HR: 1340h
AN: B33A-0856 [Abstracts]
TI: Kinetics of Microbially Mediated Iron Reduction: The Role of Biomass, Ferrous Inhibition, and Electron Shuttles
AU: * MacDonald, L H
EM: Lmacdona@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ
08544, United States
AU: Moon, H
EM: hmoon@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ
08544, United States
AU: Jaffe, P R
EM: jaffe@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ
08544, United States
AB:
Microbially mediated reduction of poorly crystalline iron oxides in the subsurface controls the fate and transport of
many organic and inorganic contaminants and plays a role in biogeochemical nutrient cycling. Despite recent
advances in understanding this important process, much remains undiscovered. In particular, the influence of
biomass on iron reducing kinetics is not well understood for surface bound microbes undergoing direct electron
transfer to ferric iron oxides. Nor do we understand how Fe(II) sorption to ferric iron influences this process under
direct electron transfer versus transfer via redox shuttles. Accordingly, this study investigates the iron reducing
kinetics and mineralogy of geobacter sulfurreducens reducing poorly crystalline iron coated sand using acetate
as electron donor, with and without AQDS, an electron shuttle and humic analog. This research demonstrates
that the rate of iron reduction depends logarithmically on initial biomass for surface bound geobacter, suggesting
surface area limitations with increasing biomass. However, electron shuttles remove these limitations and shift
the kinetics such that the rate depends linearly on biomass over the range of cell concentrations explored. This
study also finds that ferrous iron inhibits the rate of reduction with or without AQDS, but has a weaker effect in the
presence of AQDS, and adding an Fe(II) specific chelator removes the negative feedback mechanism altogether.
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0448 Geomicrobiology
DE: 0463 Microbe/mineral interactions
SC: Biogeosciences [B]
MN: 2007 Fall Meeting