EFFECT OF MODIFIED GLUCOSE-UPTAKE USING GENETIC-ENGINEERING TECHNIQUES ON HIGH-LEVEL RECOMBINANT PROTEIN-PRODUCTION IN ESCHERICHIA-COLI DENSE CULTURES

Reduction of acetate excretion using a modified cellular glucose uptake rate was examined. An Escherichia coli strain bearing a mutation in ptsG, a gene encoding enzyme II in glucose phosphotransferase system (PTS), was constructed and characterized. The growth rate of the mutant strain was slower than its parent in glucose defined medium, but was not affected in complex medium. Experimental results using this mutant strain showed a significant improvement in culture performance in simple batch cultivations due to reduced acetate excretion th tough the modified glucose uptake. Both biomass and recombinant protein productivity were increased by more than 50% with the ptsG mutant when compared to the parent strain. Recombinant protein productivity by the newly constructed strain at a level of more than 1.6 g/L was attained consistently in a simple batch bioreactor. (C) 1994 John Wiley and Sons, Inc.