Study On Extraction And Purification Technology Of C-phycocyanin From Taihu Lake Blue Algae

Mechanical and manual salvage have become an important emergency measures for bloom of blue algae. But improper disposal of the salvaged blue algae will cause environment pollution again. The aims of our study were to find a procedure for extraction and purification C-phycocyanin from blue algae. In this way, the problem of harmless disposal and resources utilizations of the salvaged blue algae can be solved. Currently, Reagent grade phycocyanin was monopolized by a few foreign companies, and the import price is extremely expensive. It is therefore, desired to developed a method with independent intellectual property rights for the extraction and purification of C-phycocyanin with high purity.Freeze-thaw were used to disrupt the cell wall of blue algae. Effects of freeze-thaw times and media on purity and yield of C-phycocyanin were studied. The results show that the optimum conditions for cell disruption, including extract C-phycocyanin from wet algae, freezing and thawing two times in the water. All of which increased the purity of C-phycocyanin up to 0.24 with the yield of 0.90%.The C-phycocyanin was extracted from blue algae by the methods of filtration and flocculation. Effects of filter size, pressurized head, concentration of PAC and solvent volume on the purity and yield of C-PC were studied. The results showed that filtration was not suitable for removing algae debris; Flocculation with PAC is very effective in dealing with algae debris. The optimal conditions for flocculation including the ratio of algae to buffer 1:6 (the concentration of algae is 0.95%), concentration of PAC is 0.75%. In this way, the purity, yield and concentration of C-phycocyanin reached to 0.31,0.19mg/mL and 0.79% respectively.C-phycocyanin was purified by methods of salting-out, aqueous two-phase extraction and dialysis. Effects of ammonium sulfate saturation, salting steps, aqueous two-phase system, molecular weight of polyethylene glycol, concentration of polyethylene glycol and potassium phosphate and MWCO of dialysis bags on purity and yield of C-phycocyanin were studied. The results showed that two-step salting-out with the saturation of ammonium sulfate 20% and 50%can improve the purity of C-phycocyanin to 2.23, the yield was 0.64%. In the PEG2000/potassium phosphate system, maintain the concentration of polyethylene glycol and potassium phosphate was 14%, the purity of C-phycocyanin increased to 3.90, the recovery was 91.26%. After two-step salting, C-phycocyanin was dialyzed with the MWCO 100KDa. The purity of C-phycocyanin reached to 4.20. According to two-step salting-out, dialysis and aqueous two-phase extraction the purity of C-PC increased to 4.60. The purity meets the generally accepted standards of fluorescent reagent grade C-phycocyanin.The influences of different reagents on the stability of C-phycocyanin were studied. In the conditions of 0.001mol/L PBS,0.002mol/L NaCl, 0.001mol/L EDTA, pH 6.8,4℃, dark, C-phycocyanin was more stable and suitable for preservation, the survival rate of pigment is 91%.Finally, based on the results of experiment the flowchart of C-phycocyanin extraction and purification from blue algae was presented. Freeze-thaw, flocculation, salting-out, dialysis and aqueous two-phase extraction were used for extraction and purification of C-phycocyanin, which is efficient, simple and easy to scale-up. This is an effective and feasible method for the resource utilization of blue algae.