title: Genomic comparisons of a bacterial lineage that inhabits both marine and terrestrial deep subsurface systems.
abstract: It is generally accepted that diverse, poorly characterized microorganisms reside deep within Earth's crust. One such lineage of deep subsurface-dwelling bacteria is an uncultivated member of theFirmicutesphylum that can dominate molecular surveys from both marine and continental rock fracture fluids, sometimes forming the sole member of a single-species microbiome. Here, we reconstructed a genome from basalt-hosted fluids of the deep subseafloor along the eastern Juan de Fuca Ridge flank and used a phylogenomic analysis to show that, despite vast differences in geographic origin and habitat, it forms a monophyletic clade with the terrestrial deep subsurface genome of "CandidatusDesulforudis audaxviator" MP104C. While a limited number of differences were observed between the marine genome of "CandidatusDesulfopertinax cowenii" modA32 and its terrestrial relative that may be of potential adaptive importance, here it is revealed that the two are remarkably similar thermophiles possessing the genetic capacity for motility, sporulation, hydrogenotrophy, chemoorganotrophy, dissimilatory sulfate reduction, and the ability to fix inorganic carbon via the Wood-Ljungdahl pathway for chemoautotrophic growth. Our results provide insights into the genetic repertoire within marine and terrestrial members of a bacterial lineage that is widespread in the global deep subsurface biosphere, and provides a natural means to investigate adaptations specific to these two environments.
authors.affiliation: Department of Oceanography, University of Hawaii at Manoa, Honolulu, HI, United States; Center for Dark Energy Biosphere Investigations, University of Southern California, Los Angeles, CA, United States; DOE Joint Genome Institute, Walnut Creek, CA, United States.
authors.forename: Sean P
authors.initials: SP
authors.lastname: Jungbluth
authors.affiliation: DOE Joint Genome Institute , Walnut Creek , CA , United States.
authors.forename: Tijana
authors.initials: T
authors.lastname: Glavina Del Rio
authors.affiliation: DOE Joint Genome Institute , Walnut Creek , CA , United States.
authors.forename: Susannah G
authors.initials: SG
authors.lastname: Tringe
authors.affiliation: Single Cell Genomics Center, Bigelow Laboratory for Ocean Sciences , East Boothbay , ME , United States.
authors.forename: Ramunas
authors.initials: R
authors.lastname: Stepanauskas
authors.affiliation: Hawaii Institute of Marine Biology, University of Hawaii at Manoa , Kaneohe , HI , United States.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Rappé
keywords: Basement biosphere; Chemoautotrophy; Deep subsurface; Firmicutes; Genomic; Juan de Fuca Ridge; Metagenomic; Microorganisms; Sporulation; Sulfate reduction