Genes on the Move: Exploring the Resistome of Viable Isolates from a First Nation Community in Manitoba

Despite wastewater treatment plants (WWTPs) and oxidation lagoons (OL) being designed for pollutant and pathogen removal, these systems can also serve as environments conducive to the exchange of mobile genetic elements (MGEs) and antibiotic resistance genes (ARGs) among microorganisms. This context facilitates the dissemination of antimicrobial resistance (AMR) among both pathogenic and non-pathogenic environmental bacteria, as well as phage populations, within these facilities. To enhance understanding of AMR dynamics in wastewater, our study examined the resistome of bacterial isolates recovered from a OL in a First Nation (FN) community in Manitoba, Canada. Thirty-five samples were collected from all OL stages, including raw sewage, lagoons, submerged attached growth reactor (SAGR), UV-treated effluent, and an upstream control site, from September 2022 to April 2023. Whole genome sequencing of 58 viable isolates was performed using Oxford Nanopore MinION, with genomes reconstructed via de novo assembly. The isolates corresponded to the following genera: Aeromonas 50.87% , Serratia 15.78%, Pantoea and Escherichia 7.01% each, Lelliottia 5.26%, Rahnella, Enterobacter and Buttiauxella 3.50% each, and finally Acinetobacter, Yersinia and Citrobacter 1.75%. Furthermore, a total of 32,559 elements were classified as ARGs. MGEs carrying ARGs were detected in 72.72% of the isolates. ARGs conferring resistance to macrolides, tetracyclines, and fluoroquinolones demonstrated a notable presence within MGEs (plasmids and bacteriophages) identified throughout the facility's stages. This research represents a non-invasive approach, enabling an in-depth exploration of AMR dynamics by discerning the resistome profiles of bacteria residing within a rural OL facility from a FN community.