The findings mean that the Geobacter bacteria, which are tiny micro-organisms, could play a vital major role in cleaning up sites contaminated by nuclear fuel. The ability of these microbes to neutralise uranium has been well documented, but how they do so has remained a mystery until now.

Researchers from Michigan State University have discovered that conductive pili or nanowires – hair-like appendages found on the outside of Geobacters – are responsible for the microbes’ neutralizing ability, by managing electrical activity.

Their effectiveness was proven during a clean-up in a uranium mill tailings site in Colorado. Researchers injected acetate into contaminated groundwater, according to a report in the Proceedings of the National Academy of Sciences journal.

Microbiologist Gemma Reguera, who led the study, said: “Our findings clearly identify nanowires as being the primary catalyst for uranium reduction. They are essentially performing nature’s version of electroplating with uranium, immobilising the radioactive material and preventing it from leaching into groundwater.”

The nanowires shield Geobacter and allow it to thrive in a toxic environment, she added. Reguera and colleagues have been able to genetically engineer a Geobacter strain with enhanced nanowire production, which improves its ability to neuralise uranium.

Maxine Perella

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