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Wolf, M. ; Kappler, A.* ; Jiang, J.* ; Meckenstock, R.U.

Effects of humic substances and quinones at low concentrations on ferrihydrite reduction by Geobacter metallireducens.

Environ. Sci. Technol. 43, 5679-5685 (2009)
DOI PMC
Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
Humic substances (HS) and quinones can accelerate dissimilatory Fe(III) reduction by electron shuttling between microorganisms and poorly soluble iron(III) (hydr)oxides. The mechanism of electron shuttling for HS is not fully understood, but it is suggested that the most important redox-active components in HS are also quinones. Here we studied the influence of HS and different quinones at low concentrations on ferrihydrite reduction by Geobacter metallireducens. The aquatic HS used were humic and fulvic acids (HA and FA) isolated from groundwater of a deep aquifer in Gorleben (Niedersachsen, Germany). HA stimulated iron reduction stronger than FA down to total HA concentrations as low as 1 mg/L. The quinones studied showed large differences: some had strong accelerating effects, whereas others showed only small effects, no effects, or even inhibitory effects on the kinetics of iron reduction. We found that the redox potentials of the most active quinones fall in a narrow range of -137 to -225 mV vs NHE at pH 7. These results give evidence that the kinetic of microbial iron reduction mediated by electron shuttles is mainly controlled by thermodynamic parameters, i.e., by the redox potential of the shuttle compound, rather than by the proportion of dissolved vs adsorbed compound.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Korrespondenzautor
Schlagwörter extracellular electron-transfer; insoluble fe(iii) oxide; sedimentary organic-carbon; sulfate-reducing bacteria; decompose fatty-acids; nov sp-nov; gen-nov; iron; environments; microorganisms
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Zeitschrift Environmental Science & Technology
Quellenangaben Band: 43, Heft: 15, Seiten: 5679-5685 Artikelnummer: , Supplement: ,
Verlag ACS
Verlagsort Washington, DC
Nichtpatentliteratur Publikationen
Begutachtungsstatus Peer reviewed
Institut(e) Institute of Groundwater Ecology (IGOE)