4,4'-Diaponeurosporene Production as C30 Carotenoid with Antioxidant Activity in Recombinant Escherichia coli.

Carotenoids, a group of isoprenoid pigments, are naturally synthesized by various microorganisms and plants, and are industrially used as ingredients in food, cosmetic, and pharmaceutical product formulations. Although several types of carotenoids and diverse microbial carotenoid producers have been reported, studies on lactic acid bacteria (LAB)-derived carotenoids are relatively insufficient. There is a notable lack of research focusing on C30 carotenoids, the functional characterizations of their biosynthetic genes and their mass production by genetically engineered microorganisms. In this study, the biosynthesis of 4,4'-diaponeurosporene in Escherichia coli harboring the core biosynthetic genes, dehydrosqualene synthase (crtM) and dehydrosqualene desaturase (crtN), from Lactiplantibacillus plantarum subsp. plantarum KCCP11226 was constructed to evaluate and enhance 4,4'-diaponeurosporene production and antioxidant activity. The production of 4,4'-diapophytoene, a substrate of 4,4'-diaponeurosporene, was confirmed in E. coli expressing only the crtM gene. In addition, recombinant E. coli carrying both C30 carotenoid biosynthesis genes (crtM and crtN) was confirmed to biosynthesize 4,4'-diaponeurosporene and exhibited a 6.1-fold increase in carotenoid production compared to the wild type and had a significantly higher antioxidant activity compared to synthetic antioxidant, butylated hydroxytoluene. This study presents the discovery of an important novel E. coli platform in consideration of the industrial applicability of carotenoids.