Abstract

The effect of different light qualities (white, blue, green and red light) on the accumulation of phycobiliproteins was studied in Anabaena circinalis. The results also showed that responding to different light, this strain change the composition of their light-harvesting pigments, phycoerythrin (PE) and phycocyanin (PC). Photosynthetic pigment’s content (PE, PC and APC) were high in white light, phycoerythrin (31.53 µgmg-1), phycocyanin (135.01 µgmg-1) and allophycocyanin (35.92 µgmg-1) after 15 days of growth. In contrast, the lowest phycocyanin was found under blue light (20.01 µgmg-1). Red light favoured the accumulation of phycoerythrin (30.29 µgmg-1) than blue and green but lower than white light. Increasing awareness of harmful effects of synthetic compounds and towards the usage of natural products have led to the exploitation of microalgae as a source of natural pigments. The findings revealed that phycobiliproteins composition and colour of strain drastically changed in response to light quality through complementary chromatic adaptation. Phycocyanin content was significantly correlated with fluorescent white light indicating its important role in cyanobacteria.

Key words: Anabaena circinalis, Light qualities, Loktak Lake, Chromatic adaptation, Phycobiliproteins, Spectrum