High Lipid Induction in Microalgae for Biodiesel Production

TLDR

Oil‑accumulating microalgae can supply biodiesel without competing for arable land, but achieving high lipid productivity is challenging because fast‑growing species produce low lipid content while high‑lipid species grow slowly, requiring reprogramming of photosynthetic assimilate allocation toward triacylglyceride storage. The review aims to explore lipid induction techniques, such as environmental stresses, to enhance lipid biosynthesis for commercial biodiesel production. Studies have investigated nutrient, osmotic, radiation, pH, temperature, heavy metal, and chemical stresses, as well as genetic strategies, to efficiently induce lipid production in microalgae.

Abstract

Oil-accumulating microalgae have the potential to enable large-scale biodiesel production without competing for arable land or biodiverse natural landscapes. High lipid productivity of dominant, fast-growing algae is a major prerequisite for commercial production of microalgal oil-derived biodiesel. However, under optimal growth conditions, large amounts of algal biomass are produced, but with relatively low lipid contents, while species with high lipid contents are typically slow growing. Major advances in this area can be made through the induction of lipid biosynthesis, e.g., by environmental stresses. Lipids, in the form of triacylglycerides typically provide a storage function in the cell that enables microalgae to endure adverse environmental conditions. Essentially algal biomass and triacylglycerides compete for photosynthetic assimilate and a reprogramming of physiological pathways is required to stimulate lipid biosynthesis. There has been a wide range of studies carried out to identify and develop efficient lipid induction techniques in microalgae such as nutrients stress (e.g., nitrogen and/or phosphorus starvation), osmotic stress, radiation, pH, temperature, heavy metals and other chemicals. In addition, several genetic strategies for increased triacylglycerides production and inducibility are currently being developed. In this review, we discuss the potential of lipid induction techniques in microalgae and also their application at commercial scale for the production of biodiesel.