Study on the genetic stability of expressing His-β~(APC) strain

Genetic stability is essential in the production practice of interest product.Therefore,in order to determine the genetic stability of the genetic strain,plasmid stability was identified through methods of determination of cell growth,plate streaking,enzyme cutting of plasmid DNA,product identification.The experiment shows the following results： the plasmid loss rate of strain His-β was 6% for 5 generation,8% for 10 generation,9% for 15 generation,15% for 20 generation during the subculture on the solid plate with no antibiotics;the size and shape of colony was essentially the same after the strain was transferred of culture on the solid plate for 20 generations;recombinant plasmids did not change before and after subculture through the identification of BamHⅠand HindⅢenzyme cutting;His-β protein in primary and 5,10,15 and 20 generations can be expressed and showed no significant difference after induction.The results showed that the plasmid had structural stability and segregational instability.