sp. nov. and sp. nov., two extremely halophilic archaea isolated from Gobi saline soil.

Two extremely halophilic archaeal strains, PSR5 and PSR8, were isolated from a saline soil sample collected from the Tarim Basin, Xinjiang, PR China. Both strains had two copies of the 16S rRNA genes and , showing 2.6 and 3.9% divergence, respectively. The gene of PSR5 showed 98.4 and 95.3% similarity to the and genes of strain PSR8; the gene of PSR5 displayed 97.4 and 96.7% similarity to those of strain PSR8, respectively. Phylogenetic analyses based on the 16S rRNA and genes revealed that strains PSR5 and PSR8 formed a single cluster, and then tightly clustered with the current four species (93.5-97.1% similarities for the 16S rRNA gene and 89.3-90.9% similarities for the gene, respectively). Several phenotypic characteristics differentiate strains PSR5 and PSR8 from current members. The polar lipids of the two strains are phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester phosphatidylglycerol sulphate and three glycolipids. One of the glycolipids is sulphated mannosyl glucosyl diether, and the remaining two glycolipids are unidentified. The average nucleotide identity, DNA-DNA hybridization, amino acid identity and percentage of conserved proteins values between the two strains were 88.5, 39.1, 89.3 and 72.8 %, respectively, much lower than the threshold values proposed as a species boundary. These values among the two strains and members were 77.9-79.2, 22.0-23.5, 75.1-78.2 and 56.8-69.9 %, respectively, much lower than the recommended threshold values for species delimitation. These results suggested that strains PSR5 and PSR8 represent two novel species of . Based on phenotypic, chemotaxonomic, genomic and phylogenetic properties, strains PSR5 (=CGMCC 1.16851=JCM 34141) and PSR8 (=CGMCC 1.17025=JCM 34142) represent two novel species of the genus , for which the names sp. nov. and sp. nov. are proposed.