凹凸棒石对鸡源大肠杆菌抗生素抗性基因的影响及相关机制研究

Antibiotic resistance is a serious threat to the public health, and the antibiotic resistance gene, a new environmental pollutant, has received widespread concern. The development of bacterial antibiotic resistance is mainly due to the antibiotic selective pressure and resistance gene transfer, and it is particularly important to reduce the occurrence, diffusion, and spread of antibiotic resistance gene. Adsorbing bacteria or substances that stimulate the development of antibiotic resistance gene would reduce the antibiotic selective pressure, and therefore decrease the occurrence of antibiotic resistance gene. Palygorskite is a natural silicate mineral that has the adsorption ability to both Escherichia coli and antibiotics. However, little is known about whether palygorskite would affect the antibiotic resistance gene abundance of Escherichia coli in vivo and in animal feces, and related underlying mechanism of this behavior is still unclear. Therefore, this project is aimed to evaluate the adsorption effect of palygorskite to Escherichia coli resistant to tetracycline and the subsequent consequences of this adsorption on the abundance of the tetracycline resistance gene in Escherichia coli, using in vitro study. After that, this project also investigates the effect of palygorskite on tetracycline resistance gene abundance of Escherichia coli in intestine and feces of broilers, and its related mechanism. The effects of palygorskite on tetracycline resistance gene in broiler feces and the related mechanism are studied by composting the feces. The results will provide theoretical and method reference for the control of development, diffusion, and spread of antibiotic resistance gene from animals, and new ideas for the protection of animal and human health.

抗生素抗性严重危害公共健康，抗生素抗性基因作为新型环境污染物广受关注，细菌产生抗药性主要是抗生素选择性压力和抗性基因传递所致，减少抗生素抗性基因的产生和扩散尤为重要。通过吸附细菌或吸附促进抗性基因产生的物质可降低选择压力，由此可减少抗性基因的产生。凹凸棒石是一种天然硅酸盐矿物，对大肠杆菌和抗生素具有吸附作用，但其在动物体内及粪便中是否影响大肠杆菌抗生素抗性基因的产生及其相关机制尚未探明。为此，本项目通过体外试验，确定凹凸棒石对抗四环素大肠杆菌的吸附作用及吸附后其四环素抗性基因丰度的影响；通过在体试验，探明凹凸棒石对肉鸡肠道内和粪便中大肠杆菌四环素抗性基因的影响及相关机制；通过对粪便进行堆肥处理，研究凹凸棒石对肉鸡粪便中四环素抗性基因的影响及相关机制。预期研究结果将为控制动物源抗生素抗性基因的产生和扩散提供理论及方法参考，为保障动物和人类健康提供新的思路。

项目背景：抗生素耐药基因作为新型环境污染物，不仅影响生态环境，亦对人类和动物健康造成威胁。非金属矿物对抗生素和细菌具有良好吸附效果，可降低细菌的抗生素选择压力，减少耐药基因产生，但其是否影响动物体内及粪便中抗生素耐药基因的产生及其相关机制尚未探明。.主要研究内容：比较不同非金属矿物对肉鸡盲肠四环素耐药基因的影响；体外探究凹凸棒石对四环素和大肠杆菌的作用效果及机制；日粮添加不同黏度凹凸棒石研究其对肉鸡肠道健康的影响，探明其凹凸棒石对肉鸡肠道和粪便中四环素耐药基因的影响；通过粪便堆肥处理，研究凹凸棒石对堆体中四环素耐药基因的影响及相关机制。.关键数据：（1）日粮中添加非金属矿物可提高肉鸡生长性能，提高肠道健康水平，调节盲肠微生物组成，并可降低盲肠内容物耐药基因丰度。与沸石相比，凹凸棒石改善效果更显著。（2）凹凸棒石对四环素的吸附过程可用准二级动力学方程进行拟合，该吸附过程为多分子层吸附，且是一个放热的自发反应。大肠杆菌与凹凸棒石之间的吸附主要为二者之间的静电作用，属于非特异性吸附，但凹凸棒石吸附后不影响大肠杆菌的形态和胞内酶活性。（3）不同黏度凹凸棒石均可调节肉鸡盲肠菌群结构。同时，日粮添加金霉素和凹凸棒石对肉鸡盲肠抗生素耐药基因具有交互作用。（4）日粮添加金霉素形成了抗生素选择压力，对粪便中不同耐药基因的丰度影响均较大。与未添加凹凸棒石组相比，高黏度凹凸棒石可降低肉鸡粪便四环素类耐药基因相对丰度，且效果优于其他两种凹凸棒石。（5）凹凸棒石可降低堆肥后堆体MLS和四环素类耐药基因相对丰度，可能与其对堆体异常球菌门和芽单胞菌门等菌群的调节作用有关。.科学意义：该研究明确了日粮添加凹凸棒石可降低四环素耐药基因丰度，一定程度上降低了耐药基因的传播。研究结果为控制动物源抗生素抗性基因的产生和扩散提供理论和研究方法，为保障动物和人类健康提供新的视角和思路。

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