engleski

Functional metagenomics reveals the presence of both known and novel antibiotic resistance genes in environment impacted by elevated concentrations of antibiotics

The selection pressure imposed by antibiotics introduced into the environment largely through wastewater discharges and land application of manure, promotes the propagation of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment, creating reservoirs of ARGs with potential to be transferred to pathogens. In addition to maintain a range of known ARGs, polluted environments may also harbor yet undescribed resistance genes. In order to search for novel resistance genes, we analyzed effluents and sediments polluted with different veterinary antibiotics by a functional metagenomics approach. By screening four metagenomic libraries for resistance to sulfonamides, tetracyclines, trimethoprim, and beta-lactams we identified 66 unique, often clinically relevant ARGs, which were frequently found in clusters and flanked by mobile genetic elements. All of the genes conferring resistance to sulfamethazine, oxytetracycline and tetracycline were highly similar (amino acid identity ≥94%) with previously known genes. In screenings on trimethoprim and ampicillin we identified 15 potentially novel ARGs, including dihydrofolate reductases, thymidylate synthases and beta-lactamases from classes A, B, and D. These findings enable insight into a resistome shaped by high and long-term antibiotic selection pressure and provides a qualitative basis for monitoring the dispersal of ARGs to other environmental reservoirs or clinical settings.

Antibiotic pollution ; Antibiotic resistance genes ; Functional metagenomics ; Gene clusters ; Horizontal gene transfer

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