Microalgae: Cultivation Aspects and Bioactive Compounds

Abstract

Microalgae are aquatic unicellular microorganisms that can be found both in freshwater and marine systems; are capable of photosynthesis; and can grow as individual cells or associated in chains or small colonies. Microalgae cultivation has gained large momentum among researchers in the past decades due to their ability to produce value metabolites, remarkable photosynthetic efficiency, and versatile nature. The wide technological potential, and thus increasing amount of scattered knowledge, may become the very first barrier that a post graduating student, or any non-specialist reader, will face when introduced to the subject. In this review paper, we access the core aspects of microalgae technology, covering their main characteristics, and comprehensively presenting the main features of their various cultivation modes and biological activity from metabolites.

Microalgae with Immunomodulatory Activities

“…But the rapid development and approval of new immune-therapeutic strategies [148,149] and the large amount of new compounds from microalgae [1,147,150], may lead to the finding of new promising drugs for immunotherapy. The number of microalgal species producing immunomodulatory molecules has not yet been adequately characterized, and considering their huge chemical diversity, eco-friendly approach for sampling and easy culturing compared to macroorganisms, they could be promising new sources of immunomodulatory molecules [151]. Finally, the application of new bioengineering tools, such as CRISP/Cas9 system for gene editing and gene knock-out in marine algae, [152,153] could be very promising in order to improve the production of microalgae enriched in molecules with immunomodulatory activity.…”

Microalgal Cell Biofactory—Therapeutic, Nutraceutical and Functional Food Applications

“…Microalgae are grown in a wide variety of indoor and outdoor cultivation systems, such as vertical column photobioreactors, raceway pools, tubular closed photobioreactors, lagoons, bubble columns, pilot tanks, earthen pots, basins, and concrete tanks (Figure 1) [13,20,190]. The cultivation system should have a short path length, adequate microalgae culture for proper mixing, and full light dispersion [191]. Microalgae growth and product formation do not occur simultaneously.…”

Enigmatic Microalgae from Aeroterrestrial and Extreme Habitats in Cosmetics: The Potential of the Untapped Natural Sources

“…This photoprotective and photostable pigment in its hydrophobic yellow-brown form was isolated from the extracellular mucilage sheaths of some aeroterrestrial (including cryophilic), cave and thermal cyanoprokaryotes of the genera Scytonema, Stigonema, Nostoc, Calothrix, Lyngbya, Rivularia, Chlorogloeopsis and Hyella [18,35,80,[84][85][86][87][88][89][90][91][92]. Additional interest for cosmetics comes from the fact that scytonemin was proven as a protein serine/threonine kinase inhibitor with anti-inflammatory activities, which can inhibit proliferation of human fibroblasts and endothelial cells [31,85,93]. Recently, from the organic extracts of Scytonema sp., dimethoxyscytonemin, tetramethoxyscytonemin and scytonin pigments have been isolated [94][95][96].…”

“…Moreover, cultivation of aeroterrestrial or extremophilic algae under ambient environmental conditions reduces the dependency on seasons and the need to shut off operations during extreme climatic conditions [2]. The diversity of methods and techniques of cultivation of microalgae developed for biotechnological purposes (e.g., [31]) is out of the scope of the present review, the aim of which is to summarize the knowledge on the application of aeroterrestrial (soil, aerophytic, cave algae) and extremophilic (thermal and cryophilic) algae and their valuable compounds in the field of cosmetics. This is accomplished by pointing out some interesting, but still unexplored, species and their compounds, with the idea to outline perspectives for their future inventions.…”