| 论文摘要： |
Nitrous oxide (N2O) emission in the partial nitrification (PN) system with Pharmaceuticals and Personal Care Products (PPCPs) exposure has aroused wide concern. This study investigated the impact and mechanism of longterm exposure to PPCPs on the N2O emission in the PN processes based on metagenomic analysis. Results revealed that exposure to PPCPs has inhibited nirK-type ammonia-oxidizing bacteria (AOB) and promoted the enrichment of nosZ clade I (nosZ-I) N2O reduction microorganisms (N2ORMs), which synergistically leads to the inhibition of N2O production. The amoABC gene abundance in control set (R0) constituted 12%, which is two times higher than in the PPCPs dosed system (R1), corresponding to the abundance of AOB metagenomeassembled genomes (MAGs) of R0 and R1, accounted for 46.4% and 26.3%, respectively. In terms of N2O reduction, abundance of nosZ in R1 was 218.9 reads-per-kilobase-per-million-mapped-reads (RPKM), far exceeding the 130.93 RPKM in R0. This discrepancy attributed to the higher abundance of nosZ-I (R1: 96.9 RPKM, R0: 9.26 RPKM). The abundance of nosZ-I increased from 0.73% (R0) to 28.55% (R1), while nosZ clade II (nosZ-II) N2ORMs MAGs was not affected. Finally, the abundance of antibiotics resistance genes (ARGs) in M_A.29 (nosZ clade I N2ORM) and MAG S_A.43 (nirK type AOB) also revealed that PPCPs facilitated the enhancement of N2ORMs and inhibition of AOB. These results provide new insights into the impact and mechanism of PPCPs on N2O emission in the PN system. |
