Risk Analysis of Drug Resistance Transfer of Salmonella in Soil under Heavy Metal Stress Copper Pressure

Heavy metals are usually present in various environments in different concentrations and may affect the transfer of exogenous genes into the soil. Currently, little research has been done on the effect of exogenous microorganisms on soil microbial resistance in the presence of different concentrations of copper heavy metals in real environments. We sampled soils containing resistant/non-resistant Salmonella in different copper concentration group treatments and identified antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and microbial communities by macrogenomic sequencing. It was found that environmentally relevant moderate concentrations of copper promoted the transfer of resistance genes to the soil microflora. It was also found that in unfertilised soils, potential hosts for ARGs carried by resistant Salmonella were Klebsiella pneumoniae and Mycobacterium bovis. In addition to the intrinsic efflux pump genes of Salmonella, the common tetracycline-resistant genes tetA(58), tetB(46), tetB(60), tetA(46) and tetB(P), the glycopeptide-resistant genes vanRI, vanOH, and the vancomycin-resistant gene vanG were potential hosts for the newly susceptible Salmonella. This study provides new insights into the spread of antibiotic resistance in soil environments under heavy metal stress, which is scientifically important for assessing the environmental health risks posed by heavy metals, as well as shedding light on the practical application of copper in animal production.