Mges (Mobile Genetic Elements), Bacteria Diversity, Bacterial-Fungal Interactions and Environmental Variables Collectively Determine the Variations of Args (Antibiotic Resistance Genes) During Excess Sludge Treatment by Vermicomposting

Abstract

Vermicomposting has a positive effect on the removal of ARGs due to earthworm’s natural immunity. However, the main factors that influence the spread of antibiotic resistance keep poorly understood. Here, we designed a vermicomposting (with earthworm) with a control (no earthworm) to dispose excess sludge to elucidate what mainly inhibit the dissemination of ARGs, especially plasmid-induced ARGs, caused by earthworms. The results indicated that Vermicomposting enable reduce the relative abundance of ARGs, with 74.5%. Notably, vermicomposting reduced ARGs donor bacteria growth and effectively enhanced RP4 plasmid control, with abundance levels decreasing by 1.05 and 1.08 logarithmic units. Furthermore, the interactions of bacteria and fungi also indirectly contributed to the reduction of ARGs through co-occurrence networks analysis. In conclusion, the structural equation model demonstrated that MGEs, bacteria diversity, bacterial-fungal interactions, and environmental variables collectively affected the ARGs dynamics during the vermicomposting treating excess sludge.

Keywords: Vermicomposting, antibiotic resistance genes, Mobile genetic elements, Plasmid-induced transfer, Structural equation model