Inhibition Of Intestinal Pathogen Biofilm Formation By The Exopolysaccharides Of Lactobacillus Plantarum 12

With the gradually understanding of bacterial biofilm,people pay more and more attention to the advantages and disadvantages of bacterial biofilm.Pathogenic bacteria biofilm formation have caused serious threat in the food processing and the people daily life,pathogenic bacteria in biofilm will become more difficult to killed,and they can also resistant to commonly used antibiotics.Therefore,we need to obtain a natural product that can inhibit or eliminate the biofilm of pathogenic bacteria to deal with the harm caused by pathogenic bacteria biofilm.In this paper,the inhibition effects of exopolysaccharide(EPS)produced by Lactobacillus plantarum 12 on the biofilm formation of several pathogens(Escherichia coli,Staphyloccocus aureus,Salmonella,Listeria monocytogenes,Vibrio Parahaemolyticus and Shigella flexneri)were studied by the micro-porous plate Crystal violet staining method.The results showed that L.plantarum 12 EPS had the different inhibition rate to the 6 kinds of pathogens.Among them,the L.plantarum 12 EPS had the strongest inhibiting effect on S.flexneri biofilm formation with inhibition rate 53.77% at the concentration of 2.0 mg/mL,and the clearing effect on the S.flexneri biofilm with removal rate 61.2%;Through the HT-29 cell model,the L.plantarum 12 EPS could inhibit the adhesion of S.flexneri on the HT-29 cells,and the inhibition rate was 57.1% under the action of 1mg/mL L.plantarum 12 EPS.Then,the L.plantarum 12 EPS significantly inhibited the adhesion and aggregation of S.flexneri on the cover glass.Moreover,the L.plantarum 12 EPS could significantly reduce the resistance of six pathogenic bacteria biofilms to levofloxacin and ciprofloxacin.The L.plantarum 12 EPS effect on the 6 kinds of pathogenic bacteria hydrophobic were studied by using of xylene.The results showed that all the 6 kinds of pathogenic bacteria hydrophobic had different degrees of inhibition by the L.plantarum 12 EPS;Among them,the S.flexneri bacteria hydrophobic fell by 90%,and S.flexneri of hydrophobic gradually reduce with EPS concentration increasing,under the action of the 4 mg/mL L.plantarum 12 EPS,the auto-aggregation of S.flexneri bacteria was reduced by 30 %.In addition,L.plantarum 12 EPS was found to have a significant inhibitory effect on the motility of E.coli.And the L.plantarum 12 EPS was found to inhibit the secretion of polysaccharide in the extracellular poly matrix of S.flexneri,the secretion of protein and extracellular DNA(e-DNA)was not significantly affected.Finally,L.plantarum 12 EPS was separated into the EPS1 and EPS2 by the DEAESepharose Fast Flow ion exchange column.Through the ultraviolet spectrum scanning,EPS1 and EPS2 were identified that they didn't contain nucleic acids and proteins,and the polysaccharide content of EPS1 and EPS2 was quantified as 84.7% and 61.2% respectively by the phenol sulfuric acid method.The main active components of the biofilm of S.flexneri were determined by using the micro-porous plate crystal violet staining method,the results showed that the main active components was the EPS2.To sum up,L.plantarum 12 EPS can inhibit six kinds of pathogenic bacteria biofilm formation,can inhibit S.flexneri adhesion on the cover glass and HT-29 cell surface,also can reduce the antibiotic resistance of six kinds of pathogenic bacteria biofilm.L.plantarum 12 EPS inhibits the formation of biofilm by inhibiting the hydrophobicity of pathogenic bacteria,auto-aggregation,motility and the expression of extracellular polymeric substances.The EPS2 of the L.plantarum 12 EPS was the main active component of inhibiting the biofilm formation of pathogenic bacteria.Therefore,L.plantarum 12 EPS has the potential to be a natural product to deal with the biofilm threat of pathogenic bacteria.