[Improving 3-dehydroshikimate production by metabolically engineered Escherichia coli]

Area of Science:

• Metabolic Engineering
• Synthetic Biology
• Biochemical Production

Background:

• 3-dehydroshikimate (DHS) is a crucial intermediate in aromatic amino acid biosynthesis.
• DHS holds significant commercial value as an antioxidant and precursor for industrial chemicals like adipate and vanillin.

Purpose of the Study:

• To investigate the co-expression of aroFFBR and tktA at varying copy numbers for enhanced DHS production.
• To further improve DHS yields by disrupting key byproduct formation genes in Escherichia coli.

Main Methods:

• Co-expression of aroFFBR (feedback-resistant 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase) and tktA (Transketolase A) in E. coli.
• Genetic disruption of ldhA, ackA-pta, and adhE genes to minimize byproduct formation.
• Optimization of gene copy numbers and fermentation conditions.

Main Results:

• Increased copy numbers of aroFFBR and tktA enhanced DHS production by 2.93-fold.
• A triple knockout strain (ldhA, ackA-pta, adhE) significantly boosted DHS production, reaching 1.83 g/L in shake flasks (5.7-fold increase).
• Fed-batch fermentation yielded 25.48 g/L of DHS, demonstrating the engineered strain's high production potential.

Conclusions:

• Metabolic engineering strategies, including gene co-expression and byproduct pathway disruption, are effective for improving DHS production in E. coli.
• The developed engineered E. coli strain shows considerable promise for industrial-scale DHS manufacturing.
• Further optimization holds potential for even greater DHS yields.