Halomicrobium zhouii sp. nov., a halophilic archaeon from a marine solar saltern

A halophilic archaeon, strain TBN51(T), was isolated from a marine solar saltern in Jiangsu, China. The colonies were red-pigmented and the cells were pleomorphic, motile and Gram-staining-negative. The strain was able to grow at 20-55 °C (optimum 42 °C), in the presence of 1.4-5.1 M NaCl (optimum 2.6 M), with 0-1.0 M MgCl(2) (optimum 0.05 M) and at pH 5.5-9.5 (optimum pH 7.0). Cells lysed in distilled water; the minimal NaCl concentration to prevent such lysis was 8 % (w/v). The major polar lipids of strain TBN51(T) were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and an unidentified glycolipid. The latter lipid and a minor glycolipid also detected in the novel strain were chromatographically identical to sulfated and non-sulfated mannosyl glucosyl diether, respectively. Analysis revealed that strain TBN51(T) had three dissimilar 16S rRNA genes. Phylogenetic analysis based on the sequences of these genes indicated that the novel strain was most closely related to Halomicrobium mukohataei JCM 9738(T) (89.2-94.8 % sequence similarity) and Halomicrobium katesii DSM 19301(T) (88.8-94.8 %). In similar comparisons of rpoB' gene sequences, strain TBN51(T) also appeared most closely related to Hmc. mukohataei JCM 9738(T) (88.5 % sequence similarity) and Hmc. katesii DSM 19301(T) (88.1 %). The genomic DNA G+C content of strain TBN51(T) was 69.1 mol%. The results of DNA-DNA hybridizations indicated that strain TBN51(T) represented a novel species since it showed relatedness values of only 23 % with Hmc. mukohataei JCM 9738(T) and 21 % with Hmc. katesii DSM 19301(T). It was concluded that strain TBN51(T) represents a novel species of the genus Halomicrobium, for which the name Halomicrobium zhouii sp. nov. is proposed. The type strain is TBN51(T) ( = CGMCC 1.10457(T) = JCM 17095(T)).