title: A distinct and active bacterial community in cold oxygenated fluids circulating beneath the western flank of the Mid-Atlantic ridge.
abstract: The rock-hosted, oceanic crustal aquifer is one of the largest ecosystems on Earth, yet little is known about its indigenous microorganisms. Here we provide the first phylogenetic and functional description of an active microbial community residing in the cold oxic crustal aquifer. Using subseafloor observatories, we recovered crustal fluids and found that the geochemical composition is similar to bottom seawater, as are cell abundances. However, based on relative abundances and functional potential of key bacterial groups, the crustal fluid microbial community is heterogeneous and markedly distinct from seawater. Potential rates of autotrophy and heterotrophy in the crust exceeded those of seawater, especially at elevated temperatures (25 °C) and deeper in the crust. Together, these results reveal an active, distinct, and diverse bacterial community engaged in both heterotrophy and autotrophy in the oxygenated crustal aquifer, providing key insight into the role of microbial communities in the ubiquitous cold dark subseafloor biosphere.
authors.affiliation: Josephine Bay Paul Center, Marine Biological Laboratory, 7 MBL St., Woods Hole, MA 02543.
authors.forename: Julie L
authors.initials: JL
authors.lastname: Meyer
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave., Cambridge, MA 02138.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Jaekel
authors.affiliation: Center for Dark Energy Biosphere Investigations, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Tully
authors.affiliation: Department of Oceanography, University of Hawai'i at Mānoa, 1000 Pope Rd., Honolulu, HI 96822.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Glazer
authors.affiliation: Global Undersea Research Unit, University of Alaska Fairbanks, P.O. Box 475, Moss Landing, CA 95039.
authors.forename: C Geoffrey
authors.initials: CG
authors.lastname: Wheat
authors.affiliation: Department of Oceanography, University of Hawai'i at Mānoa, 1000 Pope Rd., Honolulu, HI 96822.
authors.forename: Huei-Ting
authors.initials: HT
authors.lastname: Lin
authors.affiliation: Department of Oceanography, University of Hawai'i at Mānoa, 1000 Pope Rd., Honolulu, HI 96822.
authors.forename: Chih-Chiang
authors.initials: CC
authors.lastname: Hsieh
authors.affiliation: Department of Oceanography, University of Hawai'i at Mānoa, 1000 Pope Rd., Honolulu, HI 96822.
authors.forename: James P
authors.initials: JP
authors.lastname: Cowen
authors.affiliation: Moss Landing Marine Laboratory, 8272 Moss Landing Road, Moss Landing, CA 95039.
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Hulme
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave., Cambridge, MA 02138.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Girguis
authors.affiliation: Josephine Bay Paul Center, Marine Biological Laboratory, 7 MBL St., Woods Hole, MA 02543.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Huber
mesh_terms: D059001:Aquatic Organisms / Q000254:growth & development*; D001267:Atlantic Ocean; D001419:Bacteria / Q000254:growth & development*; D059013:Microbial Consortia / Q000502:physiology*; D014871:Water Microbiology