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Bosch, J. ; Heister, K.* ; Hofmann, T.* ; Meckenstock, R.U.

Nanosized iron oxide colloids strongly enhance microbial iron reduction.

Appl. Environ. Microbiol. 76, 184-189 (2010)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
Microbial iron reduction is considered to be a significant subsurface process. The rate-limiting bioavailability of the insoluble iron oxyhydroxides, however, is a topic for debate. Surface area and mineral structure are recognized as crucial parameters for microbial reduction rates of bulk, macroaggregate iron minerals. However, a significant fraction of iron oxide minerals in the subsurface is supposed to be present as nanosized colloids. We therefore studied the role of colloidal iron oxides in microbial iron reduction. In batch growth experiments with Geobacter sulfurreducens, colloids of ferrihydrite (hydrodynamic diameter, 336 nm), hematite (123 nm), goethite (157 nm), and akaganeite (64 nm) were added as electron acceptors. The colloidal iron oxides were reduced up to 2 orders of magnitude more rapidly (up to 1,255 pmol h(-1) cell(-1)) than bulk macroaggregates of the same iron phases (6 to 70 pmol h(-1) cell(-1)). The increased reactivity was not only due to the large surface areas of the colloidal aggregates but also was due to a higher reactivity per unit surface. We hypothesize that this can be attributed to the high bioavailability of the nanosized aggregates and their colloidal suspension. Furthermore, a strong enhancement of reduction rates of bulk ferrihydrite was observed when nanosized ferrihydrite aggregates were added.
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Publication type Article: Journal article
Document type Scientific Article
Keywords Extracellular electron-transfer; Geobacter-sulfurreducens; Iron(III) oxyhydroxides; Hematite nanoparticles; FE(III); Reactivity; Sediments; Surface; Kinetics; size
ISSN (print) / ISBN 0099-2240
e-ISSN 1098-5336
Journal Applied and Environmental Microbiology
Quellenangaben Volume: 76, Issue: 1, Pages: 184-189 Article Number: , Supplement: ,
Publisher American Society for Microbiology (ASM)
Reviewing status Peer reviewed
Institute(s) Institute of Groundwater Ecology (IGOE)