Please check: 
 Busalmen, J.P., Esteve-Núñez, A., Berná, A. & Feliu, J.M. C-type Cytochromes 
 Wire Electricity-Producing Bacteria to Electrodes. Angewandte Chemie 
 International Edition 47, 4874-4877 (2008) 
 5. Esteve-Nunez, A., Sosnik, J., Visconti, P. & Lovely D.R. Fluorescent properties 
 of c-type cytochromes reveal their potential role as an extracytoplasmic electron 
 sink in Geobacter sulfurreducens Environ. Microbiol. 10, 497-505 (2008) 

 Currently nanowires are being discarded as the main electron shuttle