Lipid production by Chlorella vulgaris after a shift from nutrient-rich to nitrogen starvation conditions

Abstract

A two-stage process, composed of growth under nutrient-rich conditions followed by cultivation under nitrogen starvation and controlled conditions of phosphate, light intensity, aeration, and carbon sources was applied for lipid production by the green alga Chlorella vulgaris. Using conditions without addition of nitrogen, 2mg/L PO4-P, light intensity of 100μmol/m2/s and 0.25vvm of air, about 43% of dry cell weight accumulated as lipids after 12h, which equates to a lipid productivity of 77.8mg/L/d. In a medium containing 5mg/L NO3-N and 2mg/L PO4-P, and at a light intensity of 100μmol/m2/s and 0.25vvm of 2% CO2, about 53% of dry cell weight consisted of lipids after 24h, representing a lipid productivity of 77.1mg/L/d. The low amount of nutrients, moderate aeration and light intensity were helpful for increasing lipid productivity.