Living cells are required to get rid of a large number of electrons left behind in metabolism when nutrients convert into energy. Aerobic organisms inhale oxygen to dump these excess electrons. However, some harsh environments don’t afford the luxury of such soluble, ingestible electron acceptors. Bacteria devise unique strategies using membrane proteins to export electrons outside their body, but the exact mechanism remains unclear. Electron transport in proteins generally occurs via tunneling or hopping mechanism and the possibility of electron delocalization or metal-like conductivity has been considered previously impossible. I will present nanoscale electron transport measurements on pili protein filaments of a soil microorganism Geobacter sulfurreducens that challenge this long-standing belief. Using a scanning probe microscopy-based approach to visualize charge propagation in proteins, we have found out that pili propagate charges in a delocalized manner similar to carbon nanotubes, enabling bacteria to carry out respiration and cellular communication over 100 times their size. Structural and molecular studies revealed that pili possess unique arrangement of aromatic amino acids that facilitate intermolecular electron delocalization. I will discuss the implications of conductive proteins for bacterial physiology and for the developments of electronic biomaterials and devices.