Cornell University researchers have engineered a strain of the bacterium Gluconobacter oxydans to dramatically speed up the natural weathering of ultramafic minerals such as olivine. The study, published August 5 in Scientific Reports, demonstrates that the modified microbe can extract up to 75% of the magnesium from olivine samples within 15 days while simultaneously releasing cobalt and nickel, two elements critical for electric-vehicle batteries.
Natural silicate weathering slowly removes carbon dioxide from the atmosphere as dissolved magnesium reacts with CO₂ to form stable carbonate minerals. The Cornell team, led by postdoctoral researcher Jacob D. Klug and professors Esteban Gazel and Buz Barstow, sought to accelerate this process biologically rather than invent a new one. They engineered G. oxydans to produce an acid-rich biolixiviant and found that direct contact between the bacteria and mineral surfaces increased dissolution rates far more than the acids alone.
Experiments showed the bacteria promote oxidation of iron within the mineral, sustaining acid production and prolonged weathering. A key discovery was the formation of magnesium oxalate under room-temperature, low-pH conditions. Unlike magnesite, the more commonly studied magnesium carbonate, each magnesium atom in magnesium oxalate can bind two carbon atoms, theoretically doubling the carbon storage capacity per unit of magnesium.
The researchers emphasize that the work was conducted in laboratory flasks and that several challenges remain before any large-scale application. Future studies will aim to increase the fraction of magnesium converted to magnesium oxalate, identify lower-cost feedstocks for growing the bacteria, and assess the long-term stability of magnesium oxalate as a carbon-storage mineral.
The team sees particular promise in applying the approach to ultramafic mine tailings — crushed waste rock from mining operations. These tailings are already finely ground, making them well suited for accelerated weathering, and they offer an opportunity to recover residual critical minerals while permanently storing carbon.
The peer-reviewed study, titled "Bioleaching of Olivine and Enstatite With Formation of Mg-Oxalate Mediated by Engineered Gluconobacter Oxydans," appears in Scientific Reports (DOI: 10.1038/s41598-026-63817-0). The research was supported by Cornell University.
Engineered microbe speeds CO₂ capture and recovers critical metals
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