In situ analysis of antibiotic resistance genes in anaerobically digested dairy manure and its subsequent disposal facilities

The metagenomic and quantitative polymerase chain reaction approaches were combined to evaluate the profiles of ARGs and plasmids in anaerobically digested dairy manure in situ and reveal the persistence and elevation of typical ARGs and plasmids in its subsequent disposal facilities in CAFOs, respectively. Our results indicated that the typical ARGs and plasimd were mainly sul2, mefa, tetm-01, tetm-02, tetw, aph3iiia, and clostridioides difficile strain 12,038 plasmid unnamed in CAFOs, some of which greatly enriched in AD residue after its storage, especially sul1 and sul2. Meantime, the AD slurry recycling introduced the bacteria carrying ARGs into soil, especially Romboutsia genus, which greatly enriched sul2, tetm-01, tetm-02, aphiiia, and mefa. In the present study, ARGs occurrence, persistence and distribution were understood through in situ analysis of their profiles during dairy manure AD treatment and subsequent disposals in CAFOs, which are helpful for controlling the potential environmental risks from dairy manure recycling.

Automated summary

The study combined metagenomic and quantitative polymerase chain reaction methods to evaluate the profiles of antibiotic resistant genes (ARGs) and plasmids in anaerobically digested dairy manure, revealing the persistence and increase of typical ARGs and plasmids in confined animal feeding operations (CAFOs). The study found that typical ARGs and plasmids, such as sul1 and sul2, were enriched in the AD residue after storage, and that AD slurry recycling introduced bacteria carrying ARGs into soil, particularly of the Romboutsia genus. This understanding of ARG occurrence, persistence, and distribution is important for controlling potential environmental risks from dairy manure recycling.