Microalgae are microscopic unicellular algae that can be found in various types of ecosystems. Microalgae are one of the most ancient and diverse organisms on earth, originating around 3.500 million years ago.
Microalgae constitute an efficient biological system in the conversion of sunlight into organic compounds, through photosynthesis. Microalgae can double their biomass daily, with possible yields around 60 tons/ha/year.
When compared to higher plants, microalgae have higher growth rates, and are less dependent on seasonal variations. The fact that microalgae are non-vascular plants allows a complete use of the produced biomass, opposing to higher plants, in which the products converge to structures such as leaves, roots, bark, seeds, etc.
The fact that these microorganisms can reproduce, typically, by simple binary division, not having differentiated sex stages in most cases, allows a complete cellular cycle in a few hours. This, together with microalgae simplicity, makes them a target organism for new technologies in the field of genetic improvement and biotechnology.
The concept of microalgae biotechnology is essentially the same as conventional agriculture: to use photosynthetic ability for biomass production to be used as source of food, energy and chemical compounds for several purposes.
Photosynthesis consists of converting light energy into chemical energy. Thus, in the presence of light, carbon dioxide (CO2) and plenty of water, plants, algae and other protist organisms have the ability to produce oxygen and to fix carbon. Therefore, carbon atoms from CO2 are incorporated into sugar molecules, amino acids and other compounds and incorporated into biomass.
Of all the nutrients, carbon is the one that has the greatest significance. Microalgae fix carbon through photosynthesis and, therefore, it is necessary to supply it continuously to the cultures, in order to increase the systems productivity. During the same process, microalgae release oxygen to the atmosphere.
Microalgae are composed of proteins, carbohydrates, fibers, chlorophyll, carotenoids, fatty acids, mineral salts, vitamins, enzymes, peptides and sterols, whose values depend on the species and production process. Currently, microalgae are used in a wide variety of technological applications, ranging from the food industry, animal feed, cosmetics, pharmaceuticals, energy production, effluent treatment, bioplastics, etc.