摘要： γ-PGA是自然界中微生物发酵产生的水溶性多氨基酸聚合物，是L-谷氨酸和（或）D-谷氨酸通过α- 氨基和γ- 羧基间的酰胺键连接而成，一般是由上千个谷氨酸组合而成的，而γ-PGA的合成制备一直存在着能耗大、成本高的困难。为了解决这一困难，本课题采用从γ-PGA合成前体进行工艺优化的方法，使用实验室废弃的土豆汁代替部分氮源，从而达到降低生产成本的目的。首先从氮源种类、碳源添加量、种子液接种量三个方面进行正交实验设计，经过纳豆芽孢杆菌发酵培养之后对所得发酵液进行菌体浓度测定和γ-PGA产量测定，得出氮源为蛋白胨、碳源添加40g/L、接种量6%时为最佳发酵配方。然后将氮源换为去淀粉土豆废弃物，其余条件与最适发酵配方相同，进行发酵，再对得到的发酵液进行相同的测定分析。在代替氮源实验中，γ-PGA产量为6.76g/L，相比于正交实验中氮源种类、碳源添加量、种子液接种量三个因素所得γ-PGA产量而言，提高率为1.8%~19.6%之间。最终得出结论：采用去淀粉土豆废弃物作为氮源，菌种生长情况和γ-PGA产量都得到优化，这就验证了使用去淀粉土豆废弃物作为γ-PGA合成前体的可行性。61784

毕业论文关键词： γ-聚谷氨酸；去淀粉土豆废弃物；纳豆芽孢杆菌；发酵；透析

The process optimization of the no-starch potato as a  precursor for the synthesis of γ- Polyglutamic acid

Abstract:  γ- Polyglutamic acid is a water-soluble multi amino acid polymer produced by microbial fermentation in nature，is L- glutamic acid and (or) D- glutamate adopt the amide bond which between alpha amino group and gamma carboxyl group，and it is generally composed of a combination of thousands of glutamic acid. But the synthesis and preparation of γ- Polyglutamic acid alaways have been some difficulties，such as large energy consumption，high cost.In order to solve this difficulty，this topic uses the method to optimize the process from γ- Polyglutamic acid synthesis precursors，and uses the no-starch potato instead of the nitrogen source，so as to achieve the purpose of reducing the cost of production.Firstly，the orthogonal experiment design was carried out from three aspects of the nitrogen source，carbon source，and seed inoculation.After the fermentation of Bacillus subtilis natto，we have to determinate the cell concentration and production of γ-Polyglutamic acid by the fermentation broth，and obtaining the best fermentation formula are the peptone as the nitrogen source，carbon source added 40g/L，6% inoculation quantity. Then change the nitrogen source to the no-starch potato.The next fermentation was performed using the same conditions as the optimum fermentation. And the same determination and analysis of the fermentation broth was carried out.In the experiment of no-starch potato，γ-Polyglutamic acid yield was 6.76g/L.Compared with the γ-Polyglutamic acid yield which in the orthogonal experiment，the improvement rate was 1.8%~19.6%.Finally come to the conclusion：Use of no-starch potato as nitrogen source，bacterial growth and production of γ-Polyglutamic acid were optimized.This verifies the feasibility of using the no-starch potato as a precursor for γ-Polyglutamic acid synthesis.

Key words： γ- Polyglutamic acid；No-starch potato；Bacillus subtilis natto ；   Fermentation；Dialysis

   摘要 2

1绪论 6

 1.1 γ-PGA的简介 6

 1.2 γ-PGA的理化性质 6

  1.2.1吸水特性 6

  1.2.2 生物可降解性