Short CommunicationEnhancement of subsoil denitrification using an electrode as an electron donor

•Electric potential enhanced denitrification in a subsoil slurry.•Electric potential increased the abundance of Geobacter and Pseudomonas species.•N2 was the dominant end product of denitrification induced by electric potential.•Applying an electric potential could reduce subsoil nitrate concentrations.

Laboratory culture studies have demonstrated that some microbial strains can use electrons generated by electrodes in the denitrification reaction. To test whether the native soil microbiota can use electrode electrons for denitrification, a subsoil slurry was incubated under an electric potential treatment. A potentiostat-poised (−500 mV) electrode served as an electron donor. The electric potential treatment enriches the electroactive denitrifying bacteria and accelerates the nitrate reduction in the subsoil slurry, with N2 as the dominant end product. These results demonstrate that an electrode can serve as an electron donor to enhance the subsoil denitrification. This finding supports the future development of a technique to remove accumulated nitrate in subsoils and reduce nitrate contamination in groundwater.