The Study On The Distribution Of Antibiotic Resistance Genes In Sediments Of Hetao Irrigation District

Antibiotic resistance genes（ARGs）have attracted more and more scholars’ attention as a new type of contaminant.Studies have shown that the spread of resistance genes in environmental microorganisms poses a potential threat to human and animal health.In recent years,the contamination of ARGs has become more and more serious due to various reasons,therefore,it is necessary to study the pollution level of antibiotic resistance gene.In this study,we study the abundance and diversity of ARGs and mobile gene elements（including integrase and one transposase genes）in sediments from irrigation canals and drains in Hetao Irrigation District of Inner Mongolia,which would provide a scientific basis for the pollution research and pollution control management of ARGs in Hetao Irrigation District.This study collected two irrigation channels—irrigation channel No.3（3G）and irrigation channel No.7（7G）,the north and south ends of three drainage channels（drainage No.3,5,7）named 3N,3S,5N,5S,7N and Wuliangsuhai lake into the Yellow River（RH）in Hetao Irrigation District of Inner Mongolia.We detected 36 ARGs including 15 tetracycline,3 sulfonamide,3 quinolone,3 macrolide,4 β-lactam and 8 aminoglycoside resistance genes with Fluorescence quantitative PCR method.In addition,the abundances of 2 integrase genes（int I1 and int II2）and 1 transposase gene（tnp A）were measured.The distribution characteristics of ARGs in this region were demonstrated.The results showed that the antibiotic resistance gene was widely distributed in the sediments of Hetao Irrigation District.The detection rate of 24 resistance genes reached 100%,only 5 ARGs were not detected,and other resistance genes have different degrees of detection rate in sediments.The results showed that the high abundance of resistance genes in each plot were ere A,sul I,aad A1,sul III,tet A,and tet S genes,which were the dominant genes in the region.The most detected was 31 species of ARGs in 5N plot,followed by 3G and 7G plots,with the least were 3N and 7N plots.The abundances of ARGs including bla_{amp C},bla_SHV,qnr S,mph A,aad A1,aac C,str B,sul II,tet T,tet W,tet X,tet C,tet K were significantly higher in the 7N plot than ones in the other plots.The abundance of tet E gene in 5N and 7N was significantly higher than the ones of other plots.The abundance of acc gene in 3N and 5N was also significantly higher than the ones of other plots.In addition,qnr S abundance in 3G and 7N was significantly higher than ones in other sites.The abundance and diversity of tetracyclines and sulfonamides ARGs were high in all plots.Correlation analysis showed correlations between the tetracyclines the abundances of sulfonamides and certain aminoglycoside resistance genes.Both the int I1 and tnp A genes were detected in the sediments,however,the int II2 gene was not detected in any plot.The abundances of both the int I1 and tnp A were highest in the 3G plot.The int I1 and tnp A genes were not significantly different among the plots.The int I1 gene was significantly correlated with the sulfonamide sul I gene and various tetracycline resistance genes.In addition,the tnp A was significantly correlated with the tetracycline resistance gene（tet T）and the int I1 gene.It can be obtained from the above that ARGs are ubiquitous in sediments of Hetao Irrigation District,and there are significant differences between the plots.Moreover,the transposase gene and the integron gene have an effect on the transfer of ARGs.