GENETIC TUNING OF CORYNEFORM BACTERIA FOR THE OVERPRODUCTION OF AMINO-ACIDS

Coryneform bacteria were established as the classical amino acid produ cer after the discovery during the late 1950s that some strains of Cor ynebacterium glutamicum naturally excreted large amount of L-glutamic acid. This lead to an extensive screening and breeding programme to de velop strains for the production of other amino acids. The genetic 'to ol box' for coryneform bacteria has been greatly expanded in recent ye ars and almost all modern molecular biology techniques are now availab le for this organism. In coryneform bacteria, very few of the enzymes involved in amino acid production are controlled and no isoenzymes hav e been detected. Detailed information on the biosynthetic pathways and their regulation, and the availability of the genes involved now perm it directed metabolic design, i.e. improvement of amino acid biosynthe sis and excretion by manipulation of the enzymic and regulatory functi ons of coryneform bacterium with the application of recombinant DNA te chnology. The development of molecular cloning systems in these bacter ia will enable the study of their genetic organization and also provid e a powerful new tool for future strain improvements. (C) 1998 Elsevie r Science Ltd.