High-level de novo biosynthesis of glycosylated zeaxanthin and astaxanthin in Escherichia coli

Abstract

Because of wide applications in food, feed, pharmaceutical and cosmetic industries, the carotenoid market is growing rapidly. Most carotenoids are hydrophobic, which limits their bioavailability. Glycosylation is a natural route that substantially increases the water solubility, as well as the bioavailability, photostability and biological activities of carotenoids. Here, we report metabolic engineering efforts (e.g., promoter and RBS engineering, optimization of carbon sources and supplementation of bottleneck genes) to produce glycosylated carotenoids in Escherichia coli. By fine-tuning the carotenoid-biosynthetic genes (crtX, crtZ and crtY), our strain produced up to 47.2 mg/L (~ 11,670 ppm) of zeaxanthin glucosides, ~ 78% of the total carotenoids produced. In another construct with mevalonate, astaxanthin pathway and crtX genes, 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.

Production of natural colorants by metabolically engineered microorganisms

“…Glycosylation of hydrophobic natural colorants can also increase their solubility in an aqueous solution, thereby expanding their applicability in the beverage and pharmaceutical industries [51]. For example, in E. coli, glycosylation of carotenoids by CrtX (a promiscuous GT1 family zeaxanthin glucosyltransferase) resulted in the production of seven different carotenoid glycosides with enhanced water solubility (Figure 3A) [52]. Similarly, glycosylation of violacein by a glycosyltransferase YjiC resulted in the production of 91.8 mg/l violacein 5′-O-glucosides in E. coli, showing improved water solubility [53].…”

Heterologous Expression of the Plant-Derived Astaxanthin Biosynthesis Pathway in Yarrowia lipolytica for Glycosylated Astaxanthin Production

“…On this basis, crtX from P. ananatis ATCC 19321 was further introduced . In the end, glycosylated astaxanthin accumulated in Y.…”

“…On this basis, crtX from P. ananatis ATCC 19321 was further introduced. 21 In the end, glycosylated astaxanthin accumulated in Y. lipolytica. To the best of our knowledge, this is the first report of the heterologous production of glycosylated carotenoids by yeast, and the highest yield of glycosylated astaxanthin produced by microorganisms was acquired.…”

“…Chen et al also built a glycosylated carotenoid synthetic pathway in E. coli. Seven carotenoid glucosides including astaxanthin glucoside were produced in the engineered strain of E. coli with a total yield of 8.1 mg/L, determined by mass spectrometry, but the yield of glycosylated astaxanthin was unknown, and the product obtained in this study was a mixture of carotenoid glycosides containing zeaxanthin-β- d -glucoside, adonixanthin-β- d -glucoside, zeaxanthin-β- d -diglucoside, adonixanthin-β- d -diglucoside, and astaxanthin-β- d -diglucoside, which is because several hydroxyl compounds such as zeaxanthin and adenosine are produced as intermediates in the astaxanthin biosynthesis pathway.…”

β-Cryptoxanthin Production in Escherichia coli by Optimization of the Cytochrome P450 CYP97H1 Activity

“…Moreover, the harvesting and extraction process can damage the metabolites, making the process expensive . Microbial pathways can produce carotenoids fast, regardless of the seasons, at low environmental cost and with optional functionalizations, such as esterifications. , This modularity in the biotechnological approach is valuable for adding new branches to existing bioprocesses, capitalizing on existing designs. As an example, esterifications modify the stability and the assimilation of the carotenes: natural carotenoids mainly exist as the esterified form in plants, which increases their stability, but humans can only digest the free carotenoid form.…”