Mechanism of enhanced bioleaching efficiency of Acidithiobacillus ferrooxidans after adaptation with chalcopyrite

To clarify the role and mechanism of bacterial adaptation in bioleaching, the leaching of chalcopyrite by adapted and unadapted Acidithiobacillus ferrooxidans was compared. Three extrinsic factors (adsorption, tolerance to shearing stress and copper tolerance) in relation to bioleaching were investigated. The results showed that there were significant differences in bacterial attachment and tolerance to shearing stress of unadapted and adapted cells due to the variation of cellular wall component and structure. Consequently, there was significant difference in bioleaching rate between unadapted and adapted bacteria. In addition, some differences of copper accumulation and distribution in adapted and unadapted cells also existed, but this was not one of the key factors that affected their bioleaching rates.