Recombinant production of Penicillium oxalicum PJ3 phytase in Pichia Pastoris

The 1,332 bp phytase gene of Penicilliumoxalicum PJ3 was inserted into the expression vector, pPICZαA and expressed in the methylotrophic yeast, Pichia pastoris as an active, extracellular phytase. The recombinant phytase reached a maximum yield of 12 U/ml of medium at 120 h of cultivation after methanol induction under shake-flask conditions. The enzyme was glycosylated, with a molecular mass of about 62.5 kDa. The Michaelis constant (Km) and maximum reaction rate (Vmax) for sodium phytate was 0.37 mM and 526.3 U/mg of protein, respectively. The optimal activity occurred at pH 4.5 and 55°C.