表达型质粒载体pMG36e在宿主菌中的遗传稳定性研究

目的　研究表达型质粒载体pMG36e在大肠杆菌JM10 9和乳酸乳球菌MG136 3两种宿主菌中的遗传稳定性并观察红霉素对其稳定性的影响。方法　按经典质粒遗传稳定性测定方法 ,在有选择压力 (加红霉素 )和无选择压力的条件下 ,测定pMG36e质粒在大肠杆菌JM10 9和乳酸乳球菌MG136 3中的遗传稳定率。结果　pMG36e质粒在大肠杆菌JM10 9中连续传至 12 0代时 ,在有选择压力的条件下 ,质粒稳定率保持在10 0 % ;无选择压力的条件下为 96 % ;pMG36e质粒在乳酸乳球菌MG136 3中连续传至 10 0代时 ,在有选择压力和无选择压力的条件下 ,质粒稳定率均为 98%。结论　pMG36e质粒在两种宿主菌中均具有较好的遗传稳定性。红霉素对pMG36e质粒的遗传稳定性无显著影响。

Study of the genetic stability of expression plasmid vector pMG36e in host bacteria

Objective To study the genetic stability of expression plasmid vector pMG36e in Escherichia coli JM109 and Lactococcus lactis MG1363/36e and obse rve the effect of erythomycin for its stability. Methods We us ed classical method to determine the genetic stable rates of pMG36e in E.coli JM 109 and Lactococcus lactis MG1363/36e with or without erythomycin selective pressure.Results When E.coli JM109 were continuously incuba ted to 120 generations, its pMG36e genetic st able rates were 100% and 96% respectively with or without erythomycin selective pressure. When Lactococcus lactis MG1363/36e were continuously incubated to 100 generations, its pMG36e genetic stable rates were the same 98%, with or without erythomycin selective pressure. Conclusion pMG36e had good genet ic stability in this two hosts. Erythomycin selective pressure had no significant effect for the genetic stability of pMG36e.