2025 Lee Bioleaching of ultramafic minerals with Gluconobacter oxydans

Ultramafic rocks represent a significant source of cations for carbon dioxide mineralization, which is essential for mitigating climate change. This study investigates an innovative method for enhancing the dissolution of ultramafic minerals to facilitate cation release for CO2 sequestration and critical element extraction. We employed the mineral-dissolving microbe Gluconobacter oxydans, which produces gluconic acid-based lixiviants, to accelerate the leaching process. Our results demonstrate that Mg2+ leaching is accelerated by a factor of 20 compared to deionized water, with further improvements of 73% observed when comparing leaching dynamics over 24 to 96 hours. Notably, at a 1% pulp density, G. oxydans shows only a modest improvement over gluconic acid alone; however, at 60% pulp density, it exceeds gluconic acid's effectiveness by 3.2 times. Furthermore, we found that biolixiviants derived from cellulosic hydrolysate matched the performance of those from glucose, thus widening the potential feedstock options for bioleaching. We also managed to decrease the carbon atom requirement in the biolixiviant feedstock for effective Mg2+ ion release and CO2 mineralization from 525 to 1, marking a significant advancement in carbon capture technology.