Strain CC65T, a novel extremely halophilic archaeon, was isolated from a brine sample of a salt lake in Iran. The novel strain was light yellow pigmented, non-motile, pleomorphic and required at least 1.7 M NaCl and 0.02 M MgCl2 for growth. Optimal growth was achieved at 3.5 M NaCl and 0.4 M MgCl2. The optimum pH and temperature for growth were pH 7.5 and 40 °C, respectively, while it was able to grow over a pH and a temperature range of 6.5-9.0 and 30-50 °C, respectively. Analysis of 16S rRNA gene sequence revealed that strain CC65T clustered with the sole member of the genus Halopenitus, Halopenitus persicus with a sequence similarity of 98.0%. The polar lipid pattern of strain CC65T consisted of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. An unidentified glycolipid and two minor phospholipids were also observed. The only quinone present was MK-8(ΙΙ-H2). The G+C content of its DNA was 63.8 mol%. On the basis of the biochemical and physiological characteristics, as well as DNA-DNA hybridization (44% with Halopenitus persicus IBRC 10041T), the new isolate could be classified as a novel species of the genus Halopenitus, for which the name Halopenitus malekzadehii sp. nov. is proposed. The type strain of Halopenitus malekzadehii is CC65T (=IBRC-M 10418T = KCTC 4045T).

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