Research On The Surface Layer Protein And Probiotic Functions Of Lactobacillus Plantarum ZDY2013

Lactic acid bacteria is beneficial for host health mainly by colonization in gastrointestinal tract.Its adhesion and colonization enhance its signal exchange with intestinal cells,inhibit the colonization of pathogens in the intestinal tract and improve the immunity of the host.Thus,the capacity of adhesion of lactic acid bacteria is an important criterion for evaluating it as probiotics.Recently the relationship between surface layer protein and the adhesion as well as probiotic properties of lactic acid bacteria has become a research hotspot.Based on the study of the mechanism of Lactobacillus plantarum ZDY2013 in inhibiting Helicobacter pylori in vitro,Caco-2 cells were used as the model in this study.The factors affecting the adhesion of lactic acid bacteria(cell concentration,cell growth state,environmental p H and surface protein),the effect of surface layer protein on the colonization of and its probiotic properties were analyzed systematically.The results showed that Lactobacillus plantarum ZDY2013 effectively inhibited Helicobacter pylori with an inhibition zone of 20 mm and 60% of inhibition rate of its urease activity.Human gastric cell line AGS was used as the cell model to analyze effects of Lactobacillus plantarum ZDY2013 on the adhesion of Helicobacter pylori,the results showed that Lactobacillus plantarum ZDY2013 had a strong adherence,and inhibited H.pylori adhesion on gastric cells by substitution,competition and exclusion,thereof competition is the main style.The effects of Lactobacillus plantarum ZDY2013 on the secretion of IL-10 and TNF-? in human gastric cells were also investigated,the results showed that it can effectively inhibit the expression of TNF-? induced by Helicobacter pylori and increase the expression of anti-inflammatory IL-10.In the study of adhesion,the results showed that pH 4.0-5.0,density of cells,growth status and surface layer protein significantly affected the adhesion of Lactobacillus ZDY2013.Its adhesion ratio increased with the increase of cell density,and reached a highest value either at 2 � 108 CFU / m L cells or at logarithmic growth phase.After the removal of the bacterial surface protein,the adhesion decreased significantly.Through externally adding surface layer protein,the adhesion of cells decreased significantly with the increase of surface protein.The surface protein was proved to be 44 k Da by SDS-PAGE.The comparison of the in vivo colonization of Lactobacillus ZDY2013 with or without surface protein and its heat-killing dead cells on the different place of intestinal tract of mice showed that the surface protein or the living state of Lactobacillus ZDY2013 positively affect the adhesion of the cells on Caco-2 cells,which is quite highly coincided with the results of in vitro experiments.Further study showed that the self-agglutination ability,hydrophobicity and acid tolerance of Lactobacillus plantarum ZDY2013 significantly decreased after the removal of its surface layer protein,the same is also the tolerance in simulated gastrointestinal fluid.In the experiment of substitution,exclusion and competition against the adhesion of Escherichia coli,Staphylococcus aureus and Listeria monocytogenes on Caco-2 cells,the anti-adhesion capacity of Lactobacillus ZDY2013 decreased significantly when the surface protein was removed.Adding 100 ?M D-mannose had a significant decrease in the amount of cells of Lactobacillus plantarum ZDY2013 attached on Caco-2 cells.Treatment of Caco-2 cells with trypsin(10-30 mg/m L)resulted in the decrease of adhesion of Lactobacillus plantarum ZDY2013.In summary,Lactobacillus plantarum ZDY2013 presented good capacity on its adhesion,and anti-adhesion,inhibiting the growth of Helicobacter pylori.The surface layer protein of Lactobacillus plantarum ZDY2013 played a significant role in promoting its tolerance and enhancing its inhibition against pathogenic bacteria adhesion,thus promoting lactic acid bacteria adhering to the human and animal gut.This study provides the basic data for the utilization and development of the surface layer protein of Lactobacillus plantarum ZDY2013.