Natrinema salaciae sp. nov., a halophilic archaeon isolated from the deep, hypersaline anoxic Lake Medee in the Eastern Mediterranean Sea.

Abstract Two halophilic archaea, strains MDB25 T and MDB20, were isolated from a sample of the brine from Lake Medee, at a depth of 3050 m, in the Mediterranean Sea. Cells of the organisms were Gram-negative, non-motile and pleomorphic, and colonies were red pigmented. Strains MDB25 T and MDB20 showed optimum growth at 45 °C, in 2.6–3.4 M NaCl and at pH 7.0–8.0. The major polar lipids of the two strains were phosphatidylglycerol (PG1 and PG2), phosphatidylglycerol phosphate methyl ester (PGP-Me) and mannose-2,6-dissulfate (1 → 2)-glucose glycerol diether (S 2 -DGD). Menaquinone MK-8 and MK-8(H 2 ) were the major respiratory quinones. The DNA G+C content of strain MDB25 T was 63.0%. The strains were facultatively anaerobic but grew better under aerobic conditions, nitrate served as electron acceptor. Analysis of the almost complete 16S rRNA gene sequence indicated that the strains MDB25 T and MDB20 represented a member of the genus Natrinema in the family Halobacteriaceae . Both strains formed a distinct cluster and were most closely related to Natrinema ejinorense JCM 13890 T and Haloterrigena longa JCM 13562 T (98.0% and 97.9% sequence similarity, respectively). Based on 16S rRNA gene sequence analysis, DNA–DNA hybridization results, physiological and biochemical characteristics we describe a new species represented by strain MDB25 T (=DSM 25055 T =JCM 17869 T ) for which we propose the name Natrinema salaciae sp. nov.