Phytases catalyze the hydrolysis of phytic acid into myo-inositol phosphates and inorganic phosphates and are used as animal feed additives. The main objective of this study is to discover a new phytase, which has high thermal stability, protease resistance, and pH stability for its usability in the feed industry. For this purpose, this study focused on purifying and characterizing the thermostable phytase derived from thermotolerant Aspergillus tubingensis TEM 37 strain at first time, which was isolated from a hot spring soil in the Gediz geothermal field (Turkey). The optimum pH and temperature of the phytase were determined as pH 2.0-5.5 and 45 degrees C, respectively. The molecular weight of the enzyme was determined as 48 kDa. The phytase preserved almost 100% of its activity at 80 degrees C for 3 h. The enzyme showed high resistance against K+, Ba2+, Cu2+, Mg2+, Zn2+ and Tween 20, CTAB, and isooctane among tested compounds. The enzyme also showed high stability against proteases and retained its activity as 88% for pepsin and 98% for trypsin for 120 minutes. In conclusion, it was demonstrated that the thermotolerant A. tubingensis TEM 37 strain naturally produces the phytase that was thermostable and resistant to proteases as required by feed industry.
