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Deinococcus geothermalis DSM 11300
   
   
 
 
Deinococcus geothermalis is an extremely radiation resistant, moderately thermophilic bacterium closely related to the mesophilic Deinococcus radiodurans. D. geothermalis is culturable on defined minimal medium and undefined rich medium, and is transformable with expression vectors originally constructed for D. radiodurans. Draft sequencing of D. geothermalis together with the recently reported advances in the genetic management of this organism will facilitate its development for fundamental and practical objectives that are relevant to the Science Missions of the DOE, and will provide a deeper understanding of Deinococci-specific features in general. Draft-genome comparisons are ongoing, with the first results published in Daly et al 2004 (Science. Sep 30, 2004), and the complete genome sequence is being assembled at Los Alamos National Laboratory. D. geothermalis (1) is remarkable not only for its extreme resistance to ionizing radiation, but also for its ability to grow at temperatures as high as 55 degC (1) and in the presence of chronic irradiation (50 Gy/hour) (2). The organism was isolated by Ferreira et al (1997) (1) from thermal springs at Agnano, Naples, Italy. D. geothermalis belongs to the bacterial family Deinococcaceae, currently comprised of eight distinct nonpathogenic radiation resistant species, of which Deinococcus radiodurans strain R1 is the most characterized (3). Advances in genetic engineering for D. radiodurans (4) were a stimulus for its genome sequencing (5), annotation (3), and transcriptome analyses (6), and the genome sequence of D. geothermalis will make possible similar work in this organism. In 2003, D. geothermalis was engineered to reduce Hg(II) at elevated temperatures and in the presence of 50 Gy/hour. Additionally, D. geothermalis is capable of reducing Fe(III)-NTA, U(VI) and, Cr(VI). These characteristics support the prospective development of this thermophilic radiophile for bioremediation of radioactive mixed waste environments with temperatures as high as 55 degC (6). Like D. radiodurans, D. geothermalis accumulates high intracellular Mn(II) concentrations, believed to be important to its extreme resistance phenotypes (7).

References:
1. Ferreira, A. C., M. F. Nobre, F. A. Rainey, M. T. Silva, R. Wait, J. Burghardt, A. P. Chung, and M. S. da Costa. 1997. Deinococcus geothermalis sp. nov. and Deinococcus murrayi sp. nov., two extremely radiation-resistant and slightly thermophilic species from hot springs. Int. J. Syst. Bacteriol. 47: 939-947.
2. Daly, M. J. 2000. Engineering radiation-resistant bacteria for environmental biotechnology. Curr. Opin. Biotechnol.11:280-285.
3. Makarova, K. S., L., Aravind, Y. L. Wolf, R. L. Tatusov, K.W. Minton, E.V. Koonin, and M. J. Daly. 2001. Genome of the extremely radiation-resistant bacterium Deinococcus radiodurans viewed from the perspective of comparative genomics. Microbiol. Mol. Biol. Rev. 65:44-79.
4. Brim, H., S. C. McFarlan, J. K. Fredrickson, K. W. Minton, M. Zhai, L. P. Wackett, and M. J. Daly. 2000. Engineering Deinococcus radiodurans for metal remediation in radioactive mixed waste environments. Nature Biotechnology 18: 85-90.
5. White, O. et al. 1999. Complete genome sequencing of the radioresistant bacterium Deinococcus radiodurans R1. Science 286: 1571-1577.
6. H. Brim, A. Venkateswaran, H. M. Kostandarithes, J. K. Fredrickson, and M. J. Daly. 2003. Genetic Development of Deinococcus geothermalis for bioremediation of high temperature radioactive waste environments. Appl. Environ. Microbiol., 69, 4575-4582.
Daly, M.J., E.K. Gaidamakova, V.Y. Matrosova, A. Vasilenko, M. Zhai, A. Venkateswaran, M. Hess, M.V. Omelchenko, H.M. Kostandarithes, K.S. Makarova, L.P. Wackett, J.K. Fredrickson, and D. Ghosal. 2004. Accumulation of Mn(II) in Deinococcus radiodurans Facilitates Gamma-Radiation Resistance. Science (http://www.sciencemag.org/cgi/content/abstract/1103185).