Molecular and Phenotypic Assessment of Antimicrobial Resistance Potential and Mechanisms by Mixtures of Environmental Pollutants In Wastewater
Antibiotic resistance poses a potential risk to human health. It has been proved that a variety of environmental pollutants from low environmentally relevant concentrations to relatively high minimum inhibitory concentrations (MICs), can induce antibiotic resistance. However, previous studies were mainly focused on the effect of single pollutants on antibiotic resistance induction, while the combined effects of the mixture of pollutants at environmentally relevant concentrations remain largely unknown. In this study, the effect of organic pollutants in wastewater effluents on inducing antibiotic resistance is investigated, and a library of transcriptional fusions of green fluorescent protein (GFP) that monitors the activity of promoters for 130 antibiotic resistance genes (ARGs) and antibiotic resistance (AR) pathway related genes in E. coli K12 is employed to evaluate the gene expression change induced by wastewater effluent samples. The results demonstrate that wastewater effluent extracts, at both the original concentration and concentrations factors of 500x, both before and after the disinfection process wastewater extracts, can induced significantly increased resistance to streptomycin, while the increased resistance to tetracycline is only induced by the disinfected wastewater exhibited sample at a concentrations factors of 500x. The differential expression of genes associated with outer membrane permeability change, alteration of efflux pump, and drug inactivation in exposure to effluent samples has been identified. The difference of antibiotic resistance induction potential between samples before and after disinfection has also been evaluated. This study provides evidence that continuous exposure to wastewater effluents can induce antibiotic resistance in E. coli, and the potential mechanisms of antibiotic resistance induction of wastewater effluents can be evaluated by the GFP-fused ARG library