title: Iron(II,III) hydroxycarbonate green rust formation and stabilization from lepidocrocite bioreduction.
abstract: Bioreduction of the well-crystallized ferric oxyhydroxide gamma-FeOOH lepidocrocite was investigated in batch cultures using Shewanella putrefaciens bacterium (strain CIP 8040) at initial pH 7.5 in bicarbonate buffer. The cultures were performed with formate as electron donor without phosphate, in the presence or absence of anthraquinone-2,6-disulfonate (AQDS) as electron shuttle. During lepidocrocite reduction, the iron(II,III) hydroxycarbonate green rust GR(CO32-) was characterized by X-ray diffraction, transmission electron microscopy, and transmission Mössbauer spectroscopy. The AQDS accelerated the kinetics of GR formation. GR was the major end product when bacterial reduction was not stopped by lack of electron donor, and between 55 and 86% of the iron from gamma-FeOOH precipitated in GR(CO32-). However, when the bacterial reduction was stopped by freezing/thawing or the electron donor was exhausted, the large quantity of remaining lepidocrocite induced a transformation of GR into magnetite. This confirms that GR is metastable with respect to magnetite in the presence of gamma-FeOOH.
authors.affiliation: Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564 CNRS-Université Henri Poincaré, Nancy, France.
authors.forename: Georges
authors.initials: G
authors.lastname: Ona-Nguema
authors.forename: Mustapha
authors.initials: M
authors.lastname: Abdelmoula
authors.forename: Frédéric
authors.initials: F
authors.lastname: Jorand
authors.forename: Omar
authors.initials: O
authors.lastname: Benali
authors.forename: Antoine
authors.initials: A
authors.lastname: Géhin
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Block
authors.forename: Jean-Marie R
authors.initials: JM
authors.lastname: Génin
mesh_terms: D001682:Biological Availability; D005290:Ferric Compounds; D005293:Ferritins / Q000737:chemistry* / Q000378:metabolism*; D010084:Oxidation-Reduction; D020614:Shewanella putrefaciens / Q000502:physiology*; D012995:Solubility; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; C092844:ferric oxyhydroxide; D005293:Ferritins