Impact of cultivation conditions on biomass yield and lipid content of Scenedesmus obliquus

Abstract

Microalgae have currently been considered as a promising feedstock for biodiesel production. The accumulation of microalgal lipids is species-specific and largely dependent upon cultivation conditions. The present study aimed to investigate the biomass productivity and lipid content of Scenedesmus obliquus cultivated under nitrogen (N)- and phosphorus (P)-depleted conditions. The highest microalgal density was 38.0 ± 3.5 × 106 cell/mL after 12 days of cultivation in the standard Bold’s Basal Medium (BBM) and significantly decreased with decreasing N conentrations in the media, with the density of 1.4 ± 0.5 × 106, 21.5 ± 1.4 × 106, 25.7 ± 4.9 × 106, and 33.5 ± 1.2 × 106 cell/ mL in the nutrient solutions containing 0, 25, 50, and 75% N, respectively. Conversely, the P concentrations showed negligible effects on the growth of S. obliquus across all treatments. Overall, the lipid accumulation of S. obliquus increased with decreasing N and P concentrations. The results revealed that N-starvation yielded the highest microalgal lipid content of 184.1 ± 17.4 mg/g d.w., whereas that under N-sufficient condition was only 80.0 ± 9.8 mg/g d.w. Likewise, the lipid content was almost double when S. obliquus was grown in the modified BBM containing half of P concentration of the standard medium. Taken together, this study demonstrates that alteration of the nutrients is an effective approach for enhancing lipid accumulation in S. obliquus.