2Biotechnological uses of microalgae: A review on the state of the art and challenges for the circular economy

Abstract Microalgae are important microorganisms regulating crucial biogeochemical cycles that also have a wide range of biotechnological applications. Their cultivation in conjunction with material and nutrient recycling represent a considerable opportunity as part of a regenerative economic system for exploitation of recycled matter, called the “circular economy”. In recent years, there has been considerable discussion about the potential of microalgae as feedstock for renewable biofuels, but there may be other diverse commercial opportunities for microalgae. A range of high-value products such as polyunsaturated fatty acids (PUFA), pigments, and others bioactive compounds are useful as nutraceuticals and cosmetics, as well as for industrial purposes. However, unexplored natural sources of bioactive molecules from microalgae are gaining much attention since they can lead to the discovery of new compounds or bioactivities. In terms of environmental biotechnology, microalgae have a major role to play particularly for the treatment of agro-industrial wastewater, and against numerous pollutants such as heavy metal or pesticides. The present review has been prepared to update the potential of microalgae biomass for biotechnological applications other than biofuels.