Rewiring Escherichia coli central carbon metabolism for the sustainable bioconversion of waste glycerol into biodegradable polyhydroxybutyrate

The biomaterial polyhydroxybutyrate (PHB) is a promising, renewable, and green alternative polymer. In this study, a method to incorporate gluconate 6-phosphate dehydratase (edd) deletion in Escherichia coli expressing PHB biosynthesis genes from Cupriavidus necator strain A-04 was proposed. The growth of the edd-deficient strain, which is defective in the glycolytic Entner–Doudoroff pathway, decreased significantly in Luria-Bertani (LB) medium supplemented with glucose. Surprisingly, compared with the wild-type strain, the recombinant edd-deficient strain expressing PHB biosynthesis genes exhibited expeditious PHB accumulation with a high PHB content. The edd-deficient strain reached the highest PHB concentration of 7.6 g/L and a 93 wt% PHB content within 30 h of flask-scale cultivation when commercial glucose was used as the sole carbon source. In addition, the resulting strain was able to utilize crude glycerol waste from the biodiesel industry for PHB accretion with a 74.8 wt% content in 24 h. The PHB yields obtained from glucose and crude glycerol waste were 0.37 and 0.20 g PHB/g substrate, respectively. These findings not only broaden the understanding of the effect of glucose metabolism on PHB production but also provide promising candidates for the production of polyhydroxyalkanoates in the future.