Physiological and molecular analysis of carbon source supplementation and pH stress-induced lipid accumulation in the marine diatom Phaeodactylum tricornutum
Physiological and molecular analysis of carbon source supplementation and pH stress-induced lipid accumulation in the marine diatom Phaeodactylum tricornutum
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DOI：
10.1007/s00253-013-4747-7
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发表时间：
2013-04-01
影响因子：
5
通讯作者：
Carlson, Ross P.
中科院分区：
文献类型：
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作者：
Mus, Florence;Toussaint, Jean-Paul;Carlson, Ross P.
通过对三角褐指藻（Phaeodactylum tricornutum）在氮限制、碱性pH胁迫、碳酸氢盐补充和有机酸补充等条件下油脂积累的生理学和分子生物学分析，探讨了三角褐指藻（Phaeodactylum tricornutum）的油脂积累规律。对于所有测试条件，氮限制是脂质积累的先决条件，其他培养策略仅增强积累，突出了复合胁迫对脂质代谢的重要性。体积脂质水平因条件而异;观察到的从最高到最低的排名是无机碳添加（15 mM碳酸氢盐）、有机酸添加（15 mM醋酸盐）和碱性pH应激（pH 9.0）。对于所有的脂质积累的文化，除了醋酸补充剂，一个共同的一系列的生理步骤进行了观察。在细胞外氮耗尽后，培养物的生长持续约1.5个细胞的doughness与特定的蛋白质和光合色素含量的下降。由于氮限制阻止了细胞生长，碳水化合物含量下降，相应的脂质含量增加。添加有机碳源醋酸盐似乎激活了脂质积累的替代代谢途径。超过50个中央代谢成绩单的分子水平的数据进行了测量，使用实时PCR。转录本的分析表明，与碳酸氢盐运输，碳酸酐酶和C4碳固定相关的中心代谢途径对脂质积累很重要。转录组学数据还表明，磷脂的再利用可能在脂质积累中起作用。这项研究提供了一个详细的生理和分子水平的基础，以提高理解硅藻营养循环，并有助于控制硅藻中的脂质积累的代谢蓝图。
A detailed physiological and molecular analysis of lipid accumulation under a suite of conditions including nitrogen limitation, alkaline pH stress, bicarbonate supplementation, and organic acid supplementation was performed on the marine diatom Phaeodactylum tricornutum. For all tested conditions, nitrogen limitation was a prerequisite for lipid accumulation and the other culturing strategies only enhanced accumulation highlighting the importance of compounded stresses on lipid metabolism. Volumetric lipid levels varied depending on condition; the observed rankings from highest to lowest were for inorganic carbon addition (15 mM bicarbonate), organic acid addition (15 carbon mM acetate), and alkaline pH stress (pH 9.0). For all lipid-accumulating cultures except acetate supplementation, a common series of physiological steps were observed. Upon extracellular nitrogen exhaustion, culture growth continued for approximately 1.5 cell doublings with decreases in specific protein and photosynthetic pigment content. As nitrogen limitation arrested cell growth, carbohydrate content decreased with a corresponding increase in lipid content. Addition of the organic carbon source acetate appeared to activate alternative metabolic pathways for lipid accumulation. Molecular level data on more than 50 central metabolism transcripts were measured using real-time PCR. Analysis of transcripts suggested the central metabolism pathways associated with bicarbonate transport, carbonic anhydrases, and C4 carbon fixations were important for lipid accumulation. Transcriptomic data also suggested that repurposing of phospholipids may play a role in lipid accumulation. This study provides a detailed physiological and molecular-level foundation for improved understanding of diatom nutrient cycling and contributes to a metabolic blueprint for controlling lipid accumulation in diatoms.