Impact of bioelectricity on DNRA process and microbial community composition within cathodic biofilms in dual-chambered bioelectrode microbial fuel cell (MFC).

[Display omitted] • A simultaneous bioelectricity generation and complete DNRA strain was isolated. • Genome and q-PCR analysis explain the mechanism of DNRA and outward EET pathway. • The presence of NH 4 + significantly enhances output voltage and the DNRA performance. • Bioelectricity promotes the up-regulated expression of NarG and NirB related to DNRA. • The bacterial community of cathode biofilms was affected by the bioelectricity. The synchronous bioelectricity generation and dissimilatory nitrate reduction to ammonium (DNRA) pathway in Klebsiella variicola C1 was investigated. The presence of bioelectricity facilitated cell growth on the anodic biofilms, consequently enhancing the nitrate removal efficiency decreasing total nitrogen levels and causing a negligible accumulation of NO 2 – in the supernatant. Genomic analysis revealed that K. variicola C1 possessed a complete DNRA pathway and largely annotated electron shuttles. The up-regulated expression of genes narG and nirB , encoding nitrite oxidoreductase and nitrite reductase respectively, was closely associated with increased extracellular electron transfer (EET). High-throughput sequencing analysis was employed to investigate the impact of bioelectricity on microbial community composition within cathodic biofilms. Results indicated that Halomonas , Marinobacter and Prolixibacteraceae were enriched at the cathode electrodes. In conclusion, the integration of a DNRA strain with MFC facilitated the efficient removal of wastewater containing high concentrations of NO 3 – and enabled the environmentally friendly recovery of NH 4 +. [ABSTRACT FROM AUTHOR]