Effect Of Translocation And Colonization Of Lactobacillus Plantarum WLPL04 On Immunity And Gut Microbiota Of Offspring Mice And Preparation Of Probiotic Additives

Lactic acid bacteria can inhibit the colonization of pathogens,stimulate the immunity of intestinal mucosa and maintain the balance of intestinal microbiota.Lactobacillus spp.from breast milk,as symbiotic microorganisms in breast milk,is safer and easier to colonize the intestines of newborns at a certain level.Lactobacillus in breast milk can enhance the immunity of newborns and reduce the frequency and severity of infection in infants.However,there are few studies on the influence of Lactobacillus from breast milk on newborns.Therefore,in this study effect of Lactobacillus plantarum WLPL04 on the immunity and intestinal microbiota of maternal mice and their offspring was investigated.The thesis is described into five chapters.In the first chapter,the introduction summarized the intestinal microbiota and breast-milk probiotics,summarized the effects of Lactobacillus on the newborns and the research progress of bacterial translocation during pregnancy,and prospected the development and application of breast-milk Lactobacillus.In chapter 2,we studied the effect of L.plantarum WLPL04 on the immunity of mother mice and their offspring.Skimmed milk and another L.plantarum FLPL05 were used as controls.Firstly,the changes of maternal body weight,milk yield and infant body weight were monitored during the experiment.It was found that L.plantarum WLPL04 could significantly increase the body weight of post-lactation maternal mice,but it did not affect their milk yield and organ index at the end of lactation.There was also a significant difference in the body weight of newborn rats at week 2 and week 3,and it affected the organ index(liver and kidney)of rats at week 1 and week 3.H&E staining of intestinal tissue showed that L.plantarum could not destroy the integrity of intestinal structure of maternal mice and their offspring.Then the colonization and translocation of the strain in the mother mouse and the baby mouse were detected by live count.The results showed that L.plantarum WLPL04 could colonize in the intestinal tract of female mice and transfer to other organs,such as liver,kidney,spleen and breast,while L.plantarum FLPL05 only existed in the intestinal tract of female mice,and two strains of the bacteria could be detected in the intestinal tract of baby mice.Finally,enzyme-linked immunity and immunofluorescence were used to determine the expression levels of cytokines related to Thl/Th2 response in the serum of mothers and their offspring,and the typification of T lymphocytes in the spleen and mesenteric lymph nodes of the offspring.It was found that L.plantarum WLPL04 could significantly increase the expression levels of IL-4 and IL-6 in maternal serum and IL-6 in offspring mice,and significantly increase the proportion of CD4+T lymphocytes in the spleen of the offspring mice,and thus make the Th1/Th2 response polarized to Th2 response in the maternal mice and the offspring mice..In chapter 3,the effects of L.plantarum WLPL04 on intestinal flora of female mice and their offspring were investigated.Firstly,the changes of the intestinal flora of the mother mice at the end of lactation and the offspring mice at 1-4 weeks after birth were measured.The results showed that the ?-diversity of the intestinal flora of the WLPL04 group was not significantly different from that of the other two groups,but the ?-diversity of the intestinal microbiota of the WLPL04 group was significantly higher than that of the other groups.From the level of phylum classification,the contents of Bacteroidetes and Firmicutes in the intestinal tract of female mice were high,and the proportion of Firmicutes in WLPL04 group was higher than that in other groups.At the level of class,Prevotella was the main group in the intestinal tract of female mice.However,the ?-diversity and ?-diversity of the intestinal flora of mice in the WLPL04 group were high,indicating that the species were abundant.The contents of Firmicutes,Bacteroidetes and Proteobacteria in the intestinal flora of offspring mice were high,and the bacterial proportions were different at different time points.Secondly,analyzed nursing of microbial changes 1 w and 2 w milk at class level,the results showed 1 w milk microbes mainly by the condensation of Lactobacillus and Aggregatibacter,2 w milk microorganism is mainly composed of Lactobacillus,Aggregatibacter and Veillonella,and the proportion of the Lactobacillus in WLPL04 group is on the rise.Finally,the correlation between the intestinal microorganisms and the milk microorganisms in mice of WLPL04 group was analyzed,the results showed that the same bacteria were Lactobacillus,Aggregatibacter and Veillonella.In chapter 4,the microecological preparation of L.plantarum WLPL04 was prepared by optimizing the composition of fermentation medium.In chapter 5,the effects of L.plantarum WLPL04 on the immunity and intestinal flora of maternal mice and their offspring and the preparation of the microecological preparation of L.plantarum WLPL04 were summarized.In summary,this thesis investigated the effects of L.plantarum WLPL04 on the immunity and intestinal flora of maternal and offspring mice,and prepared a microecological preparation of L.plantarum WLPL04.This thesis provides a theoretical basis for the development and application of L.plantarum-derived from breast milk and lays a working foundation for its application in the field of maternal and infant products.