Thermococcus acidaminovorans sp. nov., a new hyperthermophilic alkalophilic archaeon growing on amino acids

From a shallow marine hydrothermal system at Vulcano (Italy), a new hyperthermophilic member of the Archaea was isolated. The cells are coccoid – shaped and possess up to five flagella. They grow between 56° and 93°C (optimum 85°C) and pH 5.0–9.5 (optimum 9.0). The organism is strictly anaerobic and grows heterotrophically on defined amino acids and complex organic substrates such as casamino acids, yeast extract, peptone, meat extract, tryptone, and casein. Polysulfide and elemental sulfur are reduced to H₂S. In the absence of polysulfide or elemental sulfur, the isolate grows at a significantly reduced rate. Growth is not influenced by the presence of H₂. DNA–DNA hybridization and 16S rRNA partial sequences indicated that the new isolate belongs to the genus Thermococcus, and represents a new species, Thermococcus acidaminovorans. The type strain is isolate AEDII10 (DSM 11906). Received: September 24, 1997 / Accepted: January 1, 1998