重组大肠杆菌合成苯乳酸的工艺研究

Phenyllactic acid (PLA) is a new broad-spectrum antimicrobial agent. PLA is synthesized from Phenylalanine by recombinant Escherichia coli BL21 (DE3) harboring pRSF-aad-ldh10-fdh. In order to reduce the cost of industrial production, based on Terrific Broth (TB) medium, the types and concentrations of carbon source and nitrogen source were optimized. When the carbon source was 4 g?L-1 glucose and nitrogen source was 24 g?L-1 Angel Yeast extract FM802, it was most beneficial to the growth of cells. The effect of Study on the synthesis of phenyllactic acid by recombinant Escherichia coli rotational speed and aeration on the cell density in the 3L fermenter were investigated. When the agitation speed was 400 rpm/min and the aeration was 1.5 vvm, the cell density was 22.5, with an increase of 18.4%. In addition, the effects of constant-rate feeding, DO-stat and pH-stat feeding strategies on the cell density were further investigated. The results showed that when the glucose was fed at a constant rate of 4 g?L-1?h-1, the final OD600 reached 30.875, showing an increase of 67.4%. After cells were cultivated in the optimized medium for 2 h, the IPTG was added to a final concentration of 0.08 mM. The exogenous enzymes were induced to express for 14 h at 25 °C, and the cells were collected for biotransformation. When the cell concentration is 48 g?L-1 (based on dry cell weight), 20 g?L-1 substrate phenylalanine supplied with both 2.0-fold molar concentration of formate and equimolar glucose could be transformed into 20 g?L-1 phenyllactic acid, with the conversion rate of 100%.