Haloterrigena mahii sp. nov., an extremely halophilic archaeon from a solar saltern.

A pleomorphic, gas-vesicle-containing, halophilic archaeon, designated strain H13T, was isolated from the solar saltern of the Western Salt Co., Chula Vista, California, USA. Cells of strain H13T were non-motile, rod-shaped and 3-10 µm in length. The optimum growth conditions were 3.5-5.0 M NaCl, 45-55 °C, and pH range of 6.5-8.2. The major polar lipids were C20C20 and C20C25 derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and disulfated diglycosyl diether-1. The G+C content of he genome of strain H13T was calculated as 65.10 mol%. Phylogenetic analysis of 16S rRNA and rpoB' genes revealed that strain H13 was most closely related to Haloterrigena saccharevitans AB14T (16S rRNA gene sequence similarity: 99.51 %; rpoB' sequence similarity: 96.19 %) and Haloterrigena thermotolerans PR5T (99.11 %; 95.50 %). Strain H13T showed low genome relatedness values with Htg. saccharevitans AB14T and Htg. thermotolerans PR5T based on estimated average nucleotide identity (ANI; 92.59 and 91.68 %, respectively) and genome-to-genome distance analysis (GGDA; 47.90 and 45.00 %, respectively). Based on the phenotypic, chemotaxonomic and phylogenetic properties and the genome relatedness, it is evident that strain H13T represents a novel species of the genus Haloterrigena, for which the name Haloterrigena mahiisp. nov. is proposed. The type strain is H13T (=BCRC 910151T=NBRC 111885T).