Multi‐Enzymatic Cascade Reactions for the Synthesis of cis,cis‐Muconic Acid

Lignin valorization allows the generation of a number of value‐added products such as cis,cis‐muconic acid (ccMA), which is widely used for the synthesis of chemicals for the production of biodegradable plastic materials. In the present work, we reported the first multi‐enzymatic, one‐pot bioconversion process of vanillin into ccMA. In details, we used four sequential reactions catalyzed by xanthine oxidase, O‐demethylase LigM (and the tetrahydrofolate‐regeneration enzyme methyl transferase MetE), decarboxylase AroY (based on the use of E. coli transformed cells) and catechol 1,2‐dioxygenase CatA. The optimized lab‐scale procedure allowed to reach, for the first time, the conversion of 5 mM vanillin into ccMA in ∼30 h with a 90% yield: this achievement represents an improvement in terms of yields and time when compared to the use of a whole‐cell system. This multi‐enzymatic system represents a sustainable alternative for the production of a high value added product from a renewable resource.