Thiobacillus ferrooxidans Rachel Klapper
The genus Thiobacillus, also known as Acidithiobacillus, contains colorless, rod-shaped bacteria. These bacteria have the ability to gain energy from the oxidation of reduced sulfur compounds. Therefore environmental requirements include the presence of reduced inorganic sulfur compounds. These bacteria are respiratory, preferentially utilizing oxygen as the terminal electron acceptor
Thiobacillus ferrooxidans is a gram negative, obligately autotrophic and aerobic Proteobacteria. These bacteria are motile, and possess polar flagella. T. ferrooxidans is an acidophile, living in environments with an optimal pH range of 1.5 to 2.5. T. ferrooxidans is also thermophilic, preferring temperatures of 45 to 50 degrees Celsius. The high temperature tolerance of the bacteria may be due in part to its high GC content of 55 to 65 mole percent.
T. ferrooxidans derives energy from oxidation of ferrous iron to ferric iron, and reduced-sulfur compounds to sulfuric acid. Fine sulfur deposits may accumulate in the cell wall of the bacteria. Other byproducts of metabolism (sulfuric acid) are sometimes associated with the oxidative corrosion of concrete and pipes. In soil environments, T. ferrooxidans is useful as a slow release source of phosphate and sulfate for soil fertilization.
T. ferrooxidans is the most active bacteria in mine wastes due to acid and metal pollution. Sites of extreme acid mine drainage also expose high levels of pyrite, an element that is readily oxidized by T. ferrooxidans. This pyrite-oxidizing capacity has been exploited in the industrial desulfurization of coal. T. ferrooxidans is used in industrial mineral processing and bioleaching processes. These bacteria have the ability to attack sulfide-containing minerals and convert insoluble sulfides of metals such as copper and zinc into their soluble metal sulfates. Metals recovered through this bioleaching process include copper, uranium and gold.
Sulfidic caves and areas of extreme acid mine drainage contain sites of pyrite deposits. In these areas extremely acidic (pH 0-1) microbial biofilms hang from the walls with a snot-like consistency. These colonies are known as snottites, and contain extremophilic bacteria. T. ferrooxidans and other members of the genus Thiobacillus (and/or similar bacteria) are thought to be a main component of the consortiums present in snottites. These bacteria derive energy from chemosynthesis of sulfur compounds and water which drain through the walls of the caves.
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Kuenen, J. Gijs, et al. “The Genera Thiobacillus, Thiomicrospira, and Thiosphaera.” The Prokaryotes. Ed. Albert Balows, et al. New York: Springer-Verlog, 1992. 2638-9, 2650
Rawlings, Douglas, and Tomonobu Kusano. “Molecular Genetics of Thiobacillus ferroxidans.” Microbial Review 58.1 (1994): 39-55. 30 Mar. 2008. <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=372952>
“Thiobacillus-Microbewiki.” MicrobeWiki. 30 Mar. 2008. <http://microbewiki.kenyan.edu/index.php/Thiobacillus>.
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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