Humic Substances as a Mediator for Microbially Catalyzed Metal Reduction

作者：Derek R. Lovley, J. L. Fraga, Elizabeth L. Blunt‐Harris, L. Hayes, Elizabeth J. P. Phillips, John D. Coates · 发表于：Acta hydrochimica et hydrobiologica · 年份：1998 · DOI：10.1002/(sici)1521-401x(199805)26:3<152::aid-aheh152>3.0.co;2-d · 被引用次数：499 · 研究领域：Microbial Fuel Cells and Bioremediation、Geochemistry and Elemental Analysis、Radioactive element chemistry and processing

The potential for humic substances to serve as a terminal electron acceptor in microbial respiration and to function as an electron shuttle between Fe(III)-reducing microorganisms and insoluble Fe(III) oxides was investigated. The Fe(III)-reducing microorganism Geobacter metallireducens conserved energy to support growth from electron transport to humics as evidenced by continued oxidation of acetate to carbon dioxide after as many as nine transfers in a medium with acetate as the electron donor and soil humic acids as the electron acceptor. Growth of G. metallireducens with poorly crystalline Fe(III) oxide as the electron acceptor was greatly stimulated by the addition of as little as 100 μM of the humics analog, anthraquinone-2,6-disulfonate. Other quinones investigated, including lawsone, menadione, and anthraquinone-2-sulfonate, also stimulated Fe(III) oxide reduction. A wide phylogenetic diversity of microorganisms capable of Fe(III) reduction were also able to transfer electrons to humics. Microorganisms which can not reduce Fe(III) could not reduce humics. Humics stimulated the reduction of structural Fe(III) in clay and the crystalline Fe(III) forms, goethite and hematite. These results demonstrate that electron shuttling between Fe(III)-reducing microorganisms and Fe(III) via humics not only accelerates the microbial reduction of poorly crystalline Fe(III) oxide, but also can facilitate the reduction of Fe(III) forms that are not typically reduced by microorganisms i...