I-Corps: Translation potential of engineered microbes to extract critical metals from ultramafic mine waste

This I-Corps project is based on the development of a biological process for recovering critical metals from mine tailings that are iron- and magnesium-rich. The United States currently imports most of its nickel, cobalt, and platinum minerals, materials essential for energy infrastructure, batteries, defense systems, and manufacturing. Mines that produce these metals typically require export to overseas facilities for refining, creating a low domestic processing capacity for these metals. However, domestic mines generate hundreds of millions of tons of iron- and magnesium-rich tailings annually that contain significant concentrations of these metals, but the mineral concentrations fall below the economic threshold for conventional processing, leaving tailings as an expensive financial and environmental liability for mines. This technology converts mining waste into critical metals. This may strengthen U.S. domestic production of critical metals while also contributing to national goals. This I-Corps project utilizes experimental learning coupled with first-hand investigation of the industry ecosystem to assess the translation potential of bio-accelerated weathering technology for processing of ultramafic-rich mine tailings. This technology is based on engineered strains of Gluconobacter oxydans, a bio-mining bacteria that produces a biolixiviant, a mixture of organic acids and biomolecules capable of dissolving magnesium-rich silicate minerals at rates higher than acids alone. Biolixiviants extract critical metals and accelerate the rate-limiting step in mineralization from years to hours or days. Using whole-genome screening and targeted gene edits, high performing mutant strains were constructed to accelerate this dissolution step by more than 5-fold relative to wild-type, reaching dissolution rates of 70% in 3 days without the use of heating or strong acids. In addition, this technology operates at ambient temperature and pressure without hazardous reagents, enabling deployment directly at mine sites as a non-disruptive process unlike current hydrometallurgical or pyrometallurgical processing. Mine operators may benefit through the reduction of tailings storage liability, and recovery of valuable critical metals from waste streams. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.