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Bacteria thrive in radioactive soil

Unfamiliar microbes have been found swarming in sediment from a nuclear waste dump — organisms that could someday be used to clean up toxic environments.
/ Source: The Associated Press

Scientists have discovered bacteria swarming in the toxic sediment beneath underground tanks that have leaked radioactive waste at the Hanford nuclear reservation, home to some of the most highly contaminated soil in the world.

The discovery eventually could help researchers better understand how microorganisms can survive severe contaminants — and how to use the bacteria to help clean up toxic environments.

The results of a study of the bacteria were presented Wednesday at the American Society of Microbiology’s annual meeting in New Orleans.

“It’s exciting,” said Fred Brockman, staff scientist and group leader for the project at the Pacific Northwest National Laboratory, an Energy Department research center near the Hanford site in south-central Washington state. “One of the most important things to realize is this is a type of environment that hasn’t been studied with regard to bacteria.

“I believe it’s the most radioactive soil ever studied with regards to bacteria in the world,” Brockman said.

The team of scientists has identified more than 100 different species of bacteria in a mixture of sand, silt and clay extracted from beneath several underground Hanford tanks, which were built in 1953 to hold highly radioactive waste produced from the recovery of plutonium from irradiated nuclear reactor fuel rods.

About 53 million gallons of radioactive liquid, sludge and other material are stored in the 177 underground tanks. Some of the tanks, which are less than 10 miles from the Columbia River, have leaked into the groundwater, exposing the sediment for decades to very high radioactivity.

Scientists cultured bacteria from the sediment and analyzed their DNA to try to identify them.

“The proteins we found were quite dissimilar to what’s already in the international databases,” Brockman said. “It’s telling us that these organisms just haven’t been studied much before.”

The findings also could be important to further study into using organisms to clean contaminated sites.

“The key is that some of them have survived, and if we study them further, we may be able to understand their particular properties or the capabilities of the organism,” Brockman said.

Hanford was an important site for the top-secret Manhattan Project to build the atomic bomb during World War II. For 40 years, it processed plutonium for the nation’s nuclear weapons arsenal. Today, work there centers on a $50 billion to $60 billion cleanup, to be finished by 2035.

The bacteria research was conducted as part of the Hanford Science and Technology Program, aimed at understanding basic science critical for cleanup applications.