Metabolic engineering of endogenous MEP pathway for enhanced lycopene production in Escherichia coli

TL;DR

Scientists improved lycopene production in E. coli by engineering its metabolic pathway using genes from a different bacteria and optimizing fermentation conditions.

Contribution

The study introduces a novel chassis strain and demonstrates a 33.88-fold increase in lycopene titer through MEP pathway optimization.

Findings

Sodium pyruvate significantly enhanced lycopene production and cell growth in E. coli.

Co-expression of dxs from E. coli and idi from D. wulumuqiensis maximized lycopene titer.

The optimized strain achieved a lycopene titer of 293.70 mg/L, a significant improvement over the initial strain.

Abstract

Microbial cell factories represent the primary approach for heterologous lycopene synthesis, where gene source selection and pathway regulation have been demonstrated to have a significant impact on lycopene titer. In this study, key lycopene biosynthesis genes (crtE, crtB and crtI) derived from the extremophile Deinococcus wulumuqiensis R12 were introduced into Escherichia coli, generating the chassis strain H0. Fermentation optimization revealed sodium pyruvate significantly enhanced lycopene production and cell growth. Quantitative polymerase chain reaction (qPCR) analysis revealed that sodium pyruvate upregulated the expression of dxr, ispA, crtE, crtB and crtI genes, while downregulating the expression of dxs and idi genes. Consequently, different sources of dxs, dxr, idi and ispA genes were screened and co-expressed to reinforce the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway in E. coli. The optimized combination of dxs from E. coli MG1655 with idi from D. wulumuqiensis R12 achieved maximal lycopene titer of 293.70 mg/L (112.49 mg/g DCW), which was 33.88-fold higher than that of the initial strain H0. This study offers genetic resources for heterologous carotenoid synthesis and establishes a reference framework for the synthesis of analogous complex isoprenoid metabolites.

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