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 1 2% (w/v) NaCl to grow. The strain is highly thermotolerant: its temperature optimum is 50 degrees C and growth is possible up to 60 degrees C. Polar l ipid analysis revealed the presence of the bis-sulfated glycolipid S-2-DGD- 1 as sole glycolipid and the absence of the glycerol diether analogue of ph osphatidyl-glycerosulfate, Both C-20,C-20 and C-20,C-25 core lipids are pre sent. The G+C content of the DNA is 63.3 mol%. According to 16S rDNA sequen ce data, strain PR5(T) is closely related to the representatives of the gen era Haloterrigena and Natrinema, but on the basis of its phenotypic propert ies, 16S rDNA sequence and DNA-DNA hybridization studies, strain PR5(T) can not be assigned to any of the recognized species within these genera. On th e basis of its polar lipid composition, the isolate has been assigned to th e genus Haloterrigena. The creation of a new species, Haloterrigena thermot olerans, is therefore proposed to accommodate this isolate. The type strain is strain PR5(T) (= DSM 11552(T) = ATCC 700275T).