Haloterrigena daqingensis sp. nov., an extremely haloalkaliphilic archaeon isolated from a saline–alkaline soil

Abstract

A haloalkaliphilic archaeon, strain JX313(T), was isolated from a saline-alkaline soil from Daqing, Heilongjiang Province, China. Its morphological, physiological and biochemical features and 16S rRNA gene sequence were determined. Colonies of the strain were orange-red and cells were non-motile cocci and Gram-stain-variable. The strain required at least 1.7 M NaCl for growth, with optimal growth occurring in 2.0-2.5 M NaCl. Growth was observed at 20-50°C and pH 8.0-10.5, with optimal growth at 35°C and pH 10.0. The G+C content of its genomic DNA was 59.3 mol%. Phylogenetic analysis of 16S rRNA gene sequences showed that strain JX313(T) is associated with the genera Haloterrigena and Natrinema and is most closely related to Haloterrigena salina XH-65(T) (96.2 % sequence similarity) and Haloterrigena hispanica FP1(T) (96.2 %). DNA-DNA hybridization experiments revealed that the relatedness of strain JX313(T) to type strains of related species of the genus Haloterrigena or Natrinema was less than 50 %. Furthermore, the cellular polar lipids of strain JX313(T), identified as phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and mannose-2,6-disulfate (1→2)-glucose glycerol diether (S₂-DGD), were consistent with the polar lipid characteristics of the genus Haloterrigena. Therefore, phylogenetic analysis, phenotypic assessment and chemotaxonomic data showed that JX313(T) represents a novel species within the genus Haloterrigena, for which the name Haloterrigena daqingensis sp. nov. is proposed. The type strain is JX313(T) (=CGMCC 1.8909(T) =NBRC 105739(T)).