Lactobacillus Delbrueckii Microcapsules Performance Evaluation And Research On The Regulation Of Intestinal Flora

The probioic effect of probiotics and their preparations on human intestines may berealized on a large part by monitoring the changes of intestinal flora. Therefore, it isfeasible to reflect the prebiotic effect of these products by measuring the intestinal florachanges, which has been paid much attention in recent years. Based on the previousstudy in our group, the purpose of this is to evaluate the properties of Lactobacillusdelbrueckii microcapsule and their regulating effect on intestinal flora fromantibiotics-caused intestinal dysfunctional mice, thus providing a basis for thedevelopment and application of the products as functional food gradients.Lactobacillus delbrueckii microcapsules were prepared by pH changes. Afterfreeze drying, bacteria content in microcapsules was (10.87±0.13) lg cfu/g and survivalrate after lyophilization was (68.55±13.39)%. Scanning electric microscopy (SEM)observation revealed that the surface of microcapsule was smooth, large number ofLactobacillus delbrueckii was encapsulated into the microcapsules, leading to a fullshape. The surface of microcapsule sticked large amount of bacteria. The storagestability tests of the microcapsule showed that the best storage temperature was-20℃,the number of bacteria alive could reach109CFU/g after storaged for90days under thistemperature. The in vitro tests in simulated gastrointestinal fluid showed that the gastricfuid and bile juice had a destructive effect on the naked bacteria, with4.5log unitsdecrease. While the number of Lactobacillus delbrueckii in microcapsules decreased by2log units, with high bacteria concentration, indicating the protective effect ofmicrocapsules on Lactobacillus delbrueckii.Regulation effects of Lactobacillus delbrueckii microcapsules on intestinal flora ofmice were evaluated in this study. The dysbacteriosis model of mouse intestinal florawas established by injecting lincomycin hydrochloride. The model mouse was givennormal saline, Lactobacillus delbrueckii microcapsules or naked Lactobacillusdelbrueckii. The clinical behavior of the mouse was monitored. The content ofimmunoglobulin G (IgG), interleukin-2(IL-2) in serum, slgA in the intestinal mucosaand the number of major flora in cecum contents were detected. In addition, the pathological and histological changes of the small intestine were observed after HEstaining; the liver and spleen indexes were also calculated. The results showed that afterbeing given larger doses of antibiotics, the tested mice revealed significantly lowernumber of the targeted flora; at the same time, the content of IgG, IL-2, slgA and theweight indexes of liver and spleen also significantly decreased compared with normalcontrol group (P<0.01).The number of bifidobacterium, lactobacillus, enterobacter andenterococcus increased slowly in natural recovery group, naked group andmicrocapsules group at14days post treatment, the number of bifidobacteria andlactobacillus was significantly higher than those in normal control group (P<0.01), andthe number of bifidobacteria in microcapsule group was obviously higher than that innaked bacteria treated group (P<0.05); The content of IgG, IL-2in serum and SlgA inthe intestinal mucosa recovered to normal level in both the Lactobacillus delbrueckiimicrocapsule and naked Lactobacillus delbrueckii treated groups (P>0.05). The SlgAcontent in microcapsule treated group was significantly higher than that in nakedbacteria treated group (P<0.05); There was no significant difference in spleen indexbetween the Lactobacillus delbrueckii microcapsule and normal control group (P>0.05);while the liver indexes in Lactobacillus delbrueckii microcapsule group was higher thanthat in normal control group (P<0.01) and naked Lactobacillus delbrueckii group(P<0.05). Intestine pathological damage of the two treatment group showed obviousrestoration, while natural recovery group did not.In summary, the Lactobacillus delbrueckii microcapsules has an obvious effect onregulating the intestinal flora, which can help to restore intestinal microecologicalbalance and strengthen partial immune function in the body. In addition, theLactobacillus delbrueckii microcapsules can also relieve the intestinal tissuepathological damage. Lactobacillus delbrueckii microcapsules play an important role incuring antibiotic-induced intestinal flora dysfunction. This thesis paves a way fordeveloping this functional product in food market.