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Size dependent microbial oxidation and reduction of magnetite nano- and micro-particles

DOI: 10.1038/srep30969 DOI Help

Authors: James M. Byrne (University of Tuebingen) , Gerrit Van Der Laan (Diamond Light Source) , Adriana Figueroa-garcia (Diamond Light Source) , Odeta Qafoku (Pacific Northwest National Laboratory) , Chongmin Wang (Pacific Northwest National Laboratory) , Carolyn Pearce (University of Manchester) , Michael Jackson (University of Minnesota) , Joshua Feinberg (University of Minnesota) , Kevin M. Rosso (Pacific Northwest National Laboratory) , Andreas Kappler (University of Tuebingen)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Scientific Reports , VOL 6 , PAGES 30969

State: Published (Approved)
Published: August 2016
Diamond Proposal Number(s): 9565

Open Access Open Access

Abstract: The ability for magnetite to act as a recyclable electron donor and acceptor for Fe-metabolizing bacteria has recently been shown. However, it remains poorly understood whether microbe-mineral interfacial electron transfer processes are limited by the redox capacity of the magnetite surface or that of whole particles. Here we examine this issue for the phototrophic Fe(II)-oxidizing bacteria Rhodopseudomonas palustris TIE-1 and the Fe(III)-reducing bacteria Geobacter sulfurreducens, comparing magnetite nanoparticles (d ≈ 12 nm) against microparticles (d ≈ 100–200 nm). By integrating surface-sensitive and bulk-sensitive measurement techniques we observed a particle surface that was enriched in Fe(II) with respect to a more oxidized core. This enables microbial Fe(II) oxidation to occur relatively easily at the surface of the mineral suggesting that the electron transfer is dependent upon particle size. However, microbial Fe(III) reduction proceeds via conduction of electrons into the particle interior, i.e. it can be considered as more of a bulk electron transfer process that is independent of particle size. The finding has potential implications on the ability of magnetite to be used for long range electron transport in soils and sediments.

Journal Keywords: bionanomagnetism, bacteria

Subject Areas: Earth Science, Physics, Environment


Instruments: I10-Beamline for Advanced Dichroism