Synergistic remediation of cadmium contaminated soil and mitigation of genes encoding antibiotic resistance determinants in soil bacterial communities after anaerobic soil biological treatment

Antibiotic resistance genes (ARGs) are emerging environmental pollutants able to persist and disseminate in metal contaminated soils through metal induced co-selection mechanisms. Therefore, remediation of metal contamination in soils through soil management strategies has great potential in mitigation of ARGs in soil bacterial communities. In this study, Cd contaminated soil was water flooded to obtain anaerobic conditions with different organic materials (wheat straw and soybean meal) to remediate cadmium (Cd) contaminated paddy soils. The resistance profiles (including antibiotic and metal resistance determinants) and biological pollutants (including high risk ARGs, soil-borne pathogens, virulence factors (VFs)) were further evaluated using metagenomic sequencing. Our results showed that anaerobic biological treatment in soil was able to practically promote the Cd immobilization in polluted soils and the reduced Cd bioavailability (e.g. CaCl 2 extracted Cd and exchangeable Cd) further decreased the relative abundance of ARGs and metal resistance genes (MRGs) in the soil bacterial community. Changes in the soil resistome were able to attributed to a changing bacterial composition and reduced oxidative stress in soil under anaerobic biological treatments. In addition, our approach was also able to effectively weaken environmental risks posed by the soil bacterial community, including high risk ARGs, soil-borne human pathogens and VFs. In conclusion, this study provides a theoretical framework and technological strategy for synchronously mitigating of both ARGs and Cd contaminations in agricultural soils, which offers significant contributions to soil health preservation and sustainable environmental management. • Anaerobic soil biological treatment (ASB) promoted Cd immobilization in soils. • The abundance of antibiotic resistance genes (ARGs) decreased after ASB. • Reduced Cd bioavailability was the primary factor affecting ARGs and MRGs profiles. • ASB mitigated soil health risk by suppressing high risk ARGs and virulence factors. • Altered bacterial composition and decreased oxidative stress drove mitigation of health risk.