Diatoms have gained popularity due to their practical applications in pharmaceuticals, biotechnology, biofuel production, cosmetic products, and valuable food constituents. Diatoms have high lipid content; they can produce approximately 60% of their cellular mass as triacylglycerol (TAG) under certain growth conditions. Stress conditions, such as nutrient limitation, trigger accumulation of reserved compounds (i.e., lipids and chrysolaminarin) in diatoms. A complete understanding of TAG metabolism is required for biofuel production. They accumulate lipids as lipid droplets in cytoplasm. Lipid droplets have distinct intercellular compartments in which diatoms accumulate neutral lipids. Lipid droplets have proteins on their surface, and these proteins could be important for TAG metabolism, but a comprehensive study of lipid body-associated proteins is still pending. Lipid accumulation in diatoms can be enhanced using phytohormones, other hormone-derived compounds, and molecular engineering. Diatoms are rich in fatty acids, especially polyunsaturated fatty acids (PUFAs), which are beneficial for animal and plant growth. PUFAs extraction from diatoms has more advantages than from fish due to the fast growth of diatoms and feasible application of biotechnology on them to manipulate their genetic material. The present review focuses on the role of lipids, its accumulation, and extraction from diatoms by various methods.
Key words: Diatom, Fatty acids, Lipid Droplets, Transesterification, Triacylglycerols
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