Haloplanus vescus sp. nov., an extremely halophilic archaeon from a marine solar saltern, and emended description of the genus Haloplanus.
An extremely halophilic archaeon, strain RO5-8T, was isolated from a disused marine solar saltern in China. The cells were pleomorphic and flat. In static liquid medium, cells floated to the surface. Strain RO5-8T stained Gram-negative and colonies were pink-pigmented. It was able to grow at 30-50 degrees C (optimum 40 degrees C), at 2.6-4.3 M NaCl (optimum 3.1 M NaCl), at 0.03-0.5 M MgCl2 (optimum 0.03 M MgCl2) and at pH 5.5-7.5 (optimum pH 6.0-6.5). Cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 12% (w/v). The major polar lipids of strain RO5-8T were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and one major glycolipid chromatographically identical to the sulfated mannosyl glucosyl diether S-DGD-1. On the basis of 16S rRNA gene sequence analysis, strain RO5-8T was closely related to three strains of Haloplanus natans with similarities of 97.3-97.6%. The DNA G+C content of strain RO5-8T was 62.1 mol%. The DNA-DNA hybridization value between strain RO5-8T and Haloplanus natans JCM 14081T was 51.6%. It was concluded that strain RO5-8T represents a novel species of the genus Haloplanus, for which the name Haloplanus vescus sp. nov. is proposed. The type strain is RO5-8T (=CGMCC 1.8712T =JCM 16055T).DOI: 10.1099/ijs.0.018564-0