Recent Advances and Future Prospects of Microalgal Lipid Biotechnology

Microalgae are ubiquitous in nature that grow rapidly and thrive in harsh conditions due to their single cellular or simple multicellular structure. Microalgae are characterized as oleaginous, as they accumulate appreciable quantity of lipids ranging between 20 and 70% on dry weight basis depending on the surrounding environmental conditions. Extensive research has been performed on different aspects of microalgal lipids, as they are a source of potential compounds that have wide applications in food, chemical, pharmaceutical, and cosmetology industries. Oil-accumulating algae have the potential to enable the commercial-scale biodiesel production. This chapter discusses the current knowledge in microalgae lipids and their metabolism and various approaches and biotechnological applications for the enhancement of lipid content. Different environmental stress conditions such as nutrients (nitrogen and phosphorus) limitation, temperature, light, salinity, and heavy metals that lead to alteration of the lipid biosynthetic pathways toward the neutral lipids (20–50% DCW) formation and accumulation, have been exploited by researchers to obtain high lipid-accumulating strains for biodiesel production. Supplementation of CO₂ and phytohormones has also been used to improve the microalgae biomass/lipid productivity. Recently, genetic and metabolic engineering tools have been used for a characterization of genes encoding lipid biosynthesis enzymes and further develop highly efficient and potent strains that enable the algae-based biodiesel production feasible. In addition, microalgae have the ability to uptake CO₂ and grow on wastewaters that can be directed toward development of an eco-friendly and economically feasible strategy to produce biomass for biodiesel generation.