Study On Distribution Characteristics And Influencing Factors Of Antibiotics And Antibiotics Resistance Genes In Different Land Use Types

In recent years,antibiotics have been widely used in livestock and poultry farming and in the treatment of human and animal diseases,resulting in the "false persistence" of antibiotics in the environment.The soil environment serves as a reservoir for various pollutants,and the pollution of antibiotics and antibiotic resistance genes(ARGs)has aroused great concern.At present,many scholars have conducted research on the pollution of antibiotics and drug resistance genes in the soil,but most of the research has focused on a single type of soil,such as livestock and poultry breeding soil,vegetable base soil,etc.,and the land use method is more complicated of suburban soil research is relatively lacking.Therefore,this study took 8 different land-use types of soil in the suburban area of Tianjin as the research object and analyzed 12 kinds of methods by ultra-high performance liquid chromatography-tandem mass spectrometry,Wafergen Smartchip ultra-high-throughput quantitative PCR and Illunima high-throughput sequencing Distribution characteristics of antibiotics,14 representative resistance genes and microbial community structure in different land-use types of soil.Based on this,statistical methods were used to analyze the data to discuss the existence and transmission risk of pathogenic bacteria in different land use types of soil,as well as the impact of environmental factors and microbial communities on antibiotic and resistance genes in soil.The main conclusions are as follows:(1)The target antibiotics selected in this study were detected in soils of different land use types.The total antibiotic content was in the order of tetracyclines(TCs)>sulf onamides(SAs)>quinolones(QNs)>?-lactams>Macrolides(MLs).There are significant diffe rences in the content of antibiotics in the soil in different land use methods(p<0.05).The specific performance is that the amount of antibiotic residues in farmland is the h ighest,followed by parks,the rest are residential areas,green belts,woodlands,tidal f lats,vegetable fields,and wasteland is the lowest,which may be related to the freque nt application of fertilizers with antibiotic residues in farmland.(2)Among the 33 antibiotic resistance genes detected,13 antibiotic resistance genes(ARGs)were detected to different degrees in different land use types,and 1 MGEs were detected in 46 soil samples,which are more common in soils.The relative abundances of ARGs in soils of different land use types are quite different.Among them,the detected content of ARGs is the highest in farmland soil,and the abundance of sul2 in farmland,vegetable field and park soil with fertilizer application is significantly higher than that of other land use types(p<0.05),and the detection rate and detection abundance of multi-drug resistance genes in all soils are relatively high.The high detection abundance of these resistance genes and antibiotics are abundant in livestock breeding Use-related pollution.The relative abundance of some ARGs and MGEs has a significant correlation,indicating that ARGs have the risk of horizontal gene transfer through MGEs.(3)In this study,the analysis of the significance of the differences in the microbial community abundance in different soils showed that the land use pattern would affect the microbial community structure in the soil,and the soil microbial abundance in the wasteland with less vegetation coverage(DS)was significantly lower than that of the residents.Area(GS),farmland(LS),tidal flat(SS),forest land(TS)(p <0.05).Non-metric multi-dimensional scale analysis shows that the land use type will affect the composition of microorganisms in the soil.The microbial composition of farmland and vegetable fields is relatively consistent.The green belt is similar to that of tidal flat soil.The microbial composition of wasteland soil is similar to other land use types of soil There is a large difference,which is related to the low water content in the wasteland soil.In this study,there were certain pathogenic bacteria in the soil,among which the relative abundance of Streptomyces in the eight soils was high,and there was no significant difference.The relative abundance of Pythium bacteria in park soil is significantly higher than other soils,and streptococcus in green belt soil is significantly higher than other soils(p<0.05).(4)The environmental residues of antibiotics in soil are jointly affected by environmental factors(including physical and chemical properties and heavy metals)and the abundance of microbial communities.TN,p H,TP and antibiotic content showed a significant negative correlation,Cu,Zn and antibiotic content showed a significant positive correlation,and the relative abundance of microbial community and antibiotic content also reached a significant level.By Venn diagram analysis,it was found that microorganisms have an important role in the many influencing factors of antibiotics in soil.Environmental factors and microorganisms have a significant impact on the abundance of ARGs.Among them,the contents of soil organic matter,total nitrogen and total phosphorus have a greater contribution to the abundance of ARGs in the soil.In addition,through the structural equation,it is found that the soil microbial community also has an important influence on the change of ARGs,Streptomyces,Marmoricola,Steroidobacter and Haliangium are the key microbial genera of ARGs in soil.