Haladaptatus halobius sp. nov. and Haladaptatus salinisoli sp. nov., two extremely halophilic archaea isolated from Gobi saline soil

Abstract

Two extremely halophilic archaeal strains, PSR5T and PSR8T, were isolated from a saline soil sample collected from the Tarim Basin, Xinjiang, PR China. Both strains had two copies of the 16S rRNA genes rrn1 and rrn2, showing 2.6 and 3.9% divergence, respectively. The rrn1 gene of PSR5T showed 98.4 and 95.3% similarity to the rrn1 and rrn2 genes of strain PSR8T; the rrn2 gene of PSR5T displayed 97.4 and 96.7% similarity to those of strain PSR8T, respectively. Phylogenetic analyses based on the 16S rRNA and rpoB′ genes revealed that strains PSR5T and PSR8T formed a single cluster, and then tightly clustered with the current four Haladaptatus species (93.5–97.1% similarities for the 16S rRNA gene and 89.3–90.9% similarities for the rpoB′ gene, respectively). Several phenotypic characteristics differentiate strains PSR5T and PSR8T from current Haladaptatus members. The polar lipids of the two strains are phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester phosphatidylglycerol sulphate and three glycolipids. One of the glycolipids is sulphated mannosyl glucosyl diether, and the remaining two glycolipids are unidentified. The average nucleotide identity, in silico DNA–DNA hybridization, amino acid identity and percentage of conserved proteins values between the two strains were 88.5, 39.1, 89.3 and 72.8 %, respectively, much lower than the threshold values proposed as a species boundary. These values among the two strains and Haladaptatus members were 77.9–79.2, 22.0–23.5, 75.1–78.2 and 56.8–69.9 %, respectively, much lower than the recommended threshold values for species delimitation. These results suggested that strains PSR5T and PSR8T represent two novel species of Haladaptatus . Based on phenotypic, chemotaxonomic, genomic and phylogenetic properties, strains PSR5T (=CGMCC 1.16851T=JCM 34141T) and PSR8T (=CGMCC 1.17025T=JCM 34142T) represent two novel species of the genus Haladaptatus , for which the names Haladaptatus halobius sp. nov. and Haladaptatus salinisoli sp. nov. are proposed.

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

“…The genomes of the current Haladaptatus species range from 3.9 to 7.3 Mbp and their G+C contents are 56.1-62.1 mol% [3][4][5][6][7]. In the previous investigation of the halophilic archaeal diversity of hypersaline environments in PR China, halophilic archaeal strains XZGYJ-43 T and ZJ1 T were isolated from Mangkang ancient solar saltern (Tibet) and Zhujiang river inlet (Guangdong), respectively [8,9].…”

“…The major polar lipids of the genus Haladaptatus were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulphate (PGS), sulphated mannosyl glucosyl diether (S-DGD-1) and two to four unidentified glycolipids. The genomes of the current Haladaptatus species range from 3.9 to 7.3 Mbp and their G+C contents are 56.1–62.1 mol% [3–7]. In the previous investigation of the halophilic archaeal diversity of hypersaline environments in PR China, halophilic archaeal strains XZGYJ-43 T and ZJ1 T were isolated from Mangkang ancient solar saltern (Tibet) and Zhujiang river inlet (Guangdong), respectively [8, 9].…”

Halomicrococcus gelatinilyticus sp. nov. and Halosimplex aquaticum sp. nov., halophilic archaea isolated from saline soil and an inland solar saltern

“…Halophilic archaea of the class Halobacteria are the most abundant archaea in the saline soil from saline-alkali lands and inland solar salterns distributed in the western regions of China [1–4]. In recent years, more and more halophilic archaea isolated from the saline soil of these environments have been described as novel species, such as Halostella limicola [5], Haloprofundus halophilus [6], Haladaptatus halobius , Haladaptatus salinisoli [7], Haloprofundus salilacus and Haloprofundus salinisoli [8]. Due to harbouring diverse haloarchaea, these regions have attracted a great deal of research attention for the isolation of novel halophilic archaea.…”