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Magnetite as a precursor for green rust through the hydrogenotrophic activity of the iron‐reducing bacteria Shewanella putrefaciens
Author(s) -
Etique M.,
Jorand F. P. A.,
Ruby C.
Publication year - 2016
Publication title -
geobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.859
H-Index - 72
eISSN - 1472-4669
pISSN - 1472-4677
DOI - 10.1111/gbi.12170
Subject(s) - shewanella putrefaciens , magnetite , lepidocrocite , siderite , anoxic waters , ferrihydrite , hematite , chemistry , iron bacteria , ferrous , shewanella , environmental chemistry , inorganic chemistry , nuclear chemistry , mineralogy , geology , metallurgy , goethite , bacteria , materials science , calcite , paleontology , organic chemistry , adsorption
Magnetite (Fe II F e III 2 O 4 ) is often considered as a stable end product of the bioreduction of Fe III minerals (e.g., ferrihydrite, lepidocrocite, hematite) or of the biological oxidation of Fe II compounds (e.g., siderite), with green rust ( GR ) as a mixed Fe II ‐Fe III hydroxide intermediate. Until now, the biotic transformation of magnetite to GR has not been evidenced. In this study, we investigated the capability of an iron‐reducing bacterium, Shewanella putrefaciens , to reduce magnetite at circumneutral pH in the presence of dihydrogen as sole inorganic electron donor. During incubation, GR and/or siderite (Fe II CO 3 ) formation occurred as secondary iron minerals, resulting from the precipitation of Fe II species produced via the bacterial reduction of Fe III species present in magnetite. Taking into account the exact nature of the secondary iron minerals and the electron donor source is necessary to understand the exergonic character of the biotic transformation of magnetite to GR, which had been considered to date as thermodynamically unfavorable at circumneutral pH. This finding reinforces the hypothesis that GR would be the cornerstone of the microbial transformations of iron‐bearing minerals in the anoxic biogeochemical cycle of iron and opens up new possibilities for the interpretation of the evolution of Earth's history and for the understanding of biocorrosion processes in the field of applied science.