This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A genetically engineered bacterium can rapidly break down one of Earth's most abundant minerals, opening a promising new pathway for simultaneously removing carbon dioxide from the atmosphere and recovering critical elements used in electric vehicle batteries, according to new Cornell research. In a study published Aug. 5 in Scientific Reports, researchers determined that an engineered strain of Gluconobacter oxydans (G. oxydans) accelerated the weathering, or natural breakdown, of ultramafic minerals high in magnesium and iron.
The process not only released cobalt and nickel—two metals essential for battery manufacturing—but also converted dissolved magnesium into magnesium oxalate, an underexplored mineral capable of storing twice as much carbon per magnesium atom as the more commonly studied mineral magnesite. "This work shows that biology can dramatically accelerate one of Earth's natural carbon-removal processes while creating additional value through critical mineral recovery," said senior author Esteban Gazel, the Charles N. Mellowes Professor in the Department of Earth and Atmospheric Sciences in the Cornell Duffield College of Engineering.
"By coupling carbon sequestration with the extraction of valuable battery metals, this approach has the potential to improve the economics of large-scale carbon removal by targeting unconventional sources." The paper, "Bioleaching of Olivine and Enstatite With Formation of Mg-Oxalate Mediated by Engineered Gluconobacter Oxydans," was led by first author Jacob D. Klug, a postdoctoral researcher in the Department of Earth and Atmospheric Sciences. Co-corresponding author Buz Barstow, associate professor of biological and environmental engineering in the College of Agriculture and Life Sciences, led the engineering of the bacterial strain used in the study, while Gazel's team focused on elucidating the geochemical processes.
Geoscientists have long recognized that weathering of silicate rocks naturally removes carbon dioxide from the atmosphere. As rainwater and groundwater slowly dissolve minerals such as olivine (an iron-magnesium silicate), magnesium released from the rock reacts with carbon dioxide to form stable carbon-bearing minerals. "What we're trying to do is engineer the bacteria to accelerate something that is already happening, rather than make something happen that doesn't happen naturally," Barstow said.
The Cornell team focused on G. oxydans, a bacterium previously shown to produce organic acids capable of dissolving minerals. They engineered the microbe to produce an acid-rich biolixiviant and then compared its performance with both synthetic organic acids and a cell-free solution containing only the acids and other compounds produced by the bacteria. Experiments showed that direct contact between G. oxydans and mineral surfaces significantly increased dissolution rates compared with using the bacteria's acidic byproducts alone.
The researchers found evidence that the bacteria promoted the oxidation of iron within the minerals, allowing the microbes to continue producing acid and sustain weathering for longer periods. As a result, the engineered bacteria extracted up to 75% of the magnesium contained in olivine samples over just 15 days while also releasing nickel and cobalt from the mineral. The team also documented the formation of magnesium oxalate under room-temperature, low-pH conditions.
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