Characterization and Application of Calcium-Dependent beta-Propeller Phytase from Bacillus amyloliquefaciens DS11

Abstract

The enzyme phytase has broad biotechnological applications, especially in the reduction of phytate, antinutritional factors that chelate essential minerals, in human and animal food. We investigated the enzymatic properties of beta-propeller phytase (BPP) from Bacillus amyloliquefaciens DS11. Thermal refolding analysis demonstrated that BPP can remarkably restore its enzymatic activity in the presence of 5 mM Ca2+ to 87% of its original activity after heating to 100 degrees C and subsequent cooling, indicating that the enzyme requires Ca2+ for appropriate refolding. Furthermore, pH-dependent kinetic studies showed that BPP required excess Ca2+ for its enzymatic activity as the pH decreased, suggesting that the optimal Ca2+-phytate ratio for enzymatic catalysis depends on the pH value of the environment. Finally, we verified the practical application of BPP at two different pH's using soybean meal as a natural source of phytate. As compared to a commercial phytase, BPP efficiently hydrolyzed food phytate over neutral pH ranges.