radiodurans

Deinococcus radiodurans is a bacterium notable for extraordinary resistance to ionizing radiation, desiccation, and oxidative stress. It is the best-known species of the genus Deinococcus and is widely studied as a model organism for DNA repair and stress tolerance. The name radiodurans reflects its remarkable durability in the face of radiation.

First described in 1956 by Arthur W. Brock and colleagues after isolation from irradiated meat, D. radiodurans has since been found in diverse environments such as soils, dust, and sewage. Its resilience is not limited to radiation; it tolerates extreme dehydration and chemical stresses as well.

Resistance arises from a combination of efficient DNA repair, a multi-copy genome, and protective cellular chemistry. The bacterium can rapidly reassemble shattered chromosomes by homologous recombination, supported by RecA-like proteins, multiple genome copies, and a network of DNA repair and antioxidant enzymes.

The genome is multipartite, comprising two circular chromosomes and several plasmids. Redundancy among genome segments and highly expressed repair proteins contribute to its ability to survive extensive DNA damage and to restore full viability after irradiation.

Ecologically, D. radiodurans is a soil and environmental microbe that tolerates desiccation and radiation, often occurring in extreme or contaminated habitats. Its hardy physiology is a focus of research into microbial persistence under stress.

In biotechnology, it serves as a model for DNA repair and stress tolerance, with potential applications in bioremediation of radioactive sites and in experiments simulating life in extreme environments. It also informs astrobiology and the study of life's limits.