Effect of sodium nitrate concentration on biomass and oil production of four microalgae species

Abstract

The chemical composition of the culture medium is essential for microalgae growth, and to increase the production of biomass and oil. This work studied the influence of sodium nitrate concentration on microalgae growth, biomass production and oil recovery in Chlorella vulgaris, Nannochloropsis oculata, Tetraselmis chui, and Tetraselmis tetrathele. Microalgae were cultivated in mediums with the addition of sodium nitrate varying from 25 to 75 mg/L. The increase of sodium nitrate increased the biomass production of N.oculata (from 0.4 to 2.2 g/L) and C.vulgaris (from 1.4 to 3.4 g/L) and had limited influence on the growth of T.tetrathele, while no change was observed on the growth of T.chui. The oil to biomass ratio increased with nitrogen limitation, with N.oculata presenting the highest oil to biomass ratio. Chlorella vulgaris presented the highest lipid productivity (0.15 g/L.day), while T.chui was the only microalgae that presented its highest productivity at low sodium nitrate concentration.

Keywords

• microalgae
• biomass
• sodium nitrate
• lipids