Using Metabolic Engineering Techniques To Build The Production Of Glycerol And 1,3 - Propanediol By Recombinant Escherichia Coli

1,3-Propanediol is a monomer having potentiao utility in the production of polyester fibers and the manufacture of polyrethanes and the manufacture of polyurethanes and cyclic compounds.A variety of chemical routes to 1, 3-propanediol are known. For exAple ethylene oxide may be converted to 1, 3-propanediol over a catalyst in the presence of phosphine, water, carbon monoxide, hydrogen and an acid, by the catalytic solution phase hydration of acrolein followed by reduction, or from compounds such as glycerol, reacted in the presence of carborn monoxide and hydrogen over catalysts having atoms from group VIII of the periodic table. Although it is possible to generate 1, 3-propanediol by these methods, they are expensive and generate waste streams containing environmental pollutants. So, a single microorganism conversion of fermentable carbon source to 1,3-propanediol is desirable. Metabolic engineering, the modification, design and construction of biochemical pathways, is an emerging discipline of potential importance to chemicals.We have known that yeast can produce glycerol by converting glucose through the fructose-1, 6-bisphosphate pathway and Klebsiella pneumoniae converts glycerol to 1, 3-PD. Therefore we try to setup the metabolic pathway in Escherichia coli for the direct production of this industrial important chemical, 1, 3-propanediol.In Klebsiella pneumoniae, Citrobacter freundii, and Clostridium pasteurianum, the genes encoding the three structural subunits of glycerol dehydratase(dhaBl-3) and located adjacent to a gene encoding a specific 1, 3-propanediol oxidoreductase(dhaT). Although the genetic organization differs somewhat among these microorganismd, these genes are clustered in a group which also comprises dhaB4 and orf2b(genes encoding a dehydratase reactivation factors for glycerol dehydratase), as well as orf2a and orf2c(genes of unknown function).The specific 1,3-propanediol oxidoreductase (dhaT) of these microorganism are known to belong to the family of type III alcohol dehydrogenases;each exhibits a conserved iron-bingding motif and has a preference for the NAD+/NADH linked interconversion of 1, 3-propandiol and 3-HPA. In this paper, we analysed the impacts of different E. coli strains and metablic flows on the titer of glycerol and 1,3-propanediol.