Proteomics efforts with G. sulfurrenducens complement other projects under the DOE Microbial Genome Program and have focused on creating a database of characteristic peptide mass and elution time tags, which serve as unique 2D markers for subsequent peptide identifications. This collaborative effort with Derek Lovely and the Geobacter project (www.geobactor.org) has produced initial global protein determinations with protein expression in most functional categories assigned by The Institute for Genome Research (TIGR). Thus far, quantitative analyses of protein expression patterns in Geobacter have been derived only by using an absolute peak intensity method. Characterization of the multiple cytochrome proteins in the organism has shown interesting changes in these proteins when they are exposed to different electron acceptors. Additionally, extension of these studies to protein expression pattern clustering is revealing interesting trends in protein expression as a result of the variation in solubility among the electron acceptor.