The best recovery of Nannochloropsis oculata from the culture broth and effect on content of lipids

Abstract

Nannochloropsis oculata is an interesting microorganism in the field of marine biotechnology because of its high lipid content. Biodiesel from this microorganism has been demonstrated to be a feasible replacement of petroleum-derived fuels. The effect of pH, flocculant dosage (FeCl3), and cell density has been studied in order to maximize biomass recovery and lipids. A partial factorial design was used to screen the main factors involved in the maximal biomass recovery from the culture broth, indicating that the best harvesting efficiency of 94.2% was obtained at pH 7, 47.6 × 106 of cell density and flocculant dosage of 13 mg FeCl3/l. Oleic acid, palmitic acid, and palmitoleic acid (omega-7) were identified inside the microalgae harvested. Omega-7 fatty acid is five times more potent than omega-3 at lowering triglycerides. The lipids identified had lower degree of unsaturation; this makes microalgal lipids a potential replacement for fossil fuel. 0.76% of reduction in eicosapentaenoic unsaturated fatty acid (EPA) was observed probably due to flocculant addition and that is beneficial for providing an increased lipid stability. In summary, this work is devoted to demonstrate that the optimization of the separation of microalgae from culture broth is mostly dependent on the pH, cell density, and flocculants dosage.