is a widely applied microorganism for the reduction of toxic metal salts, as an electron source for bioelectrochemical devices, and as a reagent for the synthesis of nanoparticles. In order to understand the influence of metal salts, and of electron transporting, multiheme -cytochromes on the electron flux during respiration of , the reduction kinetic of Fe, Co, V, Cr, and Mn containing complexes were measured. Starting from the resting phase, each cell produced an electron flux of 3.7 × 10 electrons per second during the respiration process. Reduction rates were within ± 30% the same for the 6 different metal salts, and reaction kinetics were of zero order. Decrease of -cytochrome concentrations by downregulation and mutation demonstrated that -cytochromes stabilized respiration rates by variation of their redox states. Increasing Fe/heme levels increased electron flux rates, and induced respiration flexibility. The kinetic effects parallel electrochemical results of biofilms on electrodes, and might help to optimize bioelectrochemical devices.