Abundance Of Antibiotic Resistance Genes In Livestock And Poultry Farming Environment And Their Impacts On Farmland Environment

Antibiotic residues have caused serious environmental problems.Among them,the concern is that they can induce bacteria to produce antibiotic resistance genes(ARGs).ARGs have become an emerging pollutant,which is getting more and more attention.ARGs are widely present in various environmental media such as water,soil and animal intestines,and eventually enter the human body through the food chain.In addition to the ability of ARGs to be transferred between the parent and offspring of bacteria,horizontal gene transfer(HGT)can also occur,spread between different bacterial populations,and even spread across species.Once ARGs are transferred to pathogenic bacteria,they will pose a serious threat to human health.Livestock and poultry farming is the hardest hit by antibiotics.Therefore,it is very important to carry out research on the pollution of ARGs in the livestock and poultry breeding environment,and it is of great significance for improving food safety.Mengcheng County,Bozhou City,Anhui Province is a major county for agricultural production and livestock breeding.In this paper,13 farming wastes(feces)and soil samples from 13 different stations in 6 different livestock and poultry farms in Mengcheng County were selected.Real-time PCR method was used to analyze 5 types of 19 ARGs and one type of integrant gene intI1.Investigate the pollution status of ARGs in the breeding environment and farmland environment,and explore the temporal and spatial distribution of ARGs abundance in feces and soil.Using high-throughput genome sequencing to analyze the fecal samples and soil samples of a representative duck farm and pig farm in Mengcheng County,explore the migration and transformation of ARGs species and abundance in the breeding environment,and evaluate livestock and poultry breeding The impact of activities on farmland soil.The main conclusions are:(1)In the farming environment and farmland soil environment of Mengcheng County,in addition to a type of integrin gene intI1,a total of 8 antibiotic resistance genes were detected,namely sulfonamide resistance genes sul1,sul2,tetracycline resistance Genes tetA,tetC,tetG,macrolide resistance gene ermB,chloramphenicol resistance gene cmlA,multi-drug resistance gene oqxB.The detection rate has reached more than 60%.(2)In the farmland soil environment of Mengcheng County,the abundance of ARGs is relatively low,but it is still polluted by livestock and poultry farms.In the farmland soil near the farm,the types and abundance of ARGs were significantly higher than the blank samples.And when the seasonal use of the farm’s medication changes,the distribution characteristics of ARGs in the soil also change.It can be seen that the livestock and poultry farming contributes a lot to the ARGs in the soil environment.In the livestock and poultry breeding environment of Mengcheng County,ARGs have higher abundance,which is significantly higher than that of soil environment.(3)The absolute abundance of ARGs differs significantly in different seasons between breeding waste and farmland soil.ARGs in feces of chickens,ducks and other poultry farms were significantly higher in spring than in autumn.In livestock breeding,the ARGs content in pig manure is higher in autumn than in spring,and the ARGs in cattle manure does not change significantly with the seasons.The reason for this phenomenon may be due to the impact of African swine fever epidemic,and the large amount of drugs used in autumn,resulting in higher ARGs content in autumn feces than in spring.The cattle breeding cycle is longer,the amount of antibiotics in the feed is more uniform,and the ARGs in the feces and wastes of cattle farms change little with the seasons.(4)The total abundance of ARGs in livestock and poultry breeding wastes and farmland soil in Mengcheng County showed a significant positive correlation with int1 gene(p<0.01),indicating that gene horizontal transfer(HGT)is in Mengcheng County breeding and farmland environment ARGs play an important role.(5)The drug resistance experiment on farmland soil in Mengcheng County showed that for the four commonly used antibiotics erythromycin,ciprofloxacin,chloramphenicol,and tetracycline,there are microorganisms carrying corresponding resistance in the soil environment.(6)The results of high-throughput whole-genome sequencing indicate that there are transfers of ARGs and resistant bacteria from feces to farmland during duck farming,and livestock and poultry farms have some degree of ARGs pollution to farmland environment.(7)By comparing farmland soil that is not contaminated by the farm,farmland soil around the duck farm without waste disposal facilities,and farmland soil around the pig farm using compost,the results show that no matter the abundance or concentration of ARGs,duck farming The farmland soil around the site is higher than the other two.At the same time,the soil and blank groups around the pig farms that treated the breeding waste through composting were relatively similar in ARGs composition and abundance.It can be considered that composting treatment reduces the transfer of ARGs from manure to farmland to a certain extent,and reduces the pollution to farmland soil.The results of this paper help to grasp the existence and distribution of ARGs in the livestock and poultry breeding environment,and are of great significance for evaluating the potential risks of ARGs and improving the safety of agricultural products.