title: Magnetic properties of uncultivated magnetotactic bacteria and their contribution to a stratified estuary iron cycle.
abstract: Of the two nanocrystal (magnetosome) compositions biosynthesized by magnetotactic bacteria (MTB), the magnetic properties of magnetite magnetosomes have been extensively studied using widely available cultures, while those of greigite magnetosomes remain poorly known. Here we have collected uncultivated magnetite- and greigite-producing MTB to determine their magnetic coercivity distribution and ferromagnetic resonance (FMR) spectra and to assess the MTB-associated iron flux. We find that compared with magnetite-producing MTB cultures, FMR spectra of uncultivated MTB are characterized by a wider empirical parameter range, thus complicating the use of FMR for fossilized magnetosome (magnetofossil) detection. Furthermore, in stark contrast to putative Neogene greigite magnetofossil records, the coercivity distributions for greigite-producing MTB are fundamentally left-skewed with a lower median. Lastly, a comparison between the MTB-associated iron flux in the investigated estuary and the pyritic-Fe flux in the Black Sea suggests MTB play an important, but heretofore overlooked role in euxinic marine system iron cycle.
authors.affiliation: Department of Environment and Geography, Macquarie University, North Ryde, New South Wales 2109, Australia.
authors.forename: A P
authors.initials: AP
authors.lastname: Chen
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, USA.
authors.forename: V M
authors.initials: VM
authors.lastname: Berounsky
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Chan
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors.forename: M G
authors.initials: MG
authors.lastname: Blackford
authors.affiliation: 1] Department of Chemistry, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA [2].
authors.forename: C
authors.initials: C
authors.lastname: Cady
authors.affiliation: Department of Earth Sciences and Institute for Rock Magnetism, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: B M
authors.initials: BM
authors.lastname: Moskowitz
authors.affiliation: Department of Earth Sciences-Geochemistry, Utrecht University, Utrecht 3584, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Kraal
authors.affiliation: Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Lima
authors.affiliation: Department of Earth and Planetary Sciences and Rutgers Energy Institute, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Kopp
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia.
authors.forename: G R
authors.initials: GR
authors.lastname: Lumpkin
authors.affiliation: Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: B P
authors.initials: BP
authors.lastname: Weiss
authors.affiliation: Department of Environment and Geography, Macquarie University, North Ryde, New South Wales 2109, Australia.
authors.forename: P
authors.initials: P
authors.lastname: Hesse
authors.affiliation: Microscopy Unit, Faculty of Science, Macquarie University, North Ryde, New South Wales 2109, Australia.
authors.forename: N G F
authors.initials: NG
authors.lastname: Vella
mesh_terms: D020561:Alphaproteobacteria / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D059001:Aquatic Organisms; D059038:Black Sea; D063366:Estuaries; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D055944:Magnetosomes / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D013440:Sulfides / Q000737:chemistry*
chemical_list: D013440:Sulfides; C111959:greigite; D007501:Iron; D052203:Ferrosoferric Oxide