In vitro biosynthesis of xanthophylls by cell extractsof a green alga Chlorococcum

The ability of a cell-free carotenogenic system from the green alga Chlorococcum sp. to convert non-radiolabelled β-carotene into echinenone, canthaxanthin and other endogenous xanthophylls was exploited. Carotenogenic activities of this in vitro system varied with different introductions of β-carotene as substrate. Optimal activities were obtained when β-carotene was provided in chloroform (1 %, v/v) and cholic acid (0.1 %, w/v) as well as when L-α-phosphatidylcholine (100–200 μg per incubation) was present in the incubation mixture. The present investigation also indicated that oxygen was essential for the conversions. The effects of both dioxygenase cofactors and monooxygenase cofactors were presented. It was found that a dioxygenase cofactor mixture of Fe2+, ascorbic acid and 2-oxoglutarate was required to the carotenogenic activities.