Influence of glucose, fructose and sucrose as carbon sources on kinetics and stoichiometry of lysine production by Corynebacterium glutamicum.

Batch cultivations of l-lysine-producing Corynebacterium glutamicum ATCC 21253 were carried out on the different carbon sources, glucose, sucrose and fructose. The time profiles of substrate and product concentrations were evaluated to compare kinetics and stoichiometry of lysine production. The lysine yield (mol C/mol C) on glucose was 8% higher than on sucrose and 30% higher than on fructose. The highest final biomass concentration of 5.0 g/l was obtained on glucose, whereas fructose and sucrose yielded 20% less biomass. Compared to glucose, fructose resulted in significantly higher respiration rates, a higher substrate uptake rate but a lower lysine production rate during the cultivation process. This was probably due to a higher tricarboxylic cycle activity combined with a lower activity of the pentose phosphate pathway. On sucrose, specific rates and yields differed significantly from those on fructose and glucose. Transport and metabolism of sucrose, therefore, are not a simple superposition of its building blocks, glucose and fructose.