Halorubrum Gandharaense Sp Nov., An Alkaliphilic Haloarchaeon From Commercial Rock Salt

A Gram-stain-negative, non-motile, pleomorphic rod-shaped, orange-red-pigmented, facultatively aerobic and haloalkaliphilic archaeon, strain MK13-1(T), was isolated from commercial rock salt imported from Pakistan. The NaCl, pH and temperature ranges for growth of strain MK13-1(T) were 3.0-5.2 M NaCl, pH 8.0-11.0 and 15-50 degrees C, respectively. Optimal growth occurred at 3.2-3.4 M NaCl, pH 9.0-9.5 and 45 degrees C. Addition of Mg2+ was not required for growth. The major polar lipids of the isolate were C20C20 and C20C25 archaeol derivatives of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. Glycolipids were not detected. The DNA G+C content was 64.1 mol%. The 16S rRNA gene sequence of strain MK13-1(T). was most closely related to those of the species of the genus Halorubrum, Halorubrum luteum CECT 7303(T) (95.9 % similarity), Halorubrum alkaliphilum JCM 12358(T) (95.3 %), Halorubrum kocurii JCM 14978(T) (95.3 %) and Halorubrum lipolyticum JCM 13559(T) (95.3 %). The rpoB' gene sequence of strain MK13-1(T) had <90 % sequence similarity to those of other members of the genus Halorubrum. Based on the phylogenetic analysis and phenotypic characterization, strain MK13-1(T) may represent a novel species of the genus Halorubrum, for which the name Halorubrum gandharaense sp. nov. is proposed, with the type strain MK13-1(T) (=JCM 17823(T)=CECT 7963(T)).