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

摘要

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 60deg C. The enzyme retained 40% of its original activity after 30 min incubation at 80deg 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 polyphosphatecompounds such as adenosine triphosphate, sodium tripolyphosphate, and sodium phytate. and Vmax values for sodium phytate were 0.42 mM and 4.35 mumol/min, respectively.