Unraveling the effect of reductive soil disinfestation on oxytetracycline and antibiotic resistance genes in soil

Reductive soil disinfestation (RSD) is a soil remediation technology that effectively inhibits the transfer and spread of antibiotic resistance genes (ARGs) in soil. However, in soil contaminated with varying concentrations of oxytetracycline (OTC), the effect of RSD technology on OTC and ARGs remains unknown. In the laboratory, we established three soil treatments: OS (original soil samples); Soil Cultivation (control soils with five different residual concentrations of OTC (0, 5, 20, 50, 100 mg/kg)); RSD (treated soils with five different residual concentrations of OTC incubated at a constant temperature of 37 °C for 30 days). Results indicated that RSD can effectively degrade the concentration of OTC in soil, with degradation rates ranging from 22.91% to 82.83%. Additionally, RSD significantly reduced the relative abundance of ARGs, mobile genetic elements (MGEs) (P < 0.05), with reduction rates ranging from 24.39% to 86.56%. Network analysis indicated that Microbispora and Clostridium are the main potential hosts of ARGs. Redundancy analysis suggested that MGEs (42.7%) and microbial communities (19.5%) are the primary factors contributing to changes in ARGs. Therefore, the inhibition of MGEs abundance and reduction of host bacteria abundance by RSD are the primary mechanisms for reducing ARGs. In summary, RSD shows the potential for removing OTC and inhibiting the spread of ARGs in soil. This study provides a theoretical basis for using RSD in remediation of agricultural soils contaminated with antibiotics.