Scenedesmus quadricauda CASA CC202, a potent freshwater microalga is being used as a biofuel feedstock, which accumulates 2.27 fold lipid during nitrogen stress induction. Upon nitrogen starvation, S. quadricauda undergoes biochemical and metabolic changes that perturb the cell to cope up the stress condition. The nitrogen stress-induced biochemical changes in mitochondrion exhibits due to the oxidative stress-induced Reactive Oxygen species (ROS) generation at high membrane potential (Δψm). The predominant ROS generated during nitrogen starvation was H2O2, OH–, O2⋅− and to suppress them, scavenging enzymes such as peroxidase and catalase increased to about 23.16 and 0.79 U/ml as compared to control (20.2, 0.19 U/ml). The targeted metabolic analysis showed, stress-related non-proteinogenic amino acids and energy equivalents elevated during the initial hours of nitrogen starvation. The nitrogen stress-triggered biochemical and metabolic changes along with other cellular events eventually lead to lipid accumulation in S. quadricauda. Graphical Abstract Selective metabolomic and biochemical changes during nitrogen stress in microalga.

中文翻译：

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氮胁迫介导的四尾栅藻 CASA CC202 脂质积累过程中的靶向代谢组学和生化变化

Scenedesmus quadricauda CASA CC202 是一种有效的淡水微藻，被用作生物燃料原料，在氮胁迫诱导过程中，它会积累 2.27 倍的脂质。在氮饥饿时，S. quadricauda 会经历生化和代谢变化，扰乱细胞以应对压力条件。由于在高膜电位 (Δψm) 下氧化应激诱导的活性氧 (ROS) 生成，线粒体中氮应激诱导的生化变化表现出。氮饥饿期间产生的主要 ROS 是 H2O2、OH-、O2⋅-，为了抑制它们，与对照（20.2、0.19 U/ml）相比，过氧化物酶和过氧化氢酶等清除酶增加到约 23.16 和 0.79 U/ml。靶向代谢分析表明，在氮饥饿的最初几个小时内，与压力相关的非蛋白氨基酸和能量当量升高。氮应激引发的生化和代谢变化以及其他细胞事件最终导致 S. quadricauda 中的脂质积累。图形摘要微藻氮胁迫期间的选择性代谢组学和生化变化。