Production of (R)-1,3-butanediol via an Isozyme co-expression Strategy in Escherichia coli

Area of Science:

• Metabolic Engineering
• Synthetic Biology
• Biochemical Engineering

Background:

• Microbial production of chemicals relies on multi-step biosynthetic pathways.
• Pathway efficiency is often limited by enzyme performance and compatibility.
• Optimizing these pathways is crucial for industrial applications.

Purpose of the Study:

• To evaluate an isozyme co-expression strategy for enhancing (R)-1,3-butanediol ((R)-1,3-BDO) production.
• To identify optimal enzyme combinations and medium supplements for increased (R)-1,3-BDO titers.
• To demonstrate the efficacy of isozyme co-expression in improving microbial chemical synthesis.

Main Methods:

• Constructed and evaluated nine Escherichia coli strains with different combinations of thiolase and aldehyde dehydrogenase isozymes.
• Overexpressed specific isozymes (PhaA, AdhE2) in a high-producing strain.
• Screened metabolic effector molecules, including citric acid, as medium supplements.
• Performed glucose-feeding shake-flask fermentation to assess final production.

Main Results:

• The Thl-PhaB-Bld strain (B3-7) initially produced 1.4 g/L of (R)-1,3-BDO.
• Co-expression of PhaA and AdhE2 in strain B3-7 increased (R)-1,3-BDO production to 4.2 g/L.
• Citric acid was identified as an effective medium supplement.
• The optimized isozyme co-expression strain achieved a final production of 16.2 g/L (R)-1,3-BDO.

Conclusions:

• Isozyme co-expression is an effective strategy for enhancing (R)-1,3-butanediol production in microbial cell factories.
• This approach significantly improves the efficiency of multi-step biosynthetic pathways.
• The findings offer a promising method for optimizing microbial synthesis of valuable chemicals.