News and Publications - Research Highlight
EMSL Scientific Grand Challenge Biogeochemistry Team Uses a Systems Biology Approach
S. oneidensis MR-1 attached to a hematite surface.
Environmental Molecular Sciences Laboratory(EMSL) Scientific Grand Challenges are an innovative approach to solving complex, large-scale, scientific and engineering problems with a broad scientific and environmental or economic impact. They have available to them resources housed in all of EMSL's six facilities and rely upon the collaborative research efforts of scientists from multiple institutions.
The EMSL Scientific Grand Challenge Biogeochemistry team is using a systems biology approach to understand electron transfer at the microbe-mineral interface in the model organism, Shewanella oneidensis MR-1. Microorganisms such as S. oneidensis MR-1 exchange electrons with minerals in soil, sediment, and subsurface material. This exchange affects the migration of environmental contaminants, water quality, soil fertility, and trace metal availability.
Applying a combination of experimental studies and computational modeling, the research team is focusing on three aspects of electron transfer: (1) the interface between bacteria and mineral surfaces, (2) electron transfer from membrane proteins and associated co-factors to the mineral surface, and (3) subsequent electron transfer from the surface to the interior of minerals.
Results from research performed, in part, under the EMSL Scientific Grand Challenge Biogeochemistry are reported in the August 2006 issue of Public Library of Science Biology. By studying the biomolecular mechanisms of S. oneidensis MR-1 and uranium interaction, a research team from Pacific Northwest National Laboratory (PNNL), University of Wisconsin-Milwaukee, and Argonne National Laboratory, gained insight about the potential of S. oneidensis MR-1 for uranium bioremediation.
S. oneidensis MR-1 reduces the very soluble hexavalent uranium, U(VI), to less soluble uranium oxide, UO2, limiting its movement in groundwater. The research team is the first to confirm that c-type cytochromes, which are proteins on the bacterial outer membrane, are essential for U(VI) reduction and UO2 particle formation Further, the cytochromes and biogenically reduced UO2 particles are co-localized in the extracellular polymeric substance (EPS), a protective matrix on the outside of some bacteria. This association may shed some light on the long-term fate of biogenically reduced UO2 in the environment. The EPS may affect the fate of UO2 by influencing its susceptibility to oxidation or its transport in soils and sediments.
The EMSL Scientific Grand Challenge Biogeochemistry team is led by Jim Fredrickson and John Zachara from Pacific Northwest National Laboratory. The team also includes researchers from University of Guelph, Stanford University, University of Southern California, Montana State University, UEA Norwich, Georgia Institute of Technology, University of Wyoming, University of Wisconsin-Milwaukee, and Virginia Tech.
Related Links
Marshall MJ, et al. 2006. c-Type Cytochrome-Dependent Formation of U(IV) Nanoparticles by Shewanella oneidensis. Public Library of Science Biology 4(8):e268.
EMSL In Brief, EMSL Grand Challenge Offers Insight About Uranium Bioremediation.