Biochemical properties of extracellular phytases from Bacillus spp

Phytases are phosphohydrolases that catalyzes the release of phosphate from phytate (myo-inositol hexakisphosphate), the major phosphorus (P) form mostly occurring in animal feeds of plant origin. These enzymes can be supplemented in animal diets to reduce inorganic P supplementation and fecal P excretion. Four species of Bacillus, B. pumilus, B. megaterium, B. coagulans, and B. licheniformis were used to study the biochemical characteristics of their phytases. The results showed that all the strains investigated were able to hydrolyze extracellular phytate. The activity of phytase increased markedly in late stationary phase in all the species tested. The highest enzyme activity was found in B. megaterium phytase after the 4th day of culture. The crude phytases from the different Bacillus strains were optimally active at pH values from 5.5 to 7.0 at 37C and retained activity at assay temperatures up to 80C. The enzymes exhibited thermostability, retaining 6 50% activity at 70C and were fairly stable up to pH 10. These properties indicate that the Bacillus phytases appear to be suitable for animal feed supplementation to improve the availability of P from phytases.