Bacterial biofilms: the powerhouse of a microbial fuel cell

Abstract

Research in the field of microbial fuel cells has exploded in recent years and is providing insights into the specialized biological processes that occur within these systems. Fundamental to the functioning of a microbial fuel cell is the formation of highly specialized bacterial biofilms on the electrode surface. While many different bacterial species have been found to associate with electrodes, to date only a few have been isolated in pure culture with the ability to produce a high current density. One such species, Geobacter sulfurreducens, is speculated to form an electrical conductive biofilm capable of electron transfer across a considerable distance greater than 50 µm. The mechanisms for electron transfer across such distances are only just being understood and may involve a matrix of bacterially produced nanowires and/or c-type cytochromes, but limited due to proton accumulation. Evolutionary and genetic engineering studies are now being employed to increase power output on a per cell basis with differing degrees of success.

Acknowledgements

The authors wish to thank Ching Leang, University of Massachusetts, USA, for providing the scanning electron microscopy image of a current producing Geobacter sulfurreducens biofilm.

Financial & competing interests disclosure

The authors are supported by the Office of Science (BER), US Department of Energy, Cooperative Agreement No. DE-FC02-02ER63446 and Office of Naval Research Award No. N00014-07-1-0966. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties, apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.