Copper oxide nanoparticles influence on the performance of sequencing batch reactor and the transfer of antibiotic resistance genes by regulating bacterial quorum sensing system

The environmental pollution caused by copper oxide nanoparticles (CuO NPs) has attracted widespread attention. In this study, microbial community, key metabolic pathways and quorum sensing (QS) were investigated to reveal the impact of copper oxide nanoparticles (CuO NPs) on the performance of sequencing batch reactor (SBR) and the transfer of antibiotic resistance genes (ARGs). Results showed that under CuO NPs impact, the removal efficiency of COD, ammonium nitrogen (NH4+-N) and total nitrogen (TN) was stable at around 90%, 96% and 60%, respectively. However, removal efficiency of total phosphorus (TP) was reduced to below 60% under 0.1 mg/L and 1 mg/L CuO NPs exposure. Microbial community analysis showed CuO NPs was advantageous to the growth of key functional bacterial phyla Bacteroidetes, Proteobacteria and Patescibacteria. The relative abundance of Candidatus Accumulibacter genus and ppX gene were decreased, which then lower the TP removal efficiency. Besides, CuO NPs might trigger QS system, affecting Candidatus Accumulibacter, Aeromonas genus and ppX gene, and then regulated the removal of TP in the SBR system. The co-occurrence network analysis revealed a correlation among core ARGs, signaling molecule, QS-related microbial community and ARGs' hosts, suggesting that the spread of ARGs might be driven by QS system under selective pressure of CuO NP. These findings could reveal the effect of CuO NPs on the performance of activated sludge system and provides new ideas for ARGs control through regulating the QS system.