Genome-Based Reclassification of Two Haloarcula Species and Characterization of Haloarcula montana sp. nov.

The genus Haloarcula is one of the most extensively studied genera within the class Halobacteria. In this study, analyses of average nucleotide identity (ANI), average amino acid identity (AAI), digital DNA-DNA hybridization (dDDH) values, and phylogenomic data indicated that "Haloarcula californiae" ATCC 33799 and "Haloarcula sinaiiensis" ATCC 33800 served as reference strains for Haloarcula marismortui. Furthermore, a halophilic archaeal strain, GH36T, isolated from the inland Gahai Salt Lake in China, was subjected to comprehensive polyphasic taxonomic characterization. The ANI, AAI, and dDDH comparisons between strain GH36T and other Haloarcula species were below the established thresholds for species demarcation. Strain GH36T was assigned to a novel species within the genus Haloarcula based on phylogenetic, phylogenomic, and comparative genomic analyses. Moreover, distinct phenotypic differences were observed in strain GH36T. In strain GH36T, the primary phospholipids detected were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), and phosphatidylglycerol sulfate (PGS), whereas the principal glycolipids were sulfated mannosyl glucosyl diether (S-DGD-1) and mannosyl glucosyl diether (DGD-1). Accordingly, the novel species Haloarcula montana sp. nov. is proposed to accommodate strain GH36T (=CGMCC 1.62631T = MCCC 4K00122T).