Halovivax limisalsi sp. nov., an extremely halophilic archaeon from hypersaline mud.

A Gram-stain-negative, cream-pigmented, motile, extremely halophilic archaeon, designated strain IC38(T), was isolated from a saline mud sample taken from a hypersaline lake, Aran-Bidgol, in Iran. The strain required at least 2.5 M NaCl for growth. However, MgCl2 was not required. Optimal growth occurred with 4.3 M NaCl and 0.2 M MgCl2. The optimum pH and temperature for growth were pH 7.0 and 35 °C, respectively, and strain IC38(T) was able to grow over a pH range of 6.5-9.0, and a temperature range of 25-45 °C. Analysis of the 16S rRNA gene sequence revealed that strain IC38(T) clustered with the two species of the genus Halovivax, Halovivax asiaticus EJ-46(T) and Halovivax ruber XH-70(T), with sequence similarities of 96.4% and 96.1%, respectively. The similarities between the rpoB' gene of the novel strain and Halovivax asiaticus and Halovivax ruber were 90.7% and 90.3%, respectively. The polar lipid pattern of strain IC38(T) consisted of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. Three unidentified glycolipids and two minor phospholipids were also observed. The DNA G+C content of strain IC38(T) was 62.6 mol%. On the basis of the phylogenetic analysis, as well as the biochemical and physiological characteristics, the new isolate is suggested to be a representative of a novel species of the genus Halovivax, for which the name Halovivax limisalsi sp. nov. is proposed. The type strain of Halovivax limisalsi is IC38(T) ( = IBRC-M 10022(T) = KCTC 4051(T)).