Abstract:
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
(1ψm). 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.
