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 µm 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 °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% (Tm). 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 ).