| China is the world’s largest pig producer and pork consumer.In the process of pig feeding,piglet diarrhea caused by early weaning is one of the important factors restricting the healthy growth of piglets.In recent years,antimicrobial peptide microcapsules and probiotic microcapsules have received more and more attention in the production and application of prevention of piglet diarrhea.This topic is based on the reorganization of bovine lactoferrin peptides with dual characteristics of probiotics and antimicrobial peptides that have been constructed in the laboratory.Lactobacillus reuteri p PG-LFCA-E/LR-CO21,in order to enhance the stress resistance of recombinant bacteria and facilitate storage and transportation in production,the recombinant bacteria were microencapsulated by spray drying method,and the preparation of microcapsules was optimized Technological conditions;the relevant stress resistance,storage characteristics and microstructure of the recombinant bacteria microcapsules were tested,and the effects of the recombinant bacteria microcapsules as feed microecological preparations on the growth of piglets and resistance to Salmonella typ Himurium infection were analyzed.In order to prepare the recombinant bacteria microcapsules,the wall materials were first compared and selected.In the experiment,9 kinds of composite wall materials were used to prepare the recombinant bacteria microcapsules.The unembedded recombinant bacteria all died during the spray drying process.Skim milk-sodium glutamate-PVPK-30-maltodextrin-gelatin microcapsules（formulation 9）showed the highest survival rate of 83.56%.Followed by skimmed milk-sucrose-glycerol-glycine microcapsules（formulation 4）and trehalose-skim milk-maltodextrin microcapsules（formulation 8）,the survival rates were 66.67%and 64.17%,respectively.The microcapsule microstructure of the three recombinant bacteria with the highest survival rate was determined.Scanning electron microscopy showed that the microcapsule particles were irregularly sp Herical,the particles adhered to each other,and there were wrinkled pits on the surface.The microcapsule particles were less broken and the structure was maintained.Completeness.The relevant stress resistance of the recombinant bacteria microcapsules was tested,and the results showed that 9 kinds of recombinant bacteria microcapsules can exist stably in artificial gastric juice,and have strong tolerance to artificial intestinal juice,pig bile salt solution,and acid-base solution.The 9 kinds of recombinant bacteria microcapsules were stored in an environment of-20°C,4°C,25°C,30°C,and 37°C respectively,and vacuum and natural environmental conditions were set at each temperature.The results showed that under the five temperature conditions,the survival rate of the recombinant bacteria microcapsules in the vacuum environment was higher than that in the natural environment,but the difference was not significant.In the 37℃environment,the survival rate of the 9 recombinant bacteria microcapsules decreased relatively fast.The formula 9microcapsules in the four temperature environments of-20℃,4℃,25℃,and 30℃had the longest storage time,and the storage time was 154 d.The number of viable cells of the rear recombinant bacteria was 1010 CFU/g.In an environment of 25℃,the recombinant bacteria microcapsules were stored under three water activity conditions of 0.33,0.54,and 0.76.The results showed that the survival rate of recombinant bacteria microcapsules decreased the fastest under the condition of0.76 water activity,among which L-Sodium glutamate-sucrose-maltodextrin microcapsules（formulation 6）and skim milk-sodium glutamate-PVPK-30-maltodextrin-gelatin microcapsules（formulation 9）have the longest storage time.The formula 9 microcapsules with the highest survival rate were continuously fed to 3-day-old newborn piglets for 3 days,and the intestinal mucus was scraped.The plate count method and real-time fluorescent quantitative PCR method were used to detect the colonization of bacteria in piglets.It was found that compared with the bacterial solution group,the recombinant bacteria in the microcapsule group colonized the piglet intestinal more frequently,indicating that the microcapsules can protect the recombinant bacteria.Resist the invasion of gastric juice and colonize in the intestine.The 21-day-old weaned piglets were fed with recombinant bacteria microcapsules for 21 days,and a control group,an empty bacteria group and a recombinant bacteria group were set up.The feed intake and daily gain of piglets were recorded,and organs,serum and whole blood of piglets were collected.The results showed that compared with the control group,the daily weight gain,daily feed intake,and immune organ index of thymus and spleen of piglets in the recombinant bacteria group increased,and the difference was extremely significant;to a certain extent,the diarrhea caused by stress in piglets was reduced.The p Hysiology and biochemistry of piglet blood showed that the recombinant bacteria microcapsules can promote the growth of piglets.On the 14th day,weaned piglets were continuously orally infected with Salmonella typ Himurium for 3 d,and an observation period of 7 d was set up.A control group,an infected group,an empty bacteria group,and a recombinant bacteria group were set up.The weight changes and diarrhea of each group of piglets were recorded daily.Collect piglet serum,intestinal mucus and intestinal tissue.The results showed that the recombinant bacteria microcapsules alleviated the increased diarrhea rate and weight loss caused by Salmonella infection in piglets to a certain extent.Compared with the infection group,the number of white blood cells and neutrop Hils in the recombinant bacteria group was reduced,and the difference was extremely significant.The total protein increased significantly,the content of globulin increased relatively,and the content of triglycerides decreased relatively.Compared with the infection group,the levels of s IgA,IgA,IgM,and IgG in the recombinant bacteria group were significantly increased,the levels of inflammatory factors IL-10and IL-4 were significantly increased,and the levels of IL-1β,IL-6,and TNF-αwere significantly decreased.The antioxidant factor GSH-Px is extremely significantly increased.Recombinant bacteria microcapsules significantly alleviated the intestinal mucosal surface damage and inflammatory cell infiltration caused by Salmonella typ Himurium infection.The metabolism,signal transduction and other functions of the intestinal flora of piglets of the recombinant bacteria group were enhanced compared with the infection group.,The diversity of intestinal flora is closer to the control group.It shows that oral recombinant bacteria can increase the level of immunoglobulin in serum and mucus,regulate the innate immune system and inflammatory response,promote the development of immune organs of piglets,and play a certain protective effect on the intestinal environment of piglets infected by Salmonella typ Himurium.It can be seen that the recombinant Lactobacillus reuteri microcapsules expressing bovine lactoferrin peptides have a certain protective effect on piglets infected with Salmonella typ Himurium.In summary,this study screened effective embedding agents to embed recombinant bacteria,and determined that skim milk,sodium L-glutamate,PVPK-30,maltodextrin,and gelatin were used as microcapsule wall materials to spray dry recombinant bacteria.,The survival rate of bacteria is the highest,reaching 85.36%.The microencapsulated recombinant bacteria can effectively colonize the piglets,and the microencapsulated recombinant bacteria can effectively extend the storage time.Oral administration of recombinant bacteria microcapsules can improve the immunity of piglets and has a certain protective effect on piglets infected with Salmonella typ Himurium.Recombinant bacteria microcapsules have potential application prospects as microecological preparations to promote the healthy growth of piglets. |
PDF Full Text Request