E. Coli Producing 1,3-propylene Glycol Industrial Strains And Regulation

1,3-Propanediol(l,3-PDO) is a three-carbon diol. An emerging large-volume application of 1,3-PD is as a monomer in the synthesis of polyesters for use in carpet and textile fibers and so on.A variety of chemical routes to 1,3-PDO is known . It is currently manufactured by synthetic processes beginning with petroleum derivatives such as acrolein or ethylene oxide. The chemical methods are expensive and generate waste streams containing environmental pollutants. Although 1,3-PDO is presently mainly produced by these chemical ways, there is a worldwide interest in producing this chemical by a biotechnological route. Metabolic engineering, the modification, design and construction of biochemical pathways, is an emerging discipline of potential importance to chemicals.We have known that Saccharamces cerevisiae can produce glycerol by converting glucose through the fructose-1,6-bisphosphate pathway. When osmotic pressure rises, S.cerevisiae can start up the high osmolarity glycerol response pathway(HOG pathway), which synthesizes and accumulates glycerol to maintain the balance of osmotic pressure between the cell membrane. And the Klebsiella pneumoniae can convert glycerol to 1,3-PDO.In Klebsiella pneumoniae, Citrobacter freundii,and Clostridium pasteurianum, the genes encoding the three structural subunits of glycerol dehydratase(dhaB1-3) 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). The specific 1,3-propanediol oxidoreductase (dhaT) of these microorganism are known to belong to the family of type III alcohol dehydrogenases. The gene (yqhD) in E.coli encodes a hypothetical oxidoreductase and contains two alcohol dehydrogenase signatures also found in the Citrobacter freundii and Klebsiella pneumoniae 1,3-propanediol dehydrogenase encoded by the dhaT gene. It's an isozyme of the 1,3-propanediol oxidoreductase (dhaT).In this paper, metabolic pathway from glucose to 1,3-proapanediol was successfully constructed in recombinant Escherichia coli by expression of gpd1 and gpp2 genes from Saccharomyces cerevisiae EBY100 and dhaB and dhaT genes from Klebsiella pneumoniae, respectively. HPLC analysis confirmed that the conversion of glucose to 1,3-propanediol by this recombinant biocatalyst. we analysed the impacts of different type of plasmids in E.coli recombined strains and metablic flows on the titer of glycerol and 1,3-propanediol.