Interaction Between Bile Acids And 62 Core Strains

Background: Bile acids are converted from cholesterol in the liver,and then enter the intestine through gallbladder contraction.They are metabolized and converted into secondary bile acids by intestinal bacteria.Studies have found that bile acids can have an important impact on glycolipid metabolism and immune related diseases by acting on nuclear receptors.In addition,bile acids in the intestine can also affect the pathophysiology of the body by affecting the composition of intestinal bacteria.However,due to the complex composition of bile acids and intestinal bacteria,the interaction between each intestinal bacteria and various bile acids is still unclear.Objective: To explore the interaction between different bile acids and different intestinal bacteria.Method: 22 kinds of bile acids were incubated with 62 strains of intestinal bacteria.The growth of the strains was detected by enzyme labeling instrument to judge the effect of bile acids on 62 strains.Then,three kinds of bile acids with the greatest impact on 62 strains of intestinal bacteria: deoxycholic acid(DCA),lithocholic acid(LCA)and chenodeoxycholic acid(CDCA)were selected to verify the effect of these three bile acids on the overall flora profile in vivo and in vitro.They were incubated with fecal bacteria of healthy people in vitro,and were given to mice by gavage in vivo.The changes of these three bile acids on the profile of flora were judged by 16 S rRNA sequencing.The effect of intestinal bacteria on bile acid metabolism.62 strains of intestinal bacteria were incubated with different bile acids.The content of bile acids in the incubation system was detected by the established UPLC-MS/MS method to judge the metabolism of bile acids by each intestinal bacterium.Finally,the metabolites were preliminarily determined by mass spectrometry.Result: 1.Bile acids had different effects on 62 strains.The inhibition of intestinal bacteria is that unconjugated bile acid were greater than conjugated bile acid,while the glycine conjugated bile acid in conjugated bile acid are greater than taurine conjugated bile acid.2.Among the effects on mixed flora,different bile acids have different effects.In human flora,bile acid CDCA mainly increased: Dorea,Anaerostipes,Abiotrophia,Aminobacterium,Geobacter,Eubacterium＿hallii＿Group,Blautia,the bacteria with DCA rising are mainly Serratia,Geobacter and Atopobium.In rats,CDCA mainly increased Bacteroides,Alloprevotella Prevotella＿9 and Muribaculaceae and DCA increased Enterrhabdus,Alistipes,Dubosiella and Candidatus＿Saccharimonas,Muribaculaceae,Akkermansia abundance.LCA rise Treponema＿2 and Muribaculaceae.3.The results of in vitro metabolism showed that 62 strains of intestinal bacteria had different metabolism to 19 kinds of bile acids,of which 43 strains contained BSH,which could metabolize conjugated bile acids,and different bacteria had different metabolism to different conjugated bile acids.35 strains could metabolize 9 kinds of unconjugated bile acids,and different strains could metabolize different unconjugated bile acids.metabolites of unconjugated bile acids were determined by mass spectrometry.Conclusion: 1 Through the incubation of bile acids with 60 strains of intestinal bacteria,it was found that each bile acid had different effects on intestinal bacteria,and the effects of bile acids DCA,CDCA and LCA on the structure of flora were verified in vivo and in vitro.2.Through the incubation of intestinal bacteria with 19 kinds of bile acids,it could be found that different bacteria have different metabolism to different bile acids.