Laboratory-scale production of 13C-labeled lycopene and phytoene by bioengineered Escherichia coli.

Consumption of tomato products has been associated with decreased risks of chronic diseases such as cardiovascular disease and cancer, and therefore the biological functions of tomato carotenoids like lycopene, phytoene and phytofluene are being investigated. In order to study the absorption, distribution, metabolism and excretion of these carotenoids, a bioengineered Escherichia coli model was evaluated for laboratory-scale production of stable isotope-labeled carotenoids. Carotenoid biosynthetic genes from Enterobacter agglomerans were introduced into the BL21Star(DE3) strain to yield lycopene. Over 96% of accumulated lycopene was in the all-trans form, and the molecules were highly enriched with 13C by 13C-glucose dosing. In addition, error-prone PCR of phytoene desaturase (crtI) was used to create a phytoene-accumulating strain, which maintained the transcription of phytoene synthase (crtB), whereas crtI does not encode a functional phytoene desaturase because of introduced mutations. Phytoene molecules were also highly enriched with 13C when the 13C-glucose was the only carbon source. The development of this production model will provide carotenoid researchers a source of labeled tracer materials to further investigate the metabolism and biological functions of these carotenoids.