Growth kinetics of Eschericia coli containing temperature-sensitive plasmid pOU140

The growth dynamics of Escherichia coli with the temperature-sensitive plasmid, pOU140, were examined. Recombinant cells exhibited nearly identical kinetic behavior to host cells at low culture temperatures and low copy numbers. However, at higher temperatures, in which the copy number was significantly increased, the recombinant cells showed decreased stability along with lower growth rates and substrate yields as compared to the host. Furthermore, the production of a constitutive cloned-gene protein was shown to increase with temperature in an Arrhenius fashion when culture temperature was varied between 38 and 42 degrees C. These results suggest that temperature can be used to quantitatively control the production of a desirable plasmid-coded gene product.