PT - JOURNAL ARTICLE AU - Alexander Crits-Christoph AU - Diego R. Gelsinger AU - Bing Ma AU - Jacek Wierzchos AU - Jacques Ravel AU - Alfonso Davila AU - M. Cristina Casero AU - Jocelyne DiRuggiero TI - Functional analysis of the archaea, bacteria, and viruses from a halite endolithic microbial community AID - 10.1101/029934 DP - 2015 Jan 01 TA - bioRxiv PG - 029934 4099 - http://biorxiv.org/content/early/2015/10/26/029934.short 4100 - http://biorxiv.org/content/early/2015/10/26/029934.full AB - Halite endoliths in the Atacama Desert represent one of the most extreme microbial ecosystems on Earth. Here we sequenced and characterized a shotgun metagenome from halite nodules collected in Salar Grande, Chile. The community is dominated by archaea and functional analysis attributed most of the autotrophic CO2 fixation to a unique cyanobacterium. The assembled 1.1 Mbp genome of a novel nanohaloarchaeon, Candidatus Nanopetramus SG9, revealed a photoheterotrophic life style and a low median isoelectric point (pI) for all predicted proteins, suggesting a “salt-in” strategy for osmotic balance. Predicted proteins of the algae identified in the community also had pI distributions similar to “salt-in” strategists. The Nanopetramus genome contained a unique CRISPR/Cas system with a spacer that matched a partial viral genome from the metagenome. A combination of reference-independent methods identified over 30 complete or near complete viral or proviral genomes with diverse genome structure, genome size, gene content, and hosts. Putative hosts included Halobacteriaceae, Nanohaloarchaea, and Cyanobacteria. Despite the dependence of the halite community on deliquescence for liquid water availability, this study exposed an ecosystem spanning three phylogenetic domains, containing a large diversity of viruses, and a predominant “salt-in” strategy to balance the high osmotic pressure of the environment.