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

Authors: W. Zhang, H. Wu and I-M. Hsing

Ref: Electroanalysis, 27, 3, 2015, pp 648–655

Abstract

Formation of biofilm on an electrode surface is usually a prerequisite for efficient electron transfer from electrogenic bacteria onto electrode, and the geometric status of the biofilm governs the generated current. In this study, we propose a real‐time characterization method to track the dynamic formation process of biofilm on electrode using scanning electrochemical microscopy (SECM). Shewanella oneidensis MR‐1 was chosen in this work as an electrogenic model species. A plane electrode at the bottom of a electrochemical cell filled with bacteria suspension was biased at +0.04 V vs. Ag/AgCl as the sole electron acceptor under anaerobic environment, while a movable ultramicroelectrode (UME) was employed to track the localized faradaic current generated by a redox mediator, Ru(NH₃)₆Cl₃ above the bottom electrode. The growth rate of biofilm showed some spatial heterogeneity, which might be explained by inhomogeneous mass transfer and non‐uniformity of electrode surface. The application of SECM into bacterial electrogenesis studies offered a simple and label‐free monitoring method to evaluate the bacteria‐electrode coupling status.

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