Cultivation of Chlorella vulgaris in mediums with varying nitrogen sources and concentrations to induce the lipid yield

ABSTRACT The development of biofuel production is of high concern since energy and fuels have so far been fulfilled by fossil resources. Microalgae, as green biomass, has the potential to produce biofuel. Nevertheless, many studies still face low lipid yield due to insufficient nutrients in the medium, improper culture techniques, or inaccurate solvent composition used in the lipid extraction process. Therefore, this study aimed to enhance lipid production from the cultivation of Chlorella vulgaris. The cultivation was performed in mediums supplemented with low concentrations of low-cost exogenous N-sources, which are still rare to examine. The concentrations were varied at 10, 20 and 30 mg L−1 of urea and 35, 70 and 105 mg L−1 of KNO3. For both urea and KNO3, a faster growth rate (0.215 vs. 0.211 d−1) was found under the highest N-concentration in the medium. In contrast, lipid yield increased in the medium with the lowest N-concentration, with values of up to 50.27–51.63%. The produced lipids also contain palmitic, oleic and linoleic acids, and their spectra comply with the fatty acids composition in the biodiesel standard. Moreover, this study achieves a high lipid yield and offers an inexpensive lipid induction technique for C. vulgaris. GRAPHICAL ABSTRACT