Bioelectrochemical mitigation of soil antibiotic resistance: Disruption of bacteriophage transmission and resistant hosts.

The proliferation of antibiotic resistance genes (ARGs) in environment poses a threat to global public health. Although microbial fuel cell (MFC) has been demonstrated to mitigate ARG amplification, the mechanism remains unclear. This study employed metagenomic sequencing combined with the DeepARG-LS model for profiling ARGs and further analyzed the effects of MFCs on them in tetracycline-contaminated soil. Consequently, tetracycline addition (AT treatment) elevated total ARG abundance by 31 %, whereas MFC application (MT treatment) reduced it by 12 %. The deep learning model revealed a 38 % reduction in the richness of ARG subtypes in the MT compared to the AT. Proteobacteria dominated as ARG hosts, accounting for 78 % of ARGs in the AT, but declined by 18 % in the MT. Notably, the archaeal Nitrososphaeraceae was identified as a host for tetA(48). Species-level analysis identified 12 ARG-carrying bacterial taxa, the abundance of most of which was suppressed (abundance) by MFCs. The richness of ARGs host bacteria was 38 % lower in the MT treatment than that in the AT treatment. Meanwhile, the abundance of the indole biosynthesis gene (tryptophanase, EC 4.1.99.1) exhibited a consistent trend with the richness of ARGs hosts. Mechanistically, the suppression of ARG-host bacteria may be attributed to enhanced indole biosynthesis (as indicated by increased tryptophanase abundance), coupled with reduced abundances of mobile genetic elements (84 %) and virulence factors (11 %), and a decline in phage-mediated ARG transmission (19 %). Overall, these findings provide insights into bioelectrochemical controlling ARG dissemination in soils.