Optimized extraction of phycobiliproteins from Arthrospira platensis: quantitative and qualitative assessment of C-Phycocyanin, Allophycocyanin, and Phycoerythrin

Phycobiliproteins (PBPs) are light collecting pigments of cyanobacteria that attract growing interest for several industrial applications. Each step of the extraction process is crucial for yield, concentration and quality of obtained pigments. In the current work, we present an optimization scheme of major limiting steps for PBPs extraction from Arthrospira platensis biomass. As first step, the effects of pretreatment, extraction time, and separation conditions on the recovery of PBPs were compared. Subsequently, the influence of pH and concentration of the extraction buffer as well as the addition of preservatives (Polyethylene glycol (PEG), Magnesium chloride (MgCl₂), and Calcium chloride (CaCl₂)) was studied. In addition, the effect of the biomass type (dried vs wet) and its concentration in the extraction buffer was also investigated. Optimal extraction required the use of dry biomass at relatively low ratio (1:50, solvent:biomass), without previous treatment. The use of concentrated phosphate buffer (100 mM) at a neutral pH gave the highest PBPs recovery and concentration after 6 h of extraction followed with a separation at 6000 rpm during 15 min. Calcium chloride used at 1.5% improved by 30% both PBPs recovery and concentration in the crude extract. The optimized protocol allowed the recovery of 464.5 mg/g PBPs from spirulina biomass with concentration of 15.9 mg/ml. The crude PBPs obtained with this extraction method reduced the stable radical DPPH with a percentage scavenging activity of 86.45 ± 1.2%. This protocol could reduce both PBPs time and cost extraction and is easily scalable for industrial application.