Extraction And Purification Of Phycocyanins From Spirulina

Spirulina is one of the low prokaryotic aquatic plants,belonging to cyanophyta,flutter algae branch.There are rich nutrients and verious bioactive substances contained in Spirulina,which was regared as "the best health care products for human in the 21st century" by the World Health Organization.The main phycobiliprotein in spirulina is phycocyanin,which is a natural pigment protein,can be made into food colorants non-hazardous to the human body and additives of senior cosmetics etc.Meanwhile,the phycocyanin itself with fluorescent characteristics is also used as an expensive biochemical reagents.Secondly,phycocyanin has special medicinal value as well,such as it can be made into a very promising photosensitizer in photodynamic therapy of tumors etc.However,because of the high cost of phycocyanin,it is difficult to get the actual application.The purpose of this thesis is to study purification method of phycocyanin,and to get a relatively cheaper way for the purification of phycocyanin.In this thesis,the extraction conditions of Spirulina phycocyanin were optimized first,the results of experiments showed that the ratio of solid to liquid,ultrasonic time and extraction times etc.had effect on the extraction of phycocyanin.The study of single factor to get phycocyanin was optimized.Under trhe optimum conditions of extraction:ratio of solid to liquid 1:25,ultrasonic time 15 min,the extraction time 5 h and extracted for 3 times,phycocyanin with a purity of 0.577 could be got.We applied aqueous two-phase extraction to purify the optimized weightcrude extraction of phycocyanin,and studied effects of PEG average molecular,the TLL,VR and pH on the purification of phycocyanin.The results of optimum condition showed that,when the PEG average molecular weight was 2 000,TLL was 34.53%,VR was 0.55,pH was 6.5,phycocyanin with a purity of 1.47 could be got in aqueous two-phase extraction way.Finally,we use chitosan and ammonium sulfate to purify the optimized crude extraction of phycocyanin,then optimizing the conditions of chitosan purification and ammonium sulfate salting-out.Using hydroxyapatite chromatography and aqueous two-phase to purify the phycocyanin,which is purified by chitosan and salting out method,respectively,the A620/A280 was about 2.2 to both methodes.Comparison of cost,yield,purity,and time of the two methodes,respectively,the purify of phycocyanin with aqueous two-phase extraction is more economical.