gen. nov., sp. nov., an extremely halophilic archaeon isolated from a subterranean salt deposit.

A halophilic archaeon, strain H22, was isolated from a subterranean salt deposit sampled at Yunnan salt mine, PR China. Colonies of strain H22 were light pink-pigmented. Cells were coccus, non-motile, Gram-stain-negative, and did not lyse in distilled water. The strain was aerobic and grew at 20-55 °C (optimum, 37 °C), in the presence of 10-30 % (w/v) NaCl (20 %) and at pH 6.5-9.0 (pH 7.0). Mg was required for growth (optimum, 0.005 M). Major polar lipids were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and sulfated mannosyl-glucosyl-glycerol diether-1. Sequence similarity search based on the multiple 16S rRNA genes (, and ) of strain H22 revealed that it was most closely related to species of the genera , , and with relative low sequence similarities (91.9-93.7 %). The strain, however, shared highest gene sequence identities with TBN4 (90.8 % gene sequence similarity). Phylogenetic trees based on 16S rRNA and gene sequences revealed a robust lineage of the strain H22 with members of related genera of the family . The DNA G+C content of strain H22 was 62.9 mol%. Genome-based analysis of average nucleotide identity (ANI) and DNA-DNA hybridization (DDH) between strains H22 and its closest relative were equal or lower than 77.7 and 22.4 %, respectively, which were far below the threshold for delineation of a new species. Based on ANI values, DDH, and distinct morphological and physiological differences from the previously described taxa, we suggest that strain H22 represents a novel species of a new genus within the family , for which the name gen. nov., sp. nov. is proposed. The type strain is H22 (=CGMCC 1.16291=NBRC 113231).