L-天冬氨酸的提取工艺优化

利用产L-天冬氨酸酶的大肠杆菌HY-05，通过游离细胞法转化合成L-天冬氨酸，以硫酸萃取法从发酵液中提取L-天冬氨酸。为解决工艺中富马酸包结问题，通过单因素试验对脱色条件和结晶过程进行了优化，并在此基础上，选取结晶温度、硫酸滴加速度、冷却时间3个因素为响应变量，以L-天冬氨酸含量为响应值，利用Box-Behnken试验设计响应面试验。结果表明，最佳脱色条件为脱色温度60 ℃，活性炭添加量0.15%；最佳硫酸酸化工艺条件为结晶温度91 ℃，硫酸滴加速度23 mL/h，冷却时间12 min。在此优化条件下，L-天冬氨酸含量为98.22%，较优化前提高了7.42%。

Optimization of extraction technology of L-aspartic acid

L-aspartic acid was synthesized by cell-free transformation of L-aspartase producing Escherichia coli HY-05,and extracted from fermentation broth by sulfuric acid extraction.In order to solve the problem of fumartic acid coating in the extraction process,the decolorization conditions and crystallization process were optimized by single factor tests.On this basis,selecting three factors including crystallization temperature,dropping rate of sulfuric acid and cooling time as response variables,using L-aspartic acid content as the response value,the mathematical model was established by Box-Behnken experimental design for response surface analysis.The results showed that optimal decolorization conditions were decolorization temperature 60℃and active carbon addition 0.15%.The optimal conditions for sulfuric acid acidification were obtained as follows:crystallization temperature 91℃,dropping rate of sulfuric acid 23 ml/h,and cooling time 12 min.Under the optimal conditions,the content of L-aspartic acid was 98.22%,which was 7.42%higher than that before optimization.