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Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Organic matter from redoximorphic soils accelerates and sustains microbial Fe(III) reduction
Author(s): Fritzsche, Andreas
Bosch, Julian
Sander, Michael
Schroeder, Christian
Byrne, James M
Ritschel, Thomas
Joshi, Prachi
Maisch, Markus
Meckenstock, Rainer U
Kappler, Andreas
Totsche, Kai U
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Keywords: Mössbauer spectroscopy
mediated electrochemical reduction
electron-accepting capacity
iron oxide
dissolved organic matter
Issue Date: Aug-2021
Date Deposited: 22-Jul-2021
Citation: Fritzsche A, Bosch J, Sander M, Schroeder C, Byrne JM, Ritschel T, Joshi P, Maisch M, Meckenstock RU, Kappler A & Totsche KU (2021) Organic matter from redoximorphic soils accelerates and sustains microbial Fe(III) reduction. Environmental Science and Technology, 55 (15), pp. 10821-10831.
Abstract: Microbial reduction of Fe(III) minerals is a prominent process in redoximorphic soils and is strongly affected by organic matter (OM). We herein determined the rate and extent of microbial reduction of ferrihydrite (Fh) with either adsorbed or coprecipitated OM by Geobacter sulfurreducens. We focused on OM-mediated effects on electron uptake and alterations in Fh crystallinity. The OM was obtained from anoxic soil columns (effluent OM, efOM) and included –unlike water-extractable OM– compounds released by microbial activity under anoxic conditions. We found that organic molecules in efOM had generally no or only very low electron- accepting capacity and were incorporated into the Fh aggregates when coprecipitated with Fh. Compared to OM-free Fh, adsorption of efOM to Fh decelerated the microbial Fe(III) reduction by passivating the Fh surface towards electron uptake. In contrast, coprecipitation of Fh with efOM accelerated the microbial reduction, likely because efOM disrupted the Fh structure as noted by Mössbauer spectroscopy. Additionally, adsorbed and co-precipitated efOM resulted in a more sustained Fe(III) reduction, potentially because efOM could have effectively scavenged biogenic Fe(II) and prevented the passivation of the Fh surface by adsorbed Fe(II). Fe(III)-OM coprecipitates forming at anoxic-oxic interfaces are thus likely readily reducible by Fe(III)- reducing bacteria in redoximorphic soils.
DOI Link: 10.1021/acs.est.1c01183
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