利用5-氨基乙酰丙酸脱水酶缺失的重组大肠杆菌合成5-氨基乙酰丙酸

生物法合成5-氨基乙酰丙酸（5-ALA）大多通过添加5-ALA脱水酶（ALAD）的抑制剂乙酰丙酸（LA）减少5-ALA的降解，造成生产成本增高，发酵工艺复杂．本文利用ALAD缺失的大肠杆菌ZSEc2作为出发菌株，通过紫外诱变的方法，获得可利用外源血红素恢复正常生长的大肠杆菌突变株ZGEcl，并过表达来自沼泽红假单胞菌的5-ALA合成酶（ALAS）基因，最终建立一条不需要添加ALAD抑制剂的5-ALA的生物合成新路线．经过培养基初步优化，重组菌可在胞外积累约1g／L的5-ALA．

Production of 5-aminolevulinic Acid with 5-aminolevulinic Acid Dehydratase Deficient Escherichia coli Mutant

5-aminolevulinic acid （5-ALA） is most often biosynthesized by adding 5-ALA dehydratase （ALAD）inhibitor- levulinic acid （LA）to reduce 5-ALA degradation, which leads to the increase of cost and makes the fermentation technology complicated. In this study, we used a 5-ALA dehydratase deficient E. coli mutant ZSEc2 as the starting strain. By applying UV mutagenesis, the mutant ZGEcl was bred and the strain could retrieve normal growth via consumption of extracellular hemin. Then the 5-ALA synthase from Rhodopseudomonas palustris was over-expressed in the mutant ZGEcl and a new biosysthesis process of 5-ALA was developed without adding 5-ALA dehydratase inhibiton. After medium optimization, the resultant recombined strain produced about 1 g/L 5-ALA.