College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China.
College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, No. 5 Xinmofan Road, Nanjing 210009, People's Republic of China.
Biochim Biophys Acta Mol Cell Biol Lipids. 2019 Apr;1864(4):552-566. doi: 10.1016/j.bbalip.2018.10.004. Epub 2018 Oct 8.
Microalgal lipids have drawn great attention as a promising sustainable resource for biodiesel or food supplement production. The development of high-performance strains of microalgae by metabolic engineering is invaluable for increasing the quantity or quality of desired lipids. The synthesis routes of lipids used as biodiesel in microalgae are based on fatty acid synthase (FAS) and triacylglycerols (TAG) biosynthesis pathway. Polyunsaturated fatty acids (PUFAs), including ω-6 and ω-3 fatty acids, are essential nutrients for humans. Notably, microalgae possess two distinct pathways for polyunsaturated fatty acids (PUFAs) biosynthesis, including the desaturase/elongase pathway and the polyketide synthase (PKS) pathway. Thus, it is necessary to identify which biosynthetic pathways are responsible for PUFA synthesis in particular microalgae species. In recent years, various key enzymes and functional domains involved in fatty acid and TAG biosynthesis pathway were identified and potentially regulated by genetic engineering approaches to elevate specific lipids content. In addition, other studies have reported the implementation of strategies to increase lipid accumulation based on increasing acetyl-CoA/NADPH supply, enhancing photosynthetic efficiency, or blocking competing pathways. Furthermore, other efforts have used transcription factor engineering to simultaneously regulate multiple genes related to lipid accumulation. This review summarizes recent research about a variety of microalgae lipid biosynthesis pathways, and discusses multiple gene manipulation strategies that have been employed for specific lipid overproduction in industrial microalgae.
微藻油脂作为生物柴油或食品补充剂生产的有前途的可持续资源引起了极大的关注。通过代谢工程开发高性能微藻菌株对于增加所需油脂的数量或质量是非常宝贵的。微藻中用作生物柴油的油脂的合成途径基于脂肪酸合酶（FAS）和三酰基甘油（TAG）生物合成途径。多不饱和脂肪酸（PUFAs），包括ω-6 和 ω-3 脂肪酸，是人体必需的营养物质。值得注意的是，微藻具有两种不同的多不饱和脂肪酸（PUFA）生物合成途径，包括去饱和酶/延长酶途径和聚酮合酶（PKS）途径。因此，有必要确定哪些生物合成途径负责特定微藻物种中 PUFA 的合成。近年来，已经鉴定出参与脂肪酸和 TAG 生物合成途径的各种关键酶和功能结构域，并通过遗传工程方法对其进行潜在调控，以提高特定脂质的含量。此外，其他研究报告了基于增加乙酰辅酶 A/NADPH 供应、提高光合效率或阻断竞争途径来增加脂质积累的策略。此外，其他研究还利用转录因子工程来同时调节与脂质积累相关的多个基因。本综述总结了近年来关于各种微藻油脂生物合成途径的研究，并讨论了已用于工业微藻中特定脂质过量生产的多种基因操作策略。
