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Microbes Found to Clean Nuclear Waste, Generate Electricity

Gemma Reguera (Michael Steger, Michigan State Univ.)

Gemma Reguera (Michigan State Univ.)

Researchers at Michigan State University in East Lansing have shown the ability of certain microbes to generate an electric current while cleaning up uranium in wastewater. The team’s findings, for which patents have been filed, appear online in the journal Proceedings of the National Academy of Sciences (paid subscription required).

Microbiologist Gemma Reguera (pictured right) and colleagues investigated a species of micro-organisms called Geobacter bacteria that can ingest metals from waste materials, including toxic and radioactive wastes, and turn them into carbon dioxide. Geobacter can also generate electricity, and Reguerra’s research offers more insights into the way these microbes work.

The team’s research focuses on the Geobacters’ conductive pili or nanowires. These appendages on the microbe of about three nanometers — one nanometer equals one billionth of a meter — absorb and deactivate uranium found in nuclear waste, and also protect the micro-organism from the toxic material. “They are essentially performing nature’s version of electroplating with uranium,” says Reguera, “immobilizing the radioactive material and preventing it from leaching into groundwater.”

They demonstrated Geobacter’s affinity for uranium in a cleanup of a uranium mill tailings site in Rifle, Colorado. At the Rifle site, the team injected acetate — Geobacter’s favorite food — into the contaminated groundwater, which stimulated the growth of the bacteria already in the ground. The enlarged community of Geobacter then helped remove the uranium at the site.

Reguera’s team enhanced the microbe’s capabilities by genetically engineering a Geobacter strain with more nanowires. The modified Geobacter improved its ability to clean-up uranium proportionally to the number of nanowires while improving its ability as a catalytic cell.

The organism’s nanowires provide the potential for transferring electrons, forming conducive networks over long distances. The MSU researchers found using transmission electron microscopy that the genetically modified Geobacter that cleaned up the uranium held a weak electrical charge in the nanowires, apparently as a result of the uranium in the wastewater.

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.

Read More: Electronic Conductivity Found in Bacteria Nanowires

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