Improvement of Phytase Biosynthesis from Aspergillus tubingensis NBIMCC 3457 by Simple One-Step Optimization

Optimization of nutrient medium composition and cultivation conditions is a simple tool for directing enzyme biosynthesis of microbial strain towards the synthesis of a desired enzyme with maximum activity. The aim of the present study is to optimize the composition of the nutrient medium and the cultivation conditions for maximum phytase biosynthesis by Aspergillus tubingensis. The most suitable sources of carbon, inorganic and organic nitrogen, phosphorus and salts for obtaining maximum phytase activity were determined. The effect of concentration of medium components on phytase biosynthesis was investigated. The optimal component composition of the nutrient medium was determined to be rice starch, peptone and ammonium oxalate. A response surface methodology was applied for determination of the optimal concentrations of the components of the nutrient medium for maximum phytase biosynthesis. The optimal composition of the nutrient medium was determined to be rice starch 13.5 g/L, peptone 4.84 g/L and ammonium oxalate 2.92 g/L. With the optimized nutrient medium experimental value of 26.68 U/mL, phytase activity was obtained. This value was 185 % higher in comparison to the activity obtained with the initial nutrient medium (9.35 U/mL). By a simple optimization of the nutrient medium, a significant increase in phytase activity was achieved.