海洋源纤溶酶高产菌株的诱变育种及液体培养基优化

为获得纤溶酶高产菌株及其最优发酵条件，以海洋环境来源的枯草芽孢杆菌（Bacillus subtilis）H-A-03为出发菌株，经过60Co辐射诱变获得了一株遗传稳定性好的纤溶酶高产菌株F8-C，其酶活力较出发菌株提高28.78%。采用统计学优化方法获得了组分更简单、用量更少、更利于菌株产酶的培养基：可溶性淀粉41.6 g/L、黄豆粕粉26.2 g/L、CaCl2 1.0 g/L，KH2PO4 2.0 g/L。在此基础上，3 L摇瓶放大试验结果显示，菌株F8-C的产酶量达到（3 231±21） U/mL，较出发菌株H-A-3提高44.8%。结果表明利用60Co辐射诱变育种，并采用统计学方法优化培养基，对于提高枯草芽孢杆菌纤溶酶的产酶量是一种有效策略。该研究结果也将为下一步发酵罐扩大试验奠定基础。

Mutation breeding of strains with high fibrinolytic activity derived from marine and optimization of its liquid fermentation medium

A marine bacterium, Bacillus subtilis H-A-03 was used as initial strain to obtain mutants with higher fibrinolytic activity and optimal fermentation conditions. After mutagenesis by 60Co radiation, a mutant strain F8-C with good genetic stability was obtained, and the enzyme activity was 28.78% higher than the original strain. By using statistical optimization methods, an optimized fermentation medium which had simple components, less dosage, and easier for fibrinolytic enzyme production was determined as follows: soluble starch 41.2 g/L, soybean meal 26.2 g/L, CaCl2 1 g/L and KH2PO4 2 g/L. The fibrinolytic enzyme activity reached (3 231±21) U/ml in 3 L shake flask experiment under the optimal medium and fermentation conditions, which was 44.8% higher than the initial strain H-A-3. Results showed that 60Co radiation mutation breeding and statistical optimal methods were efficient strategies to improve the fibrinolytic enzyme production. The research results also established a foundation for industrial production of fibrinolytic enzyme in the future.