Influence Of Manure Fertilization On Antibiotic Resistance Genes In Soil–Lettuce Planted

The resistance of bacteria spread in different bacteria through the resistance gene,posed a health risk to human and livestock.Livestock,as one of the source of the spread of drug resistance,which has important practical significance to further study.30%-90% antibiotics administrated by livestock and poultry are excreted in the form of prototype through feces,and finally enter into the environmental soil and rivers in different ways.At the same time,the residual antibiotics and resistant bacteria in the feces may affect soil and vegetables,while plant roots play important role for microbial gene exchange,ARGs may enter the vegetables through plant endophytes.And finally it is a potential threat to human health caused by human consumption(especially some raw vegetables,such as lettuce,etc.).Therefore,it is significant important to study the feasibility and the law of migration of ARGs from vegetables to humans.This study is artificially added to different doses(0,200,2000,20000μg/kg)of enrofloxacin antibiotics,non-antibiotic-feces and soil,mixed and planted lettuce.Forming a manure-soil-vegetable potting model.Simulated under the pressure of enrofloxacin antibiotics,study on the possibility and the migration of ARGs into lettuce for 60 days.Collect the lettuc leaves,root and soil samples at 1,30 and 60 days,and determination of antibiotic residual concentration by HPLC to determine the amount of drug added and degradation in the soil.Bacterial DNA was extracted and the abundance of ARGs was detected by real-time quantitative PCR.The results of HPLC were similar to added enrofloxacin concentration.Byexperiments of plant surface disinfection methods,the best method of leaves is soak in 75% Ethanol solution for 60 s and 2% Sodium hypochlorite solution for 120 s,root is soak in 75% Ethanol solution for 60 s and 5% Sodium hypochlorite solution for 120 s.It maximizes the protection of endophytes and kills bacteria on the s urface.The sample analysis of plasmid-mediated quinolone resistance(PMQ R)genes(qnrA,qnrB,qnrC,qnrS,qepA,aac(6’)-Ib,oqx B).The results showed that the detection rates of qnrS,aac(6’)-Ib,oqx B and qepA were higher in the samples,total abundance(ΣARGs)of PMQR in soil samples was significantly higher than that in vegetable tissues(P ≤0.05),and the chicken manure treatment group was significantly higher than that of pig manure treatment group(P ≤0.05).The qnrS gene was the highest in all the genes,and the resistance rate was significantly higher than that in the soil samples,but the abundance of resistant genes in soil was lower than that of the soil,indicating that under the antibiotic and fecal pressure,the possibility of delivering resistant genes through plant endogenous biochemistry is very small.The resistance rate and relative total abundance(ΣARGs)of the low and middle dose group were higher than the high dose group,indicating that the stress of low and medium concentration was more likely to lead to drug resistance.Overall,under the stress of enrofloxacin and feces,vegetables,soil system will induced bacterial resistance,but the abundance of resistance genes from vegetable tissue resistance genes is low in the 60-day experiment.The possibility of drug-resistant and drug-resistant genes entering the tissues of vegetables through plant endocytosis is still low.In addition,in this experiment,the drug is added at one time,but in the actual agricultural production,usually fertilization is two weeks at a time,so that the drug will keep long time stress in soil,may cause accumulation of drug-resistant bacteria,drug resistance gene,a threat to human health.