title: Ferrous Iron and Sulfur Oxidation and Ferric Iron Reduction Activities of Thiobacillus ferrooxidans Are Affected by Growth on Ferrous Iron, Sulfur, or a Sulfide Ore.
abstract: Eight strains of Thiobacillus ferrooxidans (laboratory strains Tf-1 [= ATCC 13661] and Tf-2 [= ATCC 19859] and mine isolates SM-1, SM-2, SM-3, SM-4, SM-5, and SM-8) and three strains of Thiobacillus thiooxidans (laboratory strain Tt [= ATCC 8085] and mine isolates SM-6 and SM-7) were grown on ferrous iron (Fe), elemental sulfur (S), or sulfide ore (Fe, Cu, and Zn). The cells were studied for their aerobic Fe - and S-oxidizing activities (O(2) consumption) and anaerobic S-oxidizing activity with ferric iron (Fe) (Fe formation). Fe-grown T. ferrooxidans cells oxidized S aerobically at a rate of 2 to 4% of the Fe oxidation rate. The rate of anaerobic S oxidation with Fe was equal to the aerobic oxidation rate in SM-1, SM-3, SM-4, and SM-5, but was only one-half or less that in Tf-1, Tf-2, SM-2, and SM-8. Transition from growth on Fe to that on S produced cells with relatively undiminished Fe oxidation activities and increased S oxidation (both aerobic and anaerobic) activities in Tf-2, SM-4, and SM-5, whereas it produced cells with dramatically reduced Fe oxidation and anaerobic S oxidation activities in Tf-1, SM-1, SM-2, SM-3, and SM-8. Growth on ore 1 of metal-leaching Fe-grown strains and on ore 2 of all Fe-grown strains resulted in very high yields of cells with high Fe and S oxidation (both aerobic and anaerobic) activities with similar ratios of various activities. Sulfur-grown Tf-2, SM-1, SM-4, SM-6, SM-7, and SM-8 cultures leached metals from ore 3, and Tf-2 and SM-4 cells recovered showed activity ratios similar to those of other ore-grown cells. It is concluded that all the T. ferrooxidans strains studied have the ability to produce cells with Fe and S oxidation and Fe reduction activities, but their levels are influenced by growth substrates and strain differences.
authors.affiliation: Department of Microbiology, The University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
authors.forename: I
authors.initials: I
authors.lastname: Suzuki
authors.forename: T L
authors.initials: TL
authors.lastname: Takeuchi
authors.forename: T D
authors.initials: TD
authors.lastname: Yuthasastrakosol
authors.forename: J K
authors.initials: JK
authors.lastname: Oh