Electrochemically active biofilms: facts and fiction. A review

Abstract

This review examines the electrochemical techniques used to study extracellular electron transfer in the electrochemically active biofilms that are used in microbial fuel cells and other bioelectrochemical systems. Electrochemically active biofilms are defined as biofilms that exchange electrons with conductive surfaces: electrodes. Following the electrochemical conventions, and recognizing that electrodes can be considered reactants in these bioelectrochemical processes, biofilms that deliver electrons to the biofilm electrode are called anodic, ie electrode-reducing, biofilms, while biofilms that accept electrons from the biofilm electrode are called cathodic, ie electrode-oxidizing, biofilms. How to grow these electrochemically active biofilms in bioelec-trochemical systems is discussed and also the critical choices made in the experimental setup that affect the experimental results. The reactor configurations used in bioelectrochemical systems research are also described and the authors demonstrate how to use selected voltammetric techniques to study extracellular electron transfer in bioelectrochemical systems. Finally, some critical concerns with the proposed electron transfer mechanisms in bioelectrochemical systems are addressed together with the prospects of bioelectrochemical systems as energy-converting and energy-harvesting devices.

The dual role of microbes in corrosion

“…Electrochemically active biofilms have been investigated in microbial fuel cell research and researchers have tried to understand the mechanisms of electron transfer between microorganisms and metals (Babauta et al, 2012). Several molecular studies revealed the role of pili and of multiheme outer-membrane c-type cytochromes in electron transfer (Butler et al, 2010, Lovley, 2012.…”

Effect of Long Time Oxygen Exposure on Power Generation of Microbial Fuel Cell With Enriched Mixed Culture

“…The poising of the anode was to allow consistent control of the biofilm electrode potential, by making the electrode as the sole electron acceptor [16]. The reason of nitrogen bubbling into the anode compartment was to accelerate the anaerobic condition in the system simultaneously increase the MFC electrochemical performance.…”

Real‐Time Label‐Free Monitoring of Shewanella oneidensis MR‐1 Biofilm Formation on Electrode During Bacterial Electrogenesis Using Scanning Electrochemical Microscopy

“…[6][7][8][9][10]. One key factor is accumulation of biomass on electrode surfaces [11][12][13][14][15][16], which could be reflected by geometrical status of bacterial biofilm formed on MFC anode electrodes. Biofilms, a synonym of microorganism communities attached to surfaces, are commonly formed and play a crucial role during various microberelated pathogenic, fermentative and energy-harvesting processes [12,17,18].…”

“…One key factor is accumulation of biomass on electrode surfaces [11][12][13][14][15][16], which could be reflected by geometrical status of bacterial biofilm formed on MFC anode electrodes. Biofilms, a synonym of microorganism communities attached to surfaces, are commonly formed and play a crucial role during various microberelated pathogenic, fermentative and energy-harvesting processes [12,17,18]. Significant phenotypic changes happen during microbial transition from planktonic (freeswimming) to surface-attached forms, and biofilms often exhibit largely heterogeneous and complicated structures.…”