Study on the stability of growth differentiation factor ( BMP11) recombinant plasmid in Escherichia coli

To investigate the hereditary stability of recombinant plasmid ( p ET-BMP11) in host cell ( Escherichiacoli BL21 ( DE3) ) .The recombinant E.coli was subcultured for 100 generation, samples were collected every 20 generations. Bacterial morphology, bacteria growth, plasmid stability, the target protein expressing level were analyzed. The XhoⅠ and NdeⅠ double enzyme validation and determination of target sequence were performed on the origin, 20 th, 60th, 100 thgeneration strain. The results showed that the growth characteristics and the morphology of the cultures did not show differences among the generations, in the absence of kanamycin.The plasmid stability and protein expression of 40 thgeneration strain decreased significantly, and the plasmid retention rate of 100 thgenerations was only 56%. In the presence of kanamycin, the 80 th generation strain still had a high level of protein expression.The restriction enzyme map and target gene sequence of 100 thwere consistent with the original ones, and the rate of plasmid retention was up to 96%. These results showed that the use of recombinant E.coli to produce BMP11 was feasible, the addition of kanamycin in the medium kept the recombinant plasmid stable during passage, this study could provide a theoretical basis for the industrial production of BMP11 and the development of new anti-aging foods.