抗生素滥用会破坏肠道菌群的平衡，产生耐药菌株。良性共生菌与宿主细胞表面的肝素类多糖等生物大分子相互作用，通过在肠道表面形成生物被膜屏障等方式，抑制病原菌与肠道上皮细胞的接触与感染。目前，细胞表面的肝素类多糖调控良性共生菌EcN形成生物被膜的机理还不清楚。本项目将综合运用转座子插入突变、转录组测序及生物被膜分析等技术手段，通过解析依赖于肝素前体的EcN生物被膜形成、肝素结合蛋白-肝素类多糖相互作用的EcN附着机制、肝素信号调控生物被膜相关基因的表达等问题，最终阐明肝素类多糖调控EcN生物被膜形成的分子机理。该项目的顺利实施将有利于进一步采取措施增强良性共生菌的生物被膜形成与肠道持久生存能力，抑制病原菌的定殖与生长,减少抗生素的使用,为对抗耐药菌提供新的理论依据和实验基础。

The abuse of antibiotics destroys the balance of enteric bacterial flora and results in the emergence of resistant strains. However, the probiotics, which form a protective biofilm covering the intestine after its binding to host cell surface macromolecules, such as heparin-like polysaccharide, will inhibit the attachment and infection by pathogens. Currently, the mechanisms of EcN biofilm formation stimulated by heparin-like polysaccharide remain elusive. The techniques, including the construction of a transposon inserted mutant library, mRNA sequencing and the assay of biofilm, et al., will be employed to demonstrate the mechanisms of EcN biofilm formation stimulated by heparin-like polysaccharide. The following aspects will be investigated, which include the EcN biofilm formation in a heparosan dependent manner, the attachment-stimulated-interaction between heparin-like polysaccharide and the EcN heparin-binding protein, the biofilm-related-gene expression regulated by the heparin-like polysaccharide signal. The accomplishment of this project will establish a new way to consolidate the biofilm formation and viability of probiotics, to reduce the use of antibiotics by competing out of pathogens, and to contribute to the future development of novel antibacterial drugs.