Production of D-Aspartic Acid by Biotransformation

HAN Ming-hai et al(Department of Biology,Huaiyin Teachers College,Huaian,Jiangsu 223300)

DL-aspartic acid;D-aspartic acid;L-aspartate-β-decarboxylase;Biotransformation

[Objective] The research aimed to investigate the process of production of D-aspartic acid from DL-aspartic acid with L-aspartate-β-decarboxylase by biotransformation.[Method] The effects of carbon source,organic nitrogen source,pH value during transformation and transition temperature on activity of L-aspartate-β-decarboxylase were studied,the thermal stability of L-aspartate-β-decarboxylase and the effects of L-alanine on its thermal stability were discussed,and the main indices of separation products were determined.[Result] From experiments,it may be concluded that some sugars played a negative role in formation of decarboxylase and some organic acids especially fumaric and malic acid were proper carbon source for formation of that.The concentration of peptone notably effected the concentration of decarboxylase.Through the orthogonal test,the optimum concentration of beef extract,corn steep and peptone was 0.2%,1.0% and 1.0%.From test,under pH value 6-7 and temperature 50 ℃,the biotransformation process might get desired results.When temperature beyond 60 ℃,the inactivation of decarboxylase should be considerable.If the concentration of L-alanine exceeded 6.0%,the activation of decarboxylase would be mostly protected against high temperature.[Conclusion] This process of production of D-aspartic acid from DL-aspartic acid with L-aspartate-β-decarboxylase by biotransformation was simple and convenience,and its material price was suitable.The technics way was more convenient and easier to be industrialized.