Halorussusvallis sp. nov., Halorussusaquaticus sp. nov., Halorussusgelatinilyticus sp. nov., Halorussuslimi sp. nov., Halorussussalilacus sp. nov., Halorussussalinisoli sp. nov.: six extremely halophilic archaea isolated from solar saltern, salt lake and saline soil

Six novel halophilic archaeal strains of XZYJT10T, XZYJ18T, XZYJT40T, XZYJT49T, YCN54T and LT46T were isolated from a solar saltern in Tibet, a salt lake in Shanxi, and a saline soil in Xinjiang, China. Sequence similarities of 16S rRNA and rpoB′ genes among strains XZYJT10T, XZYJ18T, XZYJT40T, XZYJT49T, YCN54T, LT46T and current members of Halorussus were 90.6–97.8% and 87.8–96.4%, respectively. The average nucleotide identity and in silico DNA-DNA hybridization values among these six strains and current Halorussus members were in the range of 76.5–87.5% and 21.0–33.8%, respectively. These values were all below the species boundary threshold values. The phylogenomic tree based on 122 conserved archaeal protein marker genes revealed that the six novel strains formed individual distinct branches and clustered tightly with Halorussus members. Several phenotypic characteristics distinguished the six strains from current Halorussus members. Polar lipid analysis showed that the six novel strains contained phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and two to three glycolipids. Phenotypic, chemotaxonomic and phylogenetic properties showed that the six strains represented six novel species within the genus Halorussus, for which the names Halorussusvallis sp. nov., Halorussusaquaticus sp. nov., Halorussusgelatinilyticus sp. nov., Halorussuslimi sp. nov., Halorussussalilacus sp. nov., and Halorussussalinisoli sp. nov. are proposed.