Astaxanthin (ASTA) was originally isolated from a lobster by Kuhn and Sorensen and was first used as a pigment for aquaculture. It, together with carotenes, constitute a class of more than 600 molecules called carotenoids. In addition to its effect on color, it is known for its strong antioxidant activity and numerous health benefits to human and animals. Its antioxidant activity is known to be substantially greater than β-carotene and about a thousand times more effective than vitamin E [1]. It has diverse biological activities and potential health benefits to humans and animals and have been extensively investigated.
Source of Astaxanthin
The natural sources of astaxanthin are algae, yeast, salmon, trout, krill, shrimp and various microorganism sources. The commercial astaxanthin is mainly from Phaffia yeast, Haematococcus and through chemical synthesis. Astaxanthin from various microorganism sources are presented below. Among them, Haematococcus pluvialis is one of the best sources of natural astaxanthin.
- Haematococcus pluvialis — 3.8%
- Paracoccus carotinifaciens (NITE SD 00017) — 2.2%
- Neochloris wimmeri — 0.6%
- Xanthophyllomyces dendrorhous (JH) — 0.5%
- Xanthophyllomyces dendrorhous (VKPM Y2476) — 0.5%
- Chlorococcum — 0.2%
- Thraustochytrium sp. CHN-3 (FERM P-18556) — 0.2%
- Pandalus borealis — 0.12%
- Enteromorpha intestinalis — 0.02%
- Catenella repens — 0.02%
- Pandalus clarkia — 0.015%
- Ulva lactuca — 0.01%
- Agrobacterium aurantiacum — 0.01%
- Chlorella zofingiensis — 0.001%
Synthesis of Astaxanthin
Astaxanthin can be produced either by chemical synthesis or biosynthesis. Safety issues have arisen regarding the use of chemical synthetic astaxanthin for human consumption, while the astaxanthin derived from Haematococcus pluvialis is the main source for several human applications, including dietary supplements, cosmetics, and food.
In general, astaxanthin is produced from Haematococcus by a two-step process (figure 1). This process has been developed based on the life cycle and cell biology of Haematococcus, which mainly consists of primarily at least two stages, the green stage when replete-nutrient medium is supplied under favorable growth conditions, and the red stage when nutrients are depleted under conditions of stress. During the green stage, the cells can reproduce and accumulate biomass but not astaxanthin, while during the red stage, the cells lose the ability of reproduction and mobility but are capable of accumulating as high as 5% of astaxanthin of dry biomass weight [2].
Fig. 2 Diagrammatic representation of two-step cultivation processes for Haematococcus
References
- Zhang, C., Chen, X., & Too, H.-P. Microbial astaxanthin biosynthesis: recent achievements, challenges, and commercialization outlook. Applied Microbiology and Biotechnology, 2020.
- Li, X., Wang, X., Duan, C., et al. Biotechnological production of astaxanthin from the microalga Haematococcus pluvialis. Biotechnology Advances, 2020, 107602.
