Feedback current production by a ferrous mediator revealing the redox properties of Shewanella oneidensis MR-1

The redox properties of electroactive bacteria play an important role in biogeochemical cycling, environmental remediation and bioenergy generation. But the detailed mechanisms on the redox properties of living cells are still vague. Herein, we designed a series of electrochemical tests mediated by FcMeOH to investigate the bacterial electrode process. Cyclic voltammograms and a positive feedback current production of scanning electrochemical microscopy provided evidence on the process of electrochemical oxidation followed by biocatalytic reduction. Moreover, an irreversible process for the redox behaviours of Shewanella oneidensis MR-1 revealed that electrons may transfer by spreading among redox flavocytochromes at the cell membrane and that these proteins may form a conductive network to perpetuate cathodic electron transfer. These results provide an insight into redox reactions at the microbe-electrode interface.

Automated summary

The redox properties of electroactive bacteria are crucial for biogeochemical cycling, environmental remediation, and bioenergy generation. However, the detailed mechanisms of the redox properties of living cells remain unclear. In this study, we conducted a series of electrochemical tests mediated by FcMeOH to investigate the bacterial electrode process. The results revealed that the electrochemical oxidation followed by biocatalytic reduction occurs in the electroactive bacteria. Furthermore, an irreversible process for the redox behaviors of Shewanella oneidensis MR-1 was observed, suggesting that electrons may transfer among redox flavocytochromes at the cell membrane, forming a conductive network for cathodic electron transfer.