Bacteria that 'breathe' uranium could be used to naturally clean up radioactive waste

(NaturalNews) A newly discovered bacteria that breathes uranium as well as oxygen could be used to remove uranium contamination from water supplies, according to a study conducted by researchers from Rutgers University and published in PLOS ONE on April 13.

"After the newly discovered bacteria interact with uranium compounds in water, the uranium becomes immobile," researcher Lee Kerkhof said. "It is no longer dissolved in the groundwater and therefore can't contaminate drinking water brought to the surface."

The findings suggest that all on its own, nature might have provided a way to solve the permanent contamination produced by the nuclear power and weapons industries.

Bacteria "breathe in" uranium, change its form

The study was conducted as part of a program by the U.S. Department of Energy to see if microorganisms could be used to "lock up" uranium that leached into the soil from nuclear weapons manufacture decades ago and is now contaminating local water supplies. Prior research at the same site -- the Integrated Field-Scale Subsurface Research Challenge Site (IFRC) at Rifle, Colorado -- suggested that in some form, microbial processes were immobilizing uranium, and researchers had suggested some species that might be responsible.

Other studies have also shown that certain bacterial species are able to "breathe" certain metallic compounds, often those containing iron. Some of these iron-breathing species are also able to breathe uranium but not oxygen.

The new study provides the first direct evidence of any bacterial species from a common class capable of breathing uranium.

In previous studies at an old uranium mill at the Rifle IFRC, researchers observed that concentrations of uranium were decreasing in groundwater supplies known to have active iron-breathing bacteria.

In the new study, researchers collected bacterial samples from areas at the Rifle FIRC where uranium had become immobilized. They then slowly started adding increasing quantities of active uranium. This gradually killed off all the bacterial species that were not able to process the uranium, eventually leaving only the mysterious, uranium-breathing variety.

The bacteria are part of the common class betaproteobacteria and are able to breathe either uranium or oxygen, unlike most metal-breathing strains. The researchers do not know how these common bacteria developed the ability to breathe uranium, but they suspect that they might have acquired the uranium-breathing gene from another species of bacteria in their environment.

The scientists do not yet understand exactly what changes the bacteria make to uranium in order to immobilize it. The one reaction they have observed -- taking electrons from the uranium, known as reduction -- does not explain the phenomenon.

"It appears that they form uranium nanoparticles," Kerkhof said, but the matter requires further study. More research is also needed into the way the uranium nanoparticles behave in the environment.

The researchers have also sequenced the new bacteria's genome to enable future research into the genetic basis of the uranium-breathing ability.

Nature solves problems caused by out-of-control science

The researchers have expressed hope that the bacteria could be used to remedy some of the damage done by the nuclear industry around the world. In Rifle, scientists originally expected uranium contamination to eventually leach from groundwater to the Colorado River, then be flushed to the ocean and diluted to less dangerous levels. However, contrary to these predictions, studies continue to show high (and non-diminishing) levels of uranium contamination in Rifle's groundwater.

"Biology is a way to solve this contamination problem, especially in situations like this where the radionuclides are highly diluted but still present at levels deemed hazardous," Kerkhof said.

The problem of persistent uranium contamination of groundwater goes far beyond old uranium mills, Kerkhof noted.

"There is depleted uranium in a lot of armor-piercing munitions," he said, "so places like the Middle East that are experiencing war could be exposed to high levels of uranium in the groundwater."

Sources for this article include:
http://news.rutgers.edu
http://journals.plos.org