高产纳豆激酶地衣芽孢杆菌工程菌全合成培养基优化

以产纳豆激酶的地衣芽孢杆菌基因工程菌BL10（pP43SNT-SsacC）为出发菌株，开展其全合成培养基的发酵优化研究。通过单因素试验和正交试验优化了全合成培养基成分，获得了最优的培养基组成（g/L）：葡萄糖30、NaNO3 30、谷氨酸钠20、柠檬酸钠15、MgSO4·7H2O 0.5、K2HPO4·3H2O 1.5、CaCl2 0.5，pH 7.2。在优化的全合成培养基中，纳豆激酶最高酶活力达到25.59 FU/mL，相比于初始培养基发酵活性（4.27 FU/mL），提高了5 倍。对比分析了全合成培养基和半合成培养基的发酵产物，结果表明，全合成培养基可显著提高纳豆激酶的纯度，与半合成培养基相比，纳豆激酶比活力提高了2 倍。本研究获得了纳豆激酶的全合成培养基成分，显著提高了纳豆激酶发酵活性，并进一步提高了纳豆激酶发酵纯度。

Optimization of Synthetic Complete Medium for Enhanced Nattokinase Production by Genetically Engineered Bacillus licheniformis

The nattokinase-producing genetically engineered strain, Bacillus licheniformis BL10 (pP43SNT-SsacC) was
used in this study, and the synthetic complete medium composition for nattokinase production by the strain was optimized
using combination of single factor and orthogonal tests. The maximum nattokinase activity of 25.59 FU/mL, which was
6 times higher than that (4.27 FU/mL) before optimization, was obtained using a medium consisting of 30 g/L glucose, 30 g/L
NaNO3, 20 g/L sodium glutamate, 15 g/L sodium citrate, 0.5 g/L MgSO4·7H2O, 1.5 g/L K2HPO4·3H2O and 0.5 g/L CaCl2 at
pH 7.2. The specific activity of nattokinase in the synthetic complete medium was improved by 3 folds when compared with
that in semi-synthetic medium. In the present study, both the activity and purity of nattokinase were improved obviously by
using the optimized synthetic complete medium.