title: Functional interactions of archaea, bacteria and viruses in a hypersaline endolithic community.
abstract: Halite endoliths in the Atacama Desert represent one of the most extreme ecosystems on Earth. Cultivation-independent methods were used to examine the functional adaptations of the microbial consortia inhabiting halite nodules. The community was dominated by haloarchaea and functional analysis attributed most of the autotrophic CO2 fixation to one 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 predominance of a 'salt-in' strategy to balance the high osmotic pressure of the environment.
authors.affiliation: Biology Department, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Crits-Christoph
authors.affiliation: Biology Department, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Diego R
authors.initials: DR
authors.lastname: Gelsinger
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Bing
authors.initials: B
authors.lastname: Ma
authors.affiliation: Department of Biochemistry and Microbial Ecology, Museo Nacional de Ciencias Naturales - Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Jacek
authors.initials: J
authors.lastname: Wierzchos
authors.affiliation: Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Jacques
authors.initials: J
authors.lastname: Ravel
authors.affiliation: Carl Sagan Center, SETI Institute, Mountain View, CA, USA.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Davila
authors.affiliation: Department of Biochemistry and Microbial Ecology, Museo Nacional de Ciencias Naturales - Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Casero
authors.affiliation: Biology Department, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Jocelyne
authors.initials: J
authors.lastname: DiRuggiero
mesh_terms: D001105:Archaea / Q000235:genetics; D019843:Archaeal Proteins / Q000737:chemistry; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification*; D000458:Cyanobacteria / Q000235:genetics / Q000302:isolation & purification / Q000821:virology; D003889:Desert Climate; D017753:Ecosystem; D019605:Euryarchaeota / Q000235:genetics / Q000302:isolation & purification* / Q000821:virology; D016679:Genome, Viral; D007526:Isoelectric Point; D054892:Metagenome; D059013:Microbial Consortia; D056265:Microbial Interactions; D010802:Phylogeny; D054712:Salinity; D014780:Viruses / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D019843:Archaeal Proteins