Investigating the structure and composition of anode-associated biofilms in electrochemical systems

Microbial electrolysis cells (MECs) utilize microorganisms to catabolize organic substrates into biohydrogen and are being investigated as a potential solution to meet future energy needs. The focus of this project was to characterize the changes in mircrobial community composition of an anode-associated biofilm and to develop a method to monitor the biofilm in situ from an H-type, ethanol-fed MEC over the lifespan of the reactor. FISH and DGGE results revealed a shift in the biofilm microbial structure and composition from higher microbial diversity in the anaerobic digested sludge inoculum to a more uniform, lower diversity community towards the end of sampling. There was also an overall decrease in methanogenic community members and increase in both anode-respiring bacteria community, specifically Geobacter species, and current density over the time course, implying that a more stable community of anode-respiring bacteria, with minimal methanogens, results in higher current density and a more efficient MEC.