RÉSUMÉ
Two extremely halophilic archaea, strains MGY-184(T) and MGY-205, were isolated from sea salt produced in Japan and rock salt imported from Bolivia, respectively. Both strains were pleomorphic, non-motile, Gram-negative and required more than 5â% (w/v) NaCl for growth, with optimum at 9-12â%, in the presence of 2â% (w/v) MgCl2â.â6H2O. In the presence of 18â% (w/v) MgCl2â.â6H2O, however, both strains showed growth even at 1.0â% (w/v) NaCl. Both strains possessed two 16S rRNA genes (rrnA and rrnB), and they revealed closest similarity to Halobaculum gomorrense JCM 9908(T), the single species with a validly published name of the genus Halobaculum, with similarity of 97.8â%. The rrnA and rrnB genes of both strains were 100â% similar. The rrnA genes were 97.6â% similar to the rrnB genes in both strains. DNA G+C contents of strains MGY-184(T) and MGY-205 were 67.0 and 67.4 mol%, respectively. Polar lipid analysis revealed that the two strains contained phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester derived from C20C20 archaeol. The DNA-DNA hybridization value between the two strains was 70â% and both strains showed low levels of DNA-DNA relatedness (48-50â%) with Halobaculum gomorrense JCM 9908(T). Physiological and biochemical characteristics allowed differentiation of strains MGY-184(T) and MGY-205 from Halobaculum gomorrense JCM 9908(T). Therefore, strains MGY-184(T) and MGY-205 represent a novel species of the genus Halobaculum, for which the name Halobaculum magnesiiphilum sp. nov. is proposed; the type strain is MGY-184(T) (â=âJCM 17821(T)â=âKCTC 4100(T)).