The Study On The Effect Of Heparin On The Biofilm Formation Of Escherichia Coli Nissle 1917

Escherichia coli Nissle 1917(EcN)as a kind of Gram-negative bacterium is a probiotic colonized in the intestine.EcN,as an excellent settler in the early intestines of infants and young children,plays an important role in regulating the composition of intestinal microbes,enhances the body's resistance to pathogenic microorganisms,and promotes blood circulation in the colonic mucosa,and has been used as a drug to relieve various intestinal dysfunctions.As a probiotic,EcN is mainly due to its lack of pathogenic factors,antibiotic resistance and a variety of adaptive factors;it has certain antagonistic activities against certain pathogenic bacteria.Because EcN has a good ability to form biofilms,it can form a "protective wall" in the human intestine.Therefore,it plays a certain role in maintaining the stability of the intestinal microbial population.Previous studies have shown that heparin,a sulfonated glycosaminoglycan,which is abundant in animal intestinal mucosa and can effectively stimulate bacterial biofilm formation.Since the discovery of heparin,it has been used as a clinical anticoagulant in the world for nearly 100 years.Heparin is a linear glycosaminoglycan with uneven chain length and highly sulfonated.The molecular weight ranges from 12 k Da-40 k Da.The sulfo groups mainly has 2-O-sulfo groups,6-O-sulfo groups,3-O-sulfo groups,and Nsulfo groups,among which the 3-O-sulfo groups is the main site where the anticoagulant activity of heparin comes into play.Despite it has reported that heparin promoted bacterial biofilm formation,the relationship between heparin structure and bacterial biofilm formation remains unclear.In order to explore the relationship between the structure of heparins with the formation of bacterial biofilms,we have performed a series of chemical treatments on heparin to make it into heparin derivatives with different sulfo groups and low molecular heparin.It was found that heparin stimulated the biofilm formation of EcN in a dosedependent manner.Both the sulfo groups and molecular weight of heparin helped to enhance the biofilm formation of EcN.With the addition of native heparin,the EcN biofilm formation increased 6.9-to 10.8-fold than that without heparin,and was 1.4-,3.1-,3.0-,and 3.8-fold higher than that of N-desulfated heparin(N-DS),2-O-desulfated heparin(2-O-DS),6-O-desulfated heparin(6-O-DS),and N-/2-O-/6-O-desulfated heparin(N-/2-O-/6-O-DS),respectively.Under acidic conditions,heparins depolymerizes into heparins with low molecular weight,which has a slightly increased content of S/N.In this study,it was found that the addition of low molecular weight heparin to the medium did not significantly stimulate the formation of EcN biofilm.Furthermore,the biofilm formation of Salmonella enterica serovar Typhimurium was also investigated with the addition of heparin derivatives,and the results were consistent with that of EcN biofilm formation.This study showed that the sulfo groups and a higher molecular weight of heparin,which were helpful to promote the biofilm formation of microorganisms such as EcN.