文献类型：期刊文献

英文题名：C/N ratio-directed two-stage mixotrophic cultivation of Isochrysis galbana for enhanced production of fucoxanthin and DHA

作者：Yuan, Yuchen[1];Yang, Zhi[1];Cao, Jiajun[1];Sun, Liyun[1,2];Ji, Liang[1,2];Fan, Jianhua[1,2,3]

机构：[1]East China Univ Sci & Technol, State Key Lab Bioreactor Engn, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Dept Appl Biol, Shanghai 200237, Peoples R China;[3]Shihezi Univ, Sch Chem & Chem Engn, State Key Lab Incubat Base Green Proc Chem Engn, Shihezi 832003, Peoples R China

年份：2026

卷号：462

外文期刊名：BIORESOURCE TECHNOLOGY

收录：;EI(收录号：20263121240086);Scopus(收录号：2-s2.0-105046305219);WOS:【SCI-EXPANDED(收录号:WOS:001842336800001)】；

基金：This work was sponsored by National Key Research and Development Project of China 2025YFA0921100, Natural Science Foundation of Shanghai 24ZR1490800, Xinjiang Tianchi Talent Project BT-2025-TCYC-0060, the Open Project of the State Key Laboratory of Forage Breeding-by-Design and Utilization (SKB_2025KFB1005) , and the Fundamental Research Funds for the Central Universities and Shanghai Collaborative Innovation Center for Biomanufacturing Technology.

语种：英文

外文关键词：Isochrysis galbana; Fucoxanthin; DHA; C/N ratio; Two-stage cultivation

摘要：The haptophyte microalga Isochrysis galbana is a natural producer of the high-value nutraceuticals fucoxanthin and docosahexaenoic acid (DHA), but strategies to efficiently and directionally accumulate these compounds remain underexplored. In this study, the effects of carbon-to-nitrogen (C/N) ratio modulation on growth, carbon partitioning, and targeted production under mixotrophic conditions were investigated. With glycerol identified as the optimal carbon source for mixotrophic growth, low C/N enhanced fucoxanthin accumulation whereas high C/N stimulated DHA synthesis. Based on these findings, a two-stage strategy was developed: biomass first accumulated at C/N = 6.5, then shifted to C/N = 0.8 for fucoxanthin accumulation or C/N = 52 for DHA accumulation. This strategy significantly improved yields, achieving fucoxanthin content of 25.12 mg/g DCW (43.79% higher than one-stage C/N = 6.5 cultivation system) with a concentration of 67.83 mg/L (110.78% higher), and an overall productivity of 3.99 mg/L/d, as well as DHA content of 22.36 mg/g DCW (34.81% higher) with a concentration of 75.10 mg/L (145.84% higher), and an overall productivity of 4.42 mg/L/d. Transcriptome analysis revealed that low C/N upregulated ZEP (zeaxanthin epoxidase) for fucoxanthin overproduction, whereas high C/N sustained ELO5 (delta-5 elongase) for DHA synthesis, providing molecular evidence for the directional metabolic shifts. These results establish a simple, scalable two-stage process for the selective production of two high-value nutraceuticals in a single haptophyte platform, and identify candidate genes for future metabolic engineering in microalgal biorefineries.