ATR-SEIRAs characterization of surface redox processes in G. sulfurreducens

In this work we report on the occurrence of at least two different redox pairs on the cell surface of the electrogenic bacteria Geobacter sulfurreducens adsorbed on gold that are expressed in response to the polarization potential As previously reported on graphite (Environ Sci Technol 42 (2008) 2445) a typical low potential redox pair is found centered at around -0.06 V when cells are polarized for a few hours at 02 V. while a new pair centered at around 038 V is expressed upon polarization at 06 V. Reversible changes in the IR band pattern of whole cells where obtained by Attenuated Total Reflection-Surface Enhanced Infrared Absorption Spectroscopy (ATR-SEIRAS) upon potential cycling around both redox pairs. Changes clearly resemble the electrochemical turnover of oxidized/reduced states in c-type cytochromes, thus evidencing the nature of the involved molecules The expression of external cytochromes in response to the potential of the electron acceptor suggests the existence of alternative pathways of electron transport with different energy yield, though it remains to be demonstrated (C) 2009 Elsevier B V All rights reserved