该研究以来源于海洋放线菌（Streptomyces sp.）W007脂肪酶MAS1为研究对象，将其在大肠杆菌BL21（DE3）中表达并优化了发酵条件。首先，通过单因素实验确定重组大肠杆菌表达脂肪酶的最佳诱导时间为对数生长后期，最佳异丙基-β-D-硫代半乳糖苷（IPTG）浓度为0.6 mmol/L，最佳诱导pH值为6.5，最佳诱导温度为20 ℃。然后，用R语言rsm包设计Box-Behnken试验，并在7 L发酵罐中进行发酵试验以得到Box-Behnken实验数据。最后，通过支持向量机（Support Vector Machines，SVM）-遗传算法（Genetic Algorithm，GA）计算得到重组大肠杆菌BL21（DE3）表达脂肪酶MAS1的最优发酵条件：IPTG浓度为0.65 mmol/L、诱导温度23 ℃、诱导pH值为6.7时，理论脂肪酶MAS1酶活力为2 276.99 U/mL。在7 L发酵罐中，使用优化后的发酵条件进行重组大肠杆菌BL21（DE3）培养时，得到最大脂肪酶MAS1酶活力为2 316.02 U/mL，比未优化之前（1 733.33 U/mL）提高了33.61%。上述结果表明SVM-GA在重组大肠杆菌发酵条件优化方面具有较好的性能，为脂肪酶MAS1的高效制备提供了一定的研究依据。

In this study, the lipase MAS1 from marine actinomycetes (Streptomyces sp.) W007 was used as the research object, which was expressed in Escherichia coli BL21 (DE3) and associated fermentation conditions were optimized. First of all, the optimal induction time for the expression of lipase in recombinant Escherichia coli (E. coli) was determined by the single factor experiments to be the late logarithmic growth phase, with the optimal Isopropyl-β-D-thiogalactopyranoside (IPTG) concentration being 0.6 mmol/L, the optimal induction pH being 6.5, and the optimal induction temperature being 20 ℃. Then, the Box-Behnken test was designed by the R language rsm package, and was conducted in a 7 L fermentor to obtain the data. Finally, the optimal fermentation conditions for the expression of lipase MAS1 in the recombinant E. coli BL21(DE3) were calculated by support vector machine (SVM)-genetic algorithm (GA): the optimized IPTG concentration, induction temperature and induction pH were 0.65 mmol/L, 23 ℃ and 6.7, respectively, which led to the theoretical enzyme activity of lipase MAS1 as 2 276.99 U/mL. In the 7-L fermentor, the maximum enzyme activity of lipase MAS1 was 2 316.02 U/mL under the optimized fermentation conditions for culturing recombinant E. coli BL21(DE3). The above research results show that the SVM-GA exhibits good performance during the optimization of fermentation conditions for recombinant E. coli, which provides a research basis for the efficient preparation of lipase MAS1.

国家杰出青年科学基金项目（31725022）