High production of poly(3-hydroxybutyrate) in Escherichia coli using crude glycerol

Poly(3-hydroxybutyrate) (PHB) is a prominent bio-plastic and recognized as the potential replacement of petroleum-derived plastics. To make PHB cost-effective, the production scheme based on crude glycerol was developed using Escherichia coli. The heterogeneous synthesis pathway of PHB was introduced into the E. coli strain capable of efficiently utilizing glycerol. The central metabolism that links to the synthesis of acetyl-CoA and NADPH was further reprogrammed to improve the PHB production. Key genes were targeted for manipu-lation, involving those in glycolysis, the pentose phosphate pathway, and the tricarboxylic cycle. As a result, the engineered strain gained a 22-fold increase in the PHB titer. Finally, the fed-batch fermentation was conducted with the producer strain to give the PHB titer, content, and productivity reaching 36.3 & PLUSMN; 3.0 g/L, 66.5 & PLUSMN; 2.8%, and 1.2 & PLUSMN; 0.1 g/L/h, respectively. The PHB yield on crude glycerol accounts for 0.3 g/g. The result indicates that the technology platform as developed is promising for the production of bio-plastics.

Automated summary

By introducing the synthesis pathway of poly(3-hydroxybutyrate) (PHB) into a strain of Escherichia coli capable of efficiently utilizing glycerol, and reprogramming the central metabolism, the production of PHB was significantly improved. Through fed-batch fermentation, the PHB titer, content, and productivity reached 36.3±3.0 g/L, 66.5±2.8%, and 1.2±0.1 g/L/h, respectively. The technology platform developed shows great promise for the production of bio-plastics.