Haematococcus pluvialis

Red algae

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Have you ever wondered why salmon, lobsters or flamingos are pink? They eat the red colored algae Haematococcus pluvialis. Under high stress, this microalga contains a lot of astaxanthin, a red antioxidant. With this compound, Haematococcus protects itself against the harmful effects of sunlight, and gives color to its enemies.

Have you ever wondered why salmon, lobsters or flamingos are pink? They eat the red colored algae Haematococcus pluvialis. Under high stress, this microalga contains a lot of astaxanthin, a red antioxidant. With this compound, Haematococcus protects itself against the harmful effects of sunlight, and gives color to its enemies.

Survival stage

Haematococcus pluvialis can be found in three different cell stages: a non-motile stage, a motile biflagellate stage, an as a red cyst with a thick cell wall. The most astaxanthin is produced in this last cell type. This is a kind of survival stage in which the astaxanthin protects the alga from harmful solar rays.

Astaxanthinproduction

Haematococcus pluvialis can contain up to 6% of its dry weight in astaxanthin. This alga is therefor used industrially for the production of this strong antioxidant. Astaxanthin is 6,000 times more effective in the removal of free radicals than vitamin C. The red pigment also protects against UV-damage and has anti-inflammatory effects. Astaxanthin is primarily used, however, as a food additive to impart coloration in, for instance, farmed salmon. Astaxanthin is produced in two phases. In the first phase the algae are cultivated in high densities. The algae are then kept under stressful conditions to stimulate the production of astaxanthin.  

Microbes color the world

Haematococcus pluvialis is not the only red microbe. Dunaliella salina also has this red color. In July 2017 this algae caused a color change in the Wagejot, a salty pond in Texel (a small island of the coast of the Netherlands). Due to extreme drought and high temperatures, a lot of water from this brackish lake evaporated, resulting in an extremely high salt concentration. This is deadly to most organisms, but Dunaliella salina is a halophile and  grows very well at extreme saline conditions. There are also lakes which have a red color more regularly, like Lake Colorada in Bolivia. This salt lake contains a large population of flamingos which, by eating the algae get their pink color.