Halalkalirubrum salinum gen. nov., sp. nov., a halophilic archaeon isolated from a saline lake

A novel extremely halophilic archaeon, strain N1521 T , was isolated from a saline lake in Tibet, China. Cells of the strain were pleomorphic and Gram-stain-negative. It produced red pigments. Growth was observed at 4–42 °C (optimum, 37 °C), pH 7.0–10.5 (optimum, 8.0–9.5), NaCl 11%–25% (optimum, 15%) and in the presence of 0–0.1 M MgCl 2 (optimum, 0.05 M) in aerobic conditions. The minimum NaCl concentration that prevented cell lysis was 2% (w/v). The major polar lipids of strain N1521 T were phosphatidylglycerol sulfate, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol and an unidentified glycolipid. The DNA G + C content was 58.37 mol%. According to 16S rRNA gene sequence comparisons, strain N1521 T revealed the highest sequence similarity to Haloprofundus halophilus NK23 T (91.38%) and Halogranum amylolyticum TNN58 T (91.00%), and low sequence similarities (< 91%) with other genera in the order Haloferacales . Phylogenetic analysis based on the 16S rRNA gene and rpoB ′ gene sequence showed that strain N1521 T was distinct from the members of the order Haloferacales . The digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity values calculated from whole genome-sequence comparison between strain N1521 T and the members of the order Haloferacales were in the ranges of 15.1–18.2%, 68.8–73.0%, and 58.4–63.9%, respectively. Phylogenetic tree reconstructions based on the whole-genome sequences revealed that strain N1521 T was closer to the members of the family Halorubraceae . Based on the data obtained, strain N1521 T is thus considered to represent a novel species of a new genus within the family Halorubraceae , for which the name Halalkalirubrum salinum gen. nov., sp. nov. is proposed. The type strain is N1521 T (= CGMCC 1.16693 = JCM 33785).