Glycerol and neutral lipid production in the oleaginous marine diatom Phaeodactylum tricornutum promoted by overexpression of glycerol-3-phosphate dehydrogenase

Background: Microalgae are ideal raw materials for biodiesel and bioactive compounds. Glycerol-3-phosphate is formed from dihydroxyacetone phosphate (DHAP) through the glycolytic pathway catalyzed by glycerol-3-phosphate dehydrogenase (GPDH). Results: GPDH was characterized in the marine diatom Phaeodactylum tricornutum. In the GPDH-overexpressing P. tricornutum cells, the glycerol concentration per cell in the transformed diatom increased by 6.8-fold compared with the wild type, indicating that the overexpression of GPDH promoted the conversion of DHAP to glycerol-3-phosphate. There was a 60% increase in neutral lipid content, reaching 39.7% of dry cell weight in transgenic cells in the stationary phase, despite a 20% decrease in cell concentration. Fatty acid profiling showed that the levels of 16-and 18-carbon monounsaturated fatty acids significantly increased. Conclusion: GPDH had a significant impact on numerous metabolic processes in diatom cells, including the biosynthesis of glycerol and neutral lipids. These findings are instructive for the metabolic engineering of microalgae for biofuel production.