摘要：Wastewater treatment plants are an essential part of maintaining the health and safety of the general public. However, they are also an anthropogenic source of antibiotic resistance genes. In this study, we character‑ ized the resistome, the distribution of classes 1–3 integron-integrase genes (intI1, intI2, and intI3) as mobile genetic element biomarkers, and the bacterial and phage community compositions in the North End Sewage Treatment Plant in Winnipeg, Manitoba. Samples were collected from raw sewage, returned activated sludge, fnal efuent, and dewatered sludge. A total of 28 bacterial and viral metagenomes were sequenced over two seasons, fall and winter. Integron-integrase genes, the 16S rRNA gene, and the coliform beta-glucuronidase gene were also quantifed during this time period. Results: Bacterial classes observed above 1% relative abundance in all treatments were Actinobacteria (39.24%±0.25%), Beta-proteobacteria (23.99%±0.16%), Gamma-proteobacteria (11.06%±0.09%), and Alphaproteobacteria (9.18±0.04%). Families within the Caudovirales order: Siphoviridae (48.69%±0.10%), Podoviridae (23.99%±0.07%), and Myoviridae (19.94%±0.09%) were the dominant phage observed throughout the NESTP. The most abundant bacterial genera (in terms of average percent relative abundance) in infuent, returned activated sludge, fnal efuent, and sludge, respectively, includes Mycobacterium (37.4%, 18.3%, 46.1%, and 7.7%), Acidovorax (8.9%, 10.8%, 5.4%, and 1.3%), and Polaromonas (2.5%, 3.3%, 1.4%, and 0.4%). The most abundant class of antibi‑ otic resistance in bacterial samples was tetracycline resistance (17.86%±0.03%) followed by peptide antibiotics (14.24%±0.03%), and macrolides (10.63%±0.02%). Similarly, the phage samples contained a higher prevalence of macrolide (30.12%±0.30%), peptide antibiotic (10.78%±0.13%), and tetracycline (8.69%±0.11%) resistance. In addition, intI1 was the most abundant integron-integrase gene throughout treatment (1.14× 104 gene copies/mL) followed by intI3 (4.97× 103 gene copies/mL) while intI2 abundance remained low (6.4× 101 gene copies/mL). Conclusions: Wastewater treatment successfully reduced the abundance of bacteria, DNA phage and antibiotic resistance genes although many antibiotic resistance genes remained in efuent and biosolids. The presence of integron-integrase genes throughout treatment and in efuent suggests that antibiotic resistance genes could be actively disseminating resistance between both environmental and pathogenic bacteria.
