Reconstruction of the Carotenoid Biosynthetic Pathway of Cronobacter sakazakii BAA894 in Escherichia coli

Cronobacter sakazakii could form yellow-pigmented colonies. However, the chemical structure and the biosynthetic pathway of the yellow pigments have not been identified. In this study, the yellow pigments of C. sakazakii BAA894 were purified and analyzed. The major components of the yellow pigments were confirmed as zeaxanthin-monoglycoside and zeaxanthin-diglycoside. A gene cluster containing seven genes responsible for the yellow pigmentation in C. sakazakii BAA894 was identified. The seven genes of C. sakazakii BAA894 or parts of them were reconstructed in a heterologous host Escherichia coli DH5α. The pigments formed in these E. coli strains were isolated and analyzed by thin layer chromatography, UV-visible spectroscopy, high performance liquid chromatography, and electron spray ionization-mass spectrometry. These redesigned E. coli strains could produce different carotenoids. E. coli strain expressing all the seven genes could produce zeaxanthin-monoglycoside and zeaxanthin-diglycoside; E. coli strains expressing parts of the seven genes could produce lycopene, β-carotene, cryptoxanthin or zeaxanthin. This study identified the gene cluster responsible for the yellow pigmentation in C. sakazakii BAA894.