Crucial carotenogenic genes elevate hyperaccumulation of both fucoxanthin and β-carotene in Phaeodactylum tricornutum

Burgeoning demand for carotenoids from natural resources has urged to explore the promising metabolic engineering strategy to improve algal systems. However, existing biological intricacies in algal carotenogenesis warrant identification and exploitation of potential molecular candidate(s) for metabolic engineering to exploit the maximum potential of microalgal cell factories. Here, we identified two critical carotenogenic genes, including 1-deoxy-d-xylulose 5-phosphate synthase and lycopene cyclase and concurrently overexpressed in Phaeodactylum tricornutum. Molecular analysis proved the successful integration and expression of these two genes in engineered algal cells. Dual overexpression concurrently elevated fucoxanthin and β-carotene content up to 6.53 mg/g and 4.34 mg/g dry cell weight, respectively, which is the highest reported content of two carotenoids simultaneously, particularly the highest β-carotene content. Besides, dual overexpression did not impede algal physiological properties and biomass production. The findings exemplified the potential metabolic candidates capable of elevating the complex carotenogenesis and demonstrated a promising strategy to overcome the bottleneck in the commercial production of algal carotenoids.