Astaxanthin Production from Microalgae

Abstract

Astaxanthin is commercially sold as a pigment for animal feed and as an antioxidant for the nutraceutical sector. Astaxanthin is predominantly manufactured synthetically from petrochemicals but is also obtained from the chlorophyte Haematococcus pluvialis (Haematococcus lacustris). The petrochemical-derived synthetic alternative has conventionally been used, attributable to its lower cost ($1300–1800 kg−1). However, it is inferior as an antioxidant, prohibited for direct human consumption, and may cause toxicity in the final product. Conventionally, astaxanthin from H. lacustris is produced in a two-stage production process, incorporating a green and red stage for maximising growth and astaxanthin production, respectively, but a one-stage process has been proposed. The H. lacustris-derived astaxanthin industry has been a commercial success, but several constraints have arisen including contamination issues, relatively low biomass and astaxanthin productivities, high downstream processing costs, and photobleaching issues in the red stage. These constraints need to be addressed for the production of astaxanthin from H. lacustris for the aquaculture sector. Alternatively, through the exploitation of an alternative life cycle stage, red motile macrozooids can be formed lacking the thick walls of aplanospores. It is envisaged that the red motile macrozooids could be harvested and fed as a whole-cell product directly to the aquaculture sector rich in astaxanthin and polyunsaturated fatty acids, bypassing the cell disruption and extraction steps to deliver bioavailable astaxanthin as a biobased feed.