Haloprofundus salilacus sp. nov., Haloprofundus halobius sp. nov. and Haloprofundus salinisoli sp. nov.: three extremely halophilic archaea isolated from salt lake and saline soil

Three halophilic archaeal strains, Gai1-5T, SEDH52T and SQT7-1T were isolated from Gaize salt lake and Xiadi salt lake in Tibet, and saline soil from Xinjiang, respectively. Phylogenetic analysis based on 16S rRNA gene and rpoB’ gene sequences showed that these three strains formed different branches separating them from Haloprofundus halophilus NK23T (97.7–98.3% similarities for 16S rRNA gene and 94.7–94.8% similarities for rpoB’ gene, respectively) and Haloprofundus marisrubri SB9T (94.7–96.4% similarities for 16S rRNA gene and 92.3–93.2% similarities for rpoB’ gene, respectively). Several phenotypic characteristics distinguish the strains Gai1-5 T, SEDH52T and SQT7-1T from Haloprofundus halophilus NK23T and Haloprofundus marisrubri SB9T. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values among the three strains and current Haloprofundus members were in the range of 83.3–88.3% and 27.2–35.7%, respectively, far below the species boundary threshold values. The major polar lipids of three strains were phosphatidic acid (PA), phosphatidylglycerol (PG), phosphatidylglycerol sulphate (PGS), phosphatidylglycerol phosphate methyl ester (PGP-Me), sulfated mannosyl glucosyl diether (S-DGD-1), mannosyl glucosyl diether-phosphatidic acid (DGD-PA) and sulfated mannosyl glucosyl diether-phosphatidic acid (S-DGD-PA). These results showed that strains Gai1-5T (= CGMCC 1.16079T = JCM 33561T), SQT7-1T (= CGMCC 1.16063T = JCM 33553 T) and SEDH52T (= CGMCC 1.17434T) represented three novel species in the genus Haloprofundus, for which the names Haloprofundus salilacus sp. nov., Haloprofundus salinisoli sp. nov., and Haloprofundus halobius sp. nov. are proposed.