Halobacterium wangiae sp. nov. and Halobacterium zhouii sp. nov., two extremely halophilic archaea isolated from sediment of a salt lake and saline soil of an inland saltern.

Abstract

Two novel halophilic archaeal strains, Gai3-17T and XZYJT26T, were isolated from the sediment of Gaize salt lake and the saline soil of Mangkang ancient solar saltern in Tibet, PR China, respectively. Strains Gai3-17T and XZYJT26T were related to each other (96.5 and 89.7% similarity, respectively) and showed 97.5-95.4 and 91.5-87.7% similarities to the current members of Halobacterium based on 16S rRNA and rpoB' genes. The phylogenomic analysis indicated that strains Gai3-17T and XZYJT26T formed two distinct clades and clustered with the Halobacterium species. The two strains can be differentiated from the type strains of the six species with validly published names based on several phenotypic characteristics. The phospholipids of the two strains were phosphatidic acid, phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. One major glycolipid, sulphated galactosyl mannosyl glucosyl diether, was detected in strain Gai3-17T, while four glycolipids, mannosyl glucosyl diether, sulphated mannosyl glucosyl diether, disulphated mannosyl glucosyl diether and sulphated galactosyl mannosyl glucosyl diether were observed in strain XZYJT26T. The average nucleotide identity, digital DNA-DNA hybridization and amino acid identity values among the two strains and the members of Halobacterium were no more than 81, 25 and 77 %, respectively. These overall genome-related indices were below the threshold values for species boundary, indicating that strains Gai3-17T and XZYJT26T represent two novel species of Halobacterium. Thus, two novel species, Halobacterium wangiae sp. nov. and Halobacterium zhouii sp. nov., are proposed to accommodate strains Gai3-17T (=CGMCC 1.16101T=JCM 33551T) and XZYJT26T (=CGMCC 1.16682T=JCM 33556T), respectively.