Thermococcus

Thermococcus is a genus of thermophilic Archaea in the family the Thermococcaceae.

Members of the genus Thermococcus are typically irregularly shaped coccoid species, ranging in size from 0.6 to 2.0 μm in diameter. Some species of Thermococcus are immobile, and some species have motility, using flagella as their main mode of movement. These flagella typically exist at a specific pole of the organism. This movement has been seen at room or at high temperatures, depending on the specific organism. In some species, these microorganisms can aggregate and form white-gray plaques. Species under Thermococcus typically thrive at temperatures between 60 and 105 °C, either in the presence of black smokers (hydrothermal vents), or freshwater springs. Species in this genus are strictly anaerobes, and are thermophilic, found in a variety depths, such as in hydrothermal vents 2500m below the ocean surface, but also centimeters below the water surface in geothermal springs. These organisms thrive at pH levels of 5.6-7.9. Members of this genus have been found in many hydrothermal vent systems in the world, including from the seas of Japan, to off the coasts of California. Sodium Chloride salt is typically present in these locations at 1%-3% concentration, but is not a required substrate for these organisms, as one study showed Thermococcus members living in fresh hot water systems in New Zealand, but they do require a low concentration of lithium ions for growth. Thermococcus members are described as heterotrophic, chemotrophic, and are organotrophic sulfanogens; using elemental sulfur and carbon sources including amino acids, carbohydrates, and organic acids such as pyruvate.