Bioleaching of Pyrite by Iron-Oxidizing Acidophiles under the Influence of Reactive Oxygen Species

摘要

After 24h of exposure to acidic media, pyrite generates reactive oxygen species (ROS). Freshly-crushed pyrite with grain size between 50-100 um at 5 % (w/v) pulp density generated 0.17 ± 0.01 mM H_2O_2, while 10% pyrite generated 0.29 ± 0.01 mM and 30 % pyrite generated 0.83 ± 0.06 mM. These levels of H_2O_2 probably inhibited iron oxidation in iron-grown cells of Acidithiobacillus ferrooxidans1 but not in pyrite-grown cells. ROS originating from pyrite, which was incubated for 24 h in acidic medium, likely prohibited pyrite dissolution by iron-grown cells, while pyrite-grown cells were probably adapted to these concentrations of ROS. Periodical addition of 100 μM H_2O_2 to pyrite cultures inoculated with pyrite-grown cells did not decrease iron dissolution. By high throughput proteomics analysis, an increased expression of proteins related to oxidative stress management, iron-and sulfur oxidation systems, carbon fixation and biofilm formation was observed in biofilm cells grown on pyrite compared to iron-grown cells.