Biochar-Based Strategies for Antibiotic Resistance Genes Mitigation in Livestock Systems

The uncontrolled use of antibiotics in livestock production has resulted in the widespread dissemination of antibiotic resistance genes (ARGs) through manure, wastewater, aerosols, and direct contact, posing an escalating risk to both ecosystems and human health. Livestock systems act as critical reservoirs and transmission centers where high microbial densities, antibiotic residues, and mobile genetic elements converge to promote the persistence and mobility of ARGs. Conventional waste treatment strategies have achieved partial success in ARG mitigation but often fail to prevent horizontal gene transfer or long-term environmental dissemination. In this context, biochar has emerged as a sustainable and multifunctional material with promising capacity to adsorb extracellular DNA, inhibit microbial ARG proliferation, and catalyze reactive species for ARG degradation. Recent advances in biochar modification (e.g., metal and nonmetal doping, pore structure regulation, and surface functionalization) have enhanced its performance in both adsorption- and oxidation-driven ARG removal. Nevertheless, significant challenges remain, including the unclear quantitative contribution of concurrent mechanisms, potential trade-offs between porosity and surface reactivity, and variable performance under complex environmental conditions. Therefore, future research must integrate mechanistic quantification, multifunctional material design, and combined treatment strategies (e.g., biochar with advanced oxidation processes or constructed wetlands), while incorporating microbial community interactions, predictive modeling, and life cycle assessment. This paper highlights the environmental pathways of ARGs in livestock systems, synthesizes current progress on biochar-mediated mitigation, and outlines critical research frontiers, aiming to provide a comprehensive framework for advancing scalable, safe, and effective control of ARG dissemination at the interface of environmental engineering and public health.