Overexpression of AcoP in Acidithiobacillus ferrooxidans for Enhanced Copper Reclamation

Copper is an essential critical metal that will be indispensable as we work to reduce our dependence on fossil fuel sources and move to electrification. Here, we explored the cellular overexpression of the AcoP protein to enhance copper binding ability of a representative bioleaching acidophile, Acidithiobacillus ferrooxidans. The engineered cells exhibited enhanced copper binding, regardless of the oxidation state of copper (1.5-fold improvement), as well as in the presence of a nontarget metal, iron (up to 2.7-fold improvement). The acid- and metal-tolerant physiology of A. ferrooxidans enabled the cells to grow in the presence of bottom ash produced from a municipal waste-to-energy facility, and the genetically engineered cells also exhibited enhanced copper recovery (9.5-fold higher selectivity) from this nonconventional feedstock. This work demonstrates a promising proof of concept where bioleaching cells can be modified for the effective reclamation of critical materials from different sources for emerging future applications.