Haloferax sulfurifontis sp. nov., a halophilic archaeon isolated from a sulfide- and sulfur-rich spring

A pleomiorphic, extremely halophilic archaeon (strain M6^T) was isolated from a sulfide- and sulfur-rich spring in south-western Oklahoma (USA). It formed small (0.8-1.0 mm), salmon pink, elevated colonies on agar medium. The strain grew in a wide range of NaCl concentrations (6 % to saturation) and required at least 1 mM Mg²⁺ for growth. Strain M6^T was able to reduce sulfur to sulfide anaerobically. 16S rRNA gene sequence analysis indicated that strain M6^T belongs to the family Halobacteriaceae, genus Haloferax; it showed 96.7-98.0% similarity to other members of the genus with validly published names and 89 % similarity to Halogeometricum borinquense, its closest relative outside the genus Haloferax. Polar lipid analysis and DNA G+C content further supported placement of strain M6^T in the genus Haloterax. DNA-DNA hybridization values, as well as biochemical and physiological characterization, allowed strain M6^T to be differentiated from other members of the genus Haloterax. A novel species, Haloferax sulfurifontis sp. nov., is therefore proposed to accommodate the strain. The type strain is M6^T (=JCM 12327^T =CCM 7217^T =DSM 16227^T=CIP 108334^T).