Immobilization of genetically engineered cells: a new strategy for higher stability.

The r-DNA clones improve the bioprocess and provide better economics, if and when properly developed. In recent times, many approaches were made to improve the stability of recombinants in a reactor which includes both genetic and environmental methods, but many of them were proved to be unsuccessful in the scale-up process. The immobilization technique, exploited recently for the cultivation of recombinants, in many cases gave high cell concentrations, better expression of cloned gene products and also maintained plasmid stability for longer periods in a host under continuous operation in comparison to a free cell system. Many plasmids and hosts were tested for improved stabilities. So far, no explanation was provided for higher stability in the immobilized system. However, it was observed to reduce the competition between the plasmid harboring and plasmid free cells in a matrix. The stability of recombinant strains under immobilization technique is affected by various factors, and these are important parameters for the commercial process. Thus, the immobilization system is promising for the successful cultivation and scale-up of genetically engineered cells.