Effects and mechanism of microplastics on abundance and transfer of antibiotic resistance genes in the environment - A critical review

Antibiotic resistance genes (ARGs) are emerging pollutants that are widely present in the environment, and are affected by microplastics (MPs). The coexistence of MPs and ARGs enhances their abundance and transmission ability, thereby increasing their environmental hazard. This study summarized the effects of MPs on the abundance and transmission of ARGs. First, the effects of MPs on ARGs in aquatic, terrestrial, atmospheric, and animal intestinal environments were analyzed. Furthermore, factors that affect the enrichment and transfer ability of MPs, including MPs properties, human activities, environmental factors, and other pollutants, were discussed. Previous studies mainly focused on the abundance changes, propagation and diffusion of ARGs on MPs, however, the possible mechanism of these changes on ARGs caused by MPs has not been fully studied, which also leads to many explanations that are not appropriate. Therefore, in the fourth section, the detailed mechanism of MPs on abundance and transfer of ARGs is systematically discussed. As the core innovation in this article, it fills the gap that has been to be supplemented in recent years. Finally, the research challenges and prospects of the effects of MPs on the abundance and spread of ARGs are proposed in the hope that this review will be helpful to better understand the environmental risks and mechanisms of MPs on ARGs.