Abstract

Thraustochytrids are eukaryotes and obligate marine protists. They are increasingly considered to be a promising feed additive because of their superior and sustainable application in the production of health-benefiting bioactive compounds, such as fatty acids, carotenoids, and sterols. Moreover, the increasing demand makes it critical to rationally design the targeted products by engineering industrial strains. In this review, bioactive compounds accumulated in thraustochytrids were comprehensively evaluated according to their chemical structure, properties, and physiological function. Metabolic networks and biosynthetic pathways of fatty acids, carotenoids, and sterols were methodically summarized. Further, stress-based strategies used in thraustochytrids were reviewed to explore the potential methodologies for enhancing specific product yields. There are internal relationships between the biosynthesis of fatty acids, carotenoids, and sterols in thraustochytrids since they share some branches of the synthetic routes with some intermediate substrates in common. Although there are classic synthesis pathways presented in the previous research, the metabolic flow of how these compounds are being synthesized in thraustochytrids still remains uncovered. Further, combined with omics technologies to deeply understand the mechanism and effects of different stresses is necessary, which could provide guidance for genetic engineering. While gene-editing technology has allowed targeted gene knock-in and knock-outs in thraustochytrids, efficient gene editing is still required. This critical review will provide comprehensive information to benefit boosting the commercial productivity of specific bioactive substances by thraustochytrids.

摘要

破囊壶菌是真核生物和专性海洋原生生物。它们越来越多地被认为是一种有前途的饲料添加剂，因为它们在生产有益于健康的生物活性化合物（如脂肪酸、类胡萝卜素和甾醇）方面具有卓越且可持续的应用。此外，不断增长的需求使得通过工程工业菌株合理设计目标产品变得至关重要。在这篇综述中，根据破囊壶菌的化学结构、性质和生理功能，对破囊壶菌中积累的生物活性化合物进行了综合评价。系统地总结了脂肪酸、类胡萝卜素和甾醇的代谢网络和生物合成途径。此外，审查了破囊壶菌中使用的基于压力的策略，以探索提高特定产品产量的潜在方法。破囊壶菌中脂肪酸、类胡萝卜素和甾醇的生物合成之间存在内在联系，因为它们共享合成路线的一些分支和一些共同的中间底物。尽管在先前的研究中已经提出了经典的合成途径，但这些化合物如何在破囊壶菌中合成的代谢流仍未被发现。此外，还需要结合组学技术深入了解不同胁迫的作用机制和作用，为基因工程提供指导。虽然基因编辑技术允许在破囊壶菌中进行靶向基因敲入和敲除，但仍然需要有效的基因编辑。