Yeast-Based Whole-Cell Factory for the Ecofriendly Synthesis of Vanillylamine as a Critical Step toward Capsaicin Production

Capsaicin is a biologically active alkaloid with important pharmaceutical, food, and cosmetic applications. As capsaicin production is dependent on its extraction from plants, its industrial separation and purification capacity is greatly limited. The chemical synthesis of capsaicin via the Schotten–Baumann reaction requires vanillylamine and 8-methyl-6-nonenoic acid as reaction substrates. Currently, petrochemical products obtained by the catalysis of precious metals are used to produce vanillylamine; however, this approach does not meet the requirements advocated by the green chemical industry. Herein, we developed an efficient yeast-based whole-cell factory for the de novo biosynthesis of vanillylamine and capsaicin. A heterologous recombinant vanillylamine biosynthetic pathway in yeast yielded 6.47 g/L vanillylamine. Enhancing the phenylalanine pool by upregulating the shikimic acid pathway led to an 11% increase in vanillylamine production. Optimization of methyl transfer efficiency via a reconstituted S -adenosylmethionine (SAM) circulating cycle resulted in an 84% increase in vanillylamine production. Switching the yeast strain from Z2 to Z6 and rewiring the precursor pool and SAM circulating cycle increased vanillylamine production to 14.89 g/L (125%)─the highest reported level in the current literature. Based on the biosynthesis of vanillylamine via the heterologous recombinant fatty acid pathway, capsaicin was synthesized de novo in yeast. We also revealed that protocatechuic acid can be produced from 3-dehydroshikimic acid by phenylalanine ammonium lyase or tyrosine ammonia lyase. In summary, this study provides a feasible strategy for developing yeast-based whole-cell factories for the eco-friendly synthesis of vanillylamine, which is a critical step toward capsaicin production in yeast.