Environmental Behavior And Risk Of ARGs During The Use Of Livestock Manure Organic Fertilizer

Antibiotic resistance genes(ARGs)are one of the emerging pollutants in the environment.The study on the environmental behavior and risk of the cross medium transmission of high abundance ARGs from solid waste to soil during the use of livestock and poultry manure organic fertilizer has very important guiding significance for protecting human health and opening up the "Last Mile" of the safe use of livestock and poultry manure.In this study,swine manure,sheep manure and chicken manure organic fertilizer were used.Through ryegrass planting,the variation law of ARGs abundance,influencing factors and environmental risks were discussed in the whole process.The main conclusions are as follows:(1)The addition of livestock manure organic fertilizer had a significant impact on the bacterial community structure and the environmental behavior of ARGs in the soil at the early stage of planting.With the extension of planting time,the difference of ARGs in different organic fertilizer samples was gradually weakened.At the 25 th and45th harvest,the abundance of ARGs in soil was close to the level before planting.The effect of the amount of organic fertilizer added on soil ARGs was weaker than that of the type of organic fertilizer added.In Ryegrass plant samples,a large number of host bacteria carrying ARGs were detected at 15 days,while the abundance of ARGs in ryegrass endophytes decreased significantly at 25 days.(2)The quantitative environmental risk assessment of ARGs was carried out based on ARGs,mobile genetic elements(MGEs)and virulence factor genes(VFGs).The results showed that the environmental risk value of ARGs in soil increased at the beginning of planting,but decreased with the extension of planting time.At the end of planting,the environmental risk value of chicken manure group was higher than that of swine manure and sheep manure group,but there was little difference between each group and the control group.The environmental risk value of ARGs in ryegrass samples is lower than that in soil samples,and the environmental risk of ARGs in Ryegrass endophytes decreases significantly.Therefore,the cross medium migration ability of ARGs in soil plant system is limited.(3)The content and proportion of C,N and P in soil will affect the abundance of ARGs and its host bacteria,and then affect the environmental risk value of ARGs.Pseudomonas and Streptomyces were affected by TP in swine manure and sheep manure addition group,while Noviherbaspirillum was affected by TN in chicken manure addition group.In the actual process of agricultural production,the environmental risk of ARGs can be controlled by adjusting soil physicochemical indexes.