Technology Profile: Production of L-Lysine

Lysine (Figure 1) is an α-amino acid used in the biosynthesis of proteins. The compound contains an amino group and a carboxylic acid group. Under biological conditions, the amino group is protonated (–NH3+) and the carboxylic acid group is deprotonated (–COO–). FIGURE 1. L-lysine is an essential amino acid with a chiral center[/caption] The α-carbon of lysine is a chiral center, so two enantiomers of the compound exist. Only L-lysine is biologically active. Lysine is an essential amino acid that must be supplied through the diet. It is commercially produced as L-lysine monohydrochloride (L-lysine·HCl) and L-lysine sulfate. L-lysine·HCl is a yellowish-white, crystalline powder, mainly used as a food and feed supplement. Other uses relate to cosmetics, human medicine, culture media and pharmaceuticals. Lysine is produced from raw sugar (sucrose) using a conventional fermentation process in which raw sugar is hydrolyzed into glucose and fructose (invert sugars). The invert sugars are then fermented to produce L-lysine, which is recovered via ion-exchange adsorption. Process Fermentation-based lysine production from raw sugar is similar to the Archer-Daniels-Midland process, and comprises three major sections: (1) fermentation;…