Combination of electrochemical methods, quantum mechanical calculations, bioinformatics, and bioengineering allows understanding the photoexcited electron transfer process and set the basis for artificially tuning photo-bioelectrocatalysis.

The ability to establish successful and efficient extracellular electron transfer (EET) between bacteria and electrode surfaces is critical for the development of mediated microbial electrochemical technologies. Here, we describe a phenazine-based mediator system to facilitate electron transfer from the model bacterium Escherichia coli during glucose metabolism. Phenazine redox mediators were experimentally evaluated, demonstrating distinct mediated currents, dependent on mediator structure. Our results show that the choice of a mediator with the appropriate redox potential is not the single aspect to consider when rationally designing future mediator-based EET systems.

The development of photobioelectrochemical systems is an exciting field requiring a combination of electrochemical, biological and material science knowledge. One of the main advantages of applying anoxygenic photosynthetic microorganisms versus non-photosynthetic bacteria is the possibility to utilize sunlight as the energy source, while removing organic contaminants from a solution. Since bacterial cells utilize energy to maintain the intracellular osmolarity, bacterial species that do not rely on organic species as an energy source have an advantage over species requiring them for their sustainment. Herein, we discuss the possible use of Rhodobacter capsulatus, an extremely versatile photosynthetic purple bacteria, for application in environments within a range of low to moderately high salinity (0–25 g L⁻¹ NaCl). Bacterial cells’ capability to adapt to changing salinity, and effects on bioelectrochemical performance will be presented, as well as major drawbacks and research needs to drive future efforts and discussions.