The Study On Characteristics Of Bacterial Flora And Distribution And Migration Of Antibiotic Resistance Genes In Urban Water Source

With the development and use of antibiotics,Antibiotic Resistance Genes（ARGs）have become a new type of pollutant that has attracted much attention in recent years.In addition,the propagation and information exchange of microorganisms often provide media for the transmission of resistance genes,leading to an increase in pathogenic bacteria carrying resistance genes in the environment and threatening people’s health.In this study,the water and sediments of the Gangnan Reservoir where the source of drinking water in Shijiazhuang,were selected as the research objects.High-throughput sequencing and fluorescent quantitative PCR were used to study the distribution and migration of microbial communities in the water and sediments,abundance distribution and migration of antibiotic resistance genes（sul1,sul2,tet A,tet B,qnr B,qnr C,aad A-1,erm B,int I1）.I used Mothur,SPSS,R software,etc.to carry out a large amount of data analysis,and obtained the correlation between the structure and characteristics of the microbial community in different seasons and antibiotic resistance genes.It laid the technical foundation and data support for the ARGs pollution situation and water quality safety improvement of the water source reservoirs.The sampling and monitoring of the Gangnan Reservoir in this study covered the winter and summer,and the sampling points included inflow,reservoir and outflow.Fluorescence quantitative PCR results showed that,except for tet B,qnr B and qnr C resistance genes were not detected at some points,others ARGs all were detected both in water and sediment points.Sul1,int I1,tet A,erm B and aad A-1 genes are relatively abundant,and the distribution of resistance genes in water and sediment were similar.Most ARGs in water bodies and sediments will decrease and then increase after entering the reservoir the outflow abundance is lower than the reservor abundance,and the ARGs abundance exhibited the gradually increase or gradually decrease tendencies in some water and sediment sites.The abundance of ARGs in the water and sediments of Gangnan Reservoir does not exceed 10⁶ copies·L^-1and 10⁶ copies·g^-1,which is 100～1000 times lower than that of drinking water sources in Shanghai and representative water sources in Jiangsu Province Magnitude.This study found that the dominant bacteria phylum in Gangnan Reservoir are Proteobacteria,Actinomycetes and Bacteroides.The types of bacteria in the sediments are higher than those in the water body,and there are differences in the structure of the bacteria in and outside the reservoir.At the same time,in winter,two species of bacteria have a very significant positive correlation with temperature;six species of bacteria have a very significant negative correlation with total nitrogen;six species of bacteria have a very significant negative correlation with total phosphorus;five species of bacteria have a significant positive correlation with aad A-1;three species of bacteria have a significant positive correlation with sul1 and tet A;one species of bacteria have a significant positive correlation with sul2;one species of bacteria has a significant positive correlation with qnr C;five species of bacteria have a significant positive correlation with tet B;seven species of bacteria have a significant positive correlation with qnr B;five species of bacteria have a significant negative correlation with sul2 and erm B.In summer,three species of bacteria have a significant positive correlation to total phosphorus;one species of bacteria has a very significant positive correlation to dissolved oxygen;one species of bacteria has a significant positive correlation with sul1;two species of bacteria have a significant positive correlation with tet B;four species of bacteria have a significant positive correlation with int I1;one species of bacteria has a significant positive correlation with qnr B;seven species of bacteria have a significant positive correlation with aad A-1.It provides data support for the feasibility of man-made influence and control of the spread of resistance genes.From the seasonal comparison,it can be seen that the abundance of bacteria in the water source reservoirs at the phylum level in winter is higher than that in summer,and the abundance of bacteria in the sediments of the two seasons is higher than that in the water body.Compared the detection results in winter and summer,it is found that the Proteobacteria is the most dominant bacteria in the water and sediment.Most of the tested resistance genes were detected in winter and summer.The tet A,tet B,qnr C,aad A-1 and erm B resistance genes in the water body showed a rule that winter was higher than that in summer.And the sul1,sul2 and int I1 genes abundance in winter is lower than summer.The tet A,tet B,qnr C and erm B in the sediments is higher in winter than in summer,while the sul1,sul2,int I1 and aad A-1 genes showed an opposite distribution pattern.The distribution of resistance gene qnr B is greatly affected by environment of the reservoir.This study determined the influencing factors of ARGs in water sources,the spread of each ARGs,the flora and environmental conditions,and provided technical ideas for controlling the spread of ARGs.