Marine microalgae constitute a natural source of a variety of drugs for pharmaceutical, food and cosmetic applications—which encompass carotenoids, among others. A growing body of experimental evidence has confirmed that these compounds can play important roles in prevention (and even treatment) of human diseases and health conditions, e.g., cancer, cardiovascular problems, atherosclerosis, rheumatoid arthritis, muscular dystrophy, cataracts and some neurological disorders. The underlying features that may account for such favorable biological activities are their intrinsic antioxidant, anti-inflammatory and antitumoral features. In this invited review, the most important issues regarding synthesis of carotenoids by microalgae are described and discussed—from both physiological and processing points of view. Current gaps of knowledge, as well as technological opportunities in the near future relating to this growing field of interest, are also put forward in a critical manner.

Carotenoids are tetraterpenoids molecules present in all photosynthetic organisms, responsible for better light-harvesting and energy dissipation in photosynthesis. In cyanobacteria, the biosynthetic pathway of carotenoids is well described, and apart from the more common compounds (e.g., β-carotene, zeaxanthin, and echinenone), specific carotenoids can also be found, such as myxoxanthophyll. Moreover, cyanobacteria have a protein complex called orange carotenoid protein (OCP) as a mechanism of photoprotection. Although cyanobacteria are not the organism of choice for the industrial production of carotenoids, the optimisation of their production and the evaluation of their bioactive capacity demonstrate that these organisms may indeed be a potential candidate for future pigment production in a more environmentally friendly and sustainable approach of biorefinery. Carotenoids-rich extracts are described as antioxidant, anti-inflammatory, and anti-tumoral agents and are proposed for feed and cosmetical industries. Thus, several strategies for the optimisation of a cyanobacteria-based bioprocess for the obtention of pigments were described. This review aims to give an overview of carotenoids from cyanobacteria not only in terms of their chemistry but also in terms of their biotechnological applicability and the advances and the challenges in the production of such compounds.

Pigments from microalgae and cyanobacteria have attracted great interest for industrial applications due to their bioactive potential and their natural product attributes. These pigments are usually sold as extracts, to overcome purification costs. The extraction of these compounds is based on cell disruption methodologies and chemical solubility of compounds. Different cell disruption methodologies have been used for pigment extraction, such as sonication, homogenization, high-pressure, CO₂ supercritical fluid extraction, enzymatic extraction, and some other promising extraction methodologies such as ohmic heating and electric pulse technologies. The biggest constrain on pigment bioprocessing comes from the installation and operation costs; thus, fundamental and applied research are still needed to overcome such constrains and give the microalgae and cyanobacteria industry an opportunity in the world market. In this review, the main extraction methodologies will be discussed, taking into account the advantages and disadvantages for each kind of pigment, type of organism, cost, and final market.