Natrinema salsiterrestre sp. nov., an extremely halophilic archaeon isolated from a hypersaline soil

An extremely halophilic archaeal strain, designated S1CR25- 10T, was isolated from hypersaline soil sampled in the Odiel Salt -marshes Natural Area in Southwestern Spain (Huelva) and subjected to a polyphasic taxonomic characterization. The cells were Gram- stain-negative, motile and their colonies were pink-pigmented. It was a strictly aerobic haloarchaeon that could grow at 25-55 degrees C (optimum, 37 degrees C), at pH 6.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 12-30 % (w/v) total salts (optimum, 20-25 %, w/v). The phylogenetic analysis based on the comparison of the 16S rRNA gene sequences revealed that strain S1CR25-10T belongs to the genus Natrinema, with 98.9 % similarity to Natrinema salinisoli SLN56T. In addition, the values of orthologous average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity were below the threshold limits accepted for prokaryotic species delineation, with N. salinisoli SLN56T showing the highest relatedness values (92.6 % and 48.4 %, respectively). The major polar lipids were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and a glycolipid chromatographically identical to sulfated diglycosyl diether. The DNA G+C content of the isolate was 63.8 mol%. Based on the phylogenetic, phenotypic and chemotaxonomic characterization and the whole genome results, strain S1CR25- 10T represents a new species within the genus Natrinema, for which the name Natrinema salsiterrestre sp. nov., with type strain S1CR25- 10T (=CECT 30623T=CCM 9251T), is proposed.