Engineering Escherichia coli for efficient coproduction of polyhydroxyalkanoates and 5-aminolevulinic acid

Single-cell biorefineries are an interesting strategy for using different components of feedstock to produce multiple high-value biochemicals. In this study, a strategy was applied to refine glucose and fatty acid to produce 5-aminolevulinic acid (ALA) and polyhydroxyalkanoates (PHAs). To express the ALA and PHAs dual-production system efficiently and stably, multiple copies of the poly- β -3-hydroxybutyrate (PHB) synthesis operon were integrated into the chromosome of Escherichia coli DH5αΔ poxB . The above strain harboring the ALA C5 synthesis pathway genes hemA and hemL resulted in coproduction of 38.2% PHB (cell dry weight, CDW) and 3.2 g/L extracellular ALA. To explore coproduction of ALA and poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV), the PHBV synthetic pathway was also integrated into engineered E. coli and coexpressed with hemA and hemL ; cells produced 38.9% PHBV (CDW) with 10.3 mol% 3HV fractions and 3.0 g/L ALA. The coproduction of ALA with PHB and PHBV can improve the utilization of carbon sources and maximize the value derived from the feedstock.