首先根据nisA 与nisI 基因序列设计引物，以乳酸乳球菌的基因组为模板通过PCR 技术手段获取nisA 基因与nisI 基因。然后将nisA 基因与酶切后的载体pMG36e 进行连接，获得了含有nisA 基因的环状质粒pMG36e-nisA。pMG36e-nisA-nisI 采用相同的方法在pMG36enisA的基础上构建完成，最后再将构建好的质粒导入到乳酸乳球菌中，得到一株阳性转化子AI。发酵产nisin 实验结果表明，AI 的nisin 产量比出发菌株提高了20.07%，因此，AI 是一株稳定高产nisin 的基因工程菌。

The nisA and nisI gene were amplified through PCR technique using genomic DNA from Lactococcus lactis as template. The nisA gene was ligated to pMG36e vector and the circular plasmid pMG36e-nisA containing nisA gene was constructed. The nisI gene was later ligated to pMG36e-nisA plasmid to obtain the recombinant plasmid of pMG36e-nisA-nisI. The recombinant plasmid pMG36e -nisA -nisI was then transformed to L. lactis and a positive colony AI was successfully obtained. The result of nisin fermentation by the genetically engineered strain AI indicated that its yield increased by 20.07% compared with the original strain. AI was confirmed as a stable, high-yield nisin producing strain.