Microalgae as a source for secondary carotenoid production: a screening study

Abstract

The main secondary carotenoids used in food industries are astaxanthin and β-carotene. Microalgae are one of the best sources for these compounds. Only two taxa i.e. Dunaliella and Haematococcus are used for industrial purposes. In this contribution, we report results about the secondary carotenoid synthesis capacity of 25 different green algal strains. The different strains were cultivated in standard conditions. Their growth rates were monitored and were used as a first selection parameter, Significant differences were found between the different species. In order to estimate the capacity to synthesize secondary carotenoids, the algae were subjected to a combination of light and nitrogen-starvation stresses. Under these conditions, dramatic changes in the pigment composition were triggered: chlorophyll amount dramatically decreased while secondary carotenoids synthesis occurred. As a consequence, a change in the culture colour from green to orange or red was visually observed. The modifications in the pigment composition during this process were further analyzed by thin-layer and diode-array reversed-phase high-performance liquid chromatographies. The analysis revealed that most of the strains accumulated more than one astaxanthin form except Ankistrodesmus sp., Mychonastes zofingiensis, Chlorella fusca and Pleurastrum sarcinoideum strain LUKESOVA 23/87 which preferentially accumulated free astaxanthin, astaxanthin monoester and astaxanthin diester, respectively.