营养条件对pcDNA3\|HBS质粒DNA生产的影响

为了考查营养条件对质粒DNA的生产影响，采用不同的培养基培养含pcDNA33－HBS质粒的大肠杆菌JM109。实验结果表明：碳源、氮源质粒DNA产量有明显的影响。葡萄糖是质粒合成过程中较佳的碳源，蛋白胨是较佳的氮源。在MP9P培养基中，选择适合的硫酸铵浓度对质粒DNAR的生产有一定作用。由于Gly,Asp,Glu能提供合成核苷酸的氮源，在M9G培养基中添加1．2g/L的Asp,1.0g/L的Glu和0．4g/L的Gly后，经20h培养，质粒产量可达25mg/L。外源核苷也影响质粒DNA的产量，通过添加0．4g/L胞革与胸苷的混合物（摩尔比为1：1）到M9P培养基中，质粒DNA的产量可达35mg／L。

Effects of Nutrition Condition on pcDNA3-HBS Plasmid DNA Production

To investigate the effects of nutrition condition on plasmid DNA production, Escherichia coli JM109 containing plasmid pcDNA3S-HBA was grown in different culture media. Results show that carbon source, nitrogen source affected plasmid DNA yield significantly. Glucose and peptone was selected, since they were preferable to other investigated carbon source and nitrogen source. In M9P medium, the appropriate concentration of(NH4)2SO4 was important for plasmid DNA production, Gly, Asp, Gln were formulated into the M9G medium because they served as the nitrogen donors for nucleotides synthesis. With addition of 1.2 g/L Asp, 1.0 g/L Gln and 0.4 g/L Gly into M9G medium, plasmid DNA yield was 25 mg/L after 20 h culture. Foreign nucleotides distinctively affected plasmid DNA production. With addition of 0.4 g/L nucleosides mixture of thymidine and cytidine(moles fraction of thymidine:cytidine = 1:1) into M9P medium, plasmid DNA yield was 35 mg/L.