Haloterrigena thermotolerans sp. nov., a halophilic archaeon from Puerto Rico

An extremely halophilic Archaeon belonging to the order Halobacteriales was isolated from the solar salterns of Cabo Rojo, Puerto Rico. The organism, designated strain PR5(T), is rod-shaped, non-motile and requires at least 12% (w/v) NaCl to grow. The strain is highly thermotolerant: its temperature optimum is 50 °C and growth is possible up to 60 °C. Polar lipid analysis revealed the presence of the bis-sulfated glycolipid S₂-DGD-1 as sole glycolipid and the absence of the glycerol diether analogue of phosphatidyl- glycerosulfate. Both C₂₀,C₂₀ and C₂₀,C₂₅ core lipids are present. The G+C content of the DNA is 63·3 mol%. According to 16S rDNA sequence data, strain PR5(T) is closely related to the representatives of the genera Haloterrigena and Natrinema, but on the basis of its phenotypic properties, 16S rDNA sequence and DNA-DNA hybridization studies, strain PR5(T) cannot be assigned to any of the recognized species within these genera. On the basis of its polar lipid composition, the isolate has been assigned to the genus Haloterrigena. The creation of a new species, Haloterrigena thermotolerans, is therefore proposed to accommodate this isolate. The type strain is strain PR5(T) (= DSM 11552(T) = ATCC 700275(T)).