Bacterial nanowires are extracellular appendages that have been suggested as pathways for electron transport in phylogenetically diverse microorganisms, including dissimilatory metal-reducing bacteria, photosynthetic cyanobacteria, and thermophilic fermentative bacteria. The presence of bacterial nanowires in organisms across the metabolic spectrum challenges our understanding of extracellular electron transfer in microbial communities and has significant biotechnological implications for renewable energy recovery in microbial fuel cells. To date, several biological assays have demonstrated results consistent with electron transport along bacterial nanowires, but our direct knowledge of nanowire conductivity has been limited to local scanning probe measurements across the width of nanowires. We will present electron transport measurements along the length of individually addressed bacterial nanowires derived from electron-acceptor limited chemostat cultures of the dissimilatory metal reducing bacterium Shewanella oneidensis MR-1. We will also discuss the results of transport measurements on intact biofilms and the contribution of nanowires to their overall conductivity.
