Occurrence Feature Of Antibiotic Resistance Genes In Farm And The Effect Of Discharge Plasma On Removing Resistance Genes

In recent years,antibiotics have been extensively used in the fields of healthcare and farming;however,most antibiotics are not fully absorbed by humans and animals,so large amounts of residual antibiotics are continuously released into the environment.The overuse of antibiotics has led to the emergence of antibiotic resistance genes（ARGs）in the environment.As a new pollutant that potentially threatens human health,ARGs has attracted widespread attention.Moreover,ARGs may be transferred to some human pathogenic bacteria and pose a serious threat to human health.The existing knowledge of the distribution and spread of ARGs in the environment is scarce,as well as their potential drivers and health risks.As a consequence,it is important to understand the occurrence feature and transmission mechanisms of ARGs in the environment from the perspectives of food safety and human health,which is significant for environmental risk assessment and management.In addition,traditional physicochemical treatment methods（such as adsorption,chlorination disinfection,UV irradiation）,and advanced oxidation methods（such as ozone oxidation and Fenton oxidation）have limitations in the removal of ARGs from water.And they have the disadvantage of being both expensive and high-consumption.In order to prevent the further spread of ARGs pollution,a cost-effective treatment process for the removal of ARGs from the environment needs to be sought.In this study,we investigated the occurrence features and transmission mechanisms of ARGs in two typical environments（rivers and farms）by fluorescence quantitative PCR and High-throughput sequencing.And the risk of ARGs and pathogenic bacteria has been assessed.In response to the serious pollution of ARGs in the environment,a highly efficient and green advanced oxidation coupling system was constructed based on the strong oxidation properties of discharge plasma and peroxyacetic acid,and its efficacy and mechanism of action on the removal of ARGs were explored.The main research results are as follows:（1）The spatial and temporal distribution of ARGs and int I1 in different types of farms was investigated by q PCR,and the risk of transmission of ARGs on farms was assessed.The results showed that manure was the main source of ARGs on farms,and the mean absolute abundance of ARGs was ranked as:manure>soil>air.There are also seasonal differences in the distribution of ARGs.For example,total ARGs in pig manure are relatively high in the autumn(10^9.7 copies g^-1)and winter(10^10.0 copies g^-1),and low in the summer(10^5.0 copies g^-1),which may be related to the type and dose of antibiotics used.The association between int I1 and ARGs was explored,and we found that int I1 extensively facilitated the transmission of ARGs in the farm.The influence of the physicochemical properties of manure and soil samples on the distribution of ARGs on farms was explored by Pearson correlation analysis.We found that the physicochemical factors of the samples affect the transmission and propagation of ARGs by influencing the distribution of microbes.The distribution of ARGs in manure was significantly influenced by TOC,C/N,C/P,and N/P.TN,C/N,p H,and moisture of the soil are the main factors affecting the distribution of ARGs.Based on respiratory frequency and average exposure,the daily inhalation of int I1 and ARGs from the farm’s air was estimated at 10^0.5 copies h^-1 and 10^2.3 copies h^-1 respectively.Pseudomonas and Acinetobacter were identified as pathogenic hosts of ARGs.In summary,there is a very serious risk of contamination by ARGs in the farm.（2）The effects and mechanisms of discharge plasma technology and peroxyacetic acid（PAA）advanced oxidation technology on the removal of ARGs from farm wastewater were investigated.We found that increasing the discharge voltage,increasing the aeration volume,and extending the reaction time were all positive for the removal of ARGs by plasma.At the same time,plasma alone has the disadvantage of poor removal of ARGs.Therefore,a combined system of discharge plasma and PAA is envisaged to enhance the removal capacity of ARGs.The results showed that the combined system was able to remove the vast majority of ARGs at optimum conditions:voltage of 16 k V,aeration rate of 100 L h^-1,PAA concentration of 0.015%.Probing the contribution of reactive species in reaction systems by free radical quenching experiments.The results showed that ¹O₂ was the most dominant reactive radical in the system and played a key role in the synergistic antibacterial mechanism.Finally,when the treated wastewater was analyzed by metagenomics,we found that the combined system had a strong removal effect on all types of ARGs.However,ARGs are transferred to the virus after processing,and this phenomenon needs further study.This study identifies the occurrence features and transmission mechanism of ARGs in farming and provides a reference for monitoring ARGs pollution.And based on the PAA advanced oxidation system,we constructed a discharge plasma device to activate the PAA.The combined system enables the removal of resistance genes from wastewater and lays the foundation for effective control of resistance gene contamination.