Citation:

Dhar, B., H. Ryu, H. Ren, J. Santodomingo, J. Chae, AND H. Lee. High Biofilm Conductivity Maintained Despite Anode Potential Changes in a Geobacter-Enriched Biofilm. ChemSusChem. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany, 9(24):3485 –3491, (2016).

Impact/Purpose:

In this study, we report IET (Kapps and qmaxXf) and EET (Kbio and EKA) kinetic parameters, along with microbial community structures, at steady-state current density in an MxC run with two different Eanode conditions. We then discuss the implications of the IET and EET kinetic parameters, along with biofilm community, to identify kinetic bottlenecks responsible for the decline of current density at positive Eanode.

Description:

This study systematically assessed intracellular electron transfer (IET) and extracellular electron transfer (EET) kinetics with respect to anode potential (Eanode) in a mixed-culture biofilm anode enriched with Geobacter spp. High biofilm conductivity (0.96–1.24 mScm^-1) was maintained during Eanode changes from -0.2 to +0.2 V versus the standard hydrogen electrode (SHE), although the steady-state current density significantly decreased from 2.05 to 0.35 Am^-2 in a microbial electrochemical cell. Substantial increase of the Treponema population was observed in the biofilm anode at Eanode=+0.2 V, which reduced intracellular electron-transfer kinetics associated with the maximum specific substrate-utilization rate by a factor of ten. This result suggests that fast EET kinetics can be maintained under dynamic Eanode conditions in a highly conductive biofilm anode as a result of shift of main EET players in the biofilm anode, although Eanode changes can influence IET kinetics.

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