LAUSR

Abstract Cyanobacteria are photosynthesizing prokaryotic microorganisms that stand out by the production of phycobiliproteins, which can be used as therapeutic agents, tools for medical diagnosis and as natural compounds for food coloring and cosmetics. Therefore, in order to purify the most relevant phycobiliproteins [phycocyanin (PC), allophycocyanin (APC) and phycoerythrin (PE)] from Anabaena variabilis and Nostoc sp., an aqueous two-phase system (ATPS) with different proportions of PEG/salt was used. The system was composed by PEG1500 and different salts, including potassium phosphate, sodium citrate and ammonium sulfate. Notably, both strains revealed high concentrations of phycobiliproteins when compared to other studies, highlighting the efficacy of the method. The highest values of the partition coefficient (K) observed in A. variabilis were obtained by 13% (w/w) PEG 14% (w/w) potassium phosphate proportion (KPC = 8.63 KAPC = 5.11 and KPE = 4,94) and for Nostoc sp., 13%PEG/14% sodium citrate proportion (KPC  = 17.18, KAPC = 32,65 and KPE = 7.15).