Viability and genetic stability of the bacterium Escherichia coli HB101 with the recombinant plasmid during preservation by various methods.

The effects of various methods of preservation (freeze-drying and storage at 4 degrees C; low-temperature freezing on desiccated silica gel and storage at -70 and -150 degrees C; cryopreservation and storage at -196 degrees C) on viability and genetic stability of the bacterium Escherichia coli HB101 carrying the recombinant plasmid with the human DNA fragment were studied. Genetic stability was estimated by maintenance of the selective markers of antibiotic resistance and the stability of the restriction sites in recombinant DNA. Freezing on silica gel and cryopreservation were shown to be the optimal preservation methods providing a high level of survival and genetic stability.