Proliferation of Resistance Genes in Wastewater Pipe Under Tetracycline and Cu Stress.

Abstract

Antibiotics and heavy metals can accumulate in wastewater pipe, and they could affect the proliferation of resistance genes in pipe. This study investigated the effects of tetracycline (TC) and Cu stress on extracellular polymeric substances (EPS) of sediments and the proliferation process and mechanism of typical antibiotic resistance genes (ARGs) and heavy metal resistance genes (HMRGs) in pipe. The results showed that TC and Cu induced microorganisms to secrete more tightly bound EPS (TB-EPS) in sediments. Under the 20 days exposure of 10,000 μg/L TC, TB-EPS increased by 49.38% compared with that without TC. Under TC and Cu stress, microorganisms secreted more functional groups associated with proteins and polysaccharides, and the secondary structure of proteins (α-helix and β-sheet) was changed, which improved the stability and aggregation of cell structure. Under the single and combined stress of TC and Cu, the relative abundance of most resistance genes in the sediment of wastewater pipe increased significantly (p ≤ 0.05). And TC and Cu stress increased the abundance of genes encoding for efflux pumps (tet(A), tet(G), copA, and copB) and promoted intl1-mediated horizontal gene transfer. This study could provide the theoretical basis for reducing the further spread of resistance genes in wastewater pipe.