Production of Ultraviolet A protectant C50 carotenoid decaprenoxanthin by metabolically engineered Corynebacterium glutamicum

Carotenoids play roles as active compounds in cosmetics, food, and feed applications, for which C40 carotenoids are most common. In recent years, Corynebacterium glutamicum, a Gram-positive bacterium renowned for largescale amino acid processes, has been engineered to produce various C40 carotenoids such as the high value astaxanthin. In contrast, the native glucosylated C50 carotenoid decaprenoxanthin of C. glutamicum remained rather unexplored. Here, by using genome editing and plasmid-based overexpression of carotenogenic genes, 230 mg L-1 decaprenoxanthin was produced in shake flasks. Transfer to a 2 L fed-batch fermentation yielded 1450 mg L-1, the highest C50 carotenoid titer reported to date. Production on alternative carbon sources, solubility, glucosylation impact and antioxidative activity were investigated. The antioxidative activity of glucosylated decaprenoxanthin was higher than that of unglucosylated decaprenoxanthin. This work lays a foundation for the access to rare C50 carotenoids from C. glutamicum fermentation broth with a perspective towards higher production scales.