L-lysine production by exponential feeding of L-threonine

The effect of L-threonine feeding in the production phase on L-lysine produ ction by Brevibacterium flavum, which requires L-homoserine or L-threonine for cell growth, was investigated considering the concerted inhibition by L -threonine plus L-lysine, and the metabolism related to lysine production. Exponential feeding of L-threonine increased L-lysine production to 70 g/l about three times that without feeding. From the analysis of the metabolic flux, carbon flux of L-lysine synthesis pathway in the production phase aft er L-threonine feeding was higher than that in the growth phase. The result s show that feeding of an inhibitory substance may increase the production, especially when the substance is necessary for the continuation of cell gr owth and/or production.