Study On Extraction And Purification Technology Of C-Rhycocyanin And Removal Of Microcystin-LR From Chaohu Cyanobacteria

Recently, Chaohu cyanobacteria bloom outbreaks frequently, cyanobacteria salvage has become an important emergency measures for control of cyanobacteria, but salvaged cyanobacteria improper disposal can cause secondary pollution. This study aimed at development and technical study of Chaohu cyanobacteria high value-added products, and focused on C-phycocyanin extraction and purification research, and using immobilized microbial technology to remove generated microcystin-LR was studied.In this study, the process of freeze-thaw broken-salting-out-aqueous two-phase extraction-ultrafiltration " was used to extract and purify C-phycocyanin, effects of freeze-thaw times, thawing temperature and the ratio of cyanobacteria to water(the concentration of cyanobacteria) on purity and yield of C-phycocyanin were studied; effects of ammonium sulfate saturation and salting-out steps on purity and yield of C-phycocyanin were studied; effects of aqueous two-phase extraction system on purity of C-phycocyanin were studied,such as molecular weight and the concentration of polyethylene glycol,the inorganic salts, the concentration of potassium phosphate and pH value; the effect of molecular weight of ultrafiltration was studied. The results showed that; the optimum conditions of freeze-thaw are using fresh cyanobacteria as the raw material, the freezing temperature-20℃, thawing temperature20℃, freeze-thaw twice, the ratio of cyanobacteria to water(the concentration of cyanobacteria)1.25%; the optimum conditions of salting-out are two-step salting-out,20%and35%ammonium sulfate saturation; the optimum conditions of aqueous two-phase are pH6.0, the concentration of PEG400016%, the concentration of KHP12%; the optimum condition of ultrafiltration is30KDa ultrafiltration.Finally the purity of C-phycocyanin up to4.8, and yield2.4%, in line with internationally recognized C-phycocyanin fluorescence reagent grade purity standard (4.0).During the extraction and purification of C-phycocyanin, the intracellular microcystins will be released simultaneously, distribution of MC-LR during the extraction of C-phycocyanin and C-phycocyanin concentrate was studied.The results showed that81.23%of MC-LR existed in the ultrafiltrate during the C-phycocyanin extraction.In the C-phycocyanin concentrate didn’t detect MC-LR, thus the C-phycocyanin obtained is with higher security.A microcystin-degrading strain was immobilized by activated carbon fiber (ACF), and the effect factors, such as the pretreatment methods of activated carbon fiber, dosage of activated carbon fiber, pH value, temperature and the initial concentration of MC-LR were investigated. The results showed that the immobilized strain presented significantly better performance in MC-LR removal than the non-immobilized strain. The performance of ACF which was pretreated with (1+9) HC1was much better than others. The optimum removal conditions were as follows; dosage of activated carbon fiber was lOg/L, the temperature was35℃, the pH value was8.0, and the initial concentration of MC-LR was13.6mg/L, the removal rate reached92.8%. Therefore, immobilized strain showed a certain tolerance towards the pH value and the temperature. And MC-LR could be removed effectively in the range of pH5topH9,10℃-35℃.