Electron micrograph of a four-cell cluster of Deinococcus radiodurans.

Deinococcus radiodurans growing on agar plates in the presence of 6000 rads per hour of radiation.

A bacterium first discovered in spoiled beef and believed sterilized by radiation turned out to be "Conan the Bacterium" (aka Superbug)—the most radiation-resistant life form ever found. Deinococcus radiodurans is highly resistant to genotoxic chemicals, oxidative damage, high levels of ionizing and ultraviolet radiation, and desiccation; it can survive 3,000 times the radiation dose that is lethal to humans. The capability to survive in such extreme environments is attributed in part to a unique DNA repair system in combination with its chromosome copy number and structure. Researchers supported by the Office of Science reengineered the microbe so that it can reduce toxic metals and partially degrade harmful solvents while surviving the high radiations levels typical of those at DOE waste sites. This was the first time a microbe has been engineered to have these remarkable capabilities. The DNA of this organism was sequenced with Office of Science support as well.

Scientific Impact: This work established both the capability to engineer additional functions into D. radiodurans and the persistence of the added functionality despite exposure to radiation. Studies of this microbe will add to understanding of sensitive enzymes responsible for monitoring and repairing damage to DNA caused by radiation and other agents.

Social Impact: The astonishing DNA repair capacities of this organism, as well as the feasibility of genetically modifying it, are of interest for cleanup of radioactive wastes. The techniques used to modify the microbe could lead to new biological solutions—rather than traditional, costly "pump and treat" options—for cleaning up environmental contamination resulting from the production of weapons-grade nuclear materials in years past.

Reference: K. S. Makarova, L. Aravind, L.Tatusov, Y. I. Wolf, E. V. Koonin, and M. J. Daly, "Genome of the extremely radiation resistant bacterium Deinococcus radiodurans viewed from the perspective of comparative genomics," Microbiology and Molecular Biology Reviews, 65, 44-79 (2001).

H. Brim, S. McFarlan, L. Wackett, K. W. Minton, M. Zhai, J. Fredrickson, and M. J. Daly, "Engineering Deinococcus radiodurans for metal remediation in radioactive mixed waste environments," Nature Biotechnology, 18, 85-90 (2000).

URL: http://www.usnews.com/usnews/issue/000103/daly.htm

ftp://ncbi.nlm.nih.gov/pub/koonin/Deinococcus/

Technical Contact: Dr. Dan Drell, Life Sciences Division, Office of Biological and Environmental Research, 301-903-4742

Press Contact: Jeff Sherwood, DOE Office of Public Affairs, 202-586-5806

SC-Funding Office: Office of Biological and Environmental Research