Vegetos

Abstract

Microbial enzymes meet industrial demands. Over 60% of the total Phosphorus in cereal grains and oil seeds as well as their by-products is found as phytate, myo-inositol hexakisphosphate. Phytases are a group of enzymes that initiate the phosphate hydrolysis from phytate and produce myo-inositol and inorganic phosphate by catalyzing the stepwise removal of the phosphate groups. Microbial phytases effectively improve dietary phytate-P utilization. Extracellular phytase produced by Bacillus subtilis ATCC 6051 was purified by acetone precipitation, DEAE-sepharose and phenylsepharose column chromatographies. The molecular weight of the enzyme was estimated to be 48 kDa on gel filtration and 43kDa on SDS-polyacrylamide gel electrophoresis. Its optimum pH and temperature for phytase activity were pH 6.2 to 8.2 and 40°C without 10mM CaCl₂ and pH 6.5 to 9.5 and 60° with 10mM CaCl₂. The enzyme activity was stable from pH 6.5 to 10. The enzyme had an isoelectric point of 6.8. It was very specific for sodium phytate. The Km value for sodium phytate was 50μM. Its activity was inhibited by EDTA and metal ions such as Mn²⁺, Hg²⁺, Cu²⁺, Cr³⁺, Co²⁺, Ba²⁺ and Cd²⁺ ions. The enzyme has great potential in food industry, probiotics, animal feed supplement and transgenic crops.