Natrialba magadii is an extremophile in the extreme. It thrives in alkaline hypersaline conditions (pH 9.5, 3.5 M NaCl) and encodes enzymes that are not only salt tolerant but also often tolerant of high pH, high temperatures, and the presence of solvents. Genomic sequencing of this haloalkaliphilic (i.e., thriving in high salt concentrations and high pH) archaeon will add to our general knowledge of Archaea, a domain underrepresented in genome sequencing projects. Since many archaea thrive in environmental extremes and are important in global organic and inorganic cycles, the genomes of these organisms are of high relevance to the DOE mission.

Halophilic (salt-loving) archaea represent the model of choice for molecular, pathway, and systems study of archaea. They are readily cultured in the laboratory, are available in public repositories, and have advanced genetic tools that are shared by labs worldwide. The availability of additional haloarchaeal genomes, such as N. magadii, will serve to enhance the use of this group as a model of choice for archaeal genomes. The N. magadii genome is of broad interest based on its phylogenetic and phenotypic diversity from available genomes, its ability to complement genomes already published, its widespread study by the international community, the availability of the complete genome sequence of an infecting virus (φCh1), and the insight it will provide in understanding organismal adaptation to growth at high pH and saturating salt. This study will also assist in exploring the metabolic capacity of haloarchaea, in clarifying the phylogenomic relationships among halobacteria, and in evaluating the potential of N. magadii as a resource for the generation of renewable fuels and chemicals (e.g., identification of solvent- and salt-tolerant hydrolases and metabolic engineering of robust biocatalysts that can withstand industrial extremes). The deduced proteome will also be of immense interest to microbial biochemists in understanding the features that allow proteins to function at extreme pH and salinity.