De Novo Biosynthesis of Neoxanthin in Engineered Escherichia coli

Neoxanthin is a valuable carotenoid with antioxidant, chemopreventive, anticancer, and nephroprotective properties, showing potential for pharmaceutical, food, and cosmetic applications. Despite its valuable applications, neoxanthin's industrial production is hindered by environmental concerns and very low extraction yields. In this study, de novo neoxanthin biosynthesis was engineered in E. coli. The key precursor β-carotene biosynthetic pathway was established and systematically optimized through modulation of multiple metabolic routes, including the endogenous MEP pathway and heterologous MVA and IU pathways. The enhanced IU pathway demonstrated significantly higher β-carotene biosynthetic efficiency compared to both the MVA and MEP pathways. Cofactor availability was enhanced by engineering central metabolism through overexpression of ATP/NADPH-generating genes and knockout of ATP/NADPH-consuming genes. Ultimately, a β-carotene-to-neoxanthin conversion pathway was successfully developed in engineered E. coli, achieving an enhanced neoxanthin production of 37.3 mg/L in a 5 L fermenter. This work provides an effective strategy for de novo microbial neoxanthin production.