Freeze-thaw aged tire wear particles enhance the occurrence of antibiotic resistance genes in black soil

Antibiotic resistance genes (ARGs) are recognized as new biological pollutants, posing serious threat to human health and ecological security. Tire wear particles (TWPs), a typical type of microplastics, have caused increasing concerns due to their detrimental effects in recent years. TWPs are frequently detected in various ecosystems, yet the ecological impact of TWPs on soil ARGs under the natural freeze-thaw condition remains unclear. The study employed a soil incubation experiment to explore soil ARGs composition and diversity by adding pristine and freeze-thaw aged TWPs. Results depicted that the addition of aged TWPs increased the abundance and diversity of ARGs conferring resistance to vancomycin, multidrug, bacitracin, fosmidomycin, and Macrolides-Lincosamides-Streptogramins (MLS) compared to pristine TWPs. Besides, the abundance of intI1 in aged TWPs soil was significantly enhanced in response to freeze-thaw cycles, thereby promoting the mobility and spread of ARGs. Network analysis identified Pseudomonadota and Actinomycetota as key bacterial phyla potentially hosting ARGs. Partial least squares path modeling indicated that ARGs variations are primarily driven by virulence factors. This study holds significant implications for future assessments of environmental risks associated with TWPs-induced antibiotic resistance selection and emphasizes the necessity of considering TWPs when designing appropriate strategies to mitigate the persistent dissemination of ARGs.