Preparation Of Lactobacillus Rhamnosus Agents And Its Effect On Intestinal Flora Of Mice

Probiotics have been proved to have good functional properties and be beneficial to human immunity and health.10~6(cfu/g)of probiotics is adequate for probiotics to exert Probiotic effect.However,probiotic activity is greatly reduced due to the destruction of gastric juice and intestinal fluid,and environmental factors during storage.Therefore,measures must be taken to increase the activity of probiotics.In this study,the coated Lactobacillus rhamnosus preserved by the laboratory was prepared with a combination of extrusion microcapsule and vacuum freeze-drying in optimized the processing conditions and properties were studied.Finally,the effect of microcapsules on intestinal flora of mice was studied.The main contents and results are as follows:(1)A series of intestinal characteristics of Lactobacillus rhamnosus L427 were studied by in vitro evaluation experiments.The results showed that the strain proliferated rapidly and logarithmic growth phase was at 2 h.However,it was almost intolerant to the acidity of pH 2.0 and bile salt concentration of 0.3%and the activity of Lactobacillus rhamnosus L427 was greatly reduced after treatment with gastrointestinal fluid,so the strain needs to be protected to enhance the activity.(2)The effects of bacterial and wall material solution volume ratio,sodium alginate concentration,thorn cloud solid concentration and calcium chloride concentration on the formation of enteric microcapsules of Lactobacillus rhamnosus were investigated by single factor experiment.The orthogonal testing was carried out to determine the optimum embedding conditions:bacterial and wall material solution volume ratio was 1:6,sodium alginate concentration was 2%,thorn cloud solid glue concentration was 0.5%and calciu-m chloride concentration was 0.3 mol/L.The viable cell count and embedding yield of the microcapsules reached 4×10~8 CFU/g and 94.51%under these conditions,respectively.A-fter being treated with simulated gastric juice and simulated intestinal juice,the microcapsules showed good gastric juice tolerance and intestinal disintegrateion.(3)The effect of protective agent on the freeze-drying of Lactobacillus rhamnosus microcapsules was studied by single factor experiment.The orthogonal experiment of mannitol and trehalose was carried out to determine the optimal formulation of compound protective agent:mannitol concentration was 4%,trehalose concentration was 3.5%.The maximum survival rate of microcapsules reached 82.92%under these conditions.After being treated in simulated gastric juice and simulated intestinal juice,the freeze-dried microcapsules showed good gastric juice tolerance and intestinal disintegrateion,and it can be improved with the addition of protective agent.The water content test and shelf life test results showed that the Lactobacillus rhamnosus freeze-dried microcapsules can be maint ain good activity during storage.(4)The mice were divided into the group of control,the empty capsule,the L427bacterial suspension and the L427 microcapsuled respectively,and the normal diet was resumed after 16 days of feeding,followed for 8 days.Feces were taken every 4 days and the effects of several treatments on the intestinal flora of mice were analyzed by high thoughput sequencing.The results showed that the richness and diversity of the intestinal flora of mice was increased when the mice were feed of Lactobacillus rhamnosus microcapsuled or Lactobacillus rhamnosus bacterial suspension;the distribution of the main strains of the intestines was regulated,Proteobacteria is reduced,the Bacteroidetes is increased,the Firmicutes is reduced,and some pathogenic bacteria were reduced,such as Xanthomonas and Pasteuraceae.Therefore,it is analyzed that the probiotic effect was achieved by Lactobacillus rhamnosus due to pathogenic bacteria reducing.