Thermococcus hydrothermalis sp. nov., a New Hyperthermophilic Archaeon Isolated from a Deep-Sea Hydrothermal Vent

Abstract

An extremely thermophilic archaeon, strain AL662^T, was isolated from a deep-sea hydrothermal vent located on the East Pacific Rise at a latitude of 21°N. This strain is a strictly anaerobic coccus, and its cells range from 0.8 to 2 μ in diameter. The optimum temperature, pH, and Sea Salt concentration for growth are 85°C, 6, and 20 to 40 g/liter, respectively. Strain AL662^Tgrows preferentially on proteolysis products, on a mixture of 20 amino acids, and on maltose in the presence of elemental sulfur. The membrane lipids consist of di- and tetraether glycerol lipids. The DNA G+C content is 58 mol%. Sequencing of the 16S rRNA gene showed that strain AL662^Tbelongs to the genus Thermococcus. On the basis of hybridization results, we propose that this strain should be placed in a new species, Thermococcus hydrothermalis.