Enzymatic pretreatment mitigates the dissemination of antibiotic resistance genes via regulating microbial populations and gene expressions during food waste fermentation

Food waste (FW) has been recognized as essential reservoir for resource recovery via anaerobic fermentation, which could also bring the potential risk of antibiotic resistance genes (ARGs) dissemination. Although the structural deficiency of FW could be stimulated by enzymatic pretreatment to enhance fermentation efficiency, the influences of enzymatic pretreatment on ARGs fate and microbial metabolic pathways involved in ARGs dissemination have rarely been reported. This work proved that enzymatic pretreatment could effectively decrease the total abundance of ARGs (reduced by 13.8%-24.5%) during long-term FW fermentation. It was found that enzymatic pretreatment significantly reduced the ARGs belonging to the efflux pump, which might be ascribed to its ability to increase membrane permeability. Furthermore, enzymatic pretreatment was in favor of reducing microbial diversity and various potential ARGs host (e.g., Methanosarcina, Clostridium, Prevotella, Parabacteroides). Also, this pretreatment remarkably up-regulated the genetic expressions involved in ABC transporter (e.g., eryF and mntA) and down-regulated the genetic expressions that participated in DNA replication, two-component systems (e.g., uphA and cckA), and quorum sensing (e.g., rpfF and lsrG), thereby decreasing ARGs transmission. This study would expand the insight of the influences of pretreatment method on ARGs fate during FW fermentation, and offer practical guidance on the sustainable management of FW.