Overview of Docosahexaenoic Acid (DHA) Biosynthesis by Aurantiochytrium : Biosynthetic Pathway, High-Yield Mechanism, and Metabolic Engineering Strategies

Docosahexaenoic acid (DHA) is an essential long-chain polyunsaturated fatty acid crucial for cardiovascular health, brain development, cognitive function, immune system modulation, and ocular health. The human body can only synthesize trace amounts of DHA endogenously, necessitating its intake through dietary sources. The biosynthesis of DHA by Aurantiochytrium is favored by the market as an emerging production method for DHA, due to its health benefits and sustainability. The biosynthesis of DHA by Aurantiochytrium was first discovered in the early 1980s, and recent years have witnessed a surge in interest, driven by increasing demand for high-quality DHA, enhanced understanding of lipid synthesis pathways, and rapid development of genetic editing tools. This has propelled the industrial-scale production of DHA using Aurantiochytrium. This paper reviews the historical development of Aurantiochytrium, focusing on DHA production and lipid synthesis pathways within these organisms. Meanwhile, we highlight the potential mechanisms of high DHA production caused by industrial strains obtained through screening or mutagenesis and different environmental factors. Furthermore, we summarize the metabolic engineering of key genes involved in different pathways within Aurantiochytrium. Finally, we discuss unresolved issues and potential future research areas that promise to address limitations in DHA production, thereby facilitating more environmentally friendly and sustainable production methods.