Haloterrigena salifodinae sp. nov., an extremely halophilic archaeon isolated from a subterranean rock salt

A novel extremely halophilic strain, designated ZY19(T), was isolated from a rock salt sample from Yunnan salt mine, PR China. Strain ZY19(T) is neutrophilic, non-motile and requires at least 10% (w/v) NaCl for growth. Optimal growth is observed at 20-25% (w/v) NaCl, pH 7.5-8.0 and 42 degrees C. Mg2+ is not required for growth. The cells do not lyse in distilled water. On the basis of 16S rRNA gene sequence analysis, strain ZY19(T) belongs to the genus Haloterrigena (Htg.) and is closely related to Haloterrigena salina XH-65(T) (98.5% sequence similarity) and Haloterrigena turkmenica DSM 5511(T) (97.9%). Phylogenetic and phylogenomic analysis showed that strain ZY19(T) clusters with the species Htg. salina and Htg. turkmenica forming an independent clade separated from other members of the genus. The value of genomic average nucleotide identity (ANI) between strains ZY19(T) and its close relative, Htg. salina XH-65(T) was 94.2%. DNA-DNA relatedness between strains ZY19(T) and Htg. salina XH-65(T) revealed by in silico DNA-DNA hybridization (DDH) was 56.3%. Both the ANI value and the degree of in silico DDH are below the accepted threshold for members of the same species. The major polar lipids were found to consist of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, sulfated diglycosyl-diether-1 and mannose-2, 6-disulfate (1 -> 2)-glucose glycerol diether. The genomic DNA G+C content was determined to be 64.5 mol%. Based on the results of the phenotypic, chemotaxonomic, genetic similarity and inferred phylogeny, strain ZY19(T) is distinct from other validly named species and thus represents a novel species within the genus Haloterrigena, for which the name Haloterrigena salifodinae sp. nov. is proposed. The type strain is ZY19(T) (=CGMCC 1.16114(T)=NBRC 112981(T)).