Paving the way for bioelectrotechnology: Integrating electrochemistry into bioreactors

The reactor systems used for microbial electrosynthesis, i.e. bioelectrochemical systems for achieving bioproduction so far reported in literature are relatively small in scale and highly diverse in their architecture and modes of operation. The often diverging requirements of the electrochemical and the biological processes and the interdisciplinarity of the field make the engineering of these systems a special challenge. This has led to multiple, differently optimized approaches of reactor vessels, designs and operating conditions making standardization and normalization or even a systematic engineering almost impossible. Overcoming this lack of standardization, scalability and knowledge-driven engineering is the driving force for this work introducing an upgrade kit for bioreactors transforming these reversibly to bioelectroreactors. The prototypes of the bioreactor upgrade kit were integrated with commercial bioreactor (fermentor) systems and performances compared to a classic, small-scale bioelectrochemical glass cell system. The use of the upgrade kit allowed interfacing with the existing infrastructure of the conventional bioreactors for growing electroactive microorganisms in pure culture conditions, with the added electrochemical control and further process monitoring. The results of growing Shewanella oneidensis MR-1 clearly show that these systems can be used to control, monitor, and scale microbial bioelectrochemical processes, providing better resolution of the data for the tested experimental conditions.