A novel, extremely halophilic archaeon, strain Y73T, was isolated from a salt mine in Yunnan, China. Colonies formed on solid medium were circular (2–3 mm in diameter), smooth, orange, glistening and convex (~1 mm in elevation). Cells were Gram-stain-negative, non-motile and pleomorphic. Mg2+ was required for growth (optimum at 0.05 M). Optimal growth was observed at 20 % (w/v) NaCl, 42–45 °C and pH 7.5–8.5 under aerobic conditions. 16S rRNA gene sequence comparison showed that strain Y73T was closely related to Halorubrum halophilum B8T (similarity: 98.1 %), Halorubrum lipolyticum 9-3T (97.9 %) and Halorubrum saccharovorum JCM 8865T (97.6 %). Levels of rpoB′ gene sequence similarity between strain Y73T and H. halophilum B8T, H. lipolyticum 9-3T and H. saccharovorum JCM 8865T were 93.6, 93.8 and 94.7 %, respectively. DNA–DNA relatedness between strain Y73T and H. halophilum B8T was 38.7±0.5 %, while that between strain Y73T and H. saccharovorum JCM 8865T was 31.0±0.9 % . The DNA G+C content of strain Y73T was 61.9 mol%. The major polar lipids of strain Y73T were phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and phosphatidylglycerol sulfate as phospholipids, and sulfated diglycosyl diether-1 as glycolipid. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strain Y73T represents a novel species, for which the name Halorubrum trueperi sp. nov is proposed. The type strain is Y73T (=CGMCC 1.15503T=JCM 31271T).
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).