标题：Influence of Nutrient Manipulation on Growth and Biochemical Constituent in <i>Anabaena variabilis</i> and <i>Nostoc muscorum</i> to Enhance Biodiesel Production
摘要：The present study aims to improve biomass and biochemical constituents, especially lipid production of <i>Anabaena variabilis</i> and <i>Nostoc muscorum</i> by formulating an optimal growth condition using various concentrations of nutrients (NO<sub>3</sub><sup>−</sup>, PO<sub>4</sub><sup>3−</sup> and CO<sub>3</sub><sup>2−</sup>) for biodiesel production. The supplementation of the three nutrients by +50% showed the maximum dry weight and biomass productivity, while the macromolecule contents were varied. The depletion of N-NO<sub>3</sub><sup>−</sup> by 50% N-NO<sub>3</sub><sup>−</sup> showed the maximum lipid yield (146.67 mg L<sup>−1</sup>) in <i>A. variabilis</i> and the maximum carbohydrate contents (285.33 mg L<sup>−1</sup>) in <i>N. muscorum</i> with an increase of 35% and 30% over control of the synthetic medium, respectively. However, variation in P-PO<sub>4</sub><sup>3−</sup> and C-CO<sub>3</sub><sup>2−</sup> showed insignificant improving results for all biochemical compositions in both cyanobacteria. <i>A. variabilis</i> was the superior species for lipid and protein accumulation; however, <i>N. muscorum</i> showed the maximum carbohydrate content. Accordingly, <i>A. variabilis</i> was selected for biodiesel production. In <i>A. variabilis</i>, −50% N-NO<sub>3</sub><sup>−</sup> resulted in 35% higher lipid productivity compared to the control. Furthermore, the fatty acid profile and biodiesel quality-related parameters have improved under this condition. This study has revealed the strategies to improve <i>A. variabilis</i> lipid productivity for biodiesel production for small-scale in vitro application in terms of fuel quality under low nitrate levels.
