Backgrounds

Omega-3 and omega-6 fatty acids are examples of polyunsaturated fatty acids (PUFAs). The omega-3 α-linolenic acid and omega-6 linoleic acid cannot be generated by humans and, therefore, are considered essential fatty acids. Long-chain PUFAs, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), can be produced from α-linolenic acid in the human body, but at a level too low to meet daily requirements and must be supplemented through the diet. Daily intake of EPA and DHA reduces the risk of heart disease, Alzheimer's, bipolar disorder, schizophrenia, and type 2 diabetes; moreover, DHA is essential for proper visual and neurological postnatal development.

Scope and approach

Fish oil and seafood are the widely used as sources of omega fatty acids, which represents a two-fold problem. First, it depletes fish stocks and impacts negatively on the aquatic environment through excessive aquaculture. Second, the growing popularity of veganism and vegetarianism puts these consumers at risk of omega-3 fatty acid deficiency. Hence, alternative sources of long-chain PUFAs for human consumption should be found. Plants produce only a handful of PUFAs, such as linoleic acid, α-linolenic acid, γ-linolenic acid, and octadecatetraenoic acid.

Key findings and conclusions

Thraustochytrids, non-photosynthetic marine microorganisms often mislabeled as ‘algae’, represent a promising commercial source of omega-3 fatty acids due to their high content of PUFAs. In this review, we describe lipid synthesis in thraustochytrids and distinguish it from that of other microorganisms, including proper microalgae. Furthermore, we detail the advances in omega-3 fatty acids production from thraustochytrids at laboratory and industrial scale.