An extremely halophilic archaeon, strain D108T, was isolated from a brine sample of Aran-Bidgol salt lake in Iran. The novel strain was cream-pigmented, motile, pleomorphic rod-shaped and required at least 2.5 M NaCl but not MgCl2 for growth. Optimal growth was achieved with 4.3 M NaCl and 0.1 M MgCl2. The optimum pH and temperature for growth were pH 7.5 and 40 °C, respectively, and the strain was able to grow over a pH range of 6.5 to 9.0, and a temperature range of 30 to 50 °C. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain D108T clustered with the type strain of the sole species of the genus Halorientalis , Halorientalis regularis TNN28T, with a sequence similarity of 98.8 %. The polar lipid pattern of strain D108T consisted of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, one phosphoglycolipid and two glycolipids. The only quinone present was MK-8(II-H2). The DNA G+C content of strain D108T was 62.8 mol%. DNA–DNA hybridization studies (45 % with Halorientalis regularis IBRC-M 10760T), as well as biochemical and physiological characterization, allowed strain D108T to be differentiated from Halorientalis regularis . A novel species of the genus Halorientalis , Halorientalis persicus sp. nov., is therefore proposed to accommodate this strain. The type strain is D108T ( = IBRC-M 10043T = CECT 8375T). An emended description of the genus Halorientalis is also proposed.
A halophilic archaeal strain, GX48T, was isolated from the Gangxi marine solar saltern near Weihai city in Shandong Province, China. Cells of the strain were rod-shaped, stained Gram-negative and formed red-pigmented colonies. Strain GX48T was able to grow at 25–50 °C (optimum 37 °C), in the presence of 1.4–4.8 M NaCl (optimum 2.6 M NaCl), with 0–1.0 M MgCl2 (optimum 0.05 M MgCl2) and at pH 5.5–9.5 (optimum pH 7.0). Cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 8 % (w/v). The major polar lipids of the strain were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and two major glycolipids chromatographically identical to those of Natronoarchaeum mannanilyticum YSM-123T and Natronoarchaeum philippinense 294-194-5T. 16S rRNA gene analysis revealed that strain GX48T had two dissimilar 16S rRNA genes and both of them were phylogenetically related to those of the two current members of the genus Natronoarchaeum (96.2–98.3 % similarities). The rpoB′ gene sequence similarities between strain GX48T and Natronoarchaeum mannanilyticum YSM-123T and Natronoarchaeum philippinense 294-194-5T were 96.0 % and 94.7 %, respectively. The DNA G+C content of strain GX48T was 66.2 mol%. Strain GX48T showed low DNA–DNA relatedness with the two members of the genus Natronoarchaeum . It was concluded that strain GX48T ( = CGMCC 1.10388T = JCM 17119T) represents a novel species of the genus Natronoarchaeum , for which the name Natronoarchaeum rubrum sp. nov. is proposed. An emended description of the genus Natronoarchaeum is also presented.