The order thermococcales and the family thermococcaceae

Abstract

Thermococcaceae, the only family within the order Thermococcales, consists of three genera, Pyrococcus, Thermococcus, and Palaeococcus. Virtually all have been isolated from hydrothermal marine vents. More than 30 species of Thermococcus and Pyrococcus have been described, and 17 genome sequences are currently available. So far only three Palaeococcus species have been isolated. The three genera are distinguished by their temperature optima for growth, which are typically near 100 °C, 85 °C, and 75 °C for species of Pyrococcus, Thermococcus, and Palaeococcus, respectively. All members of the Thermococcales are strictly anaerobic heterotrophs and are characterized by their ability to grow above 80 °C using peptides and elemental sulfur as the carbon and energy sources. Many are also able to utilize a wide variety of simple and complex carbohydrates. Several species have been extensively studied in terms of their primary metabolic pathways, and genetic systems have been developed for Pyrococcus furiosus and Thermococcus kodakarensis. Some members of the Thermococcales are among the best studied of all of the so-called hyperthermophiles, which are organisms that have an optimum growth temperature of at least 80 °C.