Effect of pH on the mitigation of extracellular/intracellular antibiotic resistance genes and antibiotic resistance pathogenic bacteria during anaerobic fermentation of swine manure

[Display omitted] •Under initial acidic fermentation, the removal of ARGs and MGE was more significant.•In the fermentation system, 105 microbial hosts genera for ARGs were identified.•The removal of ARB and ARPB was greater at pH 3 and 5 than at pH 7 and 11.•Acidic pH influenced the abundance of ARGs and ARPB by reducing microbial abundance. Effects of various initial pH values (i.e., 3, 5, 7, 11) during anaerobic fermentation of swine manure on intracellular and extracellular antibiotic resistance genes (iARGs and eARGs) and ARG-carrying potential microbial hosts were investigated. The abundance of almost all iARGs and eARGs decreased by 0.1–1.7 logs at pH 3 and pH 5. The abundance of only three iARGs and eARGs decreased by 0.1–0.9 logs at pH 7 and pH 11. Under acidic initial fermentation conditions (pH 3 and pH 5), the ARG removal effect was more pronounced. Acidic conditions (pH 3 and pH 5) significantly reduced the diversity and abundance of the microbial community, thereby eliminating many potential ARG hosts and antibiotic-resistant pathogenic bacteria (ARPB). Therefore, the study results contribute to the investigation of the effects of swine manure anaerobic fermentation on the removal and risk of contamination of ARGs and ARPB.