不同聚合度低聚木糖差异化干预大肠杆菌粘附素表达抑制鸡肠道损伤的分子机制

大肠杆菌感染可造成肉鸡生产中超过15%的死亡率，带来严重经济损失。抑制大肠杆菌对肠道的感染可减轻鸡全身性症状发生。细菌引起感染的首要前提是粘附于宿主细胞，项目组前期发现不同聚合度低聚木糖（XOS）可差异化降低大肠杆菌对鸡肠细胞的粘附，但其机制不清楚。基于前期组学结果（不同聚合度XOS差异化影响细菌粘附素表达）和前人发现（sRNA可介导糖类物质对细菌粘附因子表达的调控），项目组推测不同聚合度XOS可能差异化影响大肠杆菌sRNA而干预其粘附素表达，进而差异化抑制其对肠道的粘附和损伤。故本项目拟首先探究不同聚合度XOS差异化干预大肠杆菌粘附素表达抑制鸡肠道损伤的功效；然后在体外通过构建关键基因突变菌株，阐明sRNA介导不同XOS干预大肠杆菌粘附素表达及损伤鸡肠道的分子机制。本项目的实施可完善XOS的作用机制理论并可筛选出适宜聚合度XOS，为养殖中XOS的合理应用及大肠杆菌感染的防控提供实践指导。

Escherichia coli infection can cause more than 15% mortality of chickens, resulting in serious economic losses to chicken production. Inhibiting the intestinal infection of E. coli can reduce the occurrence of systemic symptoms in chickens. In general, adhesion to host cells is the primary prerequisite for E. coli infection. The project team found that xylooligosaccharides (XOS) with different degrees of polymerization can differentially suppress E. coli adhesion to chicken intestinal cells, but the mechanism remains unclear. Based on our previous results (XOS with different degrees of polymerization can differentially affect adhesin expression profile of bacteria) and other research findings (carbohydrates can affect adherence factor expression of bacteria via regulation of sRNA), we speculate that XOS with different polymerization degrees might differentially interfere adhesin expression of E. coli by regulation of sRNA, thus differentially inhibiting the adhensive damage of E. coli to chicken intestine. Therefore, we will first explore the differential intervention of XOS with different polymerization degrees on E. coli adhesin expression and the resulting damage to chicken intestine. Afterwards, key gene mutant strains of E. coli will be constructed in vitro to reveal the mechanism of different XOS interfering E. coli adhesin expression and the resulting damage to chicken intestine via regulation of sRNA. The implementation of this project will perfect the mechanism theory of XOS and screen out the XOS with suitable polymerization degree, thus providing practical guidances for the rational application of XOS and the control of E. coli infection in chicken production.