Halorubellus salinus gen. nov., sp. nov. and Halorubellus litoreus sp. nov., novel halophilic archaea isolated from a marine solar saltern

Two extremely halophilic archaeal strains GX3ᵀ and GX26ᵀ were isolated from the Gangxi marine solar saltern near the Weihai city of Shandong Province, China. Cells from the two strains were pleomorphic and stained Gram-negative, colonies were red-pigmented. Strains GX3ᵀ and GX26ᵀ were able to grow at 25–50°C (optimum 37°C), at 1.4–5.1M NaCl (optimum 3.1M), at pH 5.5–9.5 (optimum pH 7.0) and neither strain required Mg²⁺ for growth. Cells lyse in distilled water and the minimal NaCl concentration to prevent cell-lysis was 8% (w/v). The major polar lipids of the two strains were PA (phosphatidic acid), PG (phosphatidylglycerol), PGP-Me (phosphatidylglycerol phosphate methyl ester) and three major glycolipids (GL1, GL2 & GL3) chromatographically identical to S-TGD-1 (sulfated galactosyl mannosy glucosyl diether), S-DGD-1 (sulfated mannosyl glucosyl diether), and DGD-1 (mannosyl glucosyl diether) respectively, an unidentified lipid (GL4) was also detected in strain GX26ᵀ. Phylogenetic analysis based on 16S rRNA gene revealed that strain GX3ᵀ and strain GX26ᵀ formed a distinct clade with the closest relative, Haladaptatus paucihalophilus (89.9–92.4% and 90.4–92.7, respectively). The rpoB′ gene similarities between strains GX3ᵀ and GX26ᵀ, and between the two strains and the closest relative, Halorussus rarus TBN4ᵀ are 96.5%, 84.3% and 83.9%, respectively. The DNA G+C contents of strain GX3ᵀ and strain GX26ᵀ are 67.3mol% and 67.2mol%, respectively. The DNA–DNA hybridization value between strain GX3ᵀ and strain GX26ᵀ was 44%. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strain GX3ᵀ and strain GX26ᵀ represent two novel species in a new genus within the family Halobacteriaceae, Halorubellus salinus gen. nov., sp. nov. (type strain GX3ᵀ=CGMCC 1.10384ᵀ=JCM 17115ᵀ) and Halorubellus litoreus sp. nov. (type strain GX26ᵀ=CGMCC 1.10386ᵀ=JCM 17117ᵀ).