THE ISOLATION AND CHARACTERIZATION OF NOVEL EXTREME HALOPHILIC ARCHAEA FROM A LOW-SALT, SULFIDE- AND SULFUR-RICH SPRING.

The archaeal community of a low-salt, sulfur-rich spring in south-western Oklahoma, was analyzed at two different locations along the spring. Interestingly, 36% of the archaeal mat clone library and 4% of the source clone library were phylogenetically related to the extreme halophilic Archaea family Halobacteriacea. Geochemical analysis of the spring revealed low-salt concentrations throughout ranging from 0.7-1.0% (approximately 0.2 M) and extreme halophilic Archaea are defined by their requirement for high- salt concentrations (1.5 M). The haloarchaeal community was abundant, novel and diverse forming five different groups within the order Halobacteriales. Three novel genera and one novel species belonging within the family Halobacteriacea were successfully isolated from the spring. These include the following: Haloferax sulfurifontis (sp. nov.), Haladaptatus paucihalophilus (gen. nov., sp., nov.), Halosarcina pallida (gen., nov., sp., nov.), and Haloenormitas infirmitas (gen. nov., sp., nov). Each one of these organisms was shown to be extremely resistant to low-salt concentrations, could grow over a wide range of salt concentrations, and some of them grew at relatively low salt concentrations. This study reveals a novel group of halophilic Archaea that possess distinct characteristics that would be advantageous in low-salt environments. These halophilic Archaea have since been identified in several other low-salt environments further suggesting that they are uniquely adapted to these conditions.