乳酸乳球菌（Lactococcus lactis）N8是公认食品级微生物,它可产生天然抗菌肽-乳链菌肽（Nisin）。利用合成生物学可精简基因组构建最优基因组底盘，通过与高效启动原件及功能模块适配可实现产物调节通路的协同及稳定遗传，可拓宽其在安全食品和重要医药等领域发挥更重要作用。本项目拟利用合成生物学技术手段，连续删减N8基因组构建底盘菌株；对nisin免疫耐受相关基因irpT和feuD敲除及nisI、nisFEG过表达微调N8免疫耐受能力，提高底盘细胞nisin产量；对N8菌中PKSs基因簇中pksC、pksB、pksA敲除及遗传互补，研究核糖体肽nisin与非核糖体肽PKSs合成之间协调机制。最终获得nisin高产最优基因组底盘菌株，提高nisin产业化水平，满足我国食品业对防腐剂需求。探索利用高产nisin优选底盘对外源功能肽有效环化修饰，为新型稳定性好生物多肽药物开发提供新技术。

Lactococcus lactis N8 is a recognized as food-grade microorganism which can produce natural antimicrobial peptides - nisin. Synthetic biology technology can be used to streamline the genome for constructing the optimal genomic cell chassis. The synergistic effect and the stable inheritance of product regulatory pathway can be achieved through combining the efficient promoter and the functional module adapter. The application of the food-grade L.lactis can be expanded, especially in terms of safe food and pharmaceutical products. This project intends to use synthetic biology techniques to reduce L. lactis genome. With the knockout of immune tolerance related genes irpT and feuD and the over-expression of immunity genes of nisI and nisFEG may improve nisin production in the cell chassis. Deletion of PKSs gene clusters such as pksC, pksB, pksA in L. lactis N8 and the genetic complement of those genes, respectively to reveal the coordinate regulation mechanism between synthesis of ribosomal peptide Nisin and non-ribosomal peptide PKSs. Finally achieving optimized genome chassis strains with high yield of nisin to provide reliable support to improve the level of industrialization of nisin and meet the needs of food preservatives of antimicrobial peptides in China. Using an optimized genome chassis with high nisin productivity could modify heterologous functional peptides in vivo efficiently, which can provide a new technical method to increase the stability and yield of drug based functional peptides.