Earth First

Spirulina | How It’s Grown

The blue-green algae spirulina might feel like a modern food, but Indigenous people in Mexico and Chad have been cultivating it for hundreds of years. Today, modern scientists have developed a high-tech version of growing Spirulina within a huge system of glass tubes.

Ancient, green gold

For scientists, it is an exciting field of research; entrepreneurs look at it as a resource of the future; and for some, it is a contribution to a healthy diet. The allrounder’s name? Spirulina. What might sound like a type of pasta or the newest addition to Marvel’s world of superheroes is actually the name of a blue-green algae.

We can find 30,000 different species of algae in our oceans, freshwater, in the air, snow or soil. They come in different sizes and groups, from microscopic small ones to kelp, which can grow up to 45 meters long.

Some of them, like green algae, belong to the kingdom of plants. Others, like spirulina, belong, in fact to a group of microorganisms called cyanobacteria, also known as blue-green algae (and yes, their names derive from their colouring). They use a pigment called phycocyanin which gives them their specific color and which they use for photosynthesis. Cyanobacteria have been doing this for quite a while: As one of the oldest organisms on Earth, they form a biofilm which, fossilized, has been proven to be up to 2.7 billion years old.

We can eat algae?

Humans use algae in different ways. Generally, they are low in carbohydrates and high in protein, presenting an alternative to animal products. Billions of tons grow every year in our oceans, not wasting precious arable land. Experts even think that every second molecule of oxygen in the atmosphere is produced by algae.1 They breathe more CO2 than common agricultural crops like wheat or corn, meaning they are great for carbon storage and as a source of nutrition–so why not eat them too?

Five hundred kinds of algae are eaten, often as dietary supplements. Most of us are aware of seaweed, green, red or brown algae, which are part of diets in China, Japan or Korea but also traditional European societies in Iceland, Norway or Wales. They are high in fibre and consist of up to 60% protein, with vitamins and mineral compounds working as antioxidants in our bodies. And then there are the essential Omega-3 fatty acids, something normally associated with fish.2

The curious case of Spirulina

Spirulina has always been a special case: Indigenous people harvested algae from flat, sub-tropical to tropical waters with a high salt content. When Spanish invaders reached the shores of Mexico, they discovered that Aztecs close to the capital Tenochtitlan were collecting “new food” from lagoons. This was turned into blue-coloured cakes and it is even said that marathon runners took it for extra energy. Spirulina, or as they call it “dihé”, is also one of the major protein sources in Chad. People living close to Lake Chad show low levels of malnutrition despite living mainly on millet.

Modern industry has found a new way to grow Spirulina. Aquacultures, so-called open ponds, are common. Successful growth depends on the right amount of light, temperature (up to 37°C), stirring speed, pH, water quality, the presence of nutrients like carbon or nitrogen, and so on. To harvest it, the culture is pumped through a filter or a centrifuge and then dried in the sunlight or with hot air.

Growing spirulina in giant tubes

Photo credit: Ecoduna

Yet, there are some problems with this system: “Since spirulina normally grows in steady ponds, they are not used to pumping”, says Lisa-Marie Dormayer, who works at the Austrian company Ecoduna, “we developed a system where algae can grow in a controlled environment without any stress.” Ecoduna patented a system of 44,000 glass tubes in which the algae grow. A so-called ‘air-lift principle’ operating on a hydrostatic equilibrium adds CO2 and other nutrients like phosphates and nitrates through pressure. It is an enclosed system, which keeps the algae from contamination by animals, bacteria or dirt.

How spirulina is grown

First, a single algae cell is collected in nature and then grown in the lab on a nutrition medium until it can be inserted into the big tube system. In an ideal case, cells divide once a day, while being transported slowly through the pipes (one “lap” takes 12 hours). After four to ten days they are ready for harvest. “We take a part of the cells from the system. Too many would hinder perfect conditions for growth”, explains Dormayer. To replace the removed cells, nutrients and water (80% of it recycled) are added.

Glass tubes require less cleaning than ponds which means algae can be produced almost non-stop. The clear glass allows the system to be powered by sunlight with tubes positioned vertical towards the sun. With no additional lighting necessary, ecoduna’s production is very sustainable. They also refrain from heating (except to keep employees from freezing). Instead, a local type of algae is used in the winter. This species, which is yet to be licensed, requires lower temperatures than Mexico-descendent spirulina. During days of low sunshine, productivity is simply lower as well. At the end of the process, algae are dried and processed into the green powder we all know – and maybe also love.

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  1. Chapman, R.L. (2013): Algae: the world’s most important “plants”- an introduction. Mitig Adapt Strateg Glob Change 18:5 Accessed 9th April 2019
  2. . M. Ahsan, B. Habib, Mohammad R. Hasan, Tim C. Huntington, Mashuda Parvin (2008): A review on culture, production and use of spirulina as food for humans and feeds for domestic animals and fish. Food and agriculture organization of the United Nations
  1. Asghari A, Fazilati M, Latifi AM, Salavati H, Choopani A. (2016): A Review on Antioxidant Properties of Spirulina. J Appl Biotechnol Reports; 3(1): 345-51 Accessed 9th April 2019
  2. Ecoduna Accessed 9th April 2019
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