Macronutrients: carbon, nitrogen and phosphorus
Carbon comes from CO₂ (or bicarbonate), fixed in photosynthesis; a sufficient supply is key to fast growth. Nitrogen —as nitrate, ammonium or urea— is essential to synthesise proteins and chlorophyll.
Phosphorus is involved in nucleic acids and energy transfer (ATP). The balance among these macronutrients conditions both growth rate and the final composition of the biomass.
Micronutrients and culture media
Beyond macronutrients, microalgae require micronutrients in small amounts: iron, magnesium, sulphur and trace elements such as zinc or manganese, essential for enzymes and pigments.
To supply them, defined culture media are used, tailored to each group: for example, alkaline bicarbonate-rich media for Spirulina, or specific formulations for freshwater and marine species. Water quality and pH control are an essential part of the medium.
Nutrient limitation as a tool
Adjusting nutrients does not only feed the culture: it is also a tool to steer biomass composition. Limiting nitrogen, for example, pushes many species to accumulate lipids or carotenoids.
That is why many processes use a growth phase with sufficient nutrients and a later phase of controlled limitation to maximise the target compound, such as astaxanthin or lipids.
FAQ
Light, carbon (CO₂), nitrogen and phosphorus as macronutrients, plus micronutrients such as iron, magnesium and trace elements, all supplied in the culture medium.
It is the water-and-salts solution that provides the required nutrients; it is tailored to each species (for example, alkaline for Spirulina) and its pH is controlled.
Sources
- Richmond, A. & Hu, Q. (eds.) (2013). Handbook of Microalgal Culture: Applied Phycology and Biotechnology. Wiley-Blackwell.
- Chisti, Y. (2007). Biodiesel from microalgae. Biotechnology Advances, 25(3), 294–306.
- Spolaore, P. et al. (2006). Commercial applications of microalgae. Journal of Bioscience and Bioengineering, 101(2), 87–96.
- Mata, T.M. et al. (2010). Microalgae for biodiesel production and other applications: A review. Renewable and Sustainable Energy Reviews, 14(1), 217–232.
Scientific outreach based on specialised literature. Scientific review: pending.
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