High-generation tetracyclines shifted microbial community composition and induced the emergence of antibiotic resistant bacteria in soil

Tetracyclines (TCs) have been widely detected in agricultural soil due to their widespread use in animal husbandry. The impact of low-generation TCs, i.e., the first- and second- generations, on soil ecosystem has attracted widespread attention. However, the dynamic response of soil microbial community to high-generation TCs, i.e., the third- and fourth- generations, remains largely unknown. Herein, we characterized the variations in the composition, diversity and succession of microbial community and the proliferation of antibiotic resistance genes (ARGs) under the stress of four generations of TCs in brown soil and red soil. The results demonstrated that the exposure of low- and high- generation TCs consistently decreased the alpha diversity and stimulated the succession rate of microbial community in soil. High-generation TCs strongly shifted microbial community composition by reducing community resilience. The complexity of microbial networks and cross-module associations were strengthened to cope with the stress of high-generation TCs in soil. The abundance of ARGs was exacerbated by 1.75 times in response to the fourth-generation TCs compared to control in brown soil. The potential bacterial hosts of ARGs were more diverse in brown soil exposed to high-generation TCs, but the dominant hosts were not changed. These results highlight the potential ecological risk of the newly developed antibiotics, which is helpful for a comprehensive risk assessment of emerging contaminants.