Electrochemical Activity Produced from Abundant Expression of C‐Type Cytochromes in a Filamentous Gram‐Positive Bacterium

Abstract Natural microbes employing c ‐type cytochromes ( c ‐Cyts) for extracellular electron transport (EET) were greatly valuable to develop redox‐based bioelectrochemical applications. However, low levels of c ‐Cyt expression limited the phylogenetically diverse Gram‐positive species to be used in bioelectrochemical devices. This work reported the remarkable finding that a high level of c ‐Cyts was expressed in the cells of the Gram‐positive strain Lysinibacillus varians GY32. c ‐Cyts in Lysinibacillus varians GY32 cells were expressed at a level close to those in Shewanella oneidensis . These c ‐Cyts were found to cluster in cytoplasmic membrane and periplasmic space, along the length of Lysinibacillus varians GY32 cell. With voltammetry and spectroelectrochemical titration, phenazine methosulfate‐mediated electron transfer between the c ‐Cyts and an electrode was proved. These results expanded the accessible natural models of EET and suggested a new microbial platform for developing bioelectrochemical applications.