At present, there are production processes to produce protein by Escherichia coli (E. coli) fermentation. Research on the design and optimization of the plasmid fermentation medium, however, is less advanced. The fermentation medium that is optimized for plasmid DNA production is different from the medium that is optimized for protein production. So, establishing a scientific and rational method to optimize the fermentation medium used for plasmid production is very important. Previously, our laboratory developed a novel therapeutic DNA vaccine (named pSVK-HBVA) for hepatitis B based on the alphavirus replicon, and found that E. coli XL10-Gold was the optimal host strain for the production of plasmid pSVK-HBVA. The aim of this study was to establish a scientific and rational method to optimize the fermentation medium used for plasmid production, and investigate the effect of growth medium composition on the production of plasmid pSVK-HBVA harboured in E. coli XL10-Gold, as well as to optimize the medium composition. The one-factor-at-a-time experiments demonstrated that Luria-Bertani (LB) was the optimal basic medium. The optimal carbon source and nitrogen source were glycerol and home-made proteose peptone, respectively. Based on the Plackett–Burman (PB) design, proteose peptone, glycerol and NH4Cl were identified as the significant variables, which were further optimized by the steepest ascent (descent) method and central composite design. Growth medium optimization in 500-mL shake flasks by response surface methodology resulted in a maximum volumetric yield of 13.61 mg/L, which was approximately 2.5 times higher than that obtained from the basic medium (LB).

中文翻译：

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通过优化培养基成分增加基于质粒的 DNA 疫苗构建体 (16 kb pSVK-HBVA) 在大肠杆菌XL10-Gold 中的产量

目前，有通过大肠杆菌(E.coli)发酵生产蛋白质的生产工艺。然而，对质粒发酵培养基的设计和优化的研究还不太先进。针对质粒 DNA 生产优化的发酵培养基不同于针对蛋白质生产优化的培养基。因此，建立一种科学合理的方法来优化用于质粒生产的发酵培养基是非常重要的。此前，我们实验室基于甲病毒复制子开发了一种用于乙型肝炎的新型治疗性DNA疫苗（命名为pSVK-HBVA），并发现大肠杆菌XL10-Gold是生产质粒pSVK-HBVA的最佳宿主菌株。本研究的目的是建立一种科学合理的方法来优化用于质粒生产的发酵培养基，并研究生长培养基组成对大肠杆菌XL10-Gold中携带的质粒pSVK-HBVA产生的影响，并优化培养基组成。一次一个因子的实验表明 Luria-Bertani (LB) 是最佳的基础培养基。最佳碳源和氮源分别为甘油和自制蛋白胨。基于 Plackett-Burman (PB) 设计，蛋白胨、甘油和 NH4Cl 被确定为重要变量，并通过最陡上升（下降）方法和中心复合设计进一步优化。通过响应面方法在 500 毫升摇瓶中优化生长培养基导致最大体积产量为 13.61 毫克/升，比从基础培养基 (LB) 获得的产量高约 2.5 倍。