Halobellus clavatus gen. nov., sp. nov. and Halorientalis regularis gen. nov., sp. nov., two new members of the family Halobacteriaceae

Abstract

Four halophilic archaeal strains, designated TNN18T, TBN12, TNN28T and TBN19, were isolated from brines sampled from two artificial marine solar salterns in eastern China. Strains TNN18T and TNN28T were isolated from the Tainan marine solar saltern, whereas strains TBN12 and TBN19 were from the Taibei marine solar saltern. Colonies of the four strains were red-pigmented and their cells were pleomorphic, motile, Gram-reaction-negative rods. Strains TNN18T and TBN12 were able to grow at 25–50 °C (optimum 37 °C), in 10–30 % (w/v) NaCl (optimum 15 %), with 0–1.0 M MgCl2 (optimum 0.05 M) and at pH 5.5–9.0 (optimum pH 7.0–7.5), while strains TNN28T and TBN19 were able to grow at 20–50 °C (optimum 37 °C), in 15-30 % (w/v) NaCl (optimum 18–20 %), in 0.005–1.0 M MgCl2 (optimum 0.01–0.3 M) and at pH 6.0–9.0 (optimum pH 7.0–7.5). Cells of these strains lyse in distilled water; minimal NaCl concentrations to prevent cell-lysis are 10 % (w/v) for strains TNN18T and TBN12 and 12 % (w/v) for strains TNN28T and TBN19. The major polar lipids of strains TNN18T and TBN12 were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfate (PGS) and one major glycolipid (GL1), which was chromatographically identical to sulfated mannosyl glucosyl diether (S-DGD-1). Minor amounts of other lipids (GL0, GL2, GL3 and GL4) were also detectable. The polar lipid profiles of strains TNN28T and TBN19 contained PG, PGP-Me, GL1, which was chromatographically identical to S-DGD-1, and three to four minor unidentified glycolipids (GL2–GL5). Phylogenetic analyses revealed that strains TNN18T and TBN12 formed a distinct clade with strains of the closest related species, Haloquadratum walsbyi (91.5–91.8 % 16S rRNA gene sequence similarity) and strains TNN28T and TBN19 formed a distinct clade with strains of the species Halosimplex carlsbadense (89.9–93.3 % similarity) and two members of the genus Halorhabdus (92.5–93.3 % similarity). The DNA G+C contents of strains TNN18T, TBN12, TNN28T and TBN19 were 61.5, 62.4, 61.9 and 61.5 mol%, respectively. DNA–DNA hybridization values between strains TNN18T and TBN12, and strains TNN28T and TBN19 were 82.9 % and 88.2 %, respectively. The phenotypic, chemotaxonomic and phylogenetic properties suggest that the four strains represent two novel species of two new genera within the family Halobacteriaceae, for which the names Halobellus clavatus gen. nov., sp. nov. (type strain TNN18T  = CGMCC 1.10118T  = JCM 16424T) and Halorientalis regularis gen. nov., sp. nov. (type strain TNN28T  = CGMCC 1.10123T  = JCM 16425T) are proposed.