(60i) Geobacter Sulfurrenducens Growth in Iron Oxides Media

The Department of Energy (DOE) has become very interested in using microbial systems to remediate radioactive metal contaminants, such as Technetium (Tc) and Uranium (U). These materials are found naturally in their soluble form. Water sources, such as lakes, rivers, and aquifers, contaminated with these and other metal traces represent an emerging issue for environmental and human health. After some studies it is demonstrated that dissimilatory metal reducing (DMR) microorganisms, including different types of Geobacter are able to reduce metals like iron. DOE is interested in a system where Tc and U are present because the reduction of these ones results in their precipitation as insoluble oxides that are easier to take care. To study this system, researchers have used iron reduction as a model system. Geobacter sulfurrenducens is able to reduce iron insoluble (Fe3+) into iron soluble (Fe2+). Geobacter sulfurrenducens employ carbon sources as electron donors in order to reduce the studied metals (electron acceptors). The electron donor will be sodium acetate and the electron acceptor ferrihydrite (Fe3+ source). The mainly approach of this study is the development of a technique, using iron oxide as the electron acceptor, that allows the total reduction of metals. Iron is used to develop this procedure because it is possible to measure the Fe2+ present in solutions using a ferrozine assay. The method will be used to reduce metals that are persistent in groundwater but they are insoluble after being reduced. Insoluble metals will be easier to treat in order to have water free of these pollutants. The places where Tc and U are principally found do not have all the nutrients that Geobacter needs to survive. If the interested bacterium is not able to survive it will not be able to perform the reduction of the interested metals, for this reason the substrate usage rate that Geobacter need to survive is also presented.