Study On The Mechanism Of The Effect Of Combined Pollution Of Antibiotics And Heavy Metals On Antibiotic Resistance Genes In Soil

The application of livestock and poultry manure is an important cause of agricultural soil pollution,which aggravates the pollution of heavy metals,antibiotics and antibiotic resistance genes(ARGs),and these pollutants can pose a threat to human health through the food chain.Lead(Pb),zinc(Zn)and oxytetracycline(OTC)are common pollutants in manure produced by livestock and poultry farming.The effects of different combinations of combined pollution on the accumulation and transport of ARGs and microbial community after they are introduced into agricultural soil are still unclear.This study selected the commonly used OTC as the representative of antibiotics,Pb and Zn as the representative of heavy metals,and explored the effects of OTC and heavy metals on ARGs and microbial community structure in soil through single and combined pollution at different concentrations.Associations between ARGs and environmental factors,mobile genetic elements(MGEs)and microbial communities were also investigated.The main conclusions are as follows:(1)When OTC and Pb co-existed,the inhibitory effect of 160 mg/kg Pb on ARGs was stronger than that of 80 mg/kg Pb.When OTC and Zn co-existed,30 mg/kg OTC had a stronger inhibitory effect on sul genes and 100 mg/kg OTC had a stronger inhibitory effect on tet genes.(2)According to network analysis,the abundance of ARGs in single and combined pollution experiments with Pb and OTC was mainly influenced by bacterial colonies such as Actinobacteria,Proteobacteria,and Bacteroidota.In single and combined pollution experiments with OTC and Zn,the abundance of ARGs was mainly influenced by microorganisms such as Firmicutes,Proteobacteria,Actinobacteria and Bacteroidota.(3)Redundancy analysis(RDA)showed that p H,organic matter content,soil dehydrogenase(S-DHA),soil catalase(S-CAT)were significantly positively correlated with total ARGs abundance(P < 0.05),and electrical conductivity(EC),soil nitrate reductase(S-NR)were significantly negatively correlated with total ARGs(P < 0.05).In Pb and OTC single and combined pollution experiments,S-CAT was significantly positively correlated with tet B,tet Q,sul1,sul2 and sul3(P < 0.05),S-NR was positively correlated with sul1 and sul2(P < 0.05).S-DHA was positively correlated with sul1,sul2,sul3 and tet Q(P < 0.05).In OTC and Zn single and combined contamination experiments,S-CAT and S-DHA were significantly positively correlated with tet B,tet Q,sul2 and sul3(P < 0.05),and S-NR was significantly positively correlated with sul1(P < 0.05).