Metabolic Pathways and Microbial Engineering for Vanillin Production

Vanillin, due to its unique aroma and widespread applications, has become an important molecule in food, medicine, and other fields. Currently, the main production methods include chemical synthesis, natural extraction, and biosynthesis. Although chemical synthesis is cost-effective, it is associated with environmental pollution and byproducts that affect purity. Natural extraction can maintain high purity and natural flavor, but due to low vanillin content, long cultivation cycles, and limited production sites, it is costly and yields low, making it difficult to meet market demand. In contrast, biosynthesis holds the greatest potential as it aligns with the principles of green chemistry and sustainable development. Common biosynthetic substrates include ferulic acid, glucose, and eugenol, and its metabolic pathways primarily involve the ferulic acid pathway, the tyrosine pathway, and the shikimate pathway. This article reviews the application of relevant microorganisms (such as Pseudomonas, recombinant Escherichia coli, and Bacillus subtilis) in vanillin synthesis and analyzes the advantages and limitations of biosynthesis. Results show that while biosynthesis offers significant advantages in terms of cost, safety, and environmental friendliness, it still faces challenges such as low conversion efficiency, byproduct formation, high substrate handling costs, and the toxicity of vanillin to the host microorganism. Current research is improving yields through metabolic engineering and tolerance modification, laying the foundation for future large-scale industrial production. In summary, biosynthesis of vanillin shows broad prospects for development in terms of economic and environmental benefits.