Influence of the N:P supply ratio on biomass productivity and time-resolved changes in elemental and bulk biochemical composition of Nannochloropsis sp.

• Effect of N + P supply on Nannochloropsis sp. growth dynamics and chemical content.
• Detailed and comprehensive batch culture data series for support of modelling.
• Cellular N main driver of lipid accumulation, with lesser effect of P starvation.
• P usage can be halved (to N:P of 32:1) with no significant effect on productivity.
• Maximum lipid content and concentration of 52% DW and 230 mg L−1, respectively.

This work reports for the first time the detailed impacts of dual nitrogen (N) and phosphorus (P) stress on growth dynamics and biochemical composition in the Eustigmatophyte Nannochloropsis sp. P-stress concurrent with N-stress had subtle effects on culture bulk biochemical composition, but negatively influenced biomass productivity. However, the N:P supply ratio can be raised to at least 32:1 without compromising productivity (yielding a maximum lipid content of 52% of dry weight and volumetric lipid concentration of 233 mg L−1). The maximum biomass and lipid yields per unit of cell-P were 1.2 kg DW (g P)−1 and 0.54 kg lipid (g P)−1. The P concentration of many common media is thus in surplus for optimal Nannochloropsis sp. biomass and lipid production, offering potential for significant savings in P usage and improving the sustainability of algal cultivation.