Effect of the growth rate on the enzymatic activities of L-lysine-producing cells of Corynebacterium glutamicum

The activity of 6-phosphogluconate dehydrogenase, aspartate kinase and phos phoenolpyruvate carboxylase has been studied at different dilution rates in aerobic continuous culture of Corynebacterium glutamicum. 6-Phosphoglucona te dehydrogenase and aspartate kinase reached their maximum values at the l ower dilution rates (0.02-0.06 h(-1)), when L-lysine was produced. The phos phoenolpyruvate carboxylase activity seemed to be independent of metabolite synthesis. The production of L-lysine was also studied in non-growing cell s in batch cultures. In these conditions, statistical analysis revealed sig nificant differences in L-lysine titres when glucose or gluconic acid were used as carbon sources. Higher L-lysine concentration obtained with gluconi c acid was found to be associated with a high 6-phosphogluconate dehydrogen ase activity.