoccus (Thiobacillus) versutus (Lu and Kelly, 1984a,b) and T. thioparus (Lyric and Suzuki, 1970b). The P. versutus enzyme has a molecular mass of 44 kDa and contains cytochrome c-551. The T. thioparus enzyme has one atom each of nonheme iron and molybdenum (Kessler and Rajagopalan, 1972). A membrane-bound type sulfite dehydrogenase has been obtained from Thiobacillus (Acidithiobacillus) thiooxidans JCM 7814. The enzyme has the molecular mass of 400 kDa and catalyzes the reduction of horse ferricytochrome c with sulfite (Nakamura et al., 1995, 2001). Also from Paracoccus (Thio-sphaera) pantotrophus GB17, sulfite dehydrogenase has been obtained. Its molecular mass is 190 kDa (2 x 47 kDa + 2 x 50 kDa) and it has 4 heme C molecules and 1-2 atoms of molybdenum (Quentmeier et al., 2000). Furthermore,... 

Thiosulfate is found to be oxidized to tetrathionate by the catalysis of thiosulfate-cytochrome c oxidoreductase in Acidithiobacillus thiooxidans JCM 7814 (Nakamura et al., 2001), Thiobacillus tepidarius (Lu and Kelly, 1988a) and Thio-bacillus neapolitanus (Trudinger, 1961b). Tetrathionate is thought to be oxidized in the cytoplasm. But its oxidation mechanism has not been clarified. 

Nakamura K, Nakamura M, Yoshikawa H, Amano Y (2001) Purification and properties of thiosulfate dehydrogenase from Acidithiobacillus thiooxidans JCM 7814. Biosci Biotechnol Biochem 165 102-108... 

Several bacterial groups produce potentially detrimental metabolites such as inorganic acids (e.g., Acidithiobacillus thiooxidans), organic acids (most bacteria, algae, and fungi), sulphide (sulphate-reducing bacteria), and ammonia, as discussed above. 

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