Metabolically engineered plant cell cultures as biofactories for the production of high-value carotenoid pigments astaxanthin and canthaxanthin

Ketocarotenoid pigments, namely astaxanthin and canthaxanthin, are naturally produced by a limited number of species. Demand for these high-value molecules is increasing due to their application in industries such as animal feed, cosmetics, dietary supplements, and pharmaceuticals. We developed a sustainable production platform using metabolically engineered tobacco BY-2 cell suspension cultures by expressing a β-carotene ketolase gene from a marine bacterium and/or overexpress phytoene synthase and desaturase genes. The resulting cell lines exhibited different colors and produced various combinations of ketocarotenoids based on their genetic modifications. Single transformation with the ketolase gene produced salmon-colored cell lines with up to 50 µg g ^-1 DW of canthaxanthin and 127 µg g ^-1 DW of astaxanthin, while expression of all three genes significantly increased canthaxanthin production to 788 µg g ^-1 DW. We demonstrate that undifferentiated cultured plant cells are capable of producing ketocarotenoids, offering an alternative biological solution to natural producers and chemical synthesis.