Carotenoids have wide applications in food, feed, pharmaceutical and cosmetic industries. The fast-growing market demands highlight the importance of developing new routes for carotenoid biosynthesis. Meanwhile, a complementary need is to improve low bioavailability because of the hydrophobicity of carotenoids. One solution is glycosylation, which can substantially increase the water solubility of carotenoids, and enhance the bioavailability, photostability and biological activities as food supplements and medicines. Here, we report metabolic engineering efforts to produce glycosylated carotenoids in Escherichia coli . By fine tuning the 14 gene pathway, our strain produced up to 47.2 mg/L (~11670 ppm) of zeaxanthin glucosides, ~78% of the total carotenoids produced. In another construct with 15-gene pathway, the strain produced a mixture of carotenoid glucosides including astaxanthin and adonixanthin glucosides with a total yield of 8.1 mg/L (1774 ppm). Our work demonstrated a proof-of-concept study for the microbial biosynthesis of glycosylated carotenoids. (145 words)
