Earth has its fair share of environments that we consider extreme, but even in some of the harshest habitats, organisms have found a way to get by. In the deepest oceans, where the pressure is intense and there is no light, there are still fish swimming around. In underwater volcanoes, where there is an acidic carbon dioxide environment, football-sized mussels have found a way to grow.
Even radioactive sites that are dangerous for humans are 'home sweet home' for certain microbes. And now, researchers have found a remarkable species of bacteria that 'breathes' uranium and thrives in abandoned uranium ore processing sites. The newly discovered strain, which belongs to a class called betaproteobacteria, was found in the soil at an old uranium ore mill in Rifle, Colorado. The mill was once used for nuclear weapons production and the site is still radioactive to this day.
As described in PLOS ONE, the bacteria somehow take a spare electron from the uranium in a process called 'reduction.' It is unknown whether the resulting uranium is in a state safe enough for humans to interact with. However, if this is the case, then it could be a novel way of clearing up uranium-polluted sites efficiently. Scientists are also unsure of the potential impact these organisms could have on the environment, so more research needs to be done.
“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,” said Professor Lee Kerkhof of Rutgers University.
It's not certain how this type of uranium-eating bacteria evolved to thrive off of radioactive elements. It's probably a process similar to the way that some bacteria develop resistance to antibiotics. It just so happened that this particular species “picked up a genetic element that’s now allowing it to detoxify uranium, to actually grow on uranium” said Kerkhof.
This research is part of the U.S. Department of Energy program to see if microorganisms can nibble away at radioactive uranium and make it inert. The department is hoping that this will make any polluted groundwater and well water safe to drink again.
"After the newly discovered bacteria interact with uranium compounds in water, the uranium becomes immobile," said Kerkhof. "It is no longer dissolved in the groundwater and, therefore, can't contaminate drinking water brought to the surface."
Kerkhof's concerns for contaminated drinking water don't end with the United States. If this species can be harnessed to make radioactive zones safe for humans, then there are a lot of places that could benefit from it.
"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."