Marine microorganisms: natural factories for polyunsaturated fatty acid production

Dietary consumption of omega-3 long-chain polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3), is associated with various health benefits. Numerous marine microorganisms, such as bacteria, yeast, microalgae, protists, fungi, and dinoflagellates, produce long-chain PUFAs. These PUFAs are biosynthesized via two pathways: the conventional aerobic fatty acid synthase (FAS) pathway in microalgae and the anaerobic PUFA synthase pathway, primarily in marine bacteria and eukaryotic microalgae. Understanding the mechanisms of long-chain PUFAs (LC-PUFAs) biosynthesis is crucial for developing effective strategies to engineer biosynthesis in both heterologous microbial species and native PUFAs producers. This review highlights recent findings on the biosynthetic mechanisms underlying long-chain PUFAs production, with an emphasis on marine bacteria and microalgae. Additionally, developments in metabolic engineering to enhance long-chain PUFAs production in marine microorganisms are discussed.