Biotechnology Progress, Vol.10, No.6, 644-647, 1994
Effect of Modulated Glucose-Uptake on High-Level Recombinant Protein-Production in a Dense Escherichia-Coli Culture
Methyl alpha-glucoside (alpha-MG) is a metabolically inert glucose analog sharing the same phosphotransferase system with glucose. The potential of using this compound, which acts as a nontoxic competitive inhibitor, to modulate glucose uptake and subsequently reduce the acetate accumulation rate was investigated. In a complex medium, no significant effect on the growth rate was observed when the alpha-MG to glucose ratio was low. The effect of alpha-MG supplementation on the production of a model recombinant protein, CadA-beta-galactosidase, under the regulation of a pH-inducible promoter in a batch culture was also examined. It was observed that the amount of acetate accumulation was drastically reduced in the presence of alpha-MG. More importantly, recombinant protein productivity was significantly improved. A very high volumetric productivity of approximately 1.6 g/L recombinant protein in a dense culture with an OD600 of 35 was obtained in a simple batch fermentation. Even at this high cell density, the specific protein productivity was maintained at a high level and was estimated to account for about 40% of the total cellular protein.
Keywords:HIGH-CELL-DENSITY;HUMAN INTERLEUKIN-2;FERMENTER CULTURES;EXPRESSION;EXCRETION;ACETATE;GROWTH;BATCH;K-12;FLUX