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Aqueous two-phase extraction for partial purification of Schizophyllum commune phytase produced under solid-state fermentation

Abstract This study describes a simple strategy for partial protein purification using an aqueous two- phase system (ATPS) of polyethyleneglycol (PEG)/sodium citrate. The protein studied was phytase produced by Schizophyllum commune under solid-state fermentation (SSF). A 24 experimental design (20 runs and 4 central points) was carried out with four factors (PEG molar mass, citrate concentration, PEG concentration, and pH) to evaluate the enzyme extraction. The responses’ partition coefficient (K), yield (Y), and the purification factor (PF) were analysed. The best system obtained was with 14% (w/w) sodium citrate, 22% (w/w) PEG with a molar mass of 1500 (g/mol), and pH of 7. The maximum partition coefficient (K) was 2.63 and also the citrate concentration had a positive effect. Under these conditions, in the top phase the highest phytase yield achieved was 367%, and the purification factor (PEG) was 5.43. Liquid–liquid extraction can therefore be used as a first step in the purification processes of phytase from S. commune.