Effect of nitrogen concentration, two-stage and prolonged cultivation on growth rate, lipid and protein content of Chlorella vulgaris

Abstract

BACKGROUND: The effects of the initial nitrogen concentration, as well as of two-stage and prolonged cultivation on the growth rate, lipid and protein content of Chlorella vulgaris were examined. Additionally, a kinetic model of specific growth rate in the exponential growth phase (µ exp ) was developed as a function of initial nitrogen concentration. RESULTS: As the initial nitrogen concentration in the culture medium increased, the total biomass production and µ exp went through a maximum at 300 mg N L −1 and at 200 mg N L −1 , respectively. The lipid content was found to be highly dependent on the initial nitrogen concentration and increased from 9.0% to 29.6% as the nitrogen concentration varied from 800 to 10 mg N L −1 , respectively. Cultivation in two stages resulted in an increase of the lipid content of the biomass from 15.4% to 24.9%, while prolonged cultivation led to an increase of the lipid content from 15.4% to 23.0%. CONCLUSION: Cultivation under optimum nitrogen concentration can lead to increased biomass production. In addition, optimization of lipid production can be carried out by a two-stage cultivation mode or by prolonged cultivation. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry