Bio-based production of poly(3-hydroxybutyrate- co -3-hydroxyvalerate) with modulated monomeric fraction in Escherichia coli
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY(2021)
Abstract
In this study, we applied metabolic engineering and bioprocessing strategies to enhance heterologous production of an important biodegradable copolymer, i.e., poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV), with a modulated 3-hydroxyvalerate (3-HV) monomeric fraction from structurally unrelated carbon of glycerol in engineered Escherichia coli under different oxygenic conditions. We used our previously derived propanologenic (i.e., 1-propanol-producing) E. coli strain with an activated genomic Sleeping beauty mutase (Sbm) operon as a host for heterologous expression of the phaCAB operon. The 3-HV monomeric fraction was modulated by regulating dissimilated carbon flux channeling from the tricarboxylic acid (TCA) cycle into the Sbm pathway for biosynthesis of propionyl-CoA, which is a key precursor to ( R )-3-hydroxyvaleryl-CoA (3-HV-CoA) monomer. The carbon flux channeling was regulated either by manipulating a selection of genes involved in the TCA cycle or varying oxygenic condition of the bacterial culture. With these consolidated strategies being implemented, we successfully achieved high-level PHBV biosynthesis with a wide range of 3-HV monomeric fraction from ~ 4 to 50 mol%, potentially enabling the fine-tuning of PHBV mechanical properties at the biosynthesis stage. We envision that similar strategies can be applied to enhance bio-based production of chemicals derived from succinyl-CoA. Key points • TCA cycle engineering was applied to enhance 3-HV monomeric fraction in E. coli. • Effects of oxygenic conditions on 3-HV incorporation into PHBV in E. coli were investigated. • Bacterial cultivation for high-level PHBV production in engineered E. coli was performed.
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Key words
Escherichia coli,Glyoxylate shunt,Poly(3-hydroxybutyrate-co-3-hydroxyvalerate),Propionyl-CoA,Sleeping beauty mutase,TCA cycle
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