Thermococcus gammatolerans

Overview

Thermococcus gammatolerans is an archaea extremophile and currently the most radiation resistant bacteria being able to remain viable after suffering doses of up to 30,000 Gray. The Thermococcus genus is a genus for irregularly shaped coccoid species ranging from .6-2 μm in diameter. (1) The species prefers acidic environments and favors sulfur as its reducing agent. Various members of the genus prefer different temperatures, but all of the bacteria generally prefer temperatures of around 65-100C. The mechanism behind their high radiation resistant capabilities lies within Thermococcus gammatolerans ability to quickly repair and rebuild damaged chromosomes without any loss of viability. 

Isolation

The isolation of Thermococcus gammatolerans began with various samples collected from a hydrothermal chimney located in the mid-Atlantic Ridge near the Guyamas basin (2). These chinmeys are characterized by their rich heavy metal content and their high exposure to natural radioactivity, with doses ranging hundreds of times higher than those found on earths surface(3).  The first authors to isolate this bacteria speculated that the conditions that Thermococcus gammatolerans embodied were similar to the conditions of found on early Earth's surface. The bacteria was isolated after the sample was bombarded with high amounts of gamma radiation then enriched, resulting in a culture of the bacteria. It was described as "an obligatory anaerobic heterotroph organism that grows optimally at 88C in the presense of sulfur or cystine on yeast extract, trpton, and peptone, producting H2S" (4).

Applications

An enzyme from gammatolerans called tps-S DNA polymerase has been found to exhibit more efficient binding behavior than Taq-polymerase for both long and rapid PCR (5). Additionally, enzymatic markers isolated from gammatolerans have been used in applications in which high temperature and radiation resistance are required. These markers are being used to study the effects of carcinogenesis and mitochondrial diseases. The DNA repair mechanism is also currently being studied. A genomics analysis revealed a circular chromosome which encoded for 2157 proteins largely conserved from other bacterial species. 

Citations

CANGANELLA, F., JONES, W. J., GAMBACORTA, A., & ANTRANIKIAN, G. (1998). Thermococcus guaymasensis sp. Nov. and Thermococcus aggregans SP. NOV., two NOVEL thermophilic ARCHAEA isolated from The GUAYMAS Basin hydrothermal vent site. International Journal of Systematic Bacteriology, 48(4), 1181-1185. doi:10.1099/00207713-48-4-1181

Dercourt, J., & Petit, M. (2007). Une Nouvelle Politique éditoriale de LA série geoscience des COMPTES RENDUS de L’ACADÉMIE des sciences. Comptes Rendus Geoscience, 339(16), 947-948. doi:10.1016/j.crte.2007.10.006

Hirata, A., Hori, Y., Koga, Y., Okada, J., Sakudo, A., Ikuta, K., . . . Takano, K. (2013). Enzymatic activity of a subtilisin homolog, TK-SP, FROM Thermococcus gammatolerans in detergents and its ability to degrade the abnormal prion protein. BMC Biotechnology, 13(1), 19. doi:10.1186/1472-6750-13-19

Jolivet, E., L'Haridon, S., Corre, E., Forterre, P., & Prieur, D. (2003). Thermococcus gammatolerans sp. nov., a hyperthermophilic archaeon from a deep-sea hydrothermal vent that resists ionizing radiation. International Journal of Systematic and Evolutionary Microbiology, 53(3), 847-851. doi:10.1099/ijs.0.02503-0

Tapias, A., Leplat, C., & Confalonieri, F. (2009). Recovery of ionizing-radiation damage after high doses of gamma ray in the hyperthermophilic archaeon thermococcus gammatolerans. Extremophiles, 13(2), 333-343. doi:10.1007/s00792-008-0221-3

Zivanovic, Y., Armengaud, J., Lagorce, A., Leplat, C., Guérin, P., Dutertre, M., . . . Confalonieri, F. (2009). Genome analysis and genome-wide proteomics of thermococcus Gammatolerans, the most Radioresistant organism known amongst the Archaea. Genome Biology, 10(6). doi:10.1186/gb-2009-10-6-r70