Bioelectrochemical systems (BES) are electrochemical processes in which the oxidation reaction at the anode and /or reduction at the cathode is catalysed by microorganisms. The most famous example of these processes is the microbial fuel cell (MFC), in which the treatment of organic effluents is coupled to the production of electricity. But the potential applications of these processes are very diverse, from H₂ to platform molecules production, and there is an increasing interest from researcher for this topic for the last 15 years.

The microorganisms catalyzing the reactions in the BES exchange electrons with the electrodes that they use as an electron acceptor in the case of oxidation reactions at the anode, or as an electron donor in the case of cathodic reactions. They are most often structured in biofilms on the electrode and are qualified as electroactive. One of the limiting factors in BES is the difficulty in controlling the formation of an efficient and time-stable biofilm on the electrodes.

BES are used in the LBE as models for the study of microbial interactions and for the development of eco-engineering strategies for microbial ecosystems.

We are particularly interested in the formation of biofilm on graphite electrodes through the choice and preparation of the inoculum depending on the reaction to be catalyzed and the operating conditions, the development of enrichment strategies or the reconstruction of biofilms from pure strains. In the case of complex substrates, it is also important to study the interactions between the biofilm and the planktonic community.

A recent development of this work is the electro-fermentation in which polarized electrodes are used to orient and control fermentation processes which take place in the reaction medium and not on the electrodes as in the case of the BES (Moscoviz et al. , 2016). This research also opens nice perspectives on the study of inter-species electron transfer  (Moscoviz et al., 2017).

References

• Moscoviz, R., de Fouchécour, F., Santa-Catalina, G., Bernet, N., Trably, E. (2017) Cooperative growth of Geobacter sulfurreducens and Clostridium pasteurianum with subsequent metabolic shift in glycerol fermentation. Scientific Reports, 7, 44334. DOI:10.1038/srep44334
• Moscoviz, R., Toledo-Alarcon, J., Trably, E., Bernet, N. (2016) Electro-fermentation: how to drive fermentation using electrochemical systems. Trends in Biotechnology, 34(11), 856-865. DOI:10.1016/j.tibtech.2016.04.009

• Pierra, M., Carmona-Martínez, A.A., Trably, E., Godon, J.J., Bernet, N. (2015) Specific and efficient electrochemical selection of Geoalkalibacter subterraneus and Desulfuromonas acetoxidans in high current-producing biofilms. Bioelectrochemistry, 106, 221-225. DOI:10.1016/j.bioelechem.2015.02.003.
• Pierra, M., Carmona-Martínez, A.A., Trably, E., Godon, J.J., Bernet, N. (2015). Microbial characterization of anode-respiring bacteria within biofilms developed from cultures previously enriched in dissimilatory metal-reducing bacteria. Bioresource Technology, 195, 283-287. DOI:10.1016/j.biortech.2015.07.010
• Carmona Martinez, A., Trably, E., Milferstedt, K., Lacroix, R., Etcheverry, L., Bernet, N. (2015). Long-term continuous production of H2 in a microbial electrolysis cell (MEC) treating saline wastewater. Water Research, 81, 149-156. DOI : 10.1016/j.watres.2015.05.041

Contact

Nicolas Bernet and Eric Trably