Bacteria Genomes - DEINOCOCCUS RADIODURANS

Deinococcus radiodurans represents an organism in which all systems for DNA repair, DNA damage export, desiccation and starvation recovery, and genetic redundancy are present in one cell.

Deinococcus radiodurans is a Gram-positive , red-pigmented, nonmotile bacterium that was originally identified as a contaminant of irradiated canned meat in 1956 by Arthur W. Anderson at Oregon Agricultural Experiment Station in Corvallis.

Deinococcus radiodurans is listed in the Guinness Book of World Records as "the world's toughest bacterium." This microbe can survive drought conditions, lack of nutrients, and most important, a thousand times more radiation than a person can.

It has been isolated worldwide from locations rich in organic nutrients, including soil, animal faeces, and processed meats, as well as from dry, nutrient-poor environments, including weathered granite in a dry Antarctic valley, room dust, and irradiated medical instruments . All species in the genus Deinococcus, in particular D. radiodurans, are extremely resistant to a number of agents and conditions that damage DNA, including ionising and ultraviolet (UV) radiation and hydrogen peroxide.

The physical arrangement of D. radiodurans' genome could help the organism accomplish its feats of DNA repair. The microbe carries between four and ten copies of its genome, rather than the usual single copy, and the copies appear to be stacked on top of each other. The additional genomes may allow the bacterium to recover at least one complete copy of its genome after exposure to radiation. The radiation resistance of D. radiodurans makes it an ideal candidate for bioremediation (environmental cleanup) of sites contaminated with radiation and toxic chemicals.

References:

http://web.umr.edu/~microbio/BIO221_2000/Deinococcus_radiodurans.html
Science 286(5444):1571-1577(1999).
http://www.genomenewsnetwork.org/articles/07_02/deinococcus.shtml