Abstract
Aromatic polyesters are widely used plastics currently produced from petroleum. Here we engineer Escherichia coli strains for the production of aromatic polyesters from glucose by one-step fermentation. When the Clostridium difficile isocaprenoyl-CoA:2-hydroxyisocaproate CoA-transferase (HadA) and evolved polyhydroxyalkanoate (PHA) synthase genes are overexpressed in a d-phenyllactate-producing strain, poly(52.3 mol% 3-hydroxybutyrate (3HB)-co-47.7 mol% d-phenyllactate) can be produced from glucose and sodium 3HB. Also, various poly(3HB-co-d-phenyllactate) polymers having 11.0, 15.8, 20.0, 70.8, and 84.5 mol% of d-phenyllactate are produced from glucose as a sole carbon source by additional expression of Ralstonia eutropha β-ketothiolase (phaA) and reductase (phaB) genes. Fed-batch culture of this engineered strain produces 13.9 g l−1 of poly(61.9 mol% 3HB-co-38.1 mol% d-phenyllactate). Furthermore, different aromatic polyesters containing d-mandelate and d-3-hydroxy-3-phenylpropionate are produced from glucose when feeding the corresponding monomers. The engineered bacterial system will be useful for one-step fermentative production of aromatic polyesters from renewable resources.
Highlights
Aromatic polyesters are widely used plastics currently produced from petroleum
As cinnamoyl-CoA is a non-natural metabolite in E. coli, the possibility of using acetyl-CoA, which is abundant metabolite in the cell, as a CoA-donor was examined for the synthesis of phenyllactyl-CoA by Clostridium botulinum A str
These results suggest that 4-coumarate:CoA ligase (4CL) and FldA can potentially be used for phenyllactyl-CoA generation and aromatic polyester production
Summary
Aromatic polyesters are widely used plastics currently produced from petroleum. Here we engineer Escherichia coli strains for the production of aromatic polyesters from glucose by one-step fermentation. MBEL 6–19 PHA synthase (pPohlyaeCstPes6r–s19)conptaoilnyimngerizceosrrestphoesneding2-hmydornooxmyaecrysl9-–C1o1.AsIt into has previously been reported that some bacteria such as Pseudomonas oleovorans and Pseudomonas putida strains can synthesize aromatic polyesters when grown in the culture medium containing n-phenylalkanoic acid as a direct precursor of aromatic monomer[14,15,16] These aromatic polyesters have only been produced by feeding the cells with corresponding aromatic monomers as substrates and have not been produced by direct fermentation from renewable feedstock carbohydrates such as glucose. Those mentioned above contain aromatic groups far away from the main polymer carbon chain[14,15,16] and polymer properties were found to be much different from petroleum-derived aromatic polymers, which often contain aromatic rings close to the main polymer chain, such as poly(ethylene terephthalate) (PET) and polystyrene. Such observations led us to develop metabolically engineered E. coli strains for one-step fermentative production of aromatic polyesters from glucose
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