Laboratoire de Physiologie Cellulaire Végétale, Université Grenoble Alpes, CNRS, CEA, INRA, 38054 Grenoble Cedex 9, France.
Sequentia Biotech Campus UAB, Edifici Eureka Av. de Can Domènech s/n, 08193 Bellaterra, Cerdanyola del Vallès, Spain.
Prog Lipid Res. 2019 Oct;76:101007. doi: 10.1016/j.plipres.2019.101007. Epub 2019 Sep 6.
Thraustochytrids are unicellular heterotrophic marine protists of the Stramenopile group, often considered as non-photosynthetic microalgae. They have been isolated from a wide range of habitats including deep sea, but are mostly present in waters rich in sediments and organic materials. They are abundant in mangrove forests where they are major colonizers, feeding on decaying leaves and initiating the mangrove food web. Discovered 80 years ago, they have recently attracted considerable attention due to their biotechnological potential. This interest arises from their fast growth, their specific lipid metabolism and the improvement of the genetic tools and transformation techniques. These organisms are particularly rich in ω3-docosahexaenoic acid (DHA), an 'essential' fatty acid poorly encountered in land plants and animals but required for human health. To produce their DHA, thraustochytrids use a sophisticated system different from the classical fatty acid synthase system. They are also a potential source of squalene and carotenoids. Here we review our current knowledge about the life cycle, ecophysiology, and metabolism of these organisms, with a particular focus on lipid dynamics. We describe the different pathways involved in lipid and fatty acid syntheses, emphasizing their specificity, and we report on the recent efforts aimed to engineer their lipid metabolism.
束丝藻是甲藻门的单细胞异养海洋原生生物，通常被认为是非光合微藻。它们广泛存在于各种生境中，包括深海，但主要存在于富含沉积物和有机物质的水域中。它们在红树林中大量存在，是主要的殖民者，以腐烂的树叶为食，并启动红树林食物网。它们于 80 年前被发现，最近由于其生物技术潜力而引起了相当大的关注。这种兴趣源于它们的快速生长、特定的脂质代谢以及遗传工具和转化技术的改进。这些生物特别富含 ω3-二十二碳六烯酸（DHA），这是一种在陆地植物和动物中很少遇到但对人类健康至关重要的“必需”脂肪酸。为了生产 DHA，束丝藻使用一种不同于经典脂肪酸合酶系统的复杂系统。它们也是角鲨烯和类胡萝卜素的潜在来源。在这里，我们综述了这些生物的生命周期、生理生态学和代谢的现有知识，特别关注脂质动态。我们描述了参与脂质和脂肪酸合成的不同途径，强调了它们的特异性，并报告了最近旨在工程化其脂质代谢的努力。
