A team of researchers at Michigan State University has solved the mystery of how Geobacter bacteria found in soils manage to clean up nuclear waste and generate electricity at the same time. Going a step further, the team genetically engineered a Geobacter strain that does an even better job of it.
MSU microbiologist Gemma Reguera has filed patents to build on her research, “which could lead to the development of microbial fuel cells capable of generating electricity while cleaning up environmental disasters,” according to an MSU news release.
“Geobacter bacteria are tiny micro-organisms that can play a major role in cleaning up polluted sites around the world,” said Reguera, an MSU AgBioResearch scientist. “Uranium contamination can be produced at any step in the production of nuclear fuel, and this process safely prevents its mobility and the hazard for exposure.”
The ability of Geobacter to clean up and neutralize uranium was proven when they were recruited to clean-up uranium mill tailings at a site in Rifle, Colorado. Researchers stimulated reproduction and activity of Geobacter already in the soil by injecting acetate, which they feed on, into contaminated groundwater. This gave the microbes energy sufficient for them to remove the uranium.
Exactly how Geobacter accomplished this feat wasn’t known until Reguera and her team made their discovery. It turns out conductive, hair-like appendages, called pilli or nanowires, are doing most of the work and managing electrical activity as the Geobacter bacteria essentially electroplate uranium, thereby neutralizing it and preventing it from leaching into groundwater. Their nanowires also protect the Geobacter, enabling them to live in a toxic environment.
Reguera and her team then went on to genetically engineer a Geobacter strain that enhanced the cells’ nanowire production. “The modified version improved the efficiency of the bacteria’s ability to immobilize uranium proportionally to the number of nanowires while subsequently improving its viability as a catalytic cell,” according to MSU’s news release.
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