Preparation Of FCOS And Functional Application Of Intestinal Prebiotics

Fuco Pol(Fucose-containing EPS)is a water-soluble polysaccharide with the main component of L-fucose.At present,it is mainly extracted from brown algae(Fucoidan).However,its structure is complex,which is seriously affected by the type,origin,seasons and body part of brown algae.The extraction process is complex,with low yield and high cost.In this study,we used microbial fermentation method to produce Fuco Pol which is not affected by the natural environment.By optimizing the fermentation conditions and genetic engineering transformation,we can improve the polysaccharide yield,ensure a uniform structure and reduce costs,and effectively make up for the deficiencies of extraction from natural plants.Polysaccharides from different sources have great differences in components,molecular weights and biological activities,but all of them are high molecular weight polysaccharides,with the disadvantage of difficult absorption by organisms,which limits their application.However,low molecular weight FCOS(Fucose-oligosaccharide)often exhibits a variety of better biological activities due to overcoming the above disadvantages,especially it has great application value as a prebiotic to regulate the balance of human intestinal flora,improve related clinical diseases,and so on.In this study,Kosakonia sp.CCTCC M2018092,which was screened in the laboratory,was used as the starting strain for the fermentation production of Fuco Pol.FCOS was prepared by two partial acid hydrolysis processes,and its components were accurately analyzed.At the same time,the biological activity of FCOS as a prebiotic in the regulation of intestinal flora and the alleviation of colitis was explored.The main research results are as follows:1.The preparation technology of FCOS was established and its components were analyzed.The strain Kosakonia sp.CCTCC M2018092 is use for fermenting to produce a Fuco Pol-rich fermentation broth,sulfuric acid hydrolysis is use for reducing that viscosity of the fermentation broth to extract partially acid-hydrolyzed Fuco Pol(AHEPS),trifluoroacetic acid is used for carrying out secondary hydrolysis to obtain FCOS,the purity of the oligosaccharide is 90.32% after purification,the yield was 90.1%,the molecular weight was 1725 Da,and the composition and molar ratio of FCOS were Fuc:Glc: Gal: Glc A: Pyr = 2.13: 1.07: 1.30: 1.0: 0.59.2.Oral safety evaluation of FCOS was conducted and its intervention on intestinal flora was studied by in vitro intestinal simulation system of CDMN(Chang Dao Mo Ni).FCOS could not change the body weight of healthy mice,as well as the weights of organs,liver and kidney functions,and the morphology of tissues.After being digested in simulated intestinal fluid,stomach and intestinal fluid,the molecular weight and reducing sugar content of fucoidan-oligosaccharide did not change significantly and were basically not degraded.After simulating the digestion of 1.00 mg/m L FCOS in the intestinal tract of healthy people in the CDMN system,the content of FCOS in each intestinal segment was decreased,gas production was increased,and the concentration of short-chain fatty acids was increased.The concentration of acetic acid could be increased from 21.83mmol/L to 36.61 mmol/L,and that of propionic acid could be increased from 5.41 mmol/L to 17.56 mmol/L.The abundance of intestinal pathogenic bacteria Klebsiella and Escherichia-Shigella decreased,while that of Bifidobacterium,Prevotella 9 and Parabacteroides distasonis increased.It could be seen that,by proliferating human intestinal beneficial bacteria that metabolize FCOS to produce SCFAs,and inhibit pathogenic bacteria,thereby promoting intestinal health,and possessing the potential as prebiotics.3.It has been further found that FCOS can improve the DSS-induced pathological conditions of IBD in mice.High-dose FCOS significantly increased the disease activity index and colon length of the mice,and reduced the consumption of goblet cells,improved the infiltration of inflammatory cells and epithelial shedding in the colon tissue of the mice,and reduced the levels of tumor necrosis factor,interleukin-1β,and interleukin-6 in the mouse tissue.At the same time,it enhanced the colon barrier effect by increasing the levels of ZO-1 and Occludin proteins in the colon,increased the antiinflammatory capacity of the colon of the mice,and intervened the development of IBD.The FCOS derived from microorganisms in this study not only provided better resources for prebiotics and specialty foods,but also promoted the strategic development of national nutrition plan in China,and had great application value.