| Antibiotic abuse and its induced antibiotic resistance gene（ARGs）pollution have attracted widespread attention.Tetracycline antibiotics is a common antibiotic,often used as growth promoters and drugs for livestock and poultry.In recent years,a large number of tetracycline antibiotics have been widely used in the livestock and poultry breeding industry,resulting in the production of tetracycline-resistant bacteria in the environment,and the study of the migration and spread of tetracycline resistance genes in the soil environment is rare.The Durbat Mongolian Autonomous Region（Hereinafter referred to as Dumont）is the administrative region where the animal husbandry is the primary industry.The entire autonomous region runs through large and small livestock farms.This study selected Du Meng’s livestock farm as the research object,and used Geographic Information System（GIS）to visually analyze the spatial distribution of tetracycline antibiotics and resistance genes in livestock farms,providing a basis for special governance.Methods:（1）Soil（10 samples each at 10 cm and 50 cm depth with the labels T1-10 and T11-T20）,manure and water samples were sampled based on GIS.（2）The content of four tetracycline antibiotics was determined by high performance liquid chromatography-tandem mass spectrometry.（3）High-throughput quantitative PCR was used to detect the whole tetracycline resistance gene.（4）Pearson correlation,cluster analysis and network analysis were used to explore the correlation between antibiotics and ARGs relative abundance.（5）Arc Map and Arc Scene were used to visualize pollutants and try to explore the sources of pollutants.Results:（1）In the water sample,only oxytetracycline was detected in the four tetracycline antibiotics,and the detection rate was 67%.In the feces of livestock and poultry,the detection rate of chlortetracycline was 100%,and the other three tetracycline antibiotics had only one sample or were not detected at all.In the soil samples,the detection rate of all tetracycline antibiotics exceeded 30%,and the detection rate of chlortetracycline was 100%.The average content of tetracycline antibiotics in 10 cm soil layer was 0.257～23.857μg/kg,and the average concentration of tetracycline antibiotics in 50 cm soil layer was 0.647～30.803μg/kg.The content of each tetracycline antibiotic in the 50 cm soil layer was higher than 10 cm surface soil.（2）A total of 17 tetracycline resistance genes were detected in the detection of all tetracycline ARGs.tet X and tet AP were the most detected in all samples,and tet R and tet34 were the least detected in all samples.The relative abundance order of tetracycline resistance genes is tet X > tet AP > tet M > tet W > tet S > tet PA> tet Z > tet G > tet C > tet O> tet Y > tet（32）> tet B > tet T > tet（36）> tet（34）>tet R.（3）Correlation analysis of the relative abundance of tetracycline antibiotics and resistance genes in soil shows that tet（34）,tet AP,tet PA,tet W,tet X have a negative correlation with all antibiotics,and tet B,tet C,tet M have a positive correlation with all antibiotics.tet B and DOX,tet Y and CTC have statistical differences;tet C and TC,tet M and OTC are significantly related;tet M and TC,DOX and total antibiotics are extremely significantly related.tet（34）,tet M,tet PA,tet S,tet T in livestock and poultry manure and water samples had a negative correlation with all antibiotics.OTC was significantly related to tet B,tet C,and tet Y,respectively;OTC and tet Z were statistically different.（4）The cluster analysis of the relative abundance of tetracycline resistance genes in soil showed that the distribution of tetracycline resistance genes in T3 and T4 soil samples in livestock farms was similar,and the distribution of resistance genes in soils with T1、T2、T5、T6、T7、T8、T9、T10、T15 and T16 was similar.T17 and T11 are not similar to any samples,and the distribution of resistance genes of T12-T14 and T18-T20 is similar.Cluster analysis of tetracycline antibiotics and resistance genes in soil showed that tetracycline antibiotics were divided into three categories,OTC and DOX were one class,and TC and CTC were one class.It is shown that the correlation between the two antibiotics,OTC and DOX,is similar to that of the tetracycline resistance gene.（5）From the spatial distribution of the inverse distance-weighted interpolation of tetracycline antibiotics in different soil layers of livestock farms,it can be seen that vertical pollution presents a spatial distribution characteristic that increases from top to bottom.In the horizontal direction,the horizontal pollution of tetracycline antibiotics in the 10 cm soil layer is higher in the western and partial eastern regions,and lower in the southeast;the 50 cm soil layer has the highest content in the southeast and the other regions are lower.In the vertical direction,the four antibiotics gradually accumulate from the eastern and western pollution to the southeast.The total pollution of tetracycline antibiotics in the 50 cm soil layer in the southeastern part of the livestock farm reached the most serious state.From the spatial distribution characteristics of tetracycline resistance genes,the vertical content of tetracycline-based ARGs showed a spatial distribution characteristic that gradually decreased from top to bottom,which was opposite to the spatial distribution of tetracycline antibiotics.In the horizontal direction,the severely contaminated parts of different soil layers are the eastern areas of the livestock farm,and the western part is the least polluted.Conclusion: The detection rate of tetracycline antibiotics in soil samples was higher than that of livestock and poultry manure samples and water samples.The total content of tetracycline antibiotics in 10 cm surface soil was lower than that in 50 cm soil layer,and it increased gradually in vertical pollution.The trend is that the western and eastern regions gradually migrate to the southeast region in the horizontal direction.The tetracycline resistance gene also had the highest detection rate in soil samples,and the vertical pollution gradually decreased from top to bottom,while the horizontal direction gradually increased from west to east. |
PDF Full Text Request