Transfer of class 1 integron-mediated antibiotic resistance genes from Salmonella enterica of farm fly origin to susceptible Escherichia coli and Salmonella strains

Exposure to heavy metal and antibiotic enriches antibiotic resistant genes on the tire particles in soil

The widespread occurrence of tire particles (TPs) in soils has attracted considerable attention due to their potential threats. The assemblage of bacteria and associated antibiotic resistant genes (ARGs) on TPs is yet largely unknown, especially under the stress of soil pollutants. In the present study, TPs were incubated in soils with or without the stress of heavy metal (Cu²⁺) or/and antibiotic (tetracycline), and bacterial community and ARG profile on TPs and in soils were explored using high-throughput sequencing and high-throughput quantitative PCR. Results indicated that bacterial community structure on TPs was significantly different from the surrounding soils, with a lower diversity, and significantly shifted by heavy metal and antibiotic exposure. Additionally, a diverse set of ARGs were detected on TPs, and their abundances were significantly increased under the stress of heavy metal and antibiotic, revealing a strong synergistic effect. Moreover, a good fit was observed for the correlation between bacterial community and ARG profile on TPs. Taken together, this study, for the first time, demonstrates that TPs can provide a novel niche for soil bacteria and soil resistome, and heavy metal and antibiotic exposure may potentially increase the abundance of ARGs on TPs, threatening soil ecosystems and human health.