Salinithrix halophila gen. nov., sp. nov., a halophilic bacterium in the family Thermoactinomycetaceae

Abstract

A halophilic actinomycete, strain R4S8T, was isolated from soil of Inche-Broun hypersaline wetland in the north of Iran. The isolate grew aerobically at temperatures of 30–50 °C (optimum 40 °C), pH 6–10 (optimum pH 7.0) and in the presence of 1–15 % (w/v) NaCl (optimum 3–5 %). It formed short and straight to moderately flexuous aerial mycelium without motile elements. The cell wall of strain R4S8T contained meso-diaminopimelic acid as the diamino acid without any diagnostic sugars. The polar lipid pattern consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylserine, phosphatidylmonomethylethanolamine two unknown phospholipids and one unknown aminophospholipid. It synthesized anteiso-C15 : 0 (44.8 %), iso-C15 : 0 (28.8 %) and iso-C14 : 0 (8.5 %) as major fatty acids. MK-6 was the predominant respiratory quinone. The G+C content of the genomic DNA was 52.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain R4S8T belongs to the family Thermoactinomycetaceae and showed the closest 16S rRNA gene sequence similarity with Desmospora activa IMMIB L-1269T (95.5 %) and Marininema mesophilum SCSIO 10219T (95.3 %). On the basis of phylogenetic analysis and phenotypic characteristics, strain R4S8T represents a novel species in a new genus within the family Thermoactinomycetaceae , for which the name Salinithrix halophila gen. nov., sp. nov. is proposed. The type strain of the type species is R4S8T ( = IBRC-M 10813T = CECT 8506T).