Production Of D-Aspartic Acid And L-Alanine With Enzyme

This paper describes the production of D-aspartic acid and L-alanine are accomplished by using DL-aspartic acid as the reactant and L-aspartate-β-decarboxylase(ADL)enzyme of resting Pseudomonas dacunhae cells as the biocatalyst to removal of P-carboxy group of L-aspartic acid.Optimizing the method of paper chromatography,which is used for the quantitative determination of Alanine and Aspartic acid contents.The optimal conditions are:a developing solvent N-butanol:acetic acid:water(4:1:l,v/v/v)containing 0.5%(w/v)of ninhydrin was prepared;elution time is 20 min at 30℃ water bath;absorb wavelength is 510 nm.Culture conditions of strains are optimized in order to improve enzyme activity.lt is determined that the optimal conditions as follow:culture temperature is 30℃,culture time is 24h,pH 6.0,the additive amount of sodium glutamate is 3%,inoculum size is 8%,loading quantity of liquid for 50mL/500mL,and rotate speed of table concentrator is 180 r/min.The optimal production conditions of D-aspartic acid and L-alanine are:the concentration of DL-aspartate solution is 0.5 mol/L,inoculum size is 12%(g/ml),the concentration of PLP is 0.15mmol/L at 37℃ with standing reaction.And the yield of D-aspartic acid was about 97.4%,the yield of L-alanine was about 95.3%.This paper describes some studies aimed at increasing the Pseudomonas dacunhae cells transformation,including the effects of acetone and the surfactants(CTAB,SDS,Betaine anhydrous,Tween-80)on enhancing cell permeability to increase transformation.It was concluded that the higher conversion was 93.3%,enhance 11.1%compared with none while the addition of CTAB was 0.1%for 2 d.