English: Individual cyanobacterial genera were cultured under photoautotrophic conditions and 24 h illumination cycles (12 h of light/12 h of dark). Electrogenic activity was monitored by recording MFC voltage at 1 KΩ fixed external resistance. Rapid increase in voltage was observed at the beginning of each 12 h light cycle, and rapid drop in voltage was seen at the beginning of each 12 h dark cycle. Electrogenic activity monitored from duplicate MFCs (black and gray lines) revealed reproducible electrogenic profiles for individual genera. The negative controls, where cell voltage was monitored in MFCs loaded only with corresponding media in the absence of cyanobacterial cultures (dotted line), are shown for each experiment. 12 h dark-phases are indicated by black bars along x-axis.