Mina Mousavi - Department of biochemistry Neyshabur Branch, Islamic Azad University, Neyshabur, Iran
Jamshid Mehrzad - Department of biochemistry Neyshabur Branch, Islamic Azad University, Neyshabur, Iran
Hossain Mehrani - Department of biochemistry Neyshabur Branch, Islamic Azad University, Neyshabur, Iran

Background and Aim: Phycocyanin is a blue pigment from Arthrospira platensis which is considered as a good replacement for artificial blue pigment. It is widely used in European countries and in China in different ways as additives in food, cosmetic, therapeutic and as fluorescent pigment. Since Phycocyanin is as intracellular pigment, it should be extracted from cells.Methods:To find the best method for breaking cell wall, we surveyed various methods such as the ultrasonic bath, probe ultrasonic, and freezing in two temperatures (-20˚C and -80˚C) and thawing in room temperature. Furthermore, we analyzed the effect of the number of repeated freeze-thaw cycles under -20˚C, followed by evaluating the ratio of biomass to buffer (Britton Robinson Buffer, pH 5) in 1:6, 1:8, 1:10, 1:12 and 1:14Results:The results show that probe ultrasonic can significantly lysis the cell wall so chlorophyll which is placed in the membrane release in crude extract, leading to the reduction of Phycocyanin purity. The most purity is observed in freeze thaw method by freezing at -20˚C. While fifth times freeze- thaw increase the yield of the phycocyanin production, the purity ratio (A620/A280) decreases after the forth times. The best ratio of biomass to buffer was determined 1:10 which extracted the highest amount of phycocyanin 300 mg/ml.Conclusion:The optimum condition for extraction is the freeze -thaw method under -20 °C condition in the fourth repeated cycles. The optimal ratio of algal biomass and solvent was one to ten.

Phycocyanin, ultrasonic, freeze-thaw method