Nitrogen is considered one of the most important nutrients for the growth of microalgae which affects cell development and metabolic processes, leading to the increase of lipid content of the growing cell under the deficient concentration of nitrogen. At a given concentration of 9.89 mM, the impact of six different nitrogen sources, including urea, glycine, NH₄Cl, NaNO₃, KNO₃ and yeast extract, were compared to study how nitrogen sources affect cell growth and lipid content of the green microalga Micractinium pusillum. Yeast extract was found to be the best nitrogen source for both biomass and lipid productivity (0.1 g L⁻¹ d−¹ and 5.5 μgml⁻¹ day⁻¹, respectively). M. pusillum prefers nitrate in the form of KNO₃ and NaNO₃ rather than other organic nitrogen such as urea and glycine. Laboratory results indicated that ammonium supplementation resulted in the inhibition of the growth of M. pusillum, in addition, 30 mM Sodium chloride was the optimal concentration for obtaining quantitatively high total lipid content. In conclusion, this work highlighted that saturated fatty acids increased by 95% and 75% when M. pusillum was grown at 30 mM NaCl and in the yeast extract culture, respectively.