Probing electron transfer with Escherichia coli: a method to examine exoelectronics in microbial fuel cell type systems.
Escherichia coli require mediators or composite anodes for substantial outward electron transfer, >8A/m(2). To what extent non-mediated direct electron transfer from the outer cell envelope to the anode occurs with E. coli is a debated issue. To this end, the redox behaviour of non-exoelectrogenic E. coli K12 was investigated using a bi-cathodic microbial fuel cell. The electromotive force caused by E. coli biofilms mounted 0.2-0.3 V above the value with the surrounding medium. Surprisingly, biofilms that started forming at different times synchronised their EMF even when physically separated. Non-mediated electron transfer from E. coli biofilms increased above background currents passing through the cultivation medium. In some instances, currents were rather high because of a sudden discharge of the medium constituents. Mediated conditions provided similar but more pronounced effects. The combined step-by-step method used allowed a systematic analysis of exoelectronics as encountered in microbial fuel cells.
Institute of Life Technologies, University of Applied Sciences and Arts Western Switzerland, Valais, Route du Rawyl 64, 1950 Sion, Switzerland.
Marc
M
Sugnaux
Sophie
S
Mermoud
Ana Ferreira
AF
da Costa
Manuel
M
Happe
Fabian
F
Fischer
D001674:Bioelectric Energy Sources / Q000382:microbiology*; D018441:Biofilms / Q000254:growth & development; D001709:Biotechnology / Q000379:methods*; D004560:Electricity; D004566:Electrodes; D004579:Electron Transport; D048168:Escherichia coli K12 / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D010084:Oxidation-Reduction; D010933:Plankton / Q000382:microbiology
Electron transfer; Escherichia coli; Microbial fuel cell; Synchronisation