利用四环素耐药菌群模拟食料解析蚯蚓消化道四环素抗性基因的演化机制

畜禽养殖废物及污水处理系统耐药菌和耐药基因（ARGs）的大量发生, 导致农田施肥过程的传播与扩散。由于蚯蚓在土壤生态系统及蚯蚓堆肥体系中的核心作用，研究蚯蚓消化过程对环境ARGs的作用机制具有重要意义。过去有关蚯蚓消化作用机制的研究，主要集中在有机质降解、微生态优化以及污染物转化等方面，对耐药基因污染的作用机制所知甚少。本项目拟以前期筛选的分属5个门26属的208株四环素抗性细菌为素材，通过构建组成明确的四环素抗性菌群模拟食料，在人工可控环境下，研究蚯蚓取食过程耐药基因在消化道的演化规律，究明食物来源耐药细菌及耐药基因在蚯蚓肠壁的定植及演化机制，明确环境因子对食源耐药基因在蚯蚓肠道演化的影响，从而为准确评估蚯蚓在农田系统及堆肥系统中对耐药基因的作用机制提供科学依据。

The largely occurrences of drug-resistant bacteria and genes in poultry breeding waste and sewage treatment systems lead to their spread and diffusion to farmland along with fertilization process. Due to the key role of earthworm in soil eco-system and vermi-composting, understanding the mechanism underlying the effect of digestion process on antibiotic resistance genes (ARGs) is of great importance. The past studies in this area focused on degradation of organic matters, optimization of micro-ecosystem, and transformation of pollutants, however, little is known about the mechanism underlying the effects of earthworm and its digestive tract on ARGs. In this present project, we first construct tetracycline-resistant bacteria (TRB) groups as diets for earthworm using 208 TRB belonging to 5 phyla and 26 genera isolated by our team in the past. Based on this controllable TRB groups, the pattern of the succession of TRGs in the digestive tract will be studied. Then, the mechanism of succession and colonization of TRB and TRGs in the gut wall will be illustrated. Afterwards, the effects of environmental factors on the succession of TRGs in the digestive tract will be revealed. This study will offer scientific evidences for accurately assessing the effect of earthworm on farmland system and vermi-composting.