Astaxanthin Production by Autotrophic Cultivation of Haematococcus pluvialis: a Success Story

NIIZAWA, I; ESPINACO, BY; ZORRILLA, SE; SIHUFE, GA

Global Perspectives on Astaxanthin. From Industrial Production to Food, Health, and Pharmaceutical Applications

Academic Press

Lugar: Londres; Año: 2021; p. 71 - 89

Microalgae are photosynthetic organismsthat have shown great potential for the production of large variety metabolitesof commercial interest, as well as for liquid and gas effluent bioremediation.Among the metabolites of interest and the different uses of microalgae, we can mentionthe production of lipids for biofuels of the second generation (biodiesel),extraction of carotene and other pigments to be used in the pharmaceutical andfood industry, and biomass of microalgae as food (both for humans and animals).There are over 30,000 algal species that have been identified and studied;however, it is estimated that these number could be higher than 70,000 [1].Among them the green microalga Haematococcus pluvialis (H. pluvialis) has beenrecognized as the most promising natural astaxanthin source due to its superiorability to synthesize this pigment.H. pluvialis has a distinctive growthcycle, characterized by the alternation between a green motile stage and areddish nonmotile resting stage (or cyst) according to environmental conditions[2]. Under adverse culture conditions, H. pluvialis cysts accumulate largeamounts of secondary carotenoids, particularly astaxanthin, into lipid dropletsdeposited in the cytoplasm, resulting in a characteristic bright red color ofthese cells [3]. The thick cell wall of haematocyst cell hinders astaxanthinbioavailability, making necessary the application of disruption methods forimproving the extraction procedure. However, these methods can include costlylytic enzymes, large solvent consumption, time-consuming processing, and violentmechanical disruption of the cell wall, resulting in thermal degradation of theunsaturated double-bonded astaxanthin because of the heat generated [4].Astaxanthin can be chemically synthesized at a price, fraction of the naturalone. However, differences in bioactivities and in structural isomerism have beenreported between both types of molecules [5]. Synthetic astaxanthin contains amixture of three stereoisomers associated with two chiral centers that are (3R,30R), (3R, 30S) (meso), and (3S, 30S), in approximately 1:2:1 proportions. Naturalastaxanthin is mainly in the form of (3S, 30S), which exhibited higherbioactivity related to its antioxidant capacity, when compared with thesynthesized astaxanthin [6]. Among the most important biological effects arepigmentation capacity of fish and crustacean, cardioprotective and anticanceractivity, and antiinflammatory and antidiabetic properties [7,8]. Therefore thegrowing interest in application of the natural astaxanthin as colorant and supplementsfor food and feed additives leads to the development of enterprises producing naturalastaxanthin from H. pluvialis cultures around the world [9]. The purpose ofthis chapter is to discuss the current status about H. pluvialis culturesystems for natural astaxanthin production, highlighting some of the criticalaspects of the process.