Stability of plasmid is assessed on the basis of two parameters: the level of expression of the produced recombined proteins and the ratio of the antibiotic resistant cells to the number of cells of the entire population (calculated time of generation). The analysis of the stability of plasmid is carried out in the liquid minimal medium with antibiotics (100% ownership of plasmid) as well as without antibiotic (lack of expression of the plasmid) through the next four 17 hour long passages. Dilutions are prepared from each culture – spread into the dishes without an antibiotic (as a result cells which have as well as those which do not have plasmids will be created) and with antibiotics (only those with plasmid will be created) – comparison of the number of acquired colonies – calculation of cfu/ml. The level of recombined protein is assessed by SDS-PAGE. The presentation of result e.g. cfu/ml on the surface with and without antibiotics, calculated generation time, SDS-PAGE gel.
The maintenance of expression of the produced recombined protein in the analyzed strains is confirmed for approx. 80 generations in cultures with antibiotics and in those without and is a necessary requirement for accepting the strain for production.
ATTENTION! The material provided by the customer:
The sample of frozen bacterial strain.
Planned duration: as agreed with the customer.