Evidence for Iron-Dependent Nitrate Respiration in the Dissimilatory Iron-Reducing Bacterium Geobacter metallireducens

The dissimilatory iron-reducing bacterium Geobacter metallireducens was found to require iron at a concentration in excess of 50 μM for continuous cultivation on nitrate. Growth yield (∼3-fold), cytochrome c content (∼7-fold), and nitrate (∼4.5-fold) and nitrite (∼70-fold) reductase activities were all increased significantly when the growth medium was amended with 500 μM iron.