Microbial electrolysis cells (MECs) utilise electrogenic bacteria, microbes capable of eating and breathing electrical current, for a number of beneficial applications. Fundamental to MECs are bacteria capable of utilising either an anode as an electron acceptor or a cathode as an electron donor to carry out biologically driven processes. MEC applications currently include bioremediation, biosensing, biofuel production and power generation. Although many studies have investigated the mechanisms of microbe-electrode interactions, less is known regarding the interspecies interactions within the electrogenic biofilms formed on the electrode surface. Placing these systems in situ, such as wastewater treatment reactors, has revealed that diverse and dynamic electrode-associated microbiomes develop both spatial and temporally. Thus, it is critical to increase our understanding of microbial interactions on the electrode surface to gain a deeper understanding of the microbial community interactome in its entirety.

Microbial interactions are being studied in competitive and synergistic growth conditions to examine interactions at a cellular and molecular level. One such syntrophic interaction found in this project has been between Geobacter sulfurreducens and Pseudomonas aeruginosa, whereby the growth of the combined organisms in the presence of specific electron donor and acceptor substrates exceeds the growth of these microorganisms alone. Interestingly, this syntrophic interaction is enhanced in the presence of oxygen despite the microaerophilic nature of G. sulfurreducens. Analysis of growth dynamics, biofilm community structure, redox reaction efficiency and electrical conduction on a set matrix of electrogenic bacterial pairs will reveal novel pathways that may improve electron flow in mixed communities. The knowledge gained from this research will contribute to improved optimization of MEC power output through the application of synthetic biology techniques.