The Production Of Poly(3-hydroxypropionate) And 1,3-PDO By Biosynthesis From Glycerol

Petroleum based material has brought great convenience to human life,it has also brought many environmental problems. With the declines of oil reserves it is very imporment to find a biodegradable plastic to replace the petroleum based material. As a member of the PHAs family, Poly (3-hydroxypropionate) (P3HP) has become a hot point for degradable plastics owing to its physicochemical characteristics. In this paper, we use genetic engineering to construct a new pathway which can use glycerol as substrate for the synthesis of P3HP in Escherichia coli. The main results include the following sections:(1) The synthesis of P3HP with glycerol as substrate. Glycerol dehydratase is the key enzyme of the glycerol decomposition and P3HP synthesis. We improved the microbial P3HP production from glycerol by using the glycerol dehydratase and its reactivating factor of K. pneumoniae and culture condition optimization. When dhaB123, gdrAB were coexpressed, the final engineered E. coli JM109 (DE3) strain accumulated 1.54 g/L P3HP from glycerol in aerobic fed-batch fermentation.(2) The synthesis of P3HP and 1,3-PDO with glycerol as substrate. There is a reducing power imbalance in the metabolic pathway of glycerol as substrate for the biosynthesis of 3-HP, which limiting P3HP production. In this paper, we constructed a pathway to synthesis 1, 3-PDO, which could balance the reducing power in the bacteria. By homologous recombination technology, the integration of the synthetic genes and activating factor of glycerol dehydratase into Escherichia coli genome, which can effectively reduce the loss rate of plasmid, maintain the plasmid stability. After the optimization of the fermentation conditions, the final construction of the engineering bacteria can achieve 2.7 g/L P3HP and 2.4 g/L 1,3-PDO, compared to the previous reported 1.54 g/L P3HP bottle production, it increased nearly two times, we can also got 1,3-PDO at the same time.