Study On The Intervention Pathways Of Bifidobacterium Animalis Subsp.lactis On Constipation

Bifidobacterium animalis subsp.lactis is more feasible for industrialization and commercialization than other Bifidobacteria in production applications due to its characteristics of good acid,bile salt and oxygen tolerance and its advantages of easy culture,high yield,fast growth rate and storage resistance.B.animalis subsp.lactis has many probiotic functions,including relief of constipation,prevention of obesity,and assistance in the treatment of periodontitis.Among them,the most widely studied and effective function is to alleviate constipation.However,it is difficult to compare the differences in the effects of B.animalis subsp.lactis on improving constipation because of the different intervention subjects,strain doses,and experimental periods in the study.Most of the studies investigated the effect of improvement only for single strain or few strains,single or few pathways,and it is difficult to compare the similarities and differences of intervention pathways of effective strains.Therefore,in this research,firstly,strains were selected based on the phylogenetic tree of B.animalis subsp.lactis.And the differences in the improvement effect of different strains were evaluated by the apparent index of defecation.Then,the strains with different effects were selected to explore their intervention pathways.Finally,the reasons for the differences in constipation relief of the strains were analyzed in combination with the genome.The main results are as follows:First,10 strains were selected based on a phylogenetic tree to compare their effect on relieving constipation in mice.The results showed that CCFM1278,BJHD3M6 and positive control strains HN019 and BB12 showed positive improvement by the main determinations of fecal water content,time to first black stool,small intestine propulsion rate,number of fecal pellets,and fecal weight,In contrast,there was no improvement in constipation with six strains including FJSSZ6M5,FGZ9I1M8,FSDJN2M2,FNMGEL2M3,FFJNDD7 M and FFJND6M5,indicating that there was strain specificity among B.animalis subsp.lactis strains for the improvement of constipation.Secondly,to explore the differences in the intervention pathways of B.animalis subsp.lactis to enhance constipation,taking FJSSZ6M5,the strain without enhancement effect,as the control,four strains with enhancement effect,HN019,BB12,CCFM1278,BJHD3M6,were selected to analyze the differences in the intervention pathways based on the indexes related to the gastrointestinal motility,intestinal secretion,water retention,and intestinal microecology.The results showed that CCFM1278,BB12 and HN019 regulated intestinal motility by positively regulating gastrointestinal hormones(motilin,gastrin,etc.)and neurotransmitters(somatostatin,acetylcholine,5-hydroxytryptamine,calcitonin gene-related peptide,etc.).They also improved fecal morphology by inhibiting aquaporins expression and promoting mucin secretion,resulting in better fecal excretion.It also regulated gut motility and secretion by modulating intestinal flora and intestinal metabolites(short-chain fatty acids,bile acids).BJHD3M6 only showed modulatory effects on gastrointestinal hormones(peptide YY)and neurotransmitters(somatostatin,acetylcholine,calcitonin gene-related peptide),intestinal flora and intestinal metabolites(short-chain fatty acids,bile acids).Therefore,there is also the strain specificity in the intervention pathways of B.animalis subsp.lactis for the improvement of constipation.Finally,the reasons for the strain specificity of B.animalis subsp.lactis with different improvement effects and intervention pathways to improve constipation were explored.There was no significant difference in log-phase generation time and carbohydrate utilization among strains.Homology analysis and gene function annotation showed,the strains without improvement effect had fewer genes in the glycosyl hydrolase family,glycosyltransferase family,bacterial extracellular solute binding protein,transglycosylase,and ROK family compared to the effective strains.These differences in functional genomes are probably the main reasons for strain specificity.In the end,based on the improvement effect and the composition of functional genes,it is hypothesized that strains in the branch where BB12 is located in the phylogenetic tree may have a general effect on improving constipation.