EFFECT OF IMMOBILIZATION ON STABILITY OF RECOMBINANT PLASMIDS IN GENE-ENGINEERED MICROORGANISMS

Stability of a recombinant plasmid pMCT98 was investigated for free and immobilized Escherichia coli C600/pMCT98 cells. KCl, a hardening reagent for immobilizing matrix, inhibited cell growth and decreased the stability of the plasmid for free cells. However, the immobilization within k-carrageenan gel did not affect cell growth and increased significantly the stability of the plasmid, and the amount of the gene product did not decrease through successive passage of the immobilized cells. Coexistence of plasmid pRLK13 lowered the stability of plasmid pMCT98 for both free and immobilized cells. Some oscillations in the ratio of cells harboring the plasmids were observed in the immobilized E. coli C600/pMCT98/pRLK13 system.