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 such as lycopene, phytoene, and phytofluene are being investigated. 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 was used to disrupt phytoene desaturase (crtI) function and create a phytoene-accumulating strain, which was also found to maintain the transcription of phytoene synthase (crtB). 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.