Production of caloxanthin 3'-β-D-glucoside, zeaxanthin 3,3'-β-D-diglucoside, and nostoxanthin in a recombinant Escherichia coli expressing system harboring seven carotenoid biosynthesis genes, including crtX and crtG.

The aim of this study was to produce rare β-carotene-modified carotenoids possessing 2-O (-H or -glu) and/or 3-O (-H or -glu) functionalities in their β-ionone ring(s) using a recombinant Escherichia coli approach. This involved expressing seven carotenoid biosynthesis genes (crtE, crtB, crtI, crtY, crtZ, crtX and crtG). From the cells of the recombinant E. coli, caloxanthin (β,β-carotene-2,3,2',3'-tetrol)-3'-β-D-glucose, zeaxanthin (β,β-carotene-3,3'-diol) 3,3'-β-D-diglucoside, and nostoxanthin (β,β-carotene-2,3,3'-triol) (rare carotenoids) were isolated and identified. Caloxanthin 3'-β-D-glucose displayed potent (1)O(2) quenching activity (IC(50) 19 μM).