title: Manganese in biogenic magnetite crystals from magnetotactic bacteria.
abstract: Magnetotactic bacteria produce either magnetite (Fe(3)O(4)) or greigite (Fe(3)S(4)) crystals in cytoplasmic organelles called magnetosomes. Whereas greigite magnetosomes can contain up to 10 atom% copper, magnetite produced by magnetotactic bacteria was considered chemically pure for a long time and this characteristic was used to distinguish between biogenic and abiogenic crystals. Recently, it was shown that magnetosomes containing cobalt could be produced by three strains of Magnetospirillum. Here we show that magnetite crystals produced by uncultured magnetotactic bacteria can incorporate manganese up to 2.8 atom% of the total metal content (Fe+Mn) when manganese chloride is added to microcosms. Thus, chemical purity can no longer be taken as a strict prerequisite to consider magnetite crystals to be of biogenic origin.
authors.affiliation: Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Carolina N
authors.initials: CN
authors.lastname: Keim
authors.forename: Ulysses
authors.initials: U
authors.lastname: Lins
authors.forename: Marcos
authors.initials: M
authors.lastname: Farina
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D052203:Ferrosoferric Oxide / Q000737:chemistry* / Q000378:metabolism*; D008345:Manganese / Q000032:analysis*; D017895:Manganese Compounds / Q000378:metabolism; D013057:Spectrum Analysis
chemical_list: D002712:Chlorides; D017895:Manganese Compounds; D008345:Manganese; C025340:manganese chloride; D052203:Ferrosoferric Oxide