Pigments of microalgae

What are photosynthetic pigments?

Pigments are molecules able to absorb light at specific wavelengths. In microalgae they serve a dual role: capturing light energy for photosynthesis and protecting the cell against excess light. Each microalgae group shows a characteristic combination of pigments.

Chlorophylls

Chlorophyll a is the main photosynthetic pigment of all microalgae and cyanobacteria. Green algae (Chlorophyta), such as Chlorella or Scenedesmus, also contain chlorophyll b. Chlorophylls absorb mainly blue and red light, and give the characteristic green colour.

Carotenoids

Carotenoids are accessory pigments coloured yellow, orange or red, with a light-harvesting role and, above all, photoprotection and antioxidant activity. Notable ones are astaxanthin from Haematococcus (red) and beta-carotene from Dunaliella (orange), both of great commercial value.

Phycobiliproteins

Phycobiliproteins are water-soluble pigments typical of cyanobacteria and red algae. The phycocyanin (blue) of Spirulina is the best known: it is used as a natural colorant and antioxidant. These pigments broaden the range of light the cell can use.

Pigment applications

Beyond photosynthesis, microalgae pigments are used as natural colorants (food, cosmetics), antioxidants and nutraceuticals. Their production can be induced by adjusting cultivation conditions, such as light intensity or nutrient availability.

FAQ

Mainly chlorophylls (a and, in green algae, b), carotenoids (such as astaxanthin and beta-carotene) and, in cyanobacteria, phycobiliproteins such as phycocyanin.

As natural colorants, antioxidants and high-value nutraceutical compounds in food, cosmetics and nutrition.

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.