Preparation Of Escherichia Coli Nissle 1917 Microcapsules And Study On Its Probiotic Properties

The probiotic E.coli Nissle 1917 is a type of microorganism colonized in the human body.It can change the composition of the host's intestinal flora and adjust the balance of the flora.By improving the immune defense function of the host's intestinal mucosa,it reduces the host's intestinal inflammatory response.However,E.coli Nissle 1917 is extremely vulnerable to damage during transportation and storage and entering the host body,and its activity is significantly reduced.The purpose of this paper is to prepare cellulose-based microcapsules of probiotic E.coli Nissle 1917 with cellulose nanofibers as the main raw material.In vitro experiments were carried out to analyze the resistance of probiotics to simulated digestive juices.Animal experiments were conducted to explore the colonization of probiotics in the intestinal tract of mice.Finally,the ability to resist intestinal Salmonella infection was evaluated.The main results are as follows:(1)Preparation of E.coli Nissle 1917 cellulose-based microcapsules and their ability to resist simulated digestive juices.Cellulose and Cellulose nanofiber(90% of Cellulose nanofiber)were used as carriers for packaging E.coli Nissle 1917 probiotics.The cellulose nanomaterials loaded with probiotics were digested in simulated gastric juice for 2 hours and then placed in simulated intestinal juice for 6 hours.The results showed that the Cellulose-based microcapsules had good thermal stability,reached the peak of probiotics E.coli Nissle 1917 release after 4 hours of digestion of simulated intestinal juice,and could protect probiotics against the effect of gastrointestinal digestive juices.(2)Study on the colonization ability of E.coli Nissle 1917 cellulose based microcapsules in different intestinal locations of mice.After one day,three days,five days and seven days,the feces of mice were extracted to detect the number of viable bacteria in the feces.The tissues of duodenum,jejunum and colon of mice were collected.After fixation,paraffin embedded sections were performed,and he staining and immunofluorescence staining were performed to analyze the intestinal structure and colonization effect of probiotics.The results showed that the number of viable bacteria in the intestines of mice fed with the cellulose based microcapsules loaded with probiotics increased significantly after 3 days of feeding,and the colonization of probiotics in the intestines of mice did not increase after 7 days;there was no significant effect on the intestinal microstructure of mice after 5 days of continuous intragastric administration of probiotics cellulose based microcapsules.A large number of colonization of E.coli Nissle 1917 can be seen on the surface of colon mucosa.(3)To improve the intestinal infection caused by Salmonella.Mice were inoculated with Salmonella typhimurium 14028 by gavage for 5 consecutive days.All behaviors of mice in cage were monitored 3 days after inoculation.HE staining and immune-fluorescence staining were performed after paraffin section.The results showed that compared with the probiotic E.coli Nissle 1917 cellulose-based microcapsules in the pre-gavage group,the mice in the simple S.typhimurium14028 infection group had lower food intake and lower mobility.The probiotic E.coli Nissle Inoculation in 1917 can significantly improve the inflammatory response caused by Salmonella infection in the colon of mice,and the number of Salmonella infected is significantly reduced.