Effect of Different Nitrogen Concentrations on Primary and Secondary Metabolites of Scenedesmus obliquus (Turpin) Kutzing

Abstract

The work aimed to enhance growth and biochemical substances in Scenedesmus obliquus by creating a growing suitable condition of enrichment culture with varied concentrations of KNO3 as a nitrogen source. Kuhl medium was used for the cultivation of Scenedesmus obliquus with optimized nitrogen source concentration. Growth was determined by optical density (1.94 OD680) on the 10th day of the culture; and protein (0.18 mg/ml) concentration was assessed with +50% conc. of KNO3. The diminishment of KNO3 (-50% conc. of KNO3) showed the highest lipid output (31.08µg/ml) and the maximum carbohydrate content (0.2 mg /mL) on day 10 of culture. Also, carotenoids increased by 20.51% over control. Total phenolic, flavonoid, and ascorbic acid contents were measured, recording 127.53 ±0.79 mg gallic acid equivalents/ g crude extract, 81.59 ±1.05 mg gallic acid equivalents/ g crude extract 149.27 ±1.04 mg.g−1, respectively. In conclusion, this work highlighted those polyunsaturated fatty acids (PUFAs) of S. obliquus cultivated at (-50%conc. of KNO3) that increased by 80%, compared to the control culture; linolelaidic and α-linolenic acids were the main dominant of PUFAs and constituted 17.84 % and 22%, respectively.