Anaerobic cellulolytic bacteria dominated the area where most of the EAB were found, and more EAB were found on the graphite granules than on the root surface. This result implies that current was generated via the hydrolysis of cellulose and not directly from low molecular weight rhizodeposits. When optimising elec- tricity generation in a PMFC, therefore, the focus should be on root biomass production and effective hydrolysis of the biomass.