Pigment Composition of the Green Microalga <i>Botryococcus braunii</i> Kawaguchi-1

Abstract

The extracellular and intracellular pigments of the colonial green microalga Botryococcus braunii Kawaguchi-1 were extracted separately, and their contents and compositions in the linear and stationary growth phases were analyzed. The intracellular carotenoids were composed of neoxanthin, loroxanthin, violaxanthin, lutein, α-carotene, and β-carotene. The amounts of chlorophylls and intracellular carotenoids decreased in the stationary phase. The extracellular carotenoids were fairly abundant even in the linear phase and increased still more in the stationary phase. The main component of the extracellular carotenoids was a ketocarotenoid, echinenone. The color change in the stationary phase would mainly be ascribed to the accumulation of echinenone in the intercellular matrix simultaneous with the decrease in the total amounts of intracellular pigment components. Substantial amounts of botryoxanthins and braunixanthins containing a tetramethylsqualene moiety existed unchanged in the intercellular matrix. These carotenoids also contributed to the expression of the reddish color of this alga especially in the linear phase.