Metabolic Engineering of Deinococcus radiodurans for the Production of Phytoene

Abstract

A metabolically-engineered <i>Deinococcus radiodurans</i> R1 strain capable of producing phytoene, a colorless C₄₀ carotenoid and a promising antioxidant, has been developed. To make this base strain, first, the <i>crtI</i> gene encoding phytoene desaturase was deleted to block the conversion of phytoene to other carotenoids such as lycopene and γ-carotene. This engineered strain produced 0.413 ± 0.023 mg/l of phytoene from 10 g/l of fructose. Further enhanced production of phytoene up to 4.46 ± 0.19 mg/l was achieved by overexpressing the <i>crtB</i> gene encoding phytoene synthase and the <i>dxs</i> genes encoding 1-deoxy-_D-xylulose-5-phosphate synthase gene, and by deleting the <i>crtD</i> gene. High cell-density culture of our final engineered strain allowed production of 10.3 ± 0.85 mg/l of phytoene with the yield and productivity of 1.04 ± 0.05 mg/g and 0.143 ± 0.012 mg/l/h, respectively, from 10 g/l of fructose. Furthermore, the antioxidant potential of phytoene produced by the final engineered strain was confirmed by in vitro DPPH radical-scavenging assay.