GROWTH RATE-DEPENDENT MODULATION OF CARBON FLUX THROUGH CENTRAL METABOLISM AND THE KINETIC CONSEQUENCES FOR GLUCOSE-LIMITED CHEMOSTAT CULTURES OF CORYNEBACTERIUM-GLUTAMICUM

The physiological behavior of Corynbacterium glutanicum in glucose-lim ited chemostat cultures was examined from both growth kinetics and enz ymatic viewpoints. Metabolic fluxes within the central metabolism were calculated from growth kinetics and analyzed in relation to specific enzyme activities, At high growth rates, incomplete glucose removal wa s observed, and this was attributed to rate-limiting capacity of the p hosphotransferase system transporter and the probable contribution of a low-affinity permease uptake mechanism, The improved biomass yield o bserved at high growth rates was related to a shift in the profile of anaplerotic carboxylation reactions, with pyruvate carboxylase replaci ng malic enzyme, Phosphoenolpyruvate carboxylase, an activity often as sumed to be the major anaplerotic reaction during growth of C. glutami cum on glucose, was present at only low levels and is unlikely to cont ribute significantly to tricarboxylic acid cycle fuelling other than a t low growth rates.