| Prebiotics are not easily digested and absorbed by the human body,but they can selectively proliferate some symbiotic bacteria in the intestine,so as to promote the production of short chain fatty acids in the intestine.Whether prebiotics can be used by probiotics is an important basis to evaluate their prebiotic characteristics.At present,there are few studies on the promotion of probiotics in intestinal colonization,immune regulation and intestinal flora.Therefore,it is of great significance to explore the ratio,functional characteristics and mechanism of lactic acid bacteria and a variety of prebiotics for the development of synbiotic health products.In this study,the formula of compound prebiotics to improve the adhesion of L.fermentum DALI02 was optimized through in vitro tests.At the same time,the potential impact of the compound prebiotics on Limosilactobacillus fermentum DALI02 was explored from the aspects of intestinal colonization,immune regulation,intestinal flora and short chain fatty acid content.The main research contents and results are as follows:(1)Optimization of prebiotic combination to improve the adhesion ability of L.fermentum DALI02.Using Caco-2 cell adhesion model in vitro,through single factor and quadratic orthogonal rotation experiment,taking the adhesion rate as the index,the addition amount of compound prebiotics was optimized,so as to determine the prebiotic combination of high adhesion L.fermentum DALI02.The results showed that when the compound prebiotic formula was 0.05%Fructo-oligosaccharides(FOS,w/w,the same below),0.20%galactooligosaccharide(GOS),0.30%Inulin,0.20%Stachyose and 0.30%xylooligosaccharide(XOS),the adhesion rate of L.fermentum DALI02 in vitro was significantly higher than that of other combinations,and the adhesion rate was 3.98%.(2)Study on intervention time and colonization ability.The model of immunecompromised rats was established.The intervention time of compound prebiotic fermentation broth was studied by measuring the colonization number and colonization time of strains in the intestine,and its effect on the colonization ability of L.fermentum DALI02 was explored.The results showed that in terms of colonization time,the number of strains colonized in the intestinal tract of rats was 5.20 lg(copies/g)and 5.12 lg(copies/g)after the intervention of compound prebiotic fermentation broth for 2 and 4 weeks,respectively,which was significantly higher than that of the intervention for 1 day(p<0.05).In terms of colonization time,when the compound prebiotic fermentation broth group stopped the intervention for 48 hours,the copy number of strains at the intervention for 2 weeks was 4.01 lg(copies/g),and the copy number of strains at the intervention for 4 weeks was 4.48 lg(copies/g),which were significantly higher than that at the intervention for 1 day(p<0.05),while the colonization number at the intervention for 4 weeks was higher than that at the intervention for 2 weeks.Therefore,the intervention for 4 weeks was good for the colonization number and colonization time of strains.The results showed that the number of copies of strains colonized in feces of the compound prebiotic fermentation broth group was 4.98 lg(copies/g)for 5 days,which was significantly higher than that of the blank group(p<0.05),and increased by 26.72%compared with DALI02 fermentation broth group.The results showed that compound prebiotics could promote the intestinal colonization time and quantity of L.fermentum DALI02.(3)Effect of compound prebiotics on immune regulation of L.fermentum DALI02 in vivo.The model of immunocompromised rats was established.The body weight gain,organ index,spleen lymphocyte proliferation ability,immune factor level and intestinal barrier integrity of rats in empty groups were measured,and the effect of compound prebiotics on the immune ability of L.fermentum DALI02 was studied.The results showed that the body weight increment and thymus index of rats in the compound prebiotics fermentation liquid group were significantly increased by 21.27%and 23.08%(p<0.05),the proliferation ability of spleen lymphocytes was significantly increased by 49.65%(p<0.05),and the proportion of immunoglobulin M(IgM)and leukocyte(A/G)in serum were 0.13 mmol/L and 0.80,respectively,which were significantly increased by 30%and 29.03%(p<0.05).At the same time,the contents of serum interleukin-6(IL-6)and tumor necrosis factor ?(TNF-?)were 125.70 pg/mL and 209.43 pg/mL respectively,which were significantly reduced by 5.38%and 40.04%compared with the model group(p<0.05).The contents of lipopolysaccharide(LPS)and D-lactic acid in serum were 74.11 pg/mL and 40.33 ?mol/L respectively,significantly decreased by 27.44%and 20.97%compared with the model group(p<0.05).The thymus index and splenic lymphocyte proliferation ability of rats in the compound prebiotic fermentation broth group were significantly higher than those in the compound prebiotic group by 23.08%and 20.57%(p<0.05),respectively,which were significantly higher than those in DALI02 fermentation broth group by 45.45%and 15.30%(p<0.05).The contents of LPS and D-lactic acid were significantly reduced by 24.76%,7.74%and 9.08%compared with the compound prebiotic group(p<0.05),and 27.55%,6.82%and 6.75%compared with DALI02 fermentation broth group(p<0.05).From the above results,the combined action of compound prebiotics and L.fermentum DALI02 can improve the immunomodulatory ability of immunecompromised rats.(4)Effects of compound prebiotics on the regulation of intestinal flora and short chain fatty acids by L.fermentum DALI02.The structure of intestinal flora and the composition and content of short chain fatty acids in rat feces were measured to study the effect of compound prebiotics on the regulation of intestinal short chain fatty acids and flora by L.fermentum DALI02.The results showed that after the intervention of compound prebiotic and L.fermentum DALI02,the relative abundance of Lactobacillus,Treponema and Romboutsia in the intestinal tract of rats in the compound prebiotic fermentation liquid group was significantly higher than that in the model group(p<0.05),and the relative abundance of Helicobacter,Alloprevotella and Muribaculaceae were significantly lower(p<0.05).There was no significant difference between Alloprevotella and Muribaculaceae and the blank group(p>0.05).The genus of Lactobacillus in the intestinal tract of rats in the compound prebiotic fermentation liquid group was significantly higher than that in the compound prebiotic group or sugar free fermentation liquid group(p<0.05).The results of the determination of short chain fatty acids in rat feces showed that the single intervention of compound prebiotics could significantly down regulate the contents of propionic acid,isobutyric acid and caproic acid(p<0.05),the single intervention of L.fermentum DALI02 could significantly up regulate the contents of valeric acid(p<0.05),and significantly down regulate the contents of propionic acid and caproic acid(p<0.05),The combined action of compound prebiotics and L.fermentum DALI02 could adjust the content of short chain fatty acids in the feces of rats with metabolic disorder to no significant difference from the blank group(p>0.05).From the above results,the fermentation broth of compound prebiotic and L.fermentum DALI02 can improve the intestinal flora structure and short chain fatty acid content of immunocompromised rats,so as to regulate the balance of intestinal microenvironment.In conclusion,the addition of compound prebiotic fermentation can improve the intestinal flora and short chain fatty acid metabolism of rats by improving the colonization ability of L.fermentum DALI02 in the intestine,so as to improve the immune ability of rats. |
PDF Full Text Request