Purification and Biochemical Characterization of Thermostable Phytase from Newly Isolated Bacillus subtilis CF92

Bacillus subtilis CF92, an isolate from cattle feces, produces phytase, which catalyzes the hydrolysis of phytic acid into myo-inositol and inorganic phosphates. Phytase from B. subtilis CF92 was purified via ethanol precipitation, anion-exchange chromatography, and gel filtration chromatography. Molecular weight of the purified phytase was estimated to be 46 kDa by SDS-PAGE. Purified phytase exhibited optimal activity at 60 degrees C. The enzyme retained 40% of its original activity after 30 min incubation at 80 degrees C. Optimum pH was 7.0, although activity remained fairly stable over pH range of 4.0 to 8.0. The enzyme was activated in the presence of EDTA and significantly inhibited by metal ions. Phytase exhibited substrate-specificity on polyphosphate compounds such as adenosine triphosphate, sodium hipolyphosphate, and sodium phytate. K, and V-max values for sodium phytate were 0.42 mM and 4.35 mu mol/min, respectively.