Lipid enhancement through nutrient starvation in Chlorella sp. and its fatty acid profiling for appropriate bioenergy feedstock

Abstract Selection of suitable microalgal candidate for biodiesel relies upon its biomass, lipid productivity and fatty acid profile. In this perspective, the key objective of the present research is to assess the biomass and lipid productivities of the Chlorella sp. under ambient condition and further, culture the strain under nitrate and phosphate deprivation conditions to induce the lipid accumulation. Under the standard BG-11 medium, biomass and lipid productivity of the tested strain was estimated to be 46 mg L−1 d−1 and 5.1 mg L−1 day−1 respectively. With this in view, nutrient starvation was carried out to escalate the lipid content of Chlorella sp. Under nitrate deprivation, the lipid content was 21.8 %, which was comparatively higher than standard BG -11 medium grown cells (control) i.e., 11.5 %. Similarly, under phosphate starvation, the lipid content was 13.9%. In a view to formulate cost-effective medium, sodium nitrate and dipotassium hydrogen phosphate in the medium was replaced by urea and superphosphate and lipid content, fatty acid profile of urea and superphosphate starved cells were studied. The lipid content under urea and superphosphate starvation was found to be 21.1% and 11% respectively. Further, the fatty acid profile of the Chlorella sp. grown under sodium nitrate and urea deprivation showed the predominant fatty acids like C16:0, C16:1, C18:1, C18:2, and C18:3, and notably, they were increased under nutrient starved conditions. In addition to that, fuel properties of fatty acid profile of Chlorella sp. complies EN 14214 enabling its suitability as a fuel.