The removal mechanisms and novel strategies of antibiotic resistance genes in anaerobic sludge digestion: Insight into microbial metabolic regulation.

The prevalence of antibiotic resistance genes (ARGs) contamination in sludge anaerobic digestion (AD) systems poses a critical challenge to environmental protection. This review elaborates ARGs control from a microbial metabolism perspective after systematically outlining the strategies, performance and mechanisms of ARGs removal in sludge AD systems. External addition strategies appeared to activate multiple mechanisms simultaneously. Although mechanism studies still mainly focus on microbial community structures in current publications, the substantial increase in metabolism-centered investigations has received increasing attention. The metabolisms mechanisms linked to ARGs generation and persistence include central metabolism, stress response network and quorum sensing (QS), and these pathways follow a perspective from cellular damage to collective adaptation. The metabolic regulation is proposed to influence ARGs through two principal routes: direct interference with cellular structures such as membranes and biofilms, and indirect modulation of horizontal gene transfer (HGT), including plasmid dynamics, conjugation, transduction and transformation. Finally, metabolism regulation related design principles for ARGs control in sludge AD systems are outlined, highlighting electrically assisted AD system, advanced or modified materials and specific intervention agents. Through proposing a framework of metabolic intervention strategies, this review offers novel insights and practical directions for artificial and targeted interception of ARGs propagation in sludge AD systems.