Living cell reaction process for L-isoleucine and L-valine production

SUMMARY A new process (Living Cell Reaction Process) for L-isoleucine production using viable, non-growing cells of Brevibacteriumflavum AB-07 was optimised using ethanol as the energy source and c~-ketobutyric acid (e-KB) as precursor. L-valine also could be produced from glucose at high yield by this process. This process differs from the usual fermentation method in that non-growing cells are used, and the production of L-isoleucine and L-valine were carried out under conditions of repressed cell division and growth. Minimal medium missing the essential growth factor, biotin was employed as the reaction mixture for the production of L-isoleucine and L-valine. The productivity of L-isoleucine and L-valine were 200 mmol�9 1-1. day- 1 (molecular yield to e-KB: 95%) and 300 mmol�9 1-~ �9 day-~ (molecular yield to glucose: 80%) respectively. The content of L-isoleucine and L-valine in total amino acids produced in the each mixture were 97% and 96% respectively.