‘Wired’ bacteria clean up nuclear waste

MICHIGAN STATE (US) — Researchers have unraveled the mystery of how microbes generate electricity while cleaning up nuclear waste, a finding that could prove beneficial at contaminated sites.

“Geobacter bacteria are tiny micro-organisms that can play a major role in cleaning up polluted sites around the world,” says Gemma Reguera, a microbiologist at Michigan State University. “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 immobilize uranium has been well documented, but the new study identifies Geobacter’s conductive pili, or nanowires, as doing the yeoman’s share of the work. The findings are published in Proceedings of the National Academy of Sciences.

Nanowires, hair-like appendages found on the outside of Geobacters, are the managers of electrical activity during a cleanup.

“Our findings clearly identify nanowires as being the primary catalyst for uranium reduction,” Reguera says. “They are essentially performing nature’s version of electroplating with uranium, effectively immobilizing the radioactive material and preventing it from leaching into groundwater.”

The nanowires also shield Geobacter and allow it to thrive in a toxic environment, she adds.

Their effectiveness was proven during a cleanup in a uranium mill tailings site in Rifle, Colo. Researchers injected acetate into contaminated groundwater. Since this is Geobacters’ preferred food, it stimulated the growth of the Geobacter community already in the soil, which in turn, worked to remove the uranium.

Reguera and her team of researchers were able to genetically engineer a Geobacter strain with enhanced 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.

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 after environmental disasters.

The National Institute of Environmental Health Science and the U.S. Department of Energy funded the study.

More news from Michigan State University: http://news.msu.edu/

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