Synthesis of L-lysine hydrochloride

Although lysine can also be extracted from the hydrolysate of protein raw materials (such as pig blood powder), the lysine used is mainly lysine hydrochloride produced by fermentation, and L-lysine is obtained by both extraction and fermentation methods. Among the fermentation methods, there are two steps, namely, two steps through diaminoheptanedioic acid and one step with sugar as raw material, and sugar fermentation is adopted more frequently. Diaminoheptanedioic acid production process: L-lysine is synthesized by Escherichia coli, which is a mutant of Escherichia coli that can not grow without lysine without the function of diaminohydroheptanedioic acid decarboxylase. Glycerin, corn maceration solution, ammonium phosphate, etc. are used as the culture medium. A large amount of diaminohydroheptanedioic acid will be accumulated in the culture medium. At this time, the culture medium should be neutral, This is an important factor in improving efficiency. Then use Aerobacter aerogenes or ordinary Escherichia coli that has decarboxylation function for diaminoheptanedioic acid but not for lysine. After the decarboxylase is dissolved in toluene, this enzyme can react with the aforementioned diaminoheptanedioic acid to almost quantitatively generate L-lysine, which is then separated and refined by ion exchange resin to obtain the finished L-lysine hydrochloride. In the synthesis method, caprolactam is used as the starting material or dihydrofuran is used as the starting material. The racemate obtained by the synthesis method must be optically resolved.