FIGURE 2.

Expression of CsCCD enzymes in carotenoid-producing strains of E. coli. E. coli engineered to accumulate the carotenoids β-carotene and zeaxanthin were transformed with an arabinose-inducible recombinant vector for CsCCD1a, CsCCD1b, CsCCD4a-211, and CsCCD4. A, representative HPLC elution profiles of zeaxanthin levels without (control) and with induction of CsCCD1a, CsCCD1b, CsCCD4a-211, and CsCCD4 expression. Inset, on-line spectrum and structure of zeaxanthin. B, chromatogram at absorbance of 345 nm of the zeaxanthin + CsCCD1a combination with the cleavage product peak at 15 min present in the lower chromatogram. The absorption maximum of the obtained product was consistent with that of C₁₄ dialdehyde reported previously (3). Inset, in the upper part the structure of zeaxanthin is shown and the 9,10 and 9′,10′ double bonds are indicated; in the lower part the on-line spectrum and structure of the obtained product after a 9,10(9′,10′) cleavage. C, representative HPLC elution profiles of β-carotene levels without (control) and with induction of CsCCD1a, CsCCD1b, CsCCD4a-211, and CsCCD4 expression. Inset, on-line spectrum and structure of β-carotene. D, GC/MS analysis showing β-ionone emitted by bacteria following induction of CsCCD1a, CsCCD1b, CsCCD4a-211, and CsCCD4 expression. Inset, in the upper part the structure of β-carotene is shown and the 9,10 and 9′,10′ double bonds are indicated, in the lower part the mass spectrum of the observed of β-ionone product. Controls are representative chromatograms from uninduced cultures.