(60u) Mechanism of Metal-Reduction with Geobacter Sulfurreducens

Geobacter Sulfurreducens, an iron-reducing microbe, has great potential for remediation of metal-contaminated water. The ability of Geobacter to reduce and precipitate metals provides a means to sequester toxic ions that would otherwise move freely in water systems. This is done by feeding the organism sufficient carbon to maintain respiratory activities. Several studies have been conducted to determine Geobacter's kinetic parameters on soluble terminal acceptors, but very little analysis has been conducted on the difference between the organism's kinetic parameters from a continuous culture and batch culture. This is quantitatively defined by Geobacter's growth yield and maintenance respiration requirements. A chemostat capable of operation under strictly anaerobic conditions was constructed and Geobacter grown on acetate as the terminal electron donor and ferric citrate as the terminal electron acceptor. The value of growth yield of 0.61 gDW/gacetate and maintenance coefficient of 0.356 gacetate/gDW/hr is consistent with previous reports. The dramatically different yield experienced on different electron acceptors has led speculation of divergent proposed mechanisms of metal reduction. Further research is currently aimed toward examining the kinetics of Geobacter on soluble and insoluble electron acceptors to further comprehend the mechanism of extracellular metal reduction.