Isolation, Testing, and Adaptation of Bacteria to Bioleach Metals from Pyrite

Bioleaching, mediated by selected microflora, offers a more environmentally friendly and cost-effective alternative to traditional mining techniques by transforming metals from sulfide ores into water-soluble forms. Pyrite ores often contain valuable rare or noble metals, such as gold (Au), silver (Ag), nickel (Ni), and cobalt (Co), which can be leached through the metabolic activity of specific chemoautotrophic microorganisms. This study investigates the adaptation process of the Acidithiobacillus ferriphilus bacterial strain, originally isolated from acid mine drainage (AMD), for the bioleaching of pyrite. The progress of the bioleaching process was evidenced by the release of iron (3.6 mg/mL) and significant quantities of gold (0.21 mg/L, equivalent to 3 g/t) into the post-culture liquid. The results indicate that the most effective bioleaching was achieved during the final adaptation stage, utilizing a medium with 7% pyrite content and a 0.75% supplement of an easily accessible energy source in the form of iron sulfate. These findings confirm the potential of the A. ferriphilus strain for pyrite bioleaching.