Carotenoid composition in the green microalga Chlorococcum

The carotenoid composition in cells of a ketocarotenoid-producing alga, Chlorococcum, was investigated by high-performance liquid chromatgraphy (HPLC). Astaxanthin (free and esters), adonixanthin (free and esters), canthaxanthin, β-carotene, lutein, and some cis-isomers of ketocarotenoids were found. The alga Chlorococcum cells could produce a large amount of ketocarotenoid esters, like the alga Haematococcus pluvialis. The esters of astaxanthin and adonixanthin, and free canthaxanthin were the major carotenoids in the alga Chlorococcum cells, while astaxanthin alone was the major carotenoid in the alga Haematococcus pluvialis. The alga Chlorococcum cells might synthesize astaxanthin from β-carotene via canthaxanthin and adonixanthin in parallel, respectively, which was controlled by the culture conditions.