UV-Irradiated Strain of Acidithiobacillus ferrooxidans Improved Copper Bioleaching in Chalcopyrite

Bioleaching is a process that uses microorganisms to perform dissolution of sulfide minerals. Actually, most copper is found as chalcopyrite ore, which is the most abundant form of copper sulfide, but it is recalcitrant to dissolution. The biggest challenge for biohydrometalurgy is the microorganisms involved in it. This study aims to obtain mutants of Acidithiobacillus ferrooxidans by using a methodology that uses classical genetic tools [ultraviolet radiation (UV)], and evaluates its efficiency by using mathematical tools (mathematical modeling and desirability). The mutant strains were evaluated considering their kinetics of initial velocity of ferrous ions oxidation. The selective pressure of UV caused different profiles in the consumption kinetics of strains' energy sources. The cells with higher consumption kinetics than the wild strain were submitted to shake flask experiments in the presence of chalcopyrite and evaluated by mathematical models. The cell culture irradiated for 1minute outperformed the wild strain in copper solubilization according to the desirability parameters. The mathematical tools allowed confirming that the UV protocol improved the bioleaching capability of Acidithiobacillus ferrooxidans.