title: Biosynthesis of poly(glycolate-co-lactate-co-3-hydroxybutyrate) from glucose by metabolically engineered Escherichia coli.
abstract: Metabolically engineered Escherichia coli strains were constructed to effectively produce novel glycolate-containing biopolymers from glucose. First, the glyoxylate bypass pathway and glyoxylate reductase were engineered such as to generate glycolate. Second, glycolate and lactate were activated by the Megasphaera elsdenii propionyl-CoA transferase to synthesize glycolyl-CoA and lactyl-CoA, respectively. Third, β-ketothiolase and acetoacetyl-CoA reductase from Ralstonia eutropha were introduced to synthesize 3-hydroxybutyryl-CoA from acetyl-CoA. At last, the Ser325Thr/Gln481Lys mutant of polyhydroxyalkanoate (PHA) synthase from Pseudomonas sp. 61-3 was over-expressed to polymerize glycolyl-CoA, lactyl-CoA and 3-hydroxybutyryl-CoA to produce poly(glycolate-co-lactate-co-3-hydroxybutyrate). The recombinant E. coli was able to accumulate the novel terpolymer with a titer of 3.90g/l in shake flask cultures. The structure of the resulting polymer was chemically characterized by proton NMR analysis. Assessment of thermal and mechanical properties demonstrated that the produced terpolymer possessed decreased crystallinity and improved toughness, in comparison to poly(3-hydroxybutyrate) homopolymer. This is the first study reporting efficient microbial production of poly(glycolate-co-lactate-co-3-hydroxybutyrate) from glucose.
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Zheng-Jun
authors.initials: ZJ
authors.lastname: Li
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
authors.forename: Kangjian
authors.initials: K
authors.lastname: Qiao
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
authors.forename: Weichao
authors.initials: W
authors.lastname: Shi
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
authors.forename: Brian
authors.initials: B
authors.lastname: Pereira
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
authors.forename: Haoran
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
authors.forename: Bradley D
authors.initials: BD
authors.lastname: Olsen
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States. Electronic address: gregstep@mit.edu.
authors.forename: Gregory
authors.initials: G
authors.lastname: Stephanopoulos
mesh_terms: D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005947:Glucose / Q000235:genetics / Q000378:metabolism; D000070101:Megasphaera elsdenii / Q000201:enzymology / Q000235:genetics; D060847:Metabolic Engineering; D011091:Polyesters / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics
chemical_list: D011091:Polyesters; D005947:Glucose
keywords: 3-Hydroxybutyrate; Biopolymer; Escherichia coli; Glycolate; Lactate; Polyhydroxyalkanoate