纳豆菌液态产酶条件的优化

Optimal condition for Bacillus subtilis natto fermentation in liquid

实验采用单因素试验优化纳豆菌液体发酵条件。通过蛋白凝块溶解时间法测定纳豆激酶活力,筛选出最佳培养条件。液态发酵选用甘油、乳糖以及木糖与葡萄糖的混合糖代替基础培养基中的麦芽糖;用酵母膏、干酪素、胰蛋白胨和黄豆汁代替基础培养基中的麸皮进行发酵产酶试验,筛选出最佳碳氮源,并在此基础上变换不同的碳、氮源浓度,筛选出最佳的碳、氮比。试验结果表明:液态发酵最佳条件为,甘油10%,酵母膏2%,明胶0.5%,NaCl 0.5%,KH2PO40.1%,K2HPO40.4%,MgSO40.05%,初始pH7.0。在此条件下培养,测得的纳豆激酶活力相当于尿激酶1 081.22 IU/mL。与此前报道结果800.50 IU/mL相比有了明显的提高。

The optimal ferment condition was confirmed with single factor experiment. The activity of Nattokinase was measured with the method of fibrin liquefied time, and the optimal fermentation condition of Bacillus subtilis natto was filtrated out. In this trial, maltose in the basic culture medium was replaced by glycerin, lactose, and the admixture of xylose and glucose. In the basic culture medium, bran was replaced by yeast paste, casein, pancreas peptone and soybean juice, the sources of carbon and nitrogen were found, and the optimal proportion of C/N was confirmed. The optimal condition of liquid fermentation is： 10% glycerin, 2% yeast paste, 0. 5% glutin, 0.5% NaCl, 0. 1% KH2PO4, 0.4% K2HPO4, 0.05% MgSO4, and initial pH 7.0. Cultivated in this condition, the activity of Nattokinase to urokinase is 1 081.22 IU/mL. Compared existed data 800.50 IU/mL, the activity of Nattokinase was obviously enhanced.