With the help of funding from the Small Grants Program offered by the Cornell Atkinson Center for Sustainability, postdoctoral researcher Alexa Schmitz is using bacteria to create an efficient and environmentally responsible method for extracting rare earth metals. She is part of a research team studying biological energy capture, led by Buz Barstow, assistant professor in the Department of Biological and Environmental Engineering and a Cornell Atkinson Faculty Fellow.
“Much of what we consider revolutionary for sustainable energy relies on rare earth metals,” Schmitz said. “But because mining them includes a leaching process which uses high temperatures and harsh solvents, and produces large quantities of toxic waste, these renewable energy technologies can have a large carbon footprint.”
Schmitz is working to replace chemical leaching with bioleaching, which uses microbes to extract the metals. The potential candidate: a bacterial species called Gluconobacter oxydans (Gox). A relative of the vinegar-producing bacteria used to make fermented products like kombucha, Gox produces a variety of strong but biodegradable organic acids. These acids allow the bacteria to extract rare earth metals from ore or waste products, such as coal ash or high efficiency lighting.
Gox is currently not efficient enough to be a commercially viable alternative. However, Schmitz and her collaborators at the U.S. Department of Energy’s Idaho National Laboratory think they can tap Gox’s true potential if they can understand and enhance the bacteria’s chemical toolkit.
Prior experiments at the Idaho National Laboratory showed that Gox bacteria rely on more than just organic acids for extraction. Schmitz said, “There is some other element—a gene, protein, another molecule produced by the bacteria—that is allowing the process to happen. And nobody knows what it is. That is an important target for this project.”
Cornell Atkinson’s Small Grants Program, which funds up to $8,000 for graduate and postdoctoral research proposals, has enabled Schmitz to develop a collection of new Gox variants, or “mutants,” each with a different gene disrupted. She is using the collection to identify genes involved in bioleaching, which she plans to target for improvement through bioengineering.
Over the past year, she has generated a collection of 2,733 mutants using the Knockout Sudoku method developed in the Barstow Lab. In each mutant, a non-essential gene in the Gox genome has been disrupted by the insertion of a transposon—a short piece of DNA that inactivates, or “knocks out,” the gene where it lands. Schmitz is now preparing to put her mutants to the test so she can identify any genes that affect rare earth metal bioleaching.
“The next step is to determine if knocking a gene out increases or decreases the production of organic acids, or changed its effectiveness at bioleaching,” Schmitz said. “If we can identify something that affects bioleaching beyond the production of acids, that would be the golden egg for developing an efficient and sustainable system to extract rare earth metals.”
Applications for the 2020 cycle of the Atkinson’s Small Grants Program are due March 20, 2020. More information about the request for proposals online.
Amanda Garris is a freelance writer for the Cornell Atkinson Center for Sustainability.
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