Effects Of Capsular Polysaccharide And Nucleoid Protein H-NS On Biofilm Formation Of Escherichia Coli Nissle 1917(ECN)

Bacterial biofilm formation is the root cause of chronic recurrent infection in many clinical diseases.Escherichia coli Nissle 1917(EcN)is intestinal probiotics,which can colonize the intestinal tract and inhibit the propagation of intestinal pathogenic bacteria.It is reported that capsular polysaccharides,curli amyloid proteins and histone-like nucleoid structuring protein(or nucleoid protein,H-NS)all have certain effects on biofilm formation of bacteria,but the effects on EcN biofilm formation are still unclear.Understanding the influencing factors of EcN biofilm formation will contribute to the study of host resistance to pathogens and is an important theoretical basis for slowing down the development of biofilm formation.In this study,EcN?hnsA and EcN?csgA were constructed by ?-Red system and Phage P1 transduction.EcN?kfiA was preserved in the laboratory.The results show that csgA had no effect on the biofilm formation and motility ability,but the deletion of kfiA and hnsA would lead to a significant increase in bacterial biofilm formation.And the hnsA mutant basically lost its motility ability.Some studies have shown that H-NS protein can regulate the synthesis of flagellum.Bacteria rely on flagellum for movement,and the loss of motility ability of bacteria is beneficial to the attachment of bacteria to surface,which is beneficial to the biofilm formation.Therefore,loss of hnsA leads to the loss of motility ability of EcN,which is beneficial to the adhesion of EcN to the surface to form more biofilms.However,the deletion of kfiA did not change the motor ability of bacteria,indicating that motility was not the reason of capsule polysaccharide affecting the biofilm formation of EcN,and the specific reasons still need to be further explored.In summary,we concluded that the loss of curli fimbriae of EcN did not affect the formation of biofilm,but the deletion of capsula polysaccharide and H-NS increased the formation of EcN biofilm.Moreover,H-NS affects the formation of bacterial biofilm through the movement ability of bacteria,and the reason why capsule polysaccharide affects EcN biofilm still needs to be further explored.