A Microbial Biorealm page on the genus Deinococcus radiodurans
Higher order taxa
Bacteria; Deinococcus-Thermus; Deinococci; Deinococcales; Deinococcaceae; Deinococcus
D. radiodurans, D. radiodurans R1
Description and significance
Deinococcus radiodurans was first discovered in 1956 in a can of ground meat that had been treated with large doses of radiation to remove all hazardous bacteria from the product. Since then this species has been intensely studied for its radiation resistant properties. It has been known to withstand radiation levels of up to 1,000 times that which would kill a normal human, living up to its latin name, "strange little berry that withstands radiation." D. radiodurans has since been isolated from a variety of habitats, mostly soil and feces based. Being a mesophile, this species grows relatively well between 30-37°C.
The genome of D. radiodurans consists of four major parts. The complete sequence of the R1 strain has 3,284,156 base pairs made up of two circular chromosomes (2,648,638 and 412,348 base pairs), a major plasmid (177,466 base pairs), and a small plasmid (45,704 base pairs). No current research shows whether or not these plasmids contribute specifically to functionality or virality. However, it is known that multiple copies of each gene are found on all the chromosomes and plasmids, which most likely contributes to its amazing repair capabilities associated with its radiation resistance.
Cell structure and metabolism
D. radiodurans is a gram positive bacteria that usually forms in spherical pairs or tetrads. The most interesting aspect about the cell structure of D. radiodurans is that it keeps 4-10 copies of all its genes at any given time depending on its current stage of growth. Many researchers believe this relates to the reason why it can withstand so much radiation. This ability does not rely on some "magic" gene that protects it from radiation, rather, it seems that D. radiodurans is able to more efficiently repair double strand breaks in its DNA that result from radiation damage thanks to these extra copies and a few other special proteins.
D. radiodurans has been found in a wide variety of environments which therefore make its "natural" habitat difficult to define. It is often cultured in the lab from the feces of animals, such as elephants. However, many scientists have found it peacefully existing in the soil of various settings, including the rocky granite of Anartica's dry valleys. These numerous soil dwellings have led many to classify D. radiodurans as a soil bacteria. There is no current findings that suggest that D. radiodurans significantly interacts with other organisms in nature.
Application to Biotechnology
4. Obiero J, Bonderoff SA, Goertzen MM, Sanders DA. Expression, purification, crystallization and preliminary X-ray crystallographic studies of Deinococcus radiodurans thioredoxin reductase. Acta Crystallographica, Section F Structural Biology Crystallization Communications. 2006 Aug 1;62(Pt 8):757-60.
Edited by Edwin Cook, student of Rachel Larsen and Kit Pogliano