Study Of The Characteristics Of Donkey Milk Fermented By Lactobacillus Paracasei And Its Anti-colitis Effect

Donkey milk has been widely used for thousands of years.It contains a variety of nutrients and bioactive substances,and is an important source of supplementing nutrients for infants,the elderly and the incompany.Donkey milk is rich in unsaturated fatty acids,whey protein and lactose,which has antibacterial activity,immunomodulatory activity,antioxidant activity and other biological activities,and can also promote the growth of intestinal probiotics.After fermentation,the contents of small molecular active peptides and unsaturated fatty acids increased,which enhanced the biological activity of donkey milk.The main research contents and results of this paper are as follows:(1)The characteristics of donkey milk fermented by Lactobacillus paracasei and the composition and content of amino acids and fatty acidsAccording to the inoculation amount of 3% Lactobacillus paracasei was inoculated into the recovered donkey milk(dry matter content was 9.5%),and the fermented donkey milk was incubated at 37? for18 h.The types and contents of amino acids and fatty acids in the fermented donkey milk were determined.The test results were as follows: at 14 h,p H reached 4.24;At 18 h,the titrated acidity reached 74°T and the fermentation time was determined to be 18 h.There were 16 kinds of amino acids in fermented donkey milk,including 8 kinds of essential amino acids.Glutamic acid content was the highest,followed by leucine,which has the effect of treating colitis.A total of 17 kinds of fatty acids and 9 kinds of saturated fatty acids were detected in fermented donkey milk,among which palmitic acid was the highest.5 kinds of monounsaturated fatty acids,in which oleic acid content is the highest;3 kinds of polyunsaturated fatty acids,in which linoleic acid content is the highest.(2)Effects of fermented donkey milk on colonic inflammation induced by sodium dextran sulfate in miceFirstly,the mice were fed with donkey milk and fermented donkey milk for 14 days,and then the ulcerative colitis model was established.Based on this model,the effects of fermented donkey's milk on the oxidative stress response of colon tissue,tight junction protein and inflammatory factors were further studied,and the effects of fermented donkey's milk on ulcerative colitis were explored.The results showed that fermented donkey milk restored colon length,lower spleen index,and reduced disease activity index.The content of superoxide dismutase and glutathione was increased,the content of malondialdehyde was decreased,and the oxidative stress of colon tissue was improved.Occludin and ZO-1 expression were up-regulated,and Claudin-2 expression was down-regulated,which enhanced the colonic epithelial tissue tightness,decreased permeability,and restored the colonic mechanical barrier function.IL-10 content was increased,IL-6 and TNF-? contents were decreased,and intestinal immune barrier function was restored.The results showed that fermented donkey milk had a preventive effect on ulcerative colitis.(3)Effects of fermented donkey milk on intestinal microflora induced by sodium dextran sulfate in miceThrough the above experiment,in a sterile environment,the colonic contents of the above mice were taken,the DNA in the fecal flora was extracted,and the V3-V4 region in the 16 S r DNA of microorganisms was amplified by PCR.Sequences were analyzed based on Illumina Hi Seq sequencing platform.The results were as follows: DSS-induced ulcerative colitis led to the increase of harmful bacteria and the decrease of beneficial bacteria in the intestinal flora of mice,which indirectly damaged the intestinal mucosa and further enhanced inflammation.Donkey milk and fermented donkey milk can change the composition and structure of intestinal flora,increasing the abundance of beneficial bacteria such as Prevotellaceae,Muribaculaceae,Lactobacillaceae,and reducing the number of harmful bacteria such as Erysipelotrichaceae,Burkholderiaceae,and Helicobacteraceae.Changes in microbial flora composition and structure lead to changes in intestinal metabolic pathways,resulting in dysregulation of biological signal transduction and cell processing pathways in the intestinal flora of mice with ulcerative colitis.Fermented donkey milk can alleviate such changes,restore the function of biological barrier of the intestinal tract,and reduce colon inflammation.In conclusion,the recovery of donkey milk by Lactobacillus paracasei fermentation has a certain therapeutic effect on ulcerative colitis induced by sodium dextran sulfate in mice.