Redox profiling of G. sulfurreducens biofilms by confocal Raman microscopy

ROBUSCHI LUCIANA; TOMBA JUAN PABLO; SCHROTT GERMÁN D.; BONANNI P. SEBASTIAN; DESIMONE MARIELA; BUSALMEN JUAN PABLO

Alcalá de Henares

Congreso; 2nd European Meeting of the international Society for Microbial Electrochemistry and technology (EU-ISMET 2014); 2014

Aiming at gaining information on structural and physiological features of electricity-producing biofilms, we have constructed an electrochemical cell that can be mounted on the stage of a microscope. The cell is designed to use thin film transparent electrodes, thus allowing the observation of biofilms in situ and in vivo through the electrode. Using this cell in conjunction with a confocal Raman microscope (CRM), the redox state of molecules at different focal planes of Geobacter Sulfurreducens biofilms was explored. Obtained results showed a redox gradient across electricity-producing biofilms which was dependent on the potential applied to the electrode (sole electron acceptor), with the fraction of reduced species being higher in the external layers of the biofilm. Therefore, respiration in these layers is expected to be limited. Interestingly, when the electron acceptor is removed (open circuit), a transient gradient inversion at the biofilm/electrode interface evidences electrons relocation and distribution across the biofilm matrix. The approach provided new information about internal biofilm physiology, relevant for understanding current production constrains and electron conduction mechanisms in these systems.