Thiobacillus ferrooxidans oxidation

Finally, whereas most laboratory experiments have been conducted in largely abiotic environments, the action of bacteria may control reaction rates in nature (e.g., Chapelle, 2001). In the production of acid drainage (see Chapter 31), for example, bacteria such as Thiobacillus ferrooxidans control the rate at which pyrite (FeS2) oxidizes (Taylor et al., 1984 Okereke and Stevens 1991). Laboratory ob-... 

Okereke, A. and S. E. Stevens, Jr., 1991, Kinetics of iron oxidation by Thiobacillus ferrooxidans. Applied and Environmental Microbiology 57,1052-1056. 

The ability of the chemolithoautotrophic bacteria Thiobacillus ferrooxidans to oxidize Fe has already been utilized for construction of a microbial sensor for the determination of iron [101]. The limit of determination of this biosensor is 60 pmol 1" with a response time ranging from 30 s to 5 min, depending on the Fe +-concentration in the sample. 

However chemical methods of mercury detoxification are far from adequate. It has become evident that mercury can be solubilized from HgS under conditions that could be present in a landfill. We have demonstrated chemical solubilization followed by volatilization with Fe2(S04)3, a product of oxidation of FeS04 (pyrite) by Thiobacillus ferrooxidans (data not shown). Other researchers have indicated that T. ferrooxidans can facilitate solubilization and volatilization of Hg° from HgS. Growth of T. ferrooxidans in the presence of cinnabar (mercury ore-contains HgS and some impurities) by Silver and Torma (1984) resulted in dissolved mercury concentration in the bioreactor of 64 mg/L (the form of Hg was not given). In similar experiments with T. ferrooxidans and cinnabar, Baldi and Olson (1987) did not... 

Baldi, F. and G. J. Olson. 1987. Effect of cinnabar pyrite oxidation by Thiobacillus ferrooxidans and cinnabar mobilization by a mercury-resistant strain. Appl. Environ. Microbiol. 53 772-776. 

Silver, M. and A. E. Torma. 1974. Oxidation of metal sulfides by Thiobacillus ferrooxidans grown on different substrates Can. J. Microbiol. 20 141-147. 

The "iron bacterium" Thiobacillus ferrooxidans obtains energy from the oxidation of Fe2+ to Fe3+ with subsequent precipitation of ferric hydroxide (Eq. 18-23). However, it has been recognized recently that a previously unknown species of Archaea is much more important than T. ferrooxydans in catalysis of this reaction.3243... 

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). 

Ivanov, V. I. 1962, Effect of some factors on iron oxidation by cultures of Thiobacillus ferrooxidans. Microbiol. Engl. Transl. 31 645-648. 

Lizama, H. M. and I. Suzuki. 1989. Rate equation and kinetic parameters of the reactions involved in pyrite oxidation by Thiobacillus ferrooxidans. Appl. Environ. Microbiol. 55 2918-2923. 

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. 

SABA [Spherical Agglomeration-Bacterial Adsorption] A microbiological process for leaching iron pyrite from coal. The bacterium Thiobacillus ferrooxidans adsorbs on the surface of the pyrite crystals, oxidizing them with the formation of soluble ferrous sulfate. Developed by the Canadian Center for Mineral and Energy Technology, Ottawa. In 1990, the process had been developed only on the laboratory scale, using coal from eastern Canada. 

AMD is probably the most severe environmental problem that occurs on mine sites, It happens where mineral and coal deposits contain sulfide minerals, particularly pyrite (FeS2). When waste rock containing sulfides is exposed fo air, these minerals are oxidized, releasing sulfuric acid, The process is accelerated by bacteria such as Thiobacillus ferrooxidans that obtain energy from the oxidation reaction for their growth. The release of acid can cause the pH of... 

Nielsen, A. M. Beck, J. V. (1972). Chalcocite oxidation and coupled carbon dioxide fixation by Thiobacillus ferrooxidans. Science, 175, 1124—6. 

Rusticyanin is found in Thiobacillus ferrooxidans, an acidophilic, chemolithotrophic sulfur bacterium utilizing Fe + and reduced sulfur compounds as its sole energy source. T. ferrooxidans does not produce rusticyanin when grown on reduced sulfur. Similar to other substrate-inducible cupredoxms, the msticyanin gene is activated when soluble iron is present in the media. Little is known about its redox partners and it should be noted that rusticyanin itself does not carry out Fe + oxidation. Other iron-oxidizing bacteria, for example, Leptospirillum ferrooxidans, prodnce a cytochrome which substitutes rusticyanin functionally. To date T. ferrooxidans remains the only source for rusticyanin. 

Certain microorganisms (e.g., Thiobacillus ferrooxidans) can facilitate the oxidation of Fe to Fe The Fe ion, in turn, can convert insoluble uranium dioxide to soluble U02 ions by the following reaction ... 

This principal environmental problem posed by coal-cleaning waste is that the pyrite and marcasite in the waste are oxidized to sulfuric acid in the presenee of air, water, Ferrobacillus ferrooxidans, and Thiobacillus ferrooxidans. The sulfuric acid is usually sufficiently concentrated to dissolve numerous metallic constituents and large quantities of iron from the pyrite in the leachate. Any ECT intended to prevent sulfuric acid formation must eliminate either the air, the water, or the oxidizable sulfur compounds in the waste, or inactive Ferrobacillus ferrooxidans and Thiobacillus ferrooxidans by maintaining alkaline conditions. Post-treatment of pile drainage comprises ECTs designed to neutralize the acid in the effluent and remove the metal ions by some sort of precipitation, adsorption, flocculation, or ion-exchange phenomenon. 

Concentration of Metal at which Thiobacillus ferrooxidans Can Oxidize Fe(II)... 

The principles imderlying this method have been given in Section II. The bacteria oxidize the pyrite present in the ore to give an acidic solution of Fe(III). This oxidizes UO2 to UOl, which dissolves in the acidic leach solution. Thiobacillus ferrooxidans is able to catalyze this reaction directly, but not rapidly enough to compete with oxidation by Fe(III). 

Rusticyanin is a component in the respiratory chain of the bacterium Thiobacillus ferrooxidans (44-46). This bacterium is capable of growth solely on the energy available from the oxidation of aqua Fe(II) to Fe(III) by O2. It is found in acid mine leachings, and is used commercially in the extraction of copper and uranium (see the review by Ewart and Hughes, this volume). Its ability to take into solution iron pyrites is particularly relevant. It has been suggested that an acid-stable cytochrome mediates electron transfer between rusticyanin and Fe (47, 48). The working pH is —2.0. 

---