GEOC 157 |
| Brandy M Toner1, Alain Manceau2, Mario Villalobos3, Sirine C Fakra4, Samuel M. Webb5, Matthew M Marcus4, John R. Bargar5, Bradley M. Tebo6, and Garrison Sposito1. (1) Department of Environmental Science, Policy and Management, University of California at Berkeley, Ecosystem Science Division, Berkeley, CA 94720-3110, (2) Environmental Geochemistry Group, CNRS / University of Grenoble, LGIT - Maison des GéoSciences, Grenoble Cedex 9, 38041, France, (3) Environmental Bio-Geochemistry Group, Instituto de Geografía, UNAM, LAFQA, National Autonomous University of Mexico (UNAM), CU México 04510, Mexico, (4) Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, (5) Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, Mail Stop 69, Menlo Park, CA 94025, (6) Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202 |
| Manganese oxides in natural environments are important regulators of metal cycling and organic matter degradation. Microbial catalysis is the dominant driver of Mn oxidation in these environments. Pseudomonas putida strain MnB1, a model organism for studying bacterial Mn oxidation, oxidizes Mn+2(aq) during early stationary phase of growth,precipitating a chemically reactive Mn oxide immediately adjacent to the bacterial outer membrane and interspersed among extracellular polysaccharides in a biofilm. The Mn oxidation state and molecular structure of the biogenic oxide were characterized by x-ray absorption spectroscopy. The reactivity of the oxide in the presence of bacterial cells and biofilm was assessed by its reactions with ascorbic acid and Zn+2. The hydrated biofilm does not interfere with reactions between solutes and the biogenic Mn oxide but does contribute to trace metal sorption. |
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Microbially Mediated Manganese and Iron Oxidation in the Biosphere
1:45 PM-6:20 PM, Wednesday, March 31, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |