| This study based on the areas of western sichuan and Tibet in traditional fermented yak yogurt samples test the physical and chemical indicators, contrast normal yogurt to evaluate its physical and chemical quality characteristics.At the same time separation and identification of lactic acid bacteria in traditional yak yogurt types and structure, evaluate its main fermentation strains.By in vitro digestion in vitro screening and found an excellent resistant lactobacillus fermented SUO.The stomach injury mouse model is adopted. The ability to repair the stomach injury was evaluated. Research content as follows:1) Thirteen traditional fermented yak milk samples were collected from Yangbajing region of Tibet and Northwestern Sichuan in china,and their physical and chemical properties such as protein, amino nitrogen,organic acids, vitamin B, dry matter, ash, alcohol content were analyzed. Finding that protein(4.67±1.35%), amino nitrogen(54.77±12.89mg/100g), alcohol(1208.95±903.76 mg/kg), lactic acid(19.75±8.53mg/g), vitamin B1(45.76±21.20?g/100g) in yak yogurt were significantly higher than that in ordinary commercial yogurt.The indicators may provide the basis for standard-setting of traditional fermented yak yogurt.2) The 32 strains genetically stable and vigorous lactic acid bacteria isolated from fermented yak milk made by tibetans in Sichuan that were performered microscopic examination including 10 strains of Lactobacillus and 22 strains of Lactococcus after cultured, followed DNA extraction, PCR amplification. The sequencing results were submitted to NCBI database for sequence alignment (identities>97.5%). Showed there are 5 main spcies in the traditional fermented yak yogurt:Lactobacillus 11 strains (18.97%), Lactococcus 3 strains (5.17%), Leuconostoc 5 strains (8.62%), Bacillus 3 strains (5.17%), Enterococcus 34 strains (58.62%), with two strain identified unsuccessfully(Identities is 95%). Then established the phylogenetic tree based on 16S rDNA sequence with MEGA5.05 software to analyze and provide theory reference for lactic acid bacteria genetic diversity in yak milk from the western Sichuan basin..3) 58strains of lactic acid bacteria which were separated and purified from yak yogurt in Sichuan Hongyuan, Ruoergai and Tibet Yangbajain were the object of the study. To screen lactic acid bacteria of probiotics, the survival ratio of bacteria in the artificial gastric juice of pH3.0, the growth rate in different concentration of bile salt and the hydrophobic were researched.The results showed that 11 strains of lactic acid bacteria were screened which have good probiotic properties.The survival ratio increase to 96.05% after processed by artificial gastric juice. These bacteria could grow well in bile salt and have good hydrophobic. These may provide a reference for further research with a probiotic bacterial strain and its products.4) The purpose of the study was to determine the inhibitory effects of Lactobacillus fermentumSuo (LF-Suo) on HCl/ethanol induced gastric in juryin ICR mice and explain the mechanism of these effects through the molecular biology activities of LF-Suo. The studied mice were divided into four groups:healthy, injured, LF-Suo-L and LF-Suo-H group.After the LF-Suointragastric administration, the gastric injury area was reduced compared to the injured group. The serum MOT (motilin), SP (substance P), ET (endothelin) levels of LF-Suo treated mice were lower, and SS (somatostatin), VIP(vasoactive intestinal peptide) levels were higher than theinjured group mice. The cytokine IL-6 (interleukin 6), IL-12 (interleukin 12), TNF-a(tumor necrosis factor-a) and IFN-y(interferon-?) serum levels were decreased after the LF-Suo treatment.The gastric tissues SOD (superoxide dismutase), GSH-Px (glutathione peroxidase), NO(nitric oxide)and activities of LF-Suo treated mice were increased and MDA(malondialdehyde)activity was decreased compared to the injured group mice. By the RT-PCR assay, LF-Suo raised the occludin, EGF (epidermal growth factor), EGFR (epidermal growth factor receptor), VEGF (vascular endothelial growth factor), Fit-1 (fms-like tyrosine kinase-1), I?B-? (inhibitor kappaB-a), nNOS (neuronal nitric oxide synthase), eNOS (endothelial nitric oxide synthase), Mn-SOD, Cu/Zn-SOD,CAT (catalase)mRNA or protein expressions and reduced the COX-2, NF-?B (nuclear factor kappaB), iNOS (inducible nitric oxide synthase)expressions in gastric tissues compared to the gastric injured group mice. A high concentration (1.0×109 CFU/kg b.w.) of LF-Suo treatment showed stronger anti-gastric injury effects compared to a low concentration of (0.5×109 CFU/kg b.w.) of LF-Suo treatment. From the results, LF-Suo could be used as probiotics by its gastric injury treatment effects. |
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