
60 Electrochemically Enabled Sustainability
Electron transfer mechanisms may differ from one organism to another,
depending on the nature (soluble or membrane-bonded) of the last redox
mediator that contacts the electrode. It is important to recognise that although
microorganisms have had billions of years to optimise electron transfer to
natural extracellular electron acceptors, such as Fe
3+
and Mn
4+
oxides, it is
unlikely that they have been evolved to cater for the most effective strate-
gies for electricity production. Thus, there is huge potential for the microor-
ganisms in MFCs to enhance their current-producing capacity, probably via