Although the term “algae” is often used in a negative way in the news, many people would be amazed at the benefits that this plant can provide. First, let’s define what an alga represents. These photosynthetic organisms can grow in various aquatic habitats such as rivers, lakes, ponds, and oceans. Of course, each species has different preferential growing conditions. These algae can be classified according to their colour, such as red algae (Rhodophyta), brown algae (Phaeophyta) and green algae (Chlorophyta) and according to their size. Marine algae, meaning those visible to the naked eye, are considered macroalgae, while smaller algae are called microalgae. As its name suggests, the latter are microscopic. Its size varies from a few micrometres to a few hundred micrometres depending on the species. Although this single-celled organism remains unknown to many, its existence on Earth is not to be overlooked. Indeed, it is responsible for nearly 50% of the net primary production of oxygen on our planet1.
Over the past few decades, researchers have gained a deeper understanding of microalgae metabolism, as well as their preferences for culture media and growth conditions. As photosynthetic organisms, their efficient growth is highly dependent on the supply of CO2 and light. Certain nutrients are also essential for microalgae growth, such as carbon, nitrogen, and phosphorus. Carbon is the main component of cellular makeup, followed by nitrogen. Phosphorus is essential for the formation of cell membranes and DNA, in addition to being involved in many metabolic processes within the cell. The presence of micro elements such as iron, zinc, sulphide, and copper also promote the proper development of this organism. As for the optimum temperature and pH for growth, these values differ depending on the species of algae being cultivated. It is possible to grow these plants in open systems such as ponds, but also in closed systems such as bioreactors. The latter is a very interesting option in today’s world where agricultural land is becoming increasingly limited. In addition, several microalgae have demonstrated the ability to grow in wastewater. These contaminated waters used as culture media come from various sectors including textile, municipal, dairy, pharmaceutical, swine and aquaculture. Of course, the composition of these waters varies greatly from one industry to another, and each species does not tolerate the different type of contaminants in the same way. Nevertheless, numerous studies suggest that the use of microalgae in water treatment could prove to be a revolutionary alternative.
With this biotechnology, we are exploiting the ability of microalgae to naturally degrade contaminants, while simultaneously generating the production of an economically valuable product, algal biomass. In recent years, this biomass has been highly desired by the food, nutraceutical, pharmaceutical, biomedical, cosmetics, energy, and other industries. Algae can be used in the production of biogas, for example, or biofertilizers, antimicrobial agents or dyes. Its applications are almost limitless. In short, microalgae opens up a world of possibilities, but several advances are still needed before this resource can be exploited to its full potential.