EFFECT OF DIFFERENT NITROGEN CONCENTRATIONS ON THE GROWTH, PROXIMATE AND BIOCHEMICAL COMPOSITION OF FRESHWATER MICROALGA Scenedesmus sp

Abstract

Scenedesmus sp. has grabbed attention nowadays due to its nutritious constituents such as protein, lipids, carbohydrates, and other vital trace elements, as well as potential viability as bioresource for application as fish feed, supplement, human consumption and biofuel production. Nitrogen plays an important role in microalgal cell growth, lipid accumulation, as well as production of protein, carbohydrate and pigments. The aim of this study was to enrich the growth, pigment, proximate and biochemical composition of freshwater microalgae Scenedesmus sp. cultured under different NaNO3 concentration. Scenedesmus sp. was cultured in five treatments of different NaNO3 concentrations as 13 g/L (T1), 19 g/L (T2), 25 g/L (control), 31 g/L (T3), and 37 g/L (T4) in Bold Basal Media having stationary phases on day 7, 8, 9, 10, 11 respectively. Significantly (p<0.05) maximum cell density (11.6×106 cells/ml), biomass productivity (0.58g/L), total chlorophyll, protein (23.58% dry weight) and carbohydrate (27.26% dry weight) were found in highest concentration (37 g/L) of NaNO3 compared to control and lower concentration. On the contrary, lowest (13 g/L) concentration of NaNO3 resulted in significantly highest lipid (20.92% dry weight), specific growth rate (0.521±0.01day-1), monounsaturated fatty acids (28.53% of total fatty acids) and polyunsaturated fatty acids (67.37% of total fatty acids). In case of carotenoid and total phycobiliprotein content, significantly (p<0.05) higher value of 6.43 mg/L and 6.14 mg/g, respectively were produced in control (25 g/L NaNO3) compared to other concentration of NaNO3. Significantly (p<0.05) highest value of total saturated fatty acids was found (56.51% of total fatty acids) in 31 g/L concentration of NaNO3. Therefore, higher concentrations of NaNO3 boosted the growth and nutritional profile in Scenedesmus sp. Moreover, lipid production and fatty acid profile were enriched by the lowest concentration of NaNO3 showing economic and sustainable commercial mass culture of Scenedesmus sp.