It has recently been shown that certain metal-reducing bacteria, belonging primarily to the family Geobacteraceae can directly transfer electrons to electrodes
using electrochemically active redox enzymes, such as cytochromes on their outer membrane. These microbial fuel cells does not need mediator for electron transfer to electrodes and are called as mediator less MFCs. Mediator less MFCs are considered to have more commercial application potential, because mediators used in Biofuel cells are expensive and can be toxic to the microorganisms.