Exploring Mediated Electron Transfer in Vibrio natriegens

Vibrio natriegens is a promising biotechnological chassis distinguished by exceptionally rapid growth and dynamic metabolism. This microorganism can deliver electrons both directly to electrodes via the well‐established MtrCAB electron export system, as well as mediated through redox shuttle molecules. Notably, mediated electron transfer (MET) results in higher currents. Bioelectrochemical systems offer a possibility to influence the metabolic product spectrum of V. natriegens by using a poised anode as terminal electron acceptor. This study systematically evaluated twelve mediators spanning a redox potential window from −520 to +490 mV versus Ag/AgCl (3 M KCl) to establish efficient MET in V. natriegens . Among the tested compounds, potassium ferricyanide yielded the highest current densities (104 ± 20 µA cm −2 ) and faradaic efficiency. Interestingly, riboflavin underwent less than 0.05 cycles of shuttling, indicating a low electron shuttling capability. In contrast, phenazines demonstrated efficiency for electron uptake from V. natriegens cells, but the current production was unstable. Overall, a specific redox potential window above −220 mV versus Ag/AgCl was identified within which mediator reduction occurred most efficiently. These findings establish a catalog of compatible redox shuttles and lay the basis for increased efficiency of bioelectrochemical processes leveraging V. natriegens .