Halospeciosus flavus gen. nov., sp. nov. and Haladaptatus caseinilyticus sp. nov., halophilic archaea isolated from saline soil of an inland solar saltern and offshore sediment

Two novel halophilic archaeal strains (XZGYJ-43 T and ZJ1 T ) were isolated from Mangkang ancient solar saltern (Tibet, PR China) and Zhujiang river inlet (Guangdong, PR China), respectively. The comparison of the 16S rRNA gene sequences revealed that strain XZGYJ-43 T is related to the current species of the family Halobacteriaceae (89.2–91.7% similarity) and strain ZJ1 T showed 94.7–98.3% similarity to the current species of the genus Haladaptatus . Phylogenetic analyses based on 16S rRNA genes, rpoB ′ genes and genomes indicated that strain XZGYJ-43 T is separate from the related genera, Halocalculus , Salarchaeum and Halarchaeum of the family Halobacteriaceae , and strain ZJ1 T tightly clusters with the current species of the genus Haladaptatus . The average nucleotide identity, digital DNA–DNA hybridization and average amino acid identity values between strain XZGYJ-43 T and the current species of the family Halobacteriaceae were 71–75, 20–25 and 59–68 %, and these values between strain ZJ1 T and the current species of the genus Haladaptatus were 77–81, 27–32 and 76–82 %, respectively, clearly below the thresholds for prokaryotic species demarcation. These two strains could be distinguished from their relatives according to differential phenotypic characteristics. The major polar lipids of strain XZGYJ-43 T were phosphatidic acid (PA), phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), mannosyl glucosyl diether (DGD-1; DGD-PA) and sulphated mannosyl glucosyl diether (S-DGD-1; S-DGD-PA), and those of strain ZJ1 T were PA, PG, PGP-Me, DGD-PA, S-DGD-1 (S-DGD-PA) and sulphated galactosyl mannosyl glucosyl diether. Based on phenotypic, phylogenetic and genomic data, strain XZGYJ-43 T (=CGMCC 1.13890 T =JCM 33735 T ) represents a novel species of a new genus within the family Halobacteriaceae , and strain ZJ1 T (=CGMCC 1.18785 T =JCM 34917 T ) represents a novel species of the genus Haladaptatus , for which the names Halospeciosus flavus gen. nov., sp. nov. and Haladaptatus caseinilyticus sp. nov. are proposed, respectively.