Chiang Mai Journal of Science

     Microalgae is one of the promising renewable fuel sources as it can optimize its biomass and lipid content. Lipid content is commonly associated with its potential as a biofuel. Nitrogen stress is an attempt to increase the metabolite content in microalgae. In this study the microalgae Euglena sp. was grown in a medium with different nitrogen concentrations to determine the number of cells, biomass, lipids, and FAME (Fatty Acid Methyl Esters) content cultivation of Euglena sp. had been carried out for 14 days with the gradually decreased concentration of nitrogen (1000 mg/L, 750 mg/L, 500 mg/L, 250 mg/L, and 0 mg/L) (NH₄)₂SO₄. The density of cells of Euglena sp. was counted under a light microscope and identification of lipids was done by measuring the lipid total using Bligh and Dryer and Fatty Acid Methyl Ester (FAME) was measured by Gas Chromatography-Mass Spectrophotometry (GC-MS) method. The results show that deficiency of nitrogen gave the lowest impact on cell growth, biomass, pigments, and carbohydrate of Euglena sp. While the lipid content increased with the highest yield obtained at the nitrogen concentration of 0% mg/L. The composition of FAME of Euglena sp. was dominated by Saturated Fatty Acid (SFA) methyl ester by 54.72%. The highest carbon chains are C16:0 and C18:0 at a concentration of nitrogen 0 mg/L. It is concluded that nitrogen starvation could increase the lipid content and FAME as biodiesel which had the potential to be converted into biojet fuel.