Abstract
Antibiotic resistance genes (ARGs), as emerging environmental contaminants, have become a threat to human health. Studies have shown that secondary effluent from wastewater treatment plants was an important source of ARGs, and the horizontal transfer of ARGs that took place in secondary effluent has increased its pollution to the water environment; the conjugative transfer is the main form of horizontal transfer. Powdered activated carbon was widely used in advanced wastewater treatment, it would gradually be converted into biological powdered activated carbon (BPAC) during long-term use, there was still no related research on whether the microorganisms on BPAC could promote horizontal transfer of ARGs. In this article, the system between S17-1 lamp pir Escherichia coli and MG1655-chl E. coli was constructed to explore the effect of BPAC on the conjugative transfer of resistance plasmid pHS-AVC-LW1144. The main results were as follows: the conjugative transfer of resistance plasmid could take place without and with BPAC, the effect was better with added BPAC, and the BPAC effect of promoting the conjugative transfer was strongest at 20 mg/L. When incubation time was 24 h and the BPAC dosage was 20 mg/L, the zygote concentrations and conjugative transfer frequency were the highest. The zygote concentrations were higher at low temperature (4°C) than normal (25°C) and high temperature (50°C) conditions. The zygote concentrations under alkaline (pH = 9) were higher than acidic (pH = 5) and neutral (pH = 7). Therefore, within a certain range, the longer the incubation time, the better the effect of promoting the conjugative transfer of resistance plasmid, and in low temperature and alkaline conditions, the effect of promoting the conjugative transfer were also better. Based on this study, we hoped to provide basic support for advanced treatment of reclaimed water and risk control of ARGs.
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