3-Oxoacyl acyl carrier protein reductase overexpression reveals its unprecedented roles in biofuel production and high-temperature tolerance in diatom

[Display omitted] •One critical Fab enzyme, FabG, is overexpressed successfully in P. tricornutum.•FabG overexpression enhances lipid and fatty acid biosynthesis in P. tricornutum.•High-temperature tolerance is conferred by increasing SFA and antioxidant activity.•Engineered fatty acid profile exhibits high quality in terms of fuel properties. Due to its high lipid accumulation capability, Phaeodactylum tricornutum has attracted considerable attention as a promising candidate for biofuel production. However, the derived lipid cannot satisfy the industrial biofuel manufacturing requirements given its poor fatty acid characteristics. Genetic engineering, as a prospective approach, has been employed to overcome this bottleneck. Relevant research indicates that the fabG gene plays a crucial role in fatty acid biosynthesis in bacteria, but its significance in microalgae remains unclear. In this study, FabG was successfully introduced, transcribed, and overexpressed in P. tricornutum. FabG overexpression significantly enhanced lipid (1.49-fold) and fatty acid (1.31-fold) biosynthesis without altering growth and photosynthesis, and this method thus exhibits great potential in high-quality biodiesel production. Moreover, increased saturation of fatty acids (e.g., C16:0) and improved antioxidative activities enhanced the tolerance of transgenic P. tricornutum to high temperature stress. To conclude, this study reports a feasible approach for high-quality algae-based biofuel production via the unprecedented roles of FabG retrieved from diatom.