Enhancement of glycerol metabolism in the oleaginous marine diatom Fistulifera solaris JPCC DA0580 to improve triacylglycerol productivity

Background: Microalgal oil is a promising alternative feedstock for biodiesel fuel (BDF). Mixotrophic cultivation with glycerol, the primary byproduct of BDF production, may be used to optimize BDF production. This strategy would reduce costs through glycerol recycling and improve lipid productivity and biomass productivity by overcoming the growth retardation caused by decreased light penetration in high-density culture. Results: Overexpression of the endogenous glycerol kinase (GK) gene in an oleaginous marine diatom, Fistulifera solaris JPCC DA0580, accelerates glycerol metabolism and improves lipid and biomass productivities. Two candidates were selected from a collection of 90 G418-resistant clones, based on growth and confirmation of genome integration. GK gene expression was higher in the selected clones (GK1_7 and GK2_16) than in the wild-type culture. The GK2_16 clone achieved a 12% increase in lipid productivity. Conclusion: We have demonstrated the potential of metabolic engineering in oleaginous microalgae to improve lipid productivity. Metabolic engineering techniques can be used to optimize BDF production.