Study On The Diversity Of Antibiotic Resistance Genes In Soil And Sweet Pepper Under Different Fertilization Treatments

The abuse of antibiotics and the pollution of antibiotic resistance genes(ARGs)induced by them has caused widespread concern.ARGs in farmland soil can enter the food chain through contaminated agricultural products,posing a potential threat to human health.However,the effects of long-term application of different fertilizers on the distribution characteristics of ARGs in soil and plants still lack systematic research.Therefore,in this study,high-throughput sequencing(Illumina Miseq)and high-throughput qPCR technology were used to analyze the bacterial communities and ARGs in soil and sweet pepper under four different fertilization treatments(no fertilization,single application of chemical fertilizer,single application of organic fertilizer,and conventional fertilization).The diversity and abundance of the study were conducted.On this basis,the correlation between resistance genes and heavy metals and microbial communities was discussed and analyzed.A total of 37-76 ARGs subtypes were detected in the soil without fertilization,single application of chemical fertilizer,single application of organic fertilizer,and conventional fertilization,belonging to aminoglycoside(Aminoglycoside),β-lactams(β-Lactamase),and chloramphenicol Chloramphenicol,Macrolides(MLSB),Multidrug,Clycopeptide,Sulfonamide,Tetracycline,Fluoroquinolone,Others(Others)These 10 types of ARGs.The subtypes of ARGs were the most in the soil with organic fertilizer alone,and the subtypes of ARGs were the least in the soil without fertilization.Principal component analysis showed that the application of chemical fertilizers,organic fertilizers,and mixed application of chemical fertilizers and organic fertilizers significantly changed the composition of ARGs in the soil.Among the four different fertilization treatments,the total relative abundance of the soil was the highest in the single application of organic fertilizer.Multi-drug resistant ARGs accounted for 60%of the total relative abundance in the soil with single application of organic fertilizer,which is the dominant ARGs;aminoglycosides,sulfonamides and macrolide ARGs also have higher abundance.The sulfonamide resistance gene sull was detected in all treatments,and sul2 was a unique ARG in the single organic fertilizer soil,and its content was the highest.The aminoglycoside resistance gene aac(6)-Ib(aka aacA4)-03 had high abundance in all treated soils.The soil and sweet pepper bacterial communities with 4 different fertilization methods were studied,and it was found that the common dominant bacteria in the 4 different fertilization treatments were Ralstonia,Rhodococcus,and Burkholderia.The application of organic fertilizer changed the bacterial community structure in the soil and sweet pepper.Using microdroplet digital PCR(ddPCR)to quantitatively detect 9 ARGs subtypes and class I integrons in sweet pepper,it was found that the absolute abundance of ampc-04(βlactams)was the highest in conventionally fertilized sweet peppers.It is 1.1×105 copies/g.However,the most abundant soils are multi-drug resistant ARGs,which are less abundant in sweet peppers.The physical and chemical properties of the soil were tested,and it was found that the application of chemical fertilizers and organic fertilizers can change the physical and chemical properties of the soil,and the soil changes in the conventional fertilization treatment are the most obvious.The contents of Cu,Zn,Cd,As,total nitrogen,organic matter,available phosphorus,and available potassium all have a significant correlation with the abundance of ARGs(P<0.01),and also have a significant correlation with the bacterial communities in the soil and sweet pepper.