Cleaning 500 square miles of radioactive waste starts with a single-celled organism

Courtesy Photo | Despite their unassuming appearance, D. geothermalis cells could hold the key to neutralizing large quantities of toxic waste.  

BETHESDA, MD, UNITED STATES

06.12.2017

Courtesy Story

Uniformed Services University

There are some places that are too dangerous to send soldiers. Sometimes, the best person for a job is a bacterium.

The Deinococcus genus of bacteria is known for its high radiation resistance, able to survive high doses that would reduce other organisms to tar. Researchers at Uniformed Services University of the Health Sciences’ (USU) Department of Pathology are looking to use this hardy single-celled soldier to help clean up some of the most hazardous nuclear waste sites on the planet through a process called bioremediation.

Bioremediation is the waste management technique of using living organisms to turn hazardous materials – like nuclear waste – and break them down into less toxic, or completely non-toxic, materials

Led by Prof. Michael Daly in the Department of Pathology, USU researchers have been working with Deinococcus for over a decade, and in that time have produced what might be the best solution for nuclear waste bioremediation: Deinococcus geothermalis. Not only is D. geothermalis highly radiation resistant, it also is able to thrive in higher temperatures than its close cousin, D. radiodurans, which had previously been seen as a bioremediation tool, save for a small flaw: it is susceptible to heat.

One of the largest nuclear waste disposal sites in the country is the Hanford Nuclear Reservation. The 500 square mile site is the resting place of tens of thousands of gallons of nuclear waste from the Cold War that was a byproduct of creating the era’s nuclear weapons. Due to the age of the location, much of the toxic material has since leaked from the containers and into the ground. The volume of soil and groundwater contaminated over the past six decades could cover around 10,000 football fields a yard deep, and keep Niagara Falls flowing for several weeks. Sinkholes have opened in the unstable ground and called the security of more of the waste into question.

“Because of the radioactive decay and thermal insulation in some of the million-gallon Hanford containers – these tanks have temperatures too high for using bacteria like D. radiodurans for bioremediation. So we spent several years engineering its counterpart, D. geothermalis, for bioremediation, essentially taking all the bioremediation genes we expressed in D. radiodurans and putting them in D. geothermalis,” said Daly. “They showed they work in elevated ranges of up to 50 degrees (Celsius), and yet still at the same high dose of radiation rates that we use to test it here at USU and relevant [Department of Defense] sites.”

Further research is needed, but Daly believes that D. geothermalis is a major step in the field of bioremediation.

The uses of Deinococcus go beyond just cleaning up toxic waste sites; Daly’s research has also found that the mechanism that allows Deinococcus to survive high radiation exposure could also help in the creation of vaccines and cancer treatment. The ultimate goal, though, is to transfer this radiation resistance to humans.

People can be exposed to radiation from a variety of sources. They can be occupational hazards in the case of nuclear industry technicians, intentional medical practices in the case of radiation therapy patients, or unintentional in the event of terrorist attacks or nuclear plant accidents. Being able to protect people from the destructive effects of nuclear power has been pursued since they were discovered.

Even despite decades of advances in space-travel technology, space radiation has been a hazard that humans haven’t developed adequate means of dealing with. Astronauts can only spend a limited amount of time in space because there isn’t radiation shielding strong enough to protect them from full exposure. In a way, radiation is a roadblock to the final frontier.

• Date Taken: 06.12.2017
• Date Posted: 06.12.2017 09:25
• Story ID: 237448
• Location: BETHESDA, MD, US