Fate of antibiotic resistance genes in sewage treatment plant revealed by metagenomic approach

Antibiotic resistance has become a serious threat to human health. Sewage treatment plant (STP) is one of the major sources of antibiotic resistance genes (ARGs) in natural environment. High-throughput sequencing-based metagenomic approach was applied to investigate the broad-spectrum profiles and fate of ARGs in a full scale STP. Totally, 271 ARGs subtypes belonging to 18 ARGs types were identified by the broad scanning of metagenomic analysis. Influent had the highest ARGs abundance, followed by effluent, anaerobic digestion sludge and activated sludge. 78 ARGs subtypes persisted through the biological wastewater and sludge treatment process. The high removal efficiency of 99.82% for total ARGs in wastewater suggested that sewage treatment process is effective in reducing ARGs. But the removal efficiency of ARGs in sludge treatment was not as good as that in sewage treatment. Furthermore, the composition of microbial communities was examined and the correlation between microbial community and ARGs was investigated using redundancy analysis. Significant correlation between 6 genera and the distribution of ARGs were found and 5 of the 6 genera included potential pathogens. This is the first study on the fate of ARGs in STP using metagenomic analysis with high-throughput sequencing and hopefully would enhance our knowledge on fate of ARGs in STP.