Biochar as a strategy to intercept microplastic-mediated ARGs spread in soil: Mechanisms, predictive insights, and research framework

Abstract

The proliferation of antibiotic resistance genes (ARGs) and microplastics (MPs) in the environment has raised growing public health concerns due to their potential risks to ecosystem safety and human health. Microplastics not only serve as carriers of resistant bacteria but also form unique niches for microbial colonization and biofilm development, thereby exerting selection pressure on ARGs and facilitating their horizontal gene transfer (HGT). Biochar, a widely used green adsorbent, offers a promising approach for contaminant mitigation. This review systematically examines current research on the influence of MPs and biochar on the behavior and spread of ARGs, with a particular emphasis on insights gained from data-driven approaches such as Random Forest analysis. These data-driven analyses identify specific microbial taxa (e.g., Verrucomicrobia) as key predictors for ARG proliferation, providing a mechanistic lens through which mitigation effects can be understood. We highlight that the high microbial density and pollutant accumulation on MPs favor ARG amplification and dissemination. In contrast, biochar amendment significantly reduces ARG levels in soil primarily by suppressing HGT and reducing the abundance of mobile genetic elements (MGEs), a process linked to its ability to restructure microbial communities and suppress key ARG-hosting phyla. However, further investigation is needed to clarify the enrichment, transport, and transfer mechanisms of ARGs at the interface of MPs and biochar, which is essential for accurately assessing human exposure risks and developing effective control strategies.