中文摘要：

目的：构建连接乳酸菌胞外蛋白水解酶基因的非抗性重组质粒。方法：以瑞士乳杆菌基因组DNA为模板,克隆胞外蛋白水解酶基因,连接到以thyA为选择压力的非抗性穿梭表达载体pW425et上,构建重组质粒pW425et-R,转化入thyA基因缺陷型E.coliX13感受态细胞,SDS-PAGE电泳检测显示该水解酶得到了表达。结果：成功构建了重组质粒pW425et-R,胞外蛋白水解酶基因在E.coliX13中得到正确表达。结论：成功地表达了乳酸菌胞外蛋白水解酶基因,可为进一步制备具降血压功能基因工程乳酸菌提供参考。

英文摘要：

Objective：To construct a recombinant plasmid carrying extracellular protease gene from Lactobacillus.Methods：The extracellular protease gene was cloned from genomic DNA of L.helveticus and inserted into the expression vector pW425et.Then the recombination plasmid was transformed into the competence thyA gene-mutant E.coli X13.The expressed protein was analyzed by SDS-PAGE.Results：The recombinant shuttle plasmid pW425et-R was constructed successfully and the Lactobacillus extracellular proteinase gene was expressed in E.coli X13.Conclusion：Our research idea is feasible for the successful expression of Lactobacillus extracellular protease gene in E.coli X13,which will provide a basis for further preparation of recombinant Lactobacillus with anti-hypertensive function.