Microbial Lignin Valorization to Protocatechuic Acid and Catechol: Biofunneling Pathways and Metabolic Engineering...

Area of Science:

• Biotechnology
• Biochemistry
• Synthetic Biology

Background:

• Lignin, a renewable aromatic biopolymer, is an underutilized resource for sustainable chemical production.
• Protocatechuic acid (PCA) and catechol are key lignin-derived platform molecules with broad applications in pharmaceuticals and polymers.

Purpose of the Study:

• To critically review microbial lignin valorization for producing PCA and catechol.
• To examine advances in lignin depolymerization and microbial conversion pathways.
• To highlight challenges and future directions for lignin bioconversion.

Main Methods:

• Review of thermochemical and biological lignin depolymerization techniques.
• Analysis of microbial biofunneling pathways and key enzymes (e.g., protocatechuate decarboxylase).
• Examination of metabolic engineering strategies (gene deletions, pathway rewiring, CRISPR).

Main Results:

• Lignin depolymerization yields bioavailable aromatic feedstocks for microbial conversion.
• Microbial pathways effectively funnel diverse lignin compounds into PCA and catechol.
• Metabolic engineering enhances product yields, but challenges like substrate heterogeneity and toxicity persist.

Conclusions:

• Integrated lignin depolymerization and bioconversion are crucial for efficient PCA and catechol production.
• Further research in synthetic biology and systems-level optimization is needed for robust microbial cell factories.
• Advancing lignin bioconversion supports sustainable biorefineries and a circular bioeconomy.