Understanding cyanobacteria: these multifaceted micro-organisms

Cyanobacteria, also known as blue algae, are among the oldest and most widespread micro-organisms on Earth. They play an important role in maintaining an ecological balance between aquatic and land ecosystems.

What is a cyanobacterium?

Cyanobacteria are photosynthetic bacteria that can produce energy from sunlight by way of photosynthesis. Through this process, they convert carbon dioxide (CO₂) into nutrients and oxygen, thereby contributing to the production of oxygen in the atmosphere. Cyanobacteria are found in a wide variety of habitats, such as fresh water, moist soils, hot springs and even rocks.

A brief explanation of photosynthesis:

Photosynthesis is a biochemical process by which plants, algae and certain bacteria convert the sun's light energy into chemical energy.

Photosynthesis takes place in 3 stages:

1. Light absorption: First, chlorophyll (a green pigment found in the chloroplasts of plant cells) absorbs sunlight. This excites the electrons in the chlorophyll raising them to a higher energy level.
2. Photochemical reaction (light reactions): These excited electrons are used in a series of reactions to produce ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate). ATP and NADPH are forms of chemical energy. During this process, water is split, releasing oxygen molecules as a by-product.
3. Biochemical reaction (dark reactions, also known as the Calvin cycle): The ATP and NADPH produced are used to convert carbon dioxide (CO₂) into carbohydrates (sugars). This reaction does not require direct light and can, therefore, take place even in the dark.

Photosynthesis is, therefore, a vital process for life on earth. It provides energy for the plants themselves, and is the main source of energy for the food chain. Furthermore, by producing oxygen as a by-product, photosynthesis made life possible for animals on Earth.

Characteristics of cyanobacteria

Morphology of cyanobacteria

Cyanobacteria come in different shapes and sizes, ranging from isolated cells to complex colonies. Some species form filaments, called trichomes, which may or may not have ramifications. Trichomes are often surrounded by a protective sheath, whose thickness and chemical composition may vary.

Typical blue-green colouration of cyanobacteria

The characteristic blue-green colouration of cyanobacteria comes from photosynthetic pigments, such as chlorophyll, phycocyaninor phycobiliproteins. Thanks to these pigments, cyanobacteria can capture the light they need for photosynthesis. Under certain conditions, cyanobacteria may also have reddish, brown or even black hues.

Reproduction and growth

Cyanobacteria reproduce mainly asexually, through cell division. Some species can also form resistant spores, called akinetes, which allow them to survive in adverse environmental conditions. The growth of cyanobacteria depends on several factors, such as the availability of nutrients, temperature and light.

Ecological roles of cyanobacteria

Primary producers

As photosynthetic organisms, cyanobacteria are primary producers, i.e. they are at the bottom of the food chain in aquatic and terrestrial ecosystems. So, they provide a food source for many organisms, such as zooplankton, small fish and invertebrates.

Nitrogen fixation

Some species of cyanobacteria can fix atmospheric nitrogen, a process that converts gaseous nitrogen into nitrogen compounds that can be assimilated by plants. This nitrogen fixation plays an essential role recycling nutrients and maintaining soil fertility.

Formation of particular biological structures

Cyanobacteria are also involved in the formation of complex biological structures, such as stromatolites and biofilms. Stromatolites are rock formations consisting of alternating layers of sediments and colonies of fossilised cyanobacteria , while biofilms are microbial communities with an extracellular matrix structure.

Spirulina is a cyanobacterium with numerous properties

Spirulina whose scientific name is “Arthrospira platensis” is a microalga that comes under the cyanobacteria group. It has a microscopic spiral shape, which is where it gets its common name of “spirulina”. It is often confused with plants because of its high chlorophyll content, which gives it its green appearance, but it is actually a cyanobacterium capable of photosynthesis.

Spirulina is known for its exceptional nutritional properties. It is extremely rich in protein (up to 70% of its dry weight), which is much higher than most other vegetable protein sources. It contains all the essential amino acids, making it a complete protein.

One of the main benefits of spirulina is its phycocyanin content. Phycocyanin, which is the basis of PHYCOMANIA nutritional products, is extracted from spirulina cyanobacteria. Phycocyanin, whose therapeutic properties are exceptional, especially thanks to its ability to neutralise free radicals, thereby prevents oxidative stress and inflammation. PHYCOMANIA would like to invite you to discover these benefits thanks to these 2 products: the energy drink, Rhin Blue, and the food supplement, 10 K.

Summary on cyanobacteria

Cyanobacteria are fascinating micro-organisms that play an important role in the ecological balance of our planet. A better understanding of these organisms is essential to take advantage of their beneficial properties, such as nitrogen fixation and oxygen production, to develop strategies for the sustainable management of aquatic ecosystems, and so humans can benefit from the nutritional and therapeutic help that certain cyanobacteria such as spirulina can offer.