Metabolic Engineering and Synthetic Biology Approaches to Enhancing Production of Long-Chain Polyunsaturated Fatty Acids in Microalgae

Interest in microalgal biotechnology for the production of bioactive and nutritional ingredients has increased tremendously with the urgent need for developing renewable bioresources. Microalgae represent a huge and still insufficiently tapped resource of LC-PUFA for human nutrition and health-related applications. Photosynthetic omega-3 and omega-6 LC-PUFA-producing microalgae are potent organisms and synthetic biology chassis for the production of high-value constituents for both health and aquaculture sectors. This chapter covers the diversity of eukaryotic microalgae in relation to their LC-PUFA production and outlines the fundamental role of microalgae as primary producers of LC-PUFA. We provide mechanistic insights into the biosynthesis of LC-PUFA in photosynthetic microalgae and highlight their biotechnological applications. The ongoing research aims to understand the molecular mechanisms by which microalgae of different evolutionary groups synthesize, relocate and incorporate LC-PUFA into complex lipids in the context of their multifaceted cellular organization. This research is supported by the availability of genomic information and ‘omics’ studies in a growing number of species. Recent progress in microalgal genetic transformation, genome editing and metabolic engineering has enabled the manipulation of LC-PUFA biosynthesis. We discuss the prospects for LC-PUFA manufacturing by microalgal biotechnology as a renewable and sustainable alternative to the finite resources of LC-PUFA.