Renewable Vanillylamine Synthesis from Lignin-Derived Feedstocks

Lignin is considered one of the most abundant renewable resources on earth. In this study, we developed an efficient Escherichia coli-based whole-cell biocatalytic approach for the synthesis of vanillylamine from two lignin-derived substrates (ferulic acid and vanillic acid). For the synthesis of vanillylamine from ferulic acid, we used recombinant E. coli expressing feruloyl-CoA synthetase and enoyl-CoA hydratase/aldolase from Pseudomonas putida, w-transaminase (CvTA) from Chromobacterium violaceum, and L-alanine dehydrogenase (AlaDH) from Bacillus subtilis. At the appropriate NH4Cl concentration, 20 mM ferulic acid afforded 19.22 mM vanillylamine, with a conversion rate reaching 96.1%. For the synthesis of vanillylamine from vanillic acid, we used recombinant E. coli expressing carboxylic acid reductase from Segniliparus rotundus, CvTA from C. violaceum and AlaDH from B. subtilis. Under the optimal condition, 18.9 mM vanillylamine was obtained from 20 mM vanillic acid, with a conversion rate of 94.5%. Taken together, our work represents one of the pioneering studies in the development of E. coli-based whole-cell biocatalysts for the eco-friendly synthesis of vanillylamine from lignin-derived feedstocks.