Study On Antioxidant Activity Material By Bacillus Subtilis Fermentated Millet Bran

Millet bran was a kind of agricultural by-products,which was mainly applied to fodders of livestock and poultry.It contained kinds of nutritional factors.However,it has not been used as effectively as it might be.Functional material produced from agricultural by-products microbial fermentation was a hotspot of current research.Especially bacillus subtitles fermentation,which can produce many functional products such as peptides,polysaccharides,special amino acids,etc.,has been widely applied in food industy.Microbial fermentation can procude many functional products,which will not only reduce the economic cost of production and the pollution to the environment,but also increase the safety of the products.At the same time,microbial fermentation can reduce the toxic side effect of products which can be used directly to food industry.The aim of the research was to produce a fermentation mixture with good antioxidant activity through the bcacillus subtiltles fermentation of millet bran.The main results were listed as follow:1.Screening a strain with high proteinase-producing activity.With Bacillus subtilis as the starting strain and the HC as the preliminary screening index,casein plate culture method was used to sceen high-proteinase producing strains.The obtained strains were further screened in the millet bran-containing medium.The fermentation supernatant was collected to determine the total proteinase activity,the peptide content and the total antioxidant capacity(T-AOC)were used to screen the optimal strain.The screened strain was applied to the millet bran medium and its optimal fermentation time and the antioxidant activities of its fermentation supernatant were determined.Results showed that the optimal strain was NattoD-3,which,in millet bran medium,could produce a protease activity of 90.22 U/mL.The optimal fermentation time was 72 h,and at this time,the T-AOC,DPPH free radical scavenging activity,reducing power and Fe2+ chelating ability of the millet bran fermentation supernatant were 38.04 U/mL,75.37%,18.17%and 44.34%,respectively.The peptide content in the fermentation supernatant reached 4.28 mg/mL with a plasmin activity of 522.64 IU/mL.2.Optimization of fermentation conditions for NattoD-3 to produce millet bran peptides with high antioxidant activity.With DPPH free radical scavenging activity and peptide content as dependent variables,the best level of independent variables were determined by comprehensive analysis.The key factors were determined by PB experiments,optimized by response surface methodology.Considering both the DPPH free radical scavenging activity and peptides content,the optimal fermentation conditions were as following:fermentation time 43.2h,soybean meal content 5.45g/100ml and inoculation volume 3.25%.Under these conditions,the DPPH free radical scavenging acticity was 92.16%and the peptide content was 12.53mg/ml.3.Antioxidant ability of fermented millet bran supertanant(MBFDs)in vivo and in vitro.(1)The five kinds of vitro antioxidant indexes were measured to different concentration of MBFDs.Under the same concentration,the DPPH free radical scavenging capacity of fermented millet bran supernatant was higher than that of GSH and its Fe2+chelating ability was far higher than that of BHT and GSH.When the mass concentration was between 1?5 mg/mL,its T-AOC activity was higher than that of GSH significantly.In the range of 1?6 mg/mL,its reducing power was lower than that of GSH,but its inhibition rate against lipid oxidation was higher than that of GSH and lower than that of BHT.(2)In vivo test,the antioxidant effects of MBFDs against CCl4-induced injury in mice were investigated.Treatment with different dose MBFDs after the administration of CCl4 siginificantly attenuated the CCl4-mediated depletion of antioxidant enzyme CAT and SOD activities and GSH in the liver,kidney,heart and spleen.Furthermore,it enhanced the decrease of MDA content,indicating its inhibition effect on lipid peroxidation.These results suggested that MBFDs had nice antioxidant activity in vivo.