Understanding Urea Assimilation and its Effect on Lipid Production and Fatty Acid Composition of Scenedesmus Sp

Abstract

Much advancement has been made in reducing the cost of large- scale production and harvesting of bio fuels. Nutrients contribute to one of the major cost components in algal production; hence, it is essential to understand the importance of minimizing costs at the nutrient level. In the current study, evaluation of urea as a low- cost and efficient source of nitrogen was investigated. The effect of its uptake mechanisms on growth, change in lipid productivity and fatty acid composition of Scenedesmus sp. was explored. Total Disappearance Rate (TDR) and total uptake rate were used to study the efficiency of urea as a nitrogen source. It was found that the nutrient uptake efficiency of urea was higher than that of nitrate. In addition, urea showed an increase in biomass productivity and lipid productivity by 26% and 45%, respectively, when compared to control. Results also demonstrated degradation of urea into ammonia upon uptake by algal cells, which is then diffused out of the cells into the medium. Ammonia present in the medium is converted into ammonium ion with simultaneous degradation into nitrate. Eventually, both ammonia and nitrate are absorbed by cells in the final growth phase. These results suggest that urea can be effectively used as an alternative nitrogen source.