Mapping microbial fiber networks with extraordinary electrical conductivity

Cable bacteria are filamentous, sulfur-oxidizing bacteria that evolved a unique protein structure to transport electrons over centimeter-scale distances. This protein structure consists of parallel conductive fibers that run along the length of the filament. Previous experiments show that conductive fibers are enriched in nickel and sulfur. It is theorized that the fibers are composed of a novel metalloprotein containing a sulfur-ligated nickel complex. The distribution of these Ni/S groups in the conductive fibers, their molecular structure and their role in the electron transport mechanism remain unknown. We seek to create high-resolution 2D and 3D elemental maps of cable bacteria cells and the isolated protein structure to map the distribution of Ni/S groups in the individual fibers. Ni K-edge XANES spectra will provide additional structural information on the metal group. This dual approach will improve our understanding of long-distance electron transport in cable bacteria.