Electrochemical Interaction of a Heterotrophic Bacteria Alcaligenes faecalis with a Graphite Cathode

Abstract

This study focused on the electrochemical interaction between a heterotrophic bacterium, Alcaligenes faecalis and a graphite cathode. The growth of Alcaligenes faecalis on the cathode surface was found to be stimulated by applying a polarization potential of −0.25 V (vs. SCE) to the cathode. Environmental scanning electron microscope (ESEM) showed a significant increase of the bacterial population on the poised-potential electrode and a notable change of the bacterial morphology from short rod to unusual long rod shape. Cyclic voltammetry (CV) curves of the biofilm-attached electrode showed two reductive peaks at around 0.4 V and −0.35 V vs. SCE, which were assigned to the redox potentials of outer membrane cytochromes and attached metabolites, respectively. Electrochemical impedance spectroscopy (EIS) indicated the attachment of active Alcaligenes faecalis reduced the charge transfer resistance of the electrode. The results conclusively indicated that both the bacteria and the metabolites on the electrode were involved in the electrochemical reactions, and Alcaligenes faecalis was bioelectrochemically active in cathodic electron transfer process.

Keywords:

• Alcaligenes faecalis
• electrochemically active bacteria
• poised potential
• cyclic voltammetry

Acknowledgments

This work was supported by the National Basic Research Program of China (973 Program, Program No. 2007CB815602) and National Program of Control and Treatment of Water Pollution (2009ZX07424-002).

Cuiping Zeng and Yan Li contributed to this article equally.