In white biotechnology, microorganisms serve as industrial bioreactors for large-scale production of fine chemicals, enzymes, active pharmaceutical ingredients, agro chemicals, and food additives. In particular E. coli is used for the production of aromatic amino acids (e.g., L-tryptophan, L-phenylalanine, L-tyrosine), carotenoids, or shikimic acid as starting material for chiral compounds.
Recent technological advances in biotransformation, fermentation, and metabolic engineering have made such manufacturing techniques much more attractive for chemical and protein production. E. coli strain development requires genetic modifications to gear metabolic processes toward the production of the required chemical compound. Such metabolic engineering can be accomplished through gene deletions, insertions, or differential gene expression.
The potential of homologous recombination for DNA engineering has been recognized for decades. Methods based on the endogenous Rec system have been developed for E. coli, but this approach has many limitations because linear DNA molecules become rapidly degraded and are, therefore, inapplicable as recombination partners. In addition, Rec-mediated recombination requires long (Ž500 bp) homology regions.
Gene Bridges’ Red/ET recombination technology, developed in A. Francis Stewart’s Laboratory at the European Molecular Biology Laboratory in Heidelberg, overcomes many of these drawbacks. Red/ET allows for rapid modifications of DNA molecules and does not depend on restriction sites or the size of the DNA molecule.