Prevalence and pollution characteristics of antibiotic resistant genes in one high anthropogenically-impacted river

The objectives of this study were to comprehensively investigate the occurrence, distribution, and mobility of antibiotic resistant genes (ARGs) in the biofilm, water, and sediment from a section of the Weihe-river, in the northern Henan province, China. The abundances of nine ARGs belonging to four commonly used antibiotic classes (tetracyclines, sulfonamides, fluoroquinolones, and multidrug) and class 1 integron-integrase gene (intI1) were quantified. Sulfonamides gene (sulI) accounted for the highest percentage of detected ARGs in most sampling sites, including in water, biofilm, and sediment. Among the resistance genes, IntI1 and sul1 were significantly correlated (r>0.800, p<0.01) with a fecal coliform (FC) detected in the biofilm, and there was also a significantly positive correlation between the abundances of 16SrRNA and intI1 in the biofilms. Compared with the sediment and water samples, the biofilms contained sufficient nutrients to promote bacterial reproduction. Under sufficient total nitrogen and phosphorus concentrations, the horizontal gene transfer due to intI1 plays a key role in the formation and migration of ARGs within biofilms.