Characterisation of kinetic parameters and metabolic transition of Corynebacterium glutamicum on l-lysine production in continuous culture

Kinetic parameters and physiological states of Corynebacterium glutamicum at the growing and l-lysine-overproducing phase were characterised in continuous culture on threonine-limited complex and minimal media. High l-lysine productivity occurred at dilution rates ranging from 0.1 h^–1 to 0.3 h^–1 on threonine-limited complex medium, and at dilution rates ranging from 0.1 h^–1 to 0.15 h^–1 in minimal medium. l-Lysine yields of 0.25 g/g (0.31 g/g as l-lysine hydrochloride) in complex medium, and of 0.17 g/g (0.21 g/g as l-lysine hydrochloride) in minimal medium, corresponding respectively to intrinsic yields of 0.533 g/g and 0.572 g/g were obtained. These intrinsic yield factors are closed to the theoretical ones (0.608 g/g, 0.75 mol/mol). Intrinsic biomass yields were calculated as 0.658 g/g in complex medium and 0.283 g/g in minimal medium. CO₂ production has been clearly related to l-lysine production. According to our results on specific uptake rates and specific productivities in complex medium, metabolic rearrangement should occur during the transition from the growing phase to the l-lysine-overproducing phase. This phenomenon was further investigated.