Screening And Studying On The Physiological Characteristics Of Antioxidative Bifidobacteria

In recent years,the study of natural products has been attracted much attention,especially in the research of oxidative stress and antioxidant.Evaluation and screening of natural products that have antioxidant activity has become a new trend in various fields of study.Bifidobacterium is an important part of the organism intestinal probiotics group,which has many functions,such as antibacterial,anticancer,antioxidant and improving the immunity of the human body.Therefore,this paper takes the bifidobacteria as the research object,firstly screened a number of bifidobacteria,then in vitro antioxidation and antioxidation of the cells were evaluated,and its biological characteristics were studied.The main results were as follows:1.Totally 59 suspected bifidobacteria were screened by the molecular identification.The result showed that 38 were bifidobacteria,which providing resources for the next study of antioxidant activity of bifidobacterium.2.10 bifidobacteria were screened from 38 with hydrogen peroxide tolerance.Then,10 strains were screened for next experiment via determination of DPPH free radical scavenging ability ratio.And then,6 strains were screened for another experiment by antioxidant capacity in vitro.The fermented supernatant of W13 showed strong abilities of hydroxyl radical,lipid peroxidation inhibition capacities and reducing capacities,the clearance rate were 39.21±0.31%,26.11±1.06%and 287.36±12.68?mol/mL cysteine equivalent.The cell-free extract of W112 showed strong abilities of hydroxyl radical,lipid peroxidation inhibition capacities and Fe2+-chelating abilities,which were 28.56±0.62%,14.74±0.70%and 23.22±1.16%.The intact cell exhibited strong Fe2+-chelating abilities was 40.42±3.28%.3.Evaluation of antioxidant of 6 bifidobacteria by using cellular antioxidant activity(CAA)assay.The results showed that the cell antioxidant capacity of the fermentation supernatant of W13 and W112 were the highest,which were 95.09 and 90.72 ?M quercetin equivalent,respectively.Significant difference was found between the other strains(p<0.05).4.The biological characteristics of W13 and W112 were evaluated after in vitro chemical experiment and cell antioxidant experiments.Via further identification of physiological and biochemical properties and 16S rDNA homology analysia for two bifidobacteria,constructing phylogenetic tree,eventually identified the two strains respectively as Bifidobacterium longum W13 and Bifidobacterium pseudocatenulatum W112.The results showed that the two bifidobacteria could survive at pH 3.0 and the highest bile salt tolerance was 0.15%.The cell surface hydrophobicity was 37.6%and 20.0%.The auto-aggregation was 9.8%and 8.9%respectively.5.Study on the antioxidant activity of two bifidobacteria in different incubation temperature,different incubation time and different pH.The results showed that the antioxidant activity of B.longum W13 and B.pseudocatenulatum W112 were significantly affected by temperature(p<0.05),and reached the highest antioxidant activity under the culture condition of 37?.The antioxidant capacity of the two strains were the strongest among the 18-24h.The produced metabolites made the fermentation supernatant good oxidation activity.