Following Nature: Bioinspired Mediation Strategy for Gram-Positive Bacterial Cells

Employment of redox polymers as mediators is a promising concept to facilitate electron transfer (ET) and improve operational performance of bioelectrochemical systems. Materials science offers a broad range of mediation possibilities; however, their employment so far relies on a trial-and-error approach, since there is no comprehensive understanding of the nature of the ET between bacterial cells and redox polymers. In the current work, the polymer-cell interaction is investigated in detail and clear experimental evidence that a redox polymer containing quinone moieties mimicking the natural bacterial charge carriers can be incorporated into the respiratory chain of Gram-positive Enterococcus faecalis cells and outperform monomeric mediator in ET features is reported. The presented findings disclose the main principles to overcome incompatibilities between abiotic charge carriers and microbial metabolism and provide essential knowledge for further development of mediated microbial bioelectrocatalysis.