New bacteria could clean sites contaminated by uranium

A strain of bacteria that “breathes” uranium could be used at sites where uranium was processed.

A team of Rutgers University scientists and collaborators discovered the bacteria in soil at an old uranium ore mill in Rifle, Colorado, 321 kilometres west of Denver. 

The team’s discovery, published in the April 13, 2015 issue of Public Library of Science (PLoS) One, is the first time scientists have found a bacterium from a common class known asbetaproteobacteria that breathes uranium.  This bacterium can breathe either oxygen or uranium to drive the chemical reactions that provide life-giving energy.

“After the newly discovered bacteria interact with uranium compounds in water, the uranium becomes immobile,” said Lee Kerkhof, a professor of marine and coastal science in the School of Environmental and Biological Sciences.

 “It is no longer dissolved in the groundwater and therefore can’t contaminate drinking water brought to the surface.”

According to Kerkhof, Breathing uranium is rather rare in the microbial world.

A media release from Rutgers University explains that most examples of bacteria which can respire uranium cannot breathe oxygen but often breathe compounds based on metals – typically forms of solid iron. Scientists had previously witnessed decreasing concentrations of uranium in groundwater when iron-breathing bacteria were active, but they have yet to show that those iron-breathing bacteria were directly respiring the uranium.

While the chemical reaction that the bacteria perform on uranium is a common process known as “reduction,” or the act of accepting electrons, Kerkhof said it’s still a mystery how the reduced uranium produced by this microorganism ultimately behaves in the subsurface environment.

“It appears that they form uranium nanoparticles,” he said, but the mineralogy is still not well known and will be the subject of ongoing research.

Kerkhof said he is optimistic about the potential for these bacteria to mitigate the specific groundwater pollution problem in Rifle

The research is part of a U.S. Department of Energy program to see if microorganisms can lock up uranium that leached into the soil years ago and now makes well water in the area unsafe to drink.

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