One-Pot Bioconversion of Lignin-Derived Substrates into Gallic Acid

Area of Science:

• Biotechnology
• Synthetic Biology
• Microbial Engineering

Background:

• Lignin is a globally abundant, renewable source of aromatic compounds.
• Existing methods for gallic acid production can be environmentally taxing.
• Developing sustainable routes from biomass is crucial for green chemistry.

Purpose of the Study:

• To engineer Escherichia coli (E. coli) whole-cell biocatalysts for gallic acid synthesis.
• To utilize ferulic acid and p-coumaric acid, derived from lignin, as substrates.
• To establish an efficient and eco-friendly bioprocess for gallic acid production.

Main Methods:

• Constructed recombinant E. coli strains expressing specific enzymes from Pseudomonas putida and Saccharomyces cerevisiae.
• Optimized a two-step pathway for ferulic acid conversion involving feruloyl-CoA synthetase, enoyl-CoA hydratase/aldolase, HFD1, VanAB, and PobA(Y385F).
• Modified the pathway for p-coumaric acid conversion by replacing VanAB with HpaBC from E. coli.

Main Results:

• Achieved 19.57 mM gallic acid from 20 mM ferulic acid with 97.9% conversion using fed-batch fermentation.
• Produced 19.96 mM gallic acid from 20 mM p-coumaric acid with near 100% conversion under optimal conditions.
• Demonstrated the first E. coli-based whole-cell biocatalysis for gallic acid production from lignin-derived substrates.

Conclusions:

• Engineered E. coli whole-cell systems provide a highly efficient and sustainable method for gallic acid synthesis.
• This approach leverages renewable lignin-derived feedstocks, reducing reliance on petrochemicals.
• The developed biocatalysts offer a promising green alternative for industrial gallic acid production.