Nutraceuticals – dietary nutrients and supplements – are a growing industry worldwide. The search for new and more diverse nutritional materials at a lower cost has led many researchers to discover that algae is a very viable source for a wide variety of nutraceutical ingredients.

As an example, it is now common to find Spirulina, as well as other algae strains, in nutritional drinks and foods (e.g. Odwalla Green Machine).

A recent study(7) found that microalgae lipids could serve as a source of eicosapentaenoic acid (EPA) or omega-3 as an alternative to traditional fish oils. The yield of EPA and lipid extracted from microalgae vary with different growth conditions. Therefore, for commercial feasibility, the importance of optimizing EPA production is critical.

The effects of temperature, light intensity, and nitrate level on cell growth, lipid productivity, and omega-6 (arachidonic acid (ARA))/omega-3 (EPA) ratio of Porphyridium cruentum, one of the most promising oil-rich species of microalgae, were investigated.

This study demonstrated that temperature, illumination, nitrogen level, and CO2 levels (studied using the PBR101 photobioreactor) significantly impacted cell growth, lipid production, and fatty acid compositions of P. cruentum. The results demonstrated that decreased temperature and enhanced light intensity resulted in higher lipid content and lipid production, but also reduced biomass.

Therefore, maximizing biomass production does not lead to optimizing lipid production. In addition, higher lipid production and lower biomass were observed when 5% CO2 in air was used as CO2 supplementation as compared to pure CO2. Further, optimal growth conditions were also experimentally determined to produce the lowest ARA/EPA ratio, which is most desirable for maximum nutritional value.

References: 7. Maryam Asgharpour, Brigitte Rodgers and Jamie A. Hestekin, (2015) Energies 8, 10487-10503.