Iron-Oxidizing Bacteria in the Wetland Plant Rhizosphere: Characterization of a Novel Microbial Niche

George Mason University, Fairfax VA

Investigators

Abstract

Megonigal- DEB-9986981 Iron-Oxidizing Bacteria in the Wetland Plant Rhizosphere: Characterization of a Novel Microbial Niche Wetlands are places where iron changes form a reduced form (Fe2+) to an oxidized form (Fe3+) in the presence of O2. We know this process occurs around wetland plant roots because they often have a rust-colored Fe3+ coating. Most scientists believe Fe oxidation is spontaneous and that it does not involve microorganisms. However, we discovered bacteria on wetland plant roots that oxidize Fe3+ for energy and we suspect they control Fe oxidation rates in wetland soils. We also suspect that the Fe coatings that these organisms produce are more available to Fe-reducing microbes than those in the bulk soil. We will use laboratory and field experiments to test these hypotheses. The work is important because Fe cycling affects the behavior of several other elements including some pollutants. Of particular interest is the fact that iron cycling may affect the amount of methane released from wetlands; methane is a major greenhouse gas.