Phytase activity from Aspergillus oryzae AK9 cultivated on solid state soybean meal medium

Phytase from a soy sauce koji mould was produced by solid state fermentation using soybean meal as the main substrate. The cultivation was carried out at 30 °C for 96 h. Characterization of the crude phytase showed that the maximum activity was obtained when the reaction was carried out at 75 °C and pH 5.0. However, after 2-h storage at different pH, maximum remaining activities were obtained when stored at pH 3.6 and 5.5 possibly indicting the presence of two distinct phytase enzymes. However, at different temperatures, there was only one peak of maximum remaining activity after 2-h storage at 40 °C. The presence of trypsin and taurochlorate at 1.0% (w/v) did not affect enzyme activity. Digestion of pre-mixed chicken feed with the enzyme koji at approximately 500 U/kg feed in the presence of 1% each of trypsin and taurochlorate increased the phosphate and protein available for animal consumption.