Thiobacillus thiooxidans

Acid producers. Many bacteria produce acids. Acids may be organic or inorganic depending on the specific bacterium. In either case, the acids produced lower the pH, usually accelerating attack. Although many kinds of bacteria may generate acids, Thiobacillus thiooxidans and Clostridium species have most often been linked to accelerated corrosion on steel. 

Thiobacillus thiooxidans is an aerobic organism that oxidizes various sulfur-containing compounds to form sulfuric acid. These bacteria are sometimes found near the tops of tubercles (see Chap. 3, Tubercu-lation ). There is a symbiotic relationship between Thiobacillus and sulfate reducers Thiobacillus oxidizes sulfide to sulfate, whereas the sulfate reducers convert sulfide to sulfate. It is unclear to what extent Thiobacillus directly influences corrosion processes inside tubercles. It is more likely that they indirectly increase corrosion by accelerating sulfate-reducer activity deep in the tubercles. 

The pK of Ca2+aq (204), 12.6 at zero ionic strength, rising to over 13 as ionic strength increases, means that concentrations of CaOH+aq will be negligible in body fluids (lpolluted waters, and under all conditions of biological relevance, from the very low pHs of 0.5 (Thiobacillus thiooxidans) to 1.5 at which bacteria used for oxidative metal extraction operate (205), through acid soils and acid rain (pH 3 to 6), streams, rivers, and oceans (pH 6 to 8), soda lakes (pH 10), up to the pHs of 11 or more in Jamaican Red Mud slurry ponds (206) (cf. Section II.C.l below). 

Aerobic The reactions carried out by Nitrosomonas and Nitrobacter (reactions b and c, autotrophic respectively) are known as nitrification, while those carried out by Beggiatoa and Thiobacillus thiooxidans (reactions d and e, respectively) are examples of sulfur oxidation ... 

Suzuki I. 1965b. Incorporation of atmospheric oxygen-18 into thiosulfate by the sulfur-oxidizing enzyme of Thiobacillus thiooxidans. Biochim Biophys Acta 110 97-101. 

Tc(VI) 43 D. radiodurans RT G. sulfurreducens G. metallireducens D. desulfuricans Thiobacillus thiooxidans Thiobacillus ferroxidans Rhodobacter shpaeroides Paracoccus denitrifleans Fredrickson et al. (2000) Lloyd et al. (2000) Lloyd et al. (2000) Lloyd et al. (1999) Lyalikova and Khizhnyak (1996) Lyalikova and Khizhnyak (1996) Lloyd et al. (2000) Lloyd et al. (2000)... 

Organisms such as Thiobacillus thiooxidans and Clostridium species have been linked to accelerated corrosion of mild steel. Aerobic Thiobacillus oxidizes various sulfur-containing compounds such as sulfides to sulfates. This process promotes a symbiotic relationship between Thiobacillus and sulfate-reducing bacteria. Also, Thiobacillus produces sulfuric acid as a metabolic by-product of sulfide oxidation. 

Hydrogen ion concentration (pH) was the second criterion by which growth of the bacilli was established. Sulfuric acid is a natural metabolic by-product of sulfur oxidation by the acidophillic Thiobacillus thiooxidans (5). As sulfur is used, acid is built-up in the medium thus lowering the pH. Studies in this laboratory have shown that the bacteria grow well in a pH as low as 0.5. 

Modified Waksman s medium was prepared in a Fernbach culture flask. An amount of organic sulfide normalized to an equivalent sulfur content of the standard medium (10 g/1.) was added followed by an emulsifier. The medium was then autoclaved for 30 min at 15 psi (121°C), or, as with the polysulfide and elemental sulfur, sterilization was achieved by membrane filtration. Upon cooling, the medium was inoculated with 10 cc of the pure strain of Thiobacillus thiooxidans. The culture s initial pH value was read, and an initial gravimetric sulfate assay was performed. Thereafter, pH and sulfate values were determined at two-day intervals for 25 days. 

Thiobacillus thiooxidans Aerobic acid producer that oxidizes various forms of sulfur to produce sulfuric acid (see reaction below), which in turn causes acid corrosion of steel. 

Sulfur bacteria Thiobacillus thiooxidans is an aerobic acid- and corrosion-producing sulfur bacterium. Thiothrix sp. are troublesome aerobic slime formers. The most prolific of the slime- and corrosion-producing sulfate-reducing bacteria (SRB) is the anaerobe Desulfovibrio desulfuricans. Other sulfur bacteria include the anaerobes Beggiatoa sp. and Clostridium migrificans. 

Thiobacillus ferrooxidans is an obligate chemoautotrophic and acidophilic organism and is able to oxidize Fe2+, S°, metal sulfides, and other reduced inorganic sulfur compounds. Thiobacillus thiooxidans has also been isolated from acid mine wastes and has been determined that can oxidize both elemental sulfur and sulfide to sulfuric acid (S° + 1.502 + H20 - H2S04 and S2 + 202 + 2H+ - H2S04) (Brierley, 1982 Lundgren and Silver, 1980). However, T. thiooxidans cannot oxidize Fe2+ (Harrison, 1984). 

Wakao, N., M. Mishina, Y. Sakurai, and H. Shiota. 1982. Bacteria pyrite oxidation. I. The effect of the pure and mixed cultures of Thiobacillus ferrooxidans and Thiobacillus thiooxidans on release of iron. J. Gen. Appl. Microbiol. 28 331-343. 

Microorganisms e.g. Thiobacillus thiooxidans, Thiobacillus ferrooxi-dans, Metallogenium) are involved as catalysts in many of the oxidizing... 

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... 

Bacterial leaching with thiobacillus thiooxidans is also an acid leaching process. Sulfidic sulfur, e.g. in pyrites, is oxidized to sulfate and iron(II) is oxidized to iron(lll), which itself oxidizes uranium(IV) to uranium(VI). This process has not yet been operated industrially. 

Unz, R.F. and D.G. Lundgren, 1961. A comparative nutritional study of three chemo-autotrophic bacteria Ferrobacillus ferrooxidans, Thiobacillus ferrooxidans and Thiobacillus thiooxidans. Soil Sci., 92 302—313. 

Schaeffer, W.I. and Umbreit, W.W., 1963. Phosphatidyl-inositol as a wetting agent in sulfur oxidation by Thiobacillus thiooxidans. J. Bacteriol., 85 492—493. 

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