Haloarcula sebkhae sp. nov., an extremely halophilic archaeon from Algerian hypersaline environment

Abstract

A halophilic organism, SWO25^T, was isolated from water sampled in Algeria at the salt lake (sebkha) of Ouargla. The novel strain stained Gram-negative, and cells were pleomorphic with a red pigmentation. Strain SWO25^T grew optimally at 35-45 °C, at pH 6.0-8.0 and 0.05-0.25 M MgCl2 concentrations. Cells were extremely halophilic, with optimal growth at 4.3-5.1 M NaCl. The predominant membrane polar lipids were C20C20 glycerol diether derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate, phosphatidylglycerol sulfate, triglycosyl diether and diglycosyl diether. The major respiratory menaquinone component was MK-8. Cells were highly tolerant to the presence of decane and isooctane in the growth medium. Chemotaxonomic properties supported the assignment of strain SWO25^T to the genus Haloarcula. The DNA G+C content was 61.1mol%. DNA-DNA hybridization and phylogenetic analyses of the 16S rRNA and rpoB' genes showed that strain SWO25^T is distinct from known Haloarcula species. Based on phenotypic, chemotaxonomic, genotypic and phylogenetic data, we describe a novel species of the genus Haloarcula, for which the name Haloarculasebkhae sp. nov. is proposed. The type strain is SWO25^T (=CIP 110583^T=JCM 19018^T).