Bio-based production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with modulated monomeric fraction in Escherichia coli

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 similar to 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.

Automated summary

The study applied metabolic engineering and bioprocessing strategies to enhance the heterologous production of PHBV with a modulated 3-HV monomeric fraction in engineered E. coli under different oxygenic conditions. By regulating carbon flux channeling and oxygenic conditions, high-level PHBV biosynthesis with a wide range of 3-HV monomeric fraction was achieved, potentially enabling the fine-tuning of PHBV mechanical properties at the biosynthesis stage. Similar strategies could be applied to enhance bio-based production of chemicals derived from succinyl-CoA.