乳链菌肽自身免疫基因nisI的表达对乳链菌肽产量的影响

Enhanced nisin production by overexpression of nisin immunity gene nisI in the nisin-producing strain

摘要:

摘要：【目的】通过基因工程手段增加乳链菌肽（nisin）自身免疫基因nisI在nisin产生菌Lactococcus lactis NZ9800/pHJ201中的表达水平，增强该菌对nisin的抗性，从而达到提高nisin产量的目的。【方法】将带有强组成型启动子P59的免疫基因nisI克隆到nisin表达质粒pHJ201上，将重组质粒引入L. lactis NZ9800中，使nisI基因过量表达，得到重组菌株L. lactis NZ9800/pHMI，并比较该重组菌株与对照菌株L. lactis NZ9800/pHJ201的生长曲线、对nisin的抗性水平、抑菌活性及nisin产量的差异。【结果】nisI 的表达对重组菌的生长速度没有明显的影响，却能促使重组菌株对nisin的抗性水平提高25%、在发酵6h和8h时，nisin的产量分别提高32%和25%。【结论】增加乳链菌肽自身免疫基因nisI的表达可以提高产生菌对nisin的抗性，从而提高乳链菌肽产量。

Abstract:

Abstract:【Objective】Our aim was to enhance nisin production by overexpression of nisin immunity gene nisI in nisin-producing strains.【Methods】Nisin immunity gene nisI with a strong promoter P59 was cloned into vector pHJ201 and introduced into Lacotococcus lactis NZ9800, resulting in a recombinant strain L. lactis NZ9800/pHMI. Then the differences between the recombinant strain and the control strain L. lactis NZ9800/pHJ201 were analyzed in several aspects, including their growth curves, nisin resistance level and antibacterial activity against indicator strain Microccus flavus NCIB 8166.【Results】The overexpression of nisI had no significant difference in growth rate between recombinant strain and contrast strain. However, it promoted recombinant strain tolerance 25% higer nisin resistance level and stronger antibacterial activity against M. flavus NCIB 8166, which was increased by 32% and 25% when fermented for 6 and 8 hours, respectively. 【Conclusion】These results indicated that overexpression of nisI gene in the nisin producing strain can effectively enhance nisin resistence level and thus improve nisin production.