Pigment composition and pigment-protein complex from Symbiodinium sp. strain Y106

Pigment composition and the pigment-protein complex of Symbionidium sp. strain Y106 isolated from the mantle lobe of Tridacna crocea were analyzed to investigate the photosynthetic machinery of this alga. High-performance liquid chromatography (HPLC) analysis was performed using a Waters Symmetry C8 column and a programmed binary gradient elution with a photodiode array detector. The pigments were quantified and identified by comparison with standards. HPLC analysis showed the separation of 11 species of the pigments and 9 of them were identified. The pigment peridinin, was the most abundant carotenoid, consistent with Symbiodinium belonging to the group of dinoflagellates characterized by plastids containing peridinin rather than fucoxanthin. The separation of pigment-protein complexes from the membranes of this alga were performed by either nondetergent or detergent methods after solubilized with β-dodecyl maltoside. By using the nondetergent method involving hydrophobic chromatography, several color fractions were obtained. The fraction 41 (F41) was brick-red and most probably contained peridinin-chlorophyll protein complex (PCP). The fractions were characterized with respect to their pigment composition, spectroscopic characteristics and polypeptide composition. The F41 showed strong absorbance between 420 and 520 nm due to the carotenoids bound to the PCPs, mainly peridinin. Chlorophyll (Chl) a in the complexes appeared at 674 nm. The fraction contained five polypeptides including two known polypeptides of 15 and 30 kDa separated by gel electrophoresis.