Geobacter can clean up uranium but a new study documenting how microbes generate electricity while cleaning up nuclear waste and other toxic metals could mean a big benefit for contaminated sites in the future.
Identifying the Geobacters' conductive pili (nanowires - hair-like appendages found on the outside of Geobacters) as doing the bulk of the work is a new revelation. The nanowires also shield Geobacter and allow the bacteria to thrive in a toxic environment.
Their effectiveness was proven during a cleanup in a uranium mill tailings site in Rifle, Colo. The 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.
Michigan State University microbiologist Gemma 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.
"Our findings clearly identify nanowires as being the primary catalyst for uranium reduction," Reguera said. "They are essentially performing nature's version of electroplating with uranium, effectively immobilizing the radioactive material and preventing it from leaching into groundwater."
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.