Research On Bile Salt Hydrolase's Capability To Improve The Colonization Of Lactic Acid Bacteria And The Adhesion Properties

To improve the colonization of lactic acid bacteria in gastrointestinal(GI)tract is a pressing issue that needs to be addressed in the research and application of lactic acid bacteria.In this paper,bile salt hydrolase(BSH)'s capability to improve the colonization of lactic acid bacteria and its adhesion properties will be studied with two BSH recombinant lactic acid bacteria which were constructed in our laboratory and both possessed high BSH activity.Firstly,the colonization of BSH recombinant strains in the GI tract of the mice will be studied through murine experiments by feeding the mice with bacterial suspension of experimental strains with Rif-resistant.The results of viable cell counts in mice feces showed that BSH recombinant strains survived 6 days in murine gut which was significantly extended as the control group survived 4 days,which preliminarily showed that BSH was capable of enhancing the colonization of lactic acid bacteria in GI tract.Secondly,the adhesive properties of BSH recombinant strains to intestinal cells was characterized using Caco-2 cell model,exploring the causes of BSH improving colonization of lactic acid bacteria.BSH recombinant strains and Caco-2 cells were incubated together,then,the adhesion rate were examined by Gram staining abservation,CFU counting and absorption values of the adhered strains,qualitatively and quantitatively determining the adhesion ability of BSH recombinant strains to Caco-2 cell.The result showed that the adherence of BSH recombinant strains to Caco-2 cell was enhanced significantly,comparing with control group.The strongest in vitro adherence of(14.57±1.34)cfu/cell was exhibited by strain WCFS1Rif[pSIP403::B4bshb]which possessed higher BSH activity,followed by strain WCFS1Rif[pSIP403::M6bshc]with adhesion levels of(9.21±0.95)cfu/cell,however,the control group WCFS1Rif[pSIP403]is only(1.63±0.52)cfu/cell.This study suggested that BSH was capable of enhancing the adherence of lactic acid bacteria to intestinal cells,revealing the mechanism of increasing colonization of lactic acid bacteria because of BSH.Finally,the inhibition ability of pathogen adhesion by BSH recombinant strains was studied.The pathogenic Salmonella Typhimurium ATCC 29631 and Caco-2 cells were incubated together,while adding BSH recombinant strains,studying inhibition effect from three modes of action(competitive,exclusion and displacement),respectively.Then,quantitatively analysis the effect of Salmonella adhesion to Caco-2 cell by BSH recombinant strains through plating viable count.The results showed that high BSH activity strain D had the strongest inhibition of Salmonella adhesion.In the exclusion experiment,the adhesion inhibition represented as the best,and the adhesion number is reduced from(1.61±0.26)cfu/cell to(0.88±0.07)cfu/cell.In this study,we have not only demonstrated BSH could enhance the adhesion of lactic acid bacteria to intestinal cells from a respect,but also provided a good research instance for applying research of more functions of BSH.To sum up,this paper have a research on BSH's capability to improve the colonization of lactic acid bacteria and the adhesion properties in GI tract,which will not only enable us to promote the research process of functional BSH,but also provide a theoretical basis for the development and utilization of lactic acid bacteria in food industry.