Effects Of Earthworms On Antibiotics And Their Resistance Genes In Different Soil-plant Systems

Traditional livestock and poultry manure is excellent organic fertilizer after stacked,but intensive farming uses a large number of antibiotics,resulting in livestock and poultry manure not only contains a large number of antibiotics,but also carries corresponding antibiotic-resistant microorganisms.The abundance of antibiotic resistance genes(ARGs)in soil will be significantly increased when some microorganism enters soil environment.ARGs in soil migrates and accumulates in different parts of plants and produces toxicological effects,potentially causing harm to ecological environment and human health.As an active part of the soil environment,earthworms play a vital role in the soil environment.In addition,the activities of earthworms can reduce the concentration of pollutants in the soil.However,there are few studies at home and abroad on earthworms’ reduction of antibiotics /ARGs in soil-plant system,and the influence mechanism of earthworms on each medium in soil-plant system is unknown.Therefore,through pot experiment,this paper took leafy vegetables(brassica pekinensis,brassica chinensis),herbaceous plants(setaria viridis,crabgrass)and Earthworm as examples to study the difference of earthworm’s influence on each resistance medium biotin /ARGs in different soil-plant systems.To explore the difference of earthworm distribution and transfer of antibiotics /ARGs in different soil-plant systems,and to reveal the influence mechanism of earthworm on different soil-plant systems.The main research conclusions are as follows:(1)To determine the influence of earthworms on the antibiotic content of non-rhizosphere soil,rhizosphere soil,root endophytes and phyllosphere in different soil-plant systems.The results showed that earthworms could reduce the content of antibiotics in different soil-plant systems as a whole,and earthworms had a more significant effect on soil-leafy vegetable system than soil-herbaceous plant system.In the soil-leafy vegetable system,the effects of earthworms on antibiotic content in non-rhizosphere soil and rhizosphere soil medium of brassica pekinensis and brassica chinensis were almost the same.However,in the root endophytes and phyllosphere,earthworms had a more significant effect on the content of antibiotics in the soilbrassica chinensis system.In the soil-herbaceous plant system,the effects of earthworms on the medium of soil-setaria viridis system were significantly higher than those of earthworms on the medium of soil-crabgrass system.(2)Using the abundance of non-rhizosphere soil,rhizosphere soil,root endophytes,phyllosphere and intestinal secretion of earthworms as indicators,the differences in the distribution and transfer of ARGs by earthworms in different soil-plant systems were investigated.The results showed that earthworms could significantly reduce the ARGs abundance in various media in different soil-plant systems,but their effects on different soil-plant systems were different.The removal effect of ARGs in non-rhizosphere soil,root endophytes and phyllosphere was more significant in soil-leafy vegetable plant systems.The removal effect of ARGs in rhizosphere soil was more obvious in soil-herbaceous plant system.tet X and sul3 are more easily transferred to plants than other ARGs,increasing the risk of migration along the food chain into the environment.The differences of tet M and qnr B in intestinal secretion of earthworms in different soil-plant systems were significant,which might be an important factor of earthworms’ influence on the difference of ARGs in different soil-plant systems.(3)Through 16 S rRNA high-throughput sequencing,the evolution of earthworms on bacterial communities in different soil-plant systems was explored,and the influence mechanism of earthworms on ARGs in different soil-plant systems was revealed.The results showed that earthworms could change the bacterial community structure of various media in different soil-plant systems.Proteobacteria and chlorophyta of plant phyllosphere and root endophytes are the most significant.On the whole,earthworms had a more significant effect on the bacterial community structure in soil-brassica pekinensis system than in soil-setaria viridis system.Redundancy analysis(RDA)showed that bacterial community accounted for 82.09%of ARGs,suggesting that bacterial community change was the main factor affecting ARGs.The addition of earthworms promoted the growth of chlorophyta in plant roots,and there was a significant positive correlation between chlorophyta and sul3,indicating that sul3 had a higher environmental risk than other ARGs in plant roots.