Halococcus salsus sp. nov., a novel halophilic archaeon isolated from rock salt

Two pink-pigmented halophilic archaea, designated strains ZJ1(T) and J81, were isolated from rock salt of Yunnan Salt Mine, China, and commercial salt imported from Bolivia, respectively. Cells were non-motile, coccoid, approximately 0.8-1.6 mu m in diameter, stained Gram-negative and often occurred in pairs. Colonies were wet, opaque and smooth-edged. Strain ZJ1(T) grew optimally with 20 % (w/v) NaCl, at pH 7.5 and at 38-40 degrees C, which was the same as for strain J81. 16S rRNA gene sequence similarity between strains ZJ1(T) and J81 was 99.7%. Sequence similarity searches based on the 16S rRNA gene and cell morphology suggested that strains ZJ1(T) and J81 belong to the genus Halococcus in the family Halococcaceae. The major polar lipids of the type strain, ZJ1(T), were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and sulfated diglycosyl-diether-1. The profile of polar lipids, cell shape, motility and lack of lysis of cells in distilled water show that strains ZJ1(T) and J81 were similar to other members of the genus Halococcus. Strain ZJ1(T) shared the highest 16S rRNA gene and rpoB' gene sequence similarities of 99.0 and 95.3 % with Halococcus hamelinensis 100A6(T), respectively, followed by less than 94.6% with sequences of other species in the genus Halococcus. DNA-DNA relatedness between strains ZJ1(T) and J81 was 90.1 +/- 0.7%, while 27 +/- 0.5% was found between strain ZJ1(T) and H. hamelinensis JCM 12892(T) (=100A6(T)), and 29.0 +/- 0.5 % between strains J81 and H. hamelinensis JCM 12892(T). The DNA G+C content of strain ZJ1(T) was 66.5 mol% (T-m). The stable phylogenetic position, differential physiological and biochemical properties and extensive sequence divergence suggest that strains ZJ1(T) and J81 represent a novel species, for which the name Halococcus salsus sp. nov. is proposed. The type strain is ZJ1(T) (=CGMCC 1.16025(T)=NBRC 112867(T)).