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 0.2 V, while a new pair centered at around 0.38 V is expressed upon polarization at 0.6 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.
Busalmen
Juan Pablo
JP
Instituto de Electroquímica, Universidad de Alicante, Apartado de Correos 99, 03080 Alicante, Spain. jbusalme@fi.mdp.edu.ar
Esteve-Nuñez
Abraham
A
Berná
Antonio
A
Feliu
Juan Miguel
JM
D002462:Cell Membrane / Q000502:physiology* / Q000528:radiation effects*; D045304:Cytochromes c / Q000378:metabolism*; D004574:Electromagnetic Fields; D045302:Geobacter / Q000378:metabolism* / Q000528:radiation effects*; D013058:Mass Spectrometry; D010084:Oxidation-Reduction
D045304:Cytochromes c