Metagenomic Profi ling of Antibiotic Resistance Genes and Mobile Genetic Elements in a Tannery Wastewater Treatment Plant
About 210,000 tons of antibiotics are produced annually in China, nearly half of which is used in animal agriculture for sickness prevention and production improvement [1,2]. The improper or illegal use of various antibiotics may result in the accumulation of residues in animal tissues including muscle, liver, kidney, skin and hair [3-5]. Leather production may facilitate the transfer of the antibiotic residues and resistant bacteria from animal tissues to the tannery wastewater. In addition, presence of various heavy metals  and biocides  in tannery wastewater contributes to coselection of antibiotics and heavy metals in wastewater treatment plants (WWTPs) .