An efficient low-cost, no-chemicals, water-recycling method for the production of pure phycocyanin from Arthrospira maxima

Spirulina (Arthrospira platensis), a blue-green coil shaped cyanobacterium, is known in the food and nutraceutical sectors as an important source of water soluble proteins, antioxidants, vitamins and minerals [1]. It is an important source of C-phycocyanin (CPC), a water soluble protein belonging to the phycobiliprotein family having a great potential for industrial and commercial exploitation due to its therapeutic properties including antioxidant, antiinflammatory and anti-cancer activities. The purification of CPC from Spirulina generally involves a combination of different techniques including sonication, extraction, centrifugation, chromatography, ion exchange and dialysis [2]. Here we report the results on CPC yields compared among extraction methodologies from a strain of Arthrospira maxima, cultivated in a farm devoted to produce food additives for human consumption. The simplest, the environmental and energetic sustainable methodology gave the best yield and quality of phycocyanin tested by means the SDS-PAGE patterns and mass spectrometry analysis. Samples produced at different extraction times were purified by ultrafiltration (UF) using a stirred dead-end filtration system equipped with a polyethersulphone membrane having a molecular weight cut-off of 20 kDa. Filtration experiments were performed at an operating pressure of 2.0±0.1 bar and a temperature of 25±2 °C up to a volume reduction factor (VRF) of 5. After UF, the remaining retentate was diafiltrated with distilled water in order to increase the recovery of phycocyanins in the retentate. Ultrafiltrated samples were processed by electrophoretic analyses in order to asses proteins quality and purity and to check contamination by nucleic acids. In the selected operating conditions, the rejection of the UF membrane towards phycocyanin resulted higher than 97.8% independently by the extraction yields and times. The concentration of CPC in the final retentate resulted of about 0.9-1.1 g L-1, about 5-fold when compared to the concentration of CPC in the crude extract (0.19 g L-1). The integrated extraction-UF process provides an efficient low-cost and no-chemicals method for the production of pure phycocyanin suitable for commercialization as additive in protein food, antioxidant in pharmacological and therapeutics and natural dye in cosmetics and pastry.