Skip to main content

Research Repository

Advanced Search

Characterisation of the dissimilatory reduction of Fe(III)‐oxyhydroxide at the microbe – mineral interface: the application of STXM–XMCD

COKER, V. S.; BYRNE, J. M.; TELLING, N. D.; VAN DER LAAN, G.; LLOYD, J. R.; HITCHCOCK, A. P.; WANG, J.; PATTRICK, R. A. D.

Authors

V. S. COKER

J. M. BYRNE

G. VAN DER LAAN

J. R. LLOYD

A. P. HITCHCOCK

J. WANG

R. A. D. PATTRICK



Abstract

A combination of scanning transmission X-ray microscopy and X-ray magnetic circular dichroism was used to spatially resolve the distribution of different carbon and iron species associated with Shewanella oneidensis MR-1 cells. S. oneidensis MR-1 couples the reduction of Fe(III)-oxyhydroxides to the oxidation of organic matter in order to conserve energy for growth. Several potential mechanisms may be used by S. oneidensis MR-1 to facilitate Fe(III)-reduction. These include direct contact between the cell and mineral surface, secretion of either exogenous electron shuttles or Fe-chelating agents and the production of conductive ‘nanowires’. In this study, the protein/lipid signature of the bacterial cells was associated with areas of magnetite (Fe3O4), the product of dissimilatory Fe(III) reduction, which was oversaturated with Fe(II) (compared to stoichiometric magnetite). However, areas of the sample rich in polysaccharides, most likely associated with extracellular polymeric matrix and not in direct contact with the cell surface, were undersaturated with Fe(II), forming maghemite-like (γ-Fe2O3) phases compared to stoichiometric magnetite. The reduced form of magnetite will be much more effective in environmental remediation such as the immobilisation of toxic metals. These findings suggest a dominant role for surface contact-mediated electron transfer in this study and also the inhomogeneity of magnetite species on the submicron scale present in microbial reactions. This study also illustrates the applicability of this new synchrotron-based technique for high-resolution characterisation of the microbe–mineral interface, which is pivotal in controlling the chemistry of the Earth’s critical zone.

Citation

COKER, V. S., BYRNE, J. M., TELLING, N. D., VAN DER LAAN, G., LLOYD, J. R., HITCHCOCK, A. P., …PATTRICK, R. A. D. (2012). Characterisation of the dissimilatory reduction of Fe(III)‐oxyhydroxide at the microbe – mineral interface: the application of STXM–XMCD. Geobiology, 10(4), 347-354. https://doi.org/10.1111/j.1472-4669.2012.00329.x

Journal Article Type Article
Online Publication Date Apr 20, 2012
Publication Date 2012-07
Deposit Date May 22, 2024
Journal Geobiology
Print ISSN 1472-4677
Electronic ISSN 1472-4669
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 10
Issue 4
Pages 347-354
DOI https://doi.org/10.1111/j.1472-4669.2012.00329.x
Public URL https://keele-repository.worktribe.com/output/831379
Publisher URL https://onlinelibrary.wiley.com/doi/10.1111/j.1472-4669.2012.00329.x