title: Planktonic Euryarchaeota are a significant source of archaeal tetraether lipids in the ocean.
abstract: Archaea are ubiquitous in marine plankton, and fossil forms of archaeal tetraether membrane lipids in sedimentary rocks document their participation in marine biogeochemical cycles for >100 million years. Ribosomal RNA surveys have identified four major clades of planktonic archaea but, to date, tetraether lipids have been characterized in only one, the Marine Group I Thaumarchaeota. The membrane lipid composition of the other planktonic archaeal groups--all uncultured Euryarchaeota--is currently unknown. Using integrated nucleic acid and lipid analyses, we found that Marine Group II Euryarchaeota (MG-II) contributed significantly to the tetraether lipid pool in the North Pacific Subtropical Gyre at shallow to intermediate depths. Our data strongly suggested that MG-II also synthesize crenarchaeol, a tetraether lipid previously considered to be a unique biomarker for Thaumarchaeota. Metagenomic datasets spanning 5 y indicated that depth stratification of planktonic archaeal groups was a stable feature in the North Pacific Subtropical Gyre. The consistent prevalence of MG-II at depths where the bulk of exported organic matter originates, together with their ubiquitous distribution over diverse oceanic provinces, suggests that this clade is a significant source of tetraether lipids to marine sediments. Our results are relevant to archaeal lipid biomarker applications in the modern oceans and the interpretation of these compounds in the geologic record.
authors.affiliation: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139;Center for Microbial Oceanography: Research and Education, University of Hawaii at Manoa, Honolulu, HI 96822; delong@mit.edu slincoln@alum.mit.edu.
authors.forename: Sara A
authors.initials: SA
authors.lastname: Lincoln
authors.affiliation: Center for Microbial Oceanography: Research and Education, University of Hawaii at Manoa, Honolulu, HI 96822;Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI 96822; and.
authors.forename: Brenner
authors.initials: B
authors.lastname: Wai
authors.affiliation: Center for Microbial Oceanography: Research and Education, University of Hawaii at Manoa, Honolulu, HI 96822;Department of Civil and Environmental Engineering and Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: John M
authors.initials: JM
authors.lastname: Eppley
authors.affiliation: Center for Microbial Oceanography: Research and Education, University of Hawaii at Manoa, Honolulu, HI 96822;Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI 96822; and.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Church
authors.affiliation: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139;
authors.forename: Roger E
authors.initials: RE
authors.lastname: Summons
authors.affiliation: Center for Microbial Oceanography: Research and Education, University of Hawaii at Manoa, Honolulu, HI 96822;Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI 96822; andDepartment of Civil and Environmental Engineering and Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 delong@mit.edu slincoln@alum.mit.edu.
authors.forename: Edward F
authors.initials: EF
authors.lastname: DeLong
mesh_terms: D001105:Archaea / Q000254:growth & development / Q000378:metabolism*; D001483:Base Sequence; D015415:Biomarkers / Q000378:metabolism; D017931:DNA Primers; D004463:Ecology; D004987:Ethers / Q000737:chemistry*; D008055:Lipids / Q000032:analysis* / Q000737:chemistry; D056186:Metagenomics; D010140:Pacific Ocean; D010933:Plankton / Q000254:growth & development / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D015415:Biomarkers; D017931:DNA Primers; D004987:Ethers; D008055:Lipids
keywords: TEX86 index; environmental genomics; euryarchaea; glycerol dialkyl glycerol tetraether; oceanography