Effect of glucose supply strategy on acetate accumulation, growth, and recombinant protein production by Escherichia coli BL21 (λDE3) and Escherichia coli JM109

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Abstract
Two Escherichia coli strains, widely used for the production of various recombinant proteins, were compared for their pre‐induction growth and acetate accumulation patterns. The strains studied were E. coli BL21 (λDE3), transformed with a plasmid encoding Pseudomonas exotoxin A, and an E. coli K12 derived strain, JM109, carrying a plasmid encoding maltose‐binding protein fused with HIV protease. Cultures were grown in controlled bench‐top fermentors to the optimal pre‐induction density in both high glucose batch and low glucose fed batch strategies. The results showed the superiority of E. coli BL21 (λDE3) as a host for a recombinant protein expression system. For example, JM109 responds differently to high glucose concentration and to low glucose concentration. Its acetate concentration was as high as 10 g/L in a batch mode and 5 g/L in a fed batch mode. In comparison, strain BL21 (λDE3) reached 2 g/L acetate when grown in batch mode and not more than 1 g/L acetate when grown in a fed batch mode. E. coli BL21 (λDE3), most likely, possesses an acetate self‐control mechanism which makes it possible to grow to the desired pre‐induction density in a high glucose medium using simple batch propagation techniques. Such a technique is cost effective, reproducible, and easy to scale up. © 1996 John Wiley & Sons, Inc.