STTR Phase I: Engineering Alternative Oxidation Activity in A. ferrooxidans For Enhanced Biohydrometallurgy Capabilities

The broader impact/commercial potential of this Small Business Technology Transfer (STTR) project will be to develop engineered bacteria with the ability to oxidize the copper mineral chalcopyrite and gold. The majority of copper reserves are in chalcopyrite, which currently requires smelting. The US copper mining industry, due to regulatory restrictions, has a limited smelting capacity forcing US copper manufacturers to ship copper mineral concentrates overseas for smelting, which incurs additional transportation and processing costs while losing up to 30% of the full value of the metal to the smelters. At over 400,000 tons of copper concentrate exported annually, this amounts to over $600M in lost value. In gold mining, biooxidation is increasingly used before other gold recovery techniques are utilized, and increased oxidation rates would expand the use and significantly lower the capital and operating costs of this practice. In addition, enhanced oxidation would accelerate the development of mining waste streams as biotechnology feedstocks. This project potentially furthers more economical and sustainable biohydrometallurgical techniques throughout the mining industry. This STTR Phase I project proposes the demonstration and development of new oxidation activity within bioleaching microbes, expanding the applications of biohydrometallurgy in metal mining. This would permit the application of cheaper, low impact biohydrometallurgical methods for important metal minerals. Currently, biohydrometallurgy is limited by its reliance on ferric iron as the main oxidant. The Intellectual Merit of this proposal stems from the use of hydrogen peroxide, which can enable mineral oxidation conversions and rates that are not obtainable with ferric iron alone. Adding hydrogen peroxide to biohydrometallurgy operations is not feasible or cost effective, however, the genetic engineering of biomining microbes, such as A. ferrooxidans, to produce hydrogen peroxide would be a potentially game changing advance. This innovation will result in the production of biomining microbial cells with an unprecedented ability to dissolve sulfide-rich ores leading to the expansion of biohydrometallurgical approaches in the mining industry.