Flavin-Mediated Chemotaxis near Poised Electrodes in Shewanella oneidensis

Abstract

Shewanella oneidensis is a facultative anaerobe renowned for extracellular electron transfer, achieved through direct contact with electron acceptors or via released flavins such as flavin mononucleotide. Flavins not only aid S. oneidensis adaptation to dynamic environments but also act as chemoattractants, potentially guiding the cell toward insoluble electron acceptors. While flavins are known chemoattractants, the role of their redox state in shaping bacterial navigation is unclear. We hypothesize that S. oneidensis exhibits enhanced chemotaxis toward oxidized flavins, which form near environmental electron acceptors. To test this, we developed a platform combining electrochemistry and microscopy to simultaneously control flavin redox states and visualize motility under anaerobic conditions. Preliminary results show that S. oneidensis electrolocates to electrodes enriched in oxidized flavins, whereas chemotaxis (ΔcheA-3) and electron transfer mutants do not. The findings establish an experimental framework from which to investigate the role of oxidized flavins in the redox sensing mechanisms of Shewanella.