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

A pleomorphic, gas-vesicle-containing, halophilic archaeon, designated strain H13^T, was isolated from the solar saltern of the Western Salt Co., Chula Vista, California, USA. Cells of strain H13^T were non-motile, rod-shaped and 3–10μm 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 H13^T 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 AB14^T (16S rRNA gene sequence similarity: 99.51%; rpoB′ sequence similarity: 96.19%) and Haloterrigena thermotolerans PR5^T (99.11%; 95.50%). Strain H13^T showed low genome relatedness values with Htg. saccharevitans AB14^T and Htg. thermotolerans PR5^T 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 H13^T represents a novel species of the genus Haloterrigena, for which the name Haloterrigena mahiisp. nov. is proposed. The type strain is H13^T (=BCRC 910151^T=NBRC 111885^T).