Constructing an efficient salicylate biosynthesis platform by Escherichia coli chromosome integration

Area of Science:

• Biotechnology
• Metabolic Engineering
• Synthetic Biology

Background:

• Salicylate (SA) is a valuable platform chemical with applications in the cosmetic and pharmaceutical industries.
• Developing efficient microbial production methods for SA is crucial for sustainable chemical manufacturing.

Purpose of the Study:

• To construct an efficient salicylate (SA) producing E. coli strain using chromosome integration.
• To optimize SA production by metabolic engineering strategies.
• To establish a platform strain for the biosynthesis of SA derivatives.

Main Methods:

• Step-by-step chromosome integration of the SA biosynthetic module into E. coli.
• Metabolic engineering strategies including promoter selection (P_T7 vs. P_tac), gene knockouts (pheA/tyrA, pykA/pykF), and pathway strengthening (aroG overexpression).
• Fermentation using mixed carbon sources (glucose and glycerol) and sole glycerol.

Main Results:

• The P_T7 promoter yielded higher SA titers than P_tac, reaching 233.6 mg/L.
• Disruption of pheA/tyrA and enhancement of aroG expression increased SA titers to 679.9 mg/L.
• Disruption of pykA/pykF and utilization of mixed carbon sources resulted in 769.8 mg/L SA, while sole glycerol achieved 1560.6 mg/L.
• The engineered strain successfully produced muconic acid and salicyl alcohol.

Conclusions:

• An efficient SA-producing E. coli strain was successfully constructed via chromosome integration.
• Metabolic engineering significantly enhanced SA production titers.
• The developed platform strain provides a robust system for the production of SA and its derivatives.