枯草芽孢杆菌发酵小米糠对其抗氧化肽含量与抗氧化活性的影响

Effect of Fermentation by Bacillus subtilis on Antioxidant Peptide Content and Antioxidant Activity of Millet Bran

为提高小米糠的附加值,本实验以多个枯草芽孢杆菌为起始菌株,透明圈直径与菌落直径之比(HC值)为初筛指标,通过酪蛋白平板培养法进行高产蛋白酶菌株的初步筛选。将初筛所获得菌株在小米糠基础培养基上进行发酵,对其发酵上清液的总蛋白酶活力、多肽含量及总抗氧化能力(total antioxidant capacity,T-AOC)进行测定,进一步筛选出最适菌株。用此菌株对小米糠进行发酵,并对其最适发酵时间及上清液的抗氧化活性进行测定。结果表明:Natto D-3为最佳发酵菌株,其产蛋白酶活力为90.22 IU/m L,发酵小米糠72 h时所获得发酵上清液4种体外抗氧化活性相对最高,分别为T-AOC值38.04 U/m L、1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率75.37%、总还原力0.18及Fe2+螯合能力44.34%,最终发酵上清液的多肽含量为4.28 mg/m L,纤溶酶活力为522.64 IU/m L。

In order to find the most suitable strain for the production of antioxidant peptides and plasmin from millet bran,initial screening of 27 Bacillus subtilis stains for the ratio of transparent circle diameter to bacterial colony diameter（HC value） was performed on casein agar plates and further screening of the selected strains based on total proteinase activity,peptide content and total antioxidant capacity（T-AOC） of fermentation supernatants was conducted using the basal medium containing millet bran.This study also investigated the optimal fermentation time for antioxidant activities of fermentation supernatants using the selected optimal strain.Results showed that NattoD-3 was found to be the optimal strain for the fermentation of millet bran,yielding a protease activity of 90.22 IU/mL.The optimal fermentation time was 72 h,and the resulting T-AOC,DPPH radical scavenging activity,reducing power and Fe^（2＋） chelating ability of millet bran fermentation supernatant were 38.04 U/mL,75.37%,0.18 and 44.34%,respectively.The peptide content in the fermentation supernatant reached 4.28 mg/mL with plasmin activity of 522.64 IU/mL.