Wastewater treatment processes narrow the host range of plasmids while preserving specific bacterial carriers of antibiotic resistance genes, according to a peer-reviewed study published September 7 in Nature Communications. Researchers tracked microbial communities across three water resource recovery facilities using Hi-C metagenomics to map how mobile genetic elements behave in situ during treatment.
The team identified 944 plasmid clusters across influent, activated sludge, and effluent stages. Each facility and stage showed specific plasmid distributions. Across all three plants, plasmid host ranges narrowed progressively from influent to effluent, showing that treatment stages selectively constrain plasmid–host pairings.
Certain mobile elements persisted through the treatment process despite the narrowing host ranges. Persistent plasmid clusters that contained detectable mobility markers showed a trend toward broader, less modular host networks than plasmid clusters lacking detected markers. Hi-C data directly linking antibiotic resistance genes to bacterial hosts revealed that the families Burkholderiaceae and Rhodocyclaceae served as prominent reservoirs. Across facilities, these two bacterial families frequently harbored resistance genes against beta-lactam, tetracycline, and sulfonamide antibiotics.
Researchers from Rice University, the University of Southern California, and Duke University conducted the work. The author group includes Siyi Zhou and Lauren B. Stadler from Rice, alongside Sarah E. Philo, Michael A. Saldana, and Adam L. Smith from USC. The authors declared no competing interests. Grants supporting the research included awards from the U.S.–Egypt Science and Technology Joint Fund, the U.S. Army Corps of Engineers ERDC-CERL, the National Science Foundation, and the National Institute of Allergy and Infectious Diseases.
