Improved phloroglucinol production by metabolically engineered Escherichia coli

Area of Science:

• Metabolic Engineering
• Synthetic Biology
• Biotechnology

Background:

• Phloroglucinol is a valuable chemical, but its production in engineered Escherichia coli is limited by low productivity.
• Metabolic engineering offers a promising route for cost-effective phloroglucinol biosynthesis.

Purpose of the Study:

• To enhance phloroglucinol production in Escherichia coli through metabolic engineering.
• To overcome the productivity bottleneck for large-scale and cost-effective phloroglucinol application.

Main Methods:

• Cloned the phlD gene (type III polyketide synthase) into a bacterial expression vector.
• Overexpressed the E. coli marA gene to improve phloroglucinol resistance and production.
• Augmented intracellular malonyl-CoA levels by coordinating acetyl-CoA carboxylase (ACCase) subunit expression.
• Coexpressed ACCase and marA for synergistic effects on phloroglucinol synthesis.

Main Results:

• Overexpression of marA increased phloroglucinol production to 0.27 g/g dry cell weight.
• Augmenting malonyl-CoA levels also resulted in approximately 0.27 g/g dry cell weight production.
• Coexpression of ACCase and marA led to a significant improvement, reaching 0.45 g/g dry cell weight (3.3-fold increase).
• The engineered strain achieved a final concentration of 3.8 g/L with a volumetric productivity of 0.32 g/L/h under fed-batch conditions.

Conclusions:

• Metabolic engineering strategies, including marA overexpression and malonyl-CoA augmentation, effectively enhance phloroglucinol production in E. coli.
• The combined approach of coexpressing ACCase and marA yielded the highest phloroglucinol production reported to date.
• The achieved productivity demonstrates the potential for economically feasible bioprocesses for phloroglucinol production.