Anotace:
Phytate take effect as an anti-nutrient element in food and feed materials. Thus, phytase, by catalyzing phytate, hydrolyzing the phosphomonoester bonds and releasing the inorganic phosphorous, decrease the phytate and enhance their nutritional value. Therefore, in this study, Bacillus sp. strain LA12was isolated from natural origins and the phytase production activity was evaluated. The novel extracellular phytase was produced and precipitated by saturated ammonium sulfate. The ion-exchange chromatography on DEAE-sepharose and the size-exclusion chromatography on Sephadex G-100 were used to purify the enzyme. The results showed that the purification yield and concentration of final enzyme were 5.9% and 18.4%, respectively. Based on SDS-PAGE results the molecular weight of the phytase was determined about 73 kDa. Optimal activity of the enzyme was obtained at pH of 5.5 and 60 ºC. Kinetic parameters Km and Vmax were 0.197 mM and 1.174 µmol/min, respectively. Mg2+, Co2+ and EDTA accelerated the effect on phytase activity; whilst adding other metal ions such as Ca2+, Zn2+ and Fe2+ in both concentrations could decrease its activity. Moreover, Mn2+ ion didn’t show indicative effect on its activity. The purified phytase exhibits good thermal stability after incubation at 50-70°C for 30 min, whereas the phytase activity drastically decreased up to 61% at 80°C. This study indicated that the purified phytase has the desired characteristics and can promisingly be used for hydrolyzing of phytate in food and feed.