Genomic, Physiological, Biochemical, and Phenotypic Evidences Reveal a New Species, Halomicroarcula salaria sp. nov

Abstract

An extremely halophilic archaeon strain named FL173^T was isolated from a salt mine (Anhui Province, China). Colonies on agar plate are orange-red, moist, and opaque. Cells are motile, Gram-stain-negative, polymorphic, and lyse in distilled water. Cells are able to grow at temperatures, NaCl concentrations, and pH ranging from 20 to 50 °C (optimum 42 °C), 2.6 to 5.1 M NaCl concentration (optimum 3.4 M), and 5.5 to 9.5 pH (optimum 7.0), respectively. Mg²⁺ is not necessary for growth. The major polar lipids of strain FL173^T were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfonate (PGS), sulfonated mannosyl glycolipid (S-DGD-1). It has two copies of the 16S rRNA gene, which share the highest sequence similarity (93.04-99.02% sequence similarity) to the 16S rRNA genes of Halomicroarcula salinisoli F24A^T, respectively. The rpoB' gene of strain FL173^T showed the highest sequence similarity (93.76%) to that of H. salinisoli F24A^T. The genome-based analysis showed that the average amino-acid identity (AAI), orthologous average nucleotide identity (ANI) and in silico DNA-DNA hybridization values between strains FL173^T and H. salinisoli F24A^T were 84.80%, 85.29%, and 29.70%, respectively, which are far below the threshold for the delineation of a prokaryotic new species. The DNA G+C content of strain FL173^T is 64.9%. Genomic, physiological, biochemical, and phenotypic evidences showed that strain FL173^T (CGMCC 1.18851=NBRC 114260) represents a new species of the genus Halomicroarcula, for which the name Halomicroarcula salaria sp. nov. is proposed.