Fig. 4

Functions of EET components (MtrC and electron shuttle flavins) on Pd-NPs formation by S. oneidensis MR-1. a General diagram of EET pathway and genotypic effects on Pd-NPs formation. Thin section transmission electron micrographs of different strains: b, h MR-1, c ΔhydAΔhyaB, d ΔmtrCΔomcA, e MR-1 with an empty vector, ΔmtrCΔomcA with an empty vector f or mtrC vector g, and MR-1 with i 100 μM riboflavin (RF) or j 100 μM flavin mononucleotide (FMN) after 2 h reactions with 100 μM Pd²⁺. Scale bars represent 100 nm. k–m Nanoparticle size distributions were determined by analyzing thin section transmission electron micrographs for each strain. n Outer membrane-normalized particle counts for un-supplemented and flavin-supplemented MR-1 [81]