title: Mass-dependent and -independent signature of Fe isotopes in magnetotactic bacteria.
abstract: Magnetotactic bacteria perform biomineralization of intracellular magnetite (Fe3O4) nanoparticles. Although they may be among the earliest microorganisms capable of biomineralization on Earth, identifying their activity in ancient sedimentary rocks remains challenging because of the lack of a reliable biosignature. We determined Fe isotope fractionations by the magnetotactic bacterium Magnetospirillum magneticum AMB-1. The AMB-1 strain produced magnetite strongly depleted in heavy Fe isotopes, by 1.5 to 2.5 per mil relative to the initial growth medium. Moreover, we observed mass-independent isotope fractionations in (57)Fe during magnetite biomineralization but not in even Fe isotopes ((54)Fe, (56)Fe, and (58)Fe), highlighting a magnetic isotope effect. This Fe isotope anomaly provides a potential biosignature for the identification of magnetite produced by magnetotactic bacteria in the geological record.
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 75238 Paris, France. Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Universités, Université Pierre et Marie Curie, UMR 7590 CNRS, Institut de Recherche pour le Développement UMR 206, Museum National d'Histoire Naturelle, 75252 Paris Cedex 05, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Amor
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 75238 Paris, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Busigny
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 75238 Paris, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Louvat
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 75238 Paris, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Gélabert
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 75238 Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Cartigny
authors.affiliation: Nanobactérie SARL, 36 Boulevard Flandrin, 75016 Paris, France.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Durand-Dubief
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Universités, Université Pierre et Marie Curie, UMR 7590 CNRS, Institut de Recherche pour le Développement UMR 206, Museum National d'Histoire Naturelle, 75252 Paris Cedex 05, France.
authors.forename: Georges
authors.initials: G
authors.lastname: Ona-Nguema
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Universités, Université Pierre et Marie Curie, UMR 7590 CNRS, Institut de Recherche pour le Développement UMR 206, Museum National d'Histoire Naturelle, 75252 Paris Cedex 05, France. Nanobactérie SARL, 36 Boulevard Flandrin, 75016 Paris, France.
authors.forename: Edouard
authors.initials: E
authors.lastname: Alphandéry
authors.affiliation: Nanobactérie SARL, 36 Boulevard Flandrin, 75016 Paris, France.
authors.forename: Imène
authors.initials: I
authors.lastname: Chebbi
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Universités, Université Pierre et Marie Curie, UMR 7590 CNRS, Institut de Recherche pour le Développement UMR 206, Museum National d'Histoire Naturelle, 75252 Paris Cedex 05, France.
authors.forename: François
authors.initials: F
authors.lastname: Guyot
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D003470:Culture Media; D052203:Ferrosoferric Oxide / Q000378:metabolism*; D019015:Geologic Sediments / Q000382:microbiology; D007503:Iron Isotopes / Q000378:metabolism*; D058185:Magnetite Nanoparticles; D042201:Magnetospirillum / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*; D008903:Minerals / Q000378:metabolism
chemical_list: D015415:Biomarkers; D003470:Culture Media; D007503:Iron Isotopes; D058185:Magnetite Nanoparticles; D008903:Minerals; D052203:Ferrosoferric Oxide