Analysis and model delineation of marine microalgae growth and lipid accumulation in flat-plate photobioreactor

• Logistic model to delineate algal growth and dynamic lipid accumulation is established.
• Conditions for a good trade-off balance between biomass and lipids production are defined.
• Strategy for high lipids production based on the growth model predictions is proposed.

A quantitative description of its growth and the “trade-off” between biomass production and lipid accumulation will provide a kinetic insight of the dependency of biomass and components on growth conditions and the interplays between lipid/protein production and N-limitation. The examination of the dependency of Isochrysis galbana growth on initial concentration of sodium nitrate (NaNO3) in a flat-plate photobioreactor (FPPBR) revealed that the maximal lipid 106 mg L−1 is produced at 25 mg L−1 NaNO3 and whereas the accumulation of biomass, protein and starch increases as NaNO3 increases to 100 mg L−1. The analysis and model fitting results indicate that I. galbana growth and production of lipids in a FPPBR can be quantitatively described by Baranyi-Roberts & logistic equation, and Luedeking-Piret model in a satisfactory manner, respectively. 25–75 mg L−1 was found to be proper level of NaNO3 to achieve a good trade-off balance to produce both high quantities of biomass and lipids. Based on the predictions of growth model, after culturing middle stationary phase under the high nitrogen medium, switching of culture for algal cells to a nitrogen-free medium and/or high illumination intensity might be preferable strategy to achieve high level accumulation of lipids.