猪场粪污中耐药基因的环境归趋及传播机制研究

Bacterial resistance caused by antibiotic abuse has become a global health and safety issue in recent years. The long-term abuse of veterinary antibiotics increased the development and abundance of antibiotic resistance genes (ARGs) in the livestock environment, which will be transferred into the receiving environments through waste disposal processes such as manure application on land and wastewater discharge. Considering the lack of research on the behavior and propagation mechanism of ARGs from livestock and poultry, a typical large-scale pig farm and its manure receiving environment were selected as research targets, and systematic research on the migration and fate of ARGs in the whole process of "Fecal production - Waste treatment - Manure utilization" were carried out in this project. This study aimed to reveal the pollution characteristics of ARGs in livestock breading environment and the vertical migration patterns of ARGs in soil environment with long-term application of pig manure. The effects and contributions of manure utilization on soil ARGs pollution will be determined. Meanwhile, we will try from the angles of vertical and horizontal transfers of the genes, analyze the ARGs transfer mechanism. The contribution rates to ARGs transfer by vertical and horizontal transfers will also be determined. The project research will increase the understanding of the behavior and spread mechanism of ARGs from swine farms in the environment. And it is expected to provide scientific basis for the management department to formulate the prevention and control strategy of livestock-brone ARGs.

近年来抗生素滥用所导致的细菌耐药性问题已成为一个倍受全球瞩目的健康安全问题。兽用抗生素的长期使用促进了养殖环境中大量抗生素耐药基因（ARGs）的产生与传播，而动物粪肥回用农田及废水外排可增加畜禽源ARGs的环境输入。针对目前畜禽源耐药基因的环境行为及传播机制的研究不足，本项目拟选取典型规模化生猪养殖场及其粪污受纳环境为研究对象，系统开展畜禽源ARGs在“粪污产生-粪污处理-粪污利用”全过程中的行为归趋研究，旨在揭示规模化生猪养殖环境中ARGs的污染特征及长期施用粪肥土壤环境中ARGs的垂直迁移规律，确定粪污资源化利用对农田土壤ARGs污染的影响与贡献；同时从基因垂直、水平转移两角度阐析ARGs迁移机制，以明确垂直传递和水平转移对ARGs迁移的贡献率。本项目研究将增进对猪场粪污ARGs的环境行为及传播机制的认识，有望为管理部门制定畜禽源ARGs防控策略提供科学依据。

兽用抗生素的长期使用促进了养殖环境中大量抗生素耐药基因（ARGs）的产生与传播，而粪肥还田可增加畜禽源ARGs的环境输入。本项目针对目前畜禽源ARGs环境行为及传播机制的研究不足，选取典型规模化生猪养殖场及其粪污受纳环境为研究对象，系统开展了猪粪源ARGs在粪污“产生-处理-利用”全过程的行为归趋研究。1）针对猪场粪污中ARGs污染规律不明的问题，明确了不同育龄阶段ARGs的季节排放特征及污染差异性，发现tet-ARGs污染最为严重（108-1011copies/ g dry weight），其次是sul-ARGs（106-109copies/g dry weight），冬季污染水平高于夏季且母猪粪便中含量水平明显高于仔猪和肥育猪，即从不同的角度丰富了对养殖源耐药基因污染的认知。2）针对猪场粪污处置过程中ARGs行为规律不明的问题，揭示了粪污处置全过程ARGs的消长规律及其主控因子，发现ARGs在生物处理单元含量上升，并伴随沉淀池的悬浮物的沉降和陶粒生物滤池的过滤而出现显著下降；并结合生产实际，提出了设计粪污处理工艺时多增加利于去除废水中固体悬浮物的附加工艺，可有效控制养殖粪水中ARGs的污染与外排。3）从基因垂直和水平转移两个角度，摸清了粪污处置过程中微生物群落的演变规律，明确了ARGs的主要传播载体；发现基因水平转移是猪场粪污ARGs扩散的主导分子机制，并首次提出利用阻断畜禽源ARGs分子传播途径以控制畜禽源ARGs污染的新思路。4）针对粪肥施用的后续生态风险问题，证实了长期施用猪粪显著可提高土壤ARGs的丰度，且不同土层中ARGs的富集程度各异；Procrustes分析表明，细菌群落演替是土壤ARGs消长的主驱动因子，且环境因素对ARGs迁移的驱动力随深度增加而逐渐降低。研究结果为畜禽养殖环境中ARGs的风险控制与污染消除提供了理论依据与技术指导。