Changes in lipid, protein and pigment concentrations in nitrogen-stressed Chlorella minutissima cultures

Many changes occur in the biochemical composition of microalgae in response to stress conditions. In the present study, two nitrogen-stressed Chlorella minutissima strains (MACC 360 and 452) were placed in media containing a range of nitrogen concentrations (7-700 mg L-1 N). Biomass, chlorophyll a and b, carotenoid, protein and lipid concentrations were monitored over 15 days. There was lower biomass accumulation in nitrogen-deficient treatments while lipid yields increased to 40-46% DW in response to nitrogen deficiency. Chlorophyll concentrations initially recovered in response to the nitrogen spike with maximum concentrations recorded on days 6-8 and decreased thereafter as nitrogen became limiting. In comparison, proteins recovered faster with maximum concentrations recorded on day 4. Carotenoid concentrations did not increase in response to the nitrogen spike.