Nitrogen source, an important determinant of fatty acid accumulation and profile in Scenedesmus obliquus

The potential of algae-based fuel technologies for manufacturing renewable biofuels has been attracting interest from the scientific community. Biomass productivity and cellular lipid content are important parameters affecting the feasibility of using algae oil for biodiesel production. This study compares utilization of NaNO₃, NH₄Cl and urea as different nitrogen sources in terms of their effects on biomass productivity, fatty acid profile and accumulation in Scenedesmus obliquus. Cellular lipid accumulation was analyzed by gravimetric, fluorometric, and flow-cytometric methods, besides collecting spectrophotometric data for biomass productivity analysis. In addition, fatty acid profiles were compared by using gas chromatography-mass spectrometry. The alga can utilize all tested nitrogen sources successfully however growth rates demonstrate differences. Gravimetric lipid content analysis showed approximately a ≈1.5-fold increase in total lipid accumulation under NH₄Cl regime when compared to that of NaNO₃ and a ≈ 2-fold increase when compared to that of urea at the end of ten days cultivation course. Fatty acid profiles under different nitrogen regimes present variations especially under NH₄Cl regime. Moreover, all lipid extracts mostly consist of saturated, straight- and branched-chain hydrocarbons of different chain lengths ranging from C16-C20 which grant a suitable profile for biodiesel production. Scenedesmus obliquus is a suitable species for biodiesel production. The results obtained from this study provide a better understanding of cultivation characteristics of this important species and support potential, future biodiesel production.