Selective pressure of antibiotics and heavy metals on erythromycin resistance genes in wastewater

Occurrence and distribution of six heavy metals and three antibiotics were investigated in a sewage treatment plant in Shanghai using inductively coupled plasma mass spectrometer (ICP-MS) and solid-phase extraction combined with high-performance liquid chromatograph tandem mass spectrometer (SPE-HPLC-MS/MS), respectively. Quantitative PCR (qPCR) was used to determine the distribution and removal of seven erythromycin resistance genes (ERY-ARGs) during the wastewater treatment process. The results showed that sulfamethoxazole (SMX), erythromycin (ERY) and tetracycline (TC) were detected, and their respective removal efficiency was low in the range from 3% (ERY) to 36% (TC). Heavy metals of Cr, Cu, Zn and Pb were detected with concentrations in the ranges of 136.9~235.5, 7.1~37.4, 18.1~98.4 and 143.1~383.0 μg/L, respectively. Almost completely removal of Zn was found by the two-stage anoxic/oxic (A/O) process, while the elimination rates for Cu, Pb and Cr were 48%, 43% and 18%, respectively. Additionally, all ERY-ARGs were detected in the range between 9.28×103 copies/L (ermA) and 1.83×108 copies/L (ereA) in raw influent and were significantly reduced (1.19~3.97 logs) in the wastewater treatment process. Based on the correlation analyses, the concentrations of ERY-ARGs exhibited significantly positive correlation (P ©, 2015, Chinese Society for Environmental Sciences. All right reserved.