An improved whole-cell biotransformation system for (S)-equol production

Area of Science:

• Biotechnology
• Metabolic Engineering
• Microbial Fermentation

Background:

• (S)-equol, a key metabolite of soybean isoflavones, possesses significant biological activities and clinical benefits.
• Previous research has focused on heterologous biosynthesis of (S)-equol using engineered Escherichia coli (E. coli).
• Further optimization of engineered E. coli is crucial for enhancing (S)-equol production efficiency.

Purpose of the Study:

• To improve an engineered E. coli strain for more efficient (S)-equol production.
• To optimize fermentation conditions for maximizing (S)-equol yield.
• To establish a scalable and high-yield production system for (S)-equol.

Main Methods:

• Constructed a recombinant E. coli BL21(DE3) strain expressing four key biosynthetic enzymes and a glucose dehydrogenase (GDH) for NADPH regeneration.
• Investigated and optimized reaction conditions, including substrate (daidzein) and glucose concentrations.
• Developed a 100 ml one-pot reaction system for (S)-equol biosynthesis.

Main Results:

• Achieved a high equol yield of 98.05% with 1 mM daidzein and 4% glucose.
• Maintained a high yield of 90.25% even with a substrate concentration of 1.5 mM.
• Produced 223.6 mg/L of (S)-equol within 1.5 hours in the optimized one-pot system.

Conclusions:

• The enhanced engineered E. coli strain is highly suitable for (S)-equol production.
• Optimized conditions significantly improve yield and productivity.
• This study presents a robust and efficient microbial platform for (S)-equol biosynthesis.