Effects of Irradiance and Different Nitrogen and Carbon Concentrations on the Minerals Accumulation in Scenedesmus obliquus Biomass

Abstract

Microalgae are capable of absorbing and concentrating constituent elements that have a wide variety of applications in agriculture, food industry, and medicine. Microalgae chemical composition change according to internal and external factors. In this study, the effect of irradiance, sodium nitrate and sodium acetate concentration on the accumulation of essential minerals in Scenedesmus obliquus biomass were evaluated using 23 factorial screening designs. The simultaneous effect of the three experimental factors was studied using three levels for each parameter (irradiance: 36.71, 69.50, 102.30 μE m-2 s-1, sodium nitrate: 0.27, 44.00, 87.73 g L-1 and sodium acetate: 0.00, 2.50, 5.02 g L-1). The response variables were the minerals concentration of Na, K, Ca, Mg, Fe, Zn and Mn. Results show that each mineral has an optimal operation condition in order to improve its concentration in the microalgae biomass. A significant interaction between the variables was observed, which has direct effects on the minerals accumulation in the microalgae biomass. Under these conditions, the maximum concentration of K (1515.77 [mg (100gdw)-1]), Ca (2744.24 [mg (100gdw)-1]), Mg (9697.65 [mg (100gdw)-1]), Fe (2932.42 [mg (100gdw)-1]), Mn (38.48 [mg (100gdw)-1]), Zn (324.00 [mg (100gdw)-1]) and the minimum concentration of Na (5607.20 [mg (100gdw)-1]) were obtained from the microalga biomass. Thus, Scenedesmus obliquus biomass was characterized as good essential mineral source and confirmed to be potentially valuable ingredient for utilization in the food industry.