Selective Extraction of Chlorophyll a/Photosystem Polypeptides from Spirulina maxima Using Aqueous Two Phase Extraction

Spirulina, a photosynthetic cyanobacteria, has bioactive molecules such as phycobiliproteins which are useful in bioindustries. Aqueous two-phase extraction, an industrially effective process, have been applied to extract invaluable molecules from Spirulina, but mainly focused on optimal extraction of C-Phycocyanin. This research is to selectively remove chlorophyll a-pertaining photosystem polypeptides by stably forming interfacial layer between two phases of polyethylene glycol/potassium phosphate. Under an optimal condition of aqueous two-phase extraction, a stable interfacial layer was formed, while preserving purification efficiency of C-Phycocyanin. Through UV, fluorescence, and gel electrophoresis, chlorophyll a-pertaining photosystem polypeptides were ascertained to be extracted in the interfacial layer. C-Phycocyanin was mainly present in the top phase and allophycocyanin was in the bottom phase. In addition, the safety of the purified C-Phycocyanin was confirmed by examining cytotoxicity of C-Phycocyanin. In conclusion, a stable formation of interfacial layer was proved to be helpful in understanding the selective extraction of chlorophyll a-pertaining photosystem polypeptides, and the purified C-Phycocyanin can be used without cytotoxicity.