Screening, Expression, and Characterization of Recombinant Phytase from Bacillus subtilis KM-BS for Bio-hydrolysis of Phytic Acid in Animal Feeds

In this study, phytase genes obtained from Bacillus subtilis KM-BS cultured at 37°C (PhyC-37) and 55°C (PhyC-55) were successfully expressed in Escherichia coli BL21 (DE3). The over-expression of the recombinant phytase was optimal within just 2 h after using 0.1 mM IPTG. SDS-PAGE analysis showed that the purified enzymes had a predicted molecular mass of 58 kDa and exhibited high activities at 3.73 and 2.51 U/mL for the PhyC-37 and PhyC-55, respectively. Optimal temperature for both enzymes was 55°C, and these enzymes displayed the highest activity at pH 7.0 and 5.0 for purified PhyC-37 and PhyC-55, respectively. Metal ions such as Na+, K+, Mg2+, Ca2+, Mn2+, Co2+, and Zn2+ stimulated enzyme activities, while their activities were moderately to completely inhibited in the presence of Cu2+, SDS, EDTA, Triton X-100, and Tween-80. KM and Vmax values for PhyC-37 using sodium phytate as substrate were 0.18 mM and 0.45 µmol/min, respectively, while for PhyC-55, the corresponding values were 0.17 mM and 0.35 µmol/min. The hydrolysis of rice bran using the in-house crude phytases increased phytic acid digestion efficiency by 3.9−5.9-fold compared to without enzyme addition, with high hydrolysis rates within the first 2 h. The data emphasizes their potential application in the animal feed industry, offering a promising solution to mitigate environmental eutrophication.