过量表达自身hemA基因的重组大肠杆菌发酵生产5-氨基乙酰丙酸的研究

研究了优化重组大肠杆菌产5-氨基乙酰丙酸（ALA）的条件，提高大肠杆菌发酵生产AL气的产量。在测定重组大肠杆菌GT48的生长曲线的基础上，确定诱导时间，优化摇瓶发酵条件。然后，进一步在5L发酵罐上进行间歇和流加发酵研究。摇瓶实验表明，细胞培养最佳初始pH为6．5，最佳诱导时间为稳定期前期，最佳接种量为2％，过高的葡萄糖浓度对细胞生长和产物合成均有一定的抑制作用。在5L发酵罐间歇发酵中，重组菌产ALA能力达到47．8mg／L。采用流加发酵可以进一步将产物产量提高到63．8mg／L。构建的过量表达自身的hemA基因的大肠杆菌具有较高的产ALA能力，通过发酵条件优化和采用流加发酵可以提高AL气产量。

Production of 5-aminolevulinic acid by recombinant E.coli over-expressing the hemA gene of itself

Optimization of the conditions for 5-aminolevulinic acid production by a recombinant E. coli strain GT48 over-expressing the hemA gene of itself to enhance the productivity of ALA were studied in this paper. Based on the growth curve of the strain, the inducing time was determined and fermentation conditions were optimized in flasks. Then the batch and fed-batch fermentation process were investigated in a 5 L fermentor. The experimental data by shaking flask showed that the optimal pH of 6.5, induction time in early stationary phase and inoculation volume of 2% respectively. High initial concentration of glucose exhibits obvious inhibition on cell growth and product biosynthesis. The batch fermentation productivity by the strain in a 5 L fermentor leads to the ALA concentration of 47.8 mg/L. By fed-batch operation, the productivity of ALA was further improved to reach concentration of 63.8 mg/L. Results indicated the recombinant strain over-expressing of hemA gene gave higher yields of ALA. The productivity of ALA could be increased obviously by optimization of fermentation conditions and by fed-batch process.