Thermococcus gammatolerans is an archaea

Archaea

The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...

 extremophile

Extremophile

An extremophile is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth. In contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles...

 and the most radiation

Radiation

In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...

 resistant known organism.

Discovered in 2003 in a submarine hydrothermal vent in the Guaymas Basin

Guaymas Basin

The Guaymas Basin is a submarine depression located on the seabed in the central area of the Gulf of California. It is the largest such basin in the Gulf. The basin results from the activity of one of the several spreading centers in the Gulf. The basin is linked to the Carmen Fault to the...

 about 2,000 meters deep off the coast of California. Thermococcus gammatolerans thrives in temperatures between 55-95 °C with an optimum development at approximately 88 °C.
The optimal growth pH is 6, favoring the presence of sulfur (S), which is reduced to hydrogen sulfide (H2S). It is the organism with the strongest resistance to radiation

Radioresistance

Radioresistance is the property of organisms that are capable of living in environments with very high levels of ionizing radiation.Radioresistance is surprisingly high in many organisms, in contrast to previously held views...

 , supporting a radiation of gamma rays from 30 KGy.

Along with the genera Palaeococcus and Pyrococcus, Thermococcus belongs to the Thermococcaceae

Thermococcaceae

In taxonomy, the Thermococcaceae are a family of the Thermococcales.- External links :...

 family, sole family of the Thermococci

Thermococci

In taxonomy, the Thermococci are a class of the Euryarchaeota.-External links:...

 (called "Protoarchaea" by Cavalier-Smith), a class in the phylum Euryarchaeota

Euryarchaeota

In the taxonomy of microorganisms, the Euryarchaeota are a phylum of the Archaea.The Euryarchaeota include the methanogens, which produce methane and are often found in intestines, the halobacteria, which survive extreme concentrations of salt, and some extremely thermophilic aerobes and anaerobes...

 of Archaea.
Thermococcus species live in extremely hot environments such as hydrothermal vents with a growth optimum temperature above 80 °C. Thermococcus and Pyrococcus (literally "ball of fire") are both chemoorganotrophic anaerobic

Anaerobic organism

An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It could possibly react negatively and may even die if oxygen is present...

 required. Thermococcus spp. prefer 70-95 °C, whereas Pyrococcus prefer 70-100 °C.

The resistance to ionizing radiation of T. gammatolerans is enormous. While a dose of 5 Gy is sufficient to kill a human being, and a dose of 60 Gy is able to kill all cells in a colony of E. coli, Thermococcus gammatolerans can withstand doses of up to 30,000 Gy, and an instantaneous dose of up to 5,000 Gy with no loss of viability.

History

Thermococcus gammatolerans was discovered in 2003 in samples collected from a hydrothermal chimney at the Guaymas Basin about 2,000 meters deep off the coast of California (27° 1' N, 111° 24' W).

Mechanisms of resistance to radiation

Unlike other organisms, cell survival in Thermococcus gammatolerans is not altered by changing conditions in its growth phase, but the lack of ideal conditions and nutrients decreases its radioresistance.
The system of chromosomal DNA repair shows that cells in stationary phase of growth reconstitute DNA more rapidly than cells in exponential growth phase.
T. gammatolerans can slowly or quickly rebuild damaged chromosomes without loss of viability.

Applications

There has been study of its application to the development of new enzymatic markers that are resistant to high temperatures and their application in the study of carcinogenesis and the study of the development of mitochondrial diseases.
It has been speculated that DNA repair mechanisms of T. gammatolerans could be incorporated into the genome of higher species in order to improve DNA repair and reduce cellular ageing.

Etymology

Thermococcus: Greek feminine

Grammatical gender

Grammatical gender is defined linguistically as a system of classes of nouns which trigger specific types of inflections in associated words, such as adjectives, verbs and others. For a system of noun classes to be a gender system, every noun must belong to one of the classes and there should be...

 noun thermê (θέρμη), heat; Neolatin masculine noun coccus (from Greek masculine noun kokkos (κόκκος), berry), coccus

Bacterial cellular morphologies

Bacteria are classified by direct examination with the light microscope through its morphology and aggregation.The basic forms are spheres and round-ended cylinders . But there may be others such as helically-twisted cylinders , cylinders curved in one plane and unusual morphologies...

; Neolatin masculine noun Thermococcus, coccus existing in hot environment.
gammatolerans: Gr. gamma (γάμμα), referring to gamma rays; Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

participle adjective tolerans, tolerating; Neolatin participle adjective gammatolerans, referring to its ability to tolerate high levels of γ-rays.