Certainties and doubts on the electrochemical interaction between Geobacter sulfurreducens and electrodes

BUSALMEN, JUAN PABLO

Nice

Conferencia; 61st Annual Meeting of the International Society of Electrochemistry; 2010

ISE

Electrical connection between bacterial cells and electrodes has been the mater of numerous studies during decades, but the interest on the topic has been boosted less than 10 years ago with the discovery of “electrogenic” or “electroexogenic” microbes. Geobacter sulfurreducens is one of the model species with the ability to respire electrodes and produce electricity, and the most efficient ever reported. Interfacial mechanisms allowing the heterogeneous electron transfer to electrodes in G. sulfurreducens has been described including conduction through “nanowires”, through external cytochromes or a combination of both. However, details about the structure of the respiratory pathway to electrodes have been elusive to researchers. There is also a lack of information about the way in which electrons from bacterial cells in upper layers of a biofilm are collected on the electrode. Again, conductive pili and a network of cytochromes have been called to support the proposed mechanisms. The use of Attenuated Total Reflection-Surface Enhanced IR Absorption Spectroscopy (ATR-SEIRAS), Subtractively normalized interfacial Fourier transform IR spectra (SNIFTIRS) and classical electrochemical tools has been of valuable help to gain interfacial information and appears as a promising avenue for future investigation. Controlling culture conditions on the other side, allows the interrogation of the biological counterpart providing very useful complimentary data. In this talk previous and present results will be discussed trying to advance in the definition of bacterial electron transport mechanisms, considering the molecules involved and the strategies of bacterial respiration.