纳豆激酶高产菌的快速筛选及其发酵纳豆特性

Rapid Isolation of a Strain with High Nattokinase Activity and Characterization of As-Fermented Natto Food

通过纤溶活性筛选法和纳豆激酶基因筛选法,快速、准确筛选到一株纳豆激酶高产菌株MJ-1,经16S r RNA基因序列分析,该菌株被鉴定为枯草芽孢杆菌。以黄豆为原料进行固体发酵制备纳豆食品,考察了纳豆食品的纳豆激酶活力、抗凝活性和抗氧化活性。在初始含水量60%、发酵温度37℃的条件下,纳豆激酶发酵活力在20 h达到最大值(90.18 FU/g,以干质量计),达到了商业化纳豆的酶活力水平。抗凝活性分析显示该菌株可合成抗凝成分,赋予纳豆食品抗凝活性,在提取物质量浓度为3 mg/m L时,抗凝效率达91%。同时,与未发酵黄豆相比,发酵过程显著提高了其抗氧化活性。

Using the screening method based on fibrinolytic activity and nattokinase gene,a strain named MJ-1 with nattokinase-producing capacity was obtained and identified as Bacillus subtilis by 16 S rRNA gene sequence analysis.A natto functional food was prepared by fermentation of soybean with MJ-1,and its nattokinase activity,and anticoagulant and antioxidant activity were evaluated.Under the conditions of 60% initial moisture content and 37 ℃,the maximum nattokinase activity of 90.18 FU/g dry weight was obtained after 20 h fermentation,which reached the activity level of commercial natto.The strain MJ-1 could secret anticoagulant components,resulting in rich anticoagulant activity in natto foods,and the anticoagulant activity of natto water extract at 3 mg/mL reached 91%.Moreover,fermentation with MJ-1 improved the antioxidant activity of soybean significantly.