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

A pleomorphic, 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 Haloferax. DNA-DNA hybridization values, as well as biochemical and physiological characterization, allowed strain M6(T) to be differentiated from other members of the genus Haloferax. 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)).