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Dominant iron-oxidizing bacteria include the chemoautolithotrophic Leptospirillum-like species in many commercial processes for biooxidation of pyrite (FeS2), as well as Thiobacillus thiooxidans and T. ferrooxidans. T, ferrooxidans grows best and outcompetes L. ferroxidans at a low redox potential (low Fe+3:Fe+2), while L. ferroxidans outcompetes at a high redox dominated by Fe+3 (Rawlings, Tributsch and Hansford 1999). There are also various acidophilic heterotrophs or facultative heterotrophs such as Acidiphilium spp., Acidocella spp. and Ferromicrobium spp. (Johnson and Roberto 1997). Some species of sulfur-oxidizing bacteria such as Thiobacillus thiooxidans, as well as sulfur and ferrous-oxidizing species such as thermophilic and acidophilic Sulfolobus acidocaldarius, are also able to reduce ferric to ferrous iron by oxidizing elemental sulfur (Brock and Gustafson 1976).. |
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References |
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Brock, T.D., and J. Gustafson 1976. Ferric iron reduction by sulfur- and iron-oxidizing bacteria. Applied and Environmental Microbiology 32(4):567-571. Johnson, D. B. & Roberto, F. F. (1997). Heterotrophic acidophiles and their roles in the bioleaching of sulfide minerals. In: Biomining: Theory, Microbes and Industrial Processes, pp.259±279. Edited by D. E. Rawlings. Berlin : Springer. Rawlings, D.E., H. Tributsch and G.S. Hansfore 1999. Reasons why ‘Leptospirillum’-like species rather than Thiobacillus ferrooxidans are the dominant iron-oxidizing bacteria in many commercial processes for the biooxidation of pyrite and related ored. Microbiology 145:5-13. |
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