Production and characterization of thermostable alkaline phytase from Bacillus laevolacticus isolated from rhizosphere soil

A novel phytase producing thermophilic strain of Bacillus laevolacticus insensitive to inorganic phosphate was isolated from the rhizosphere soil of leguminous plant methi (Medicago falacata). The culture conditions for production of phytase by B. laevolacticus under shake flask culture were optimized to obtain high levels of phytase (2.957 +/- 0.002 U/ml). The partially purified phytase from B. laevolacticus strain was optimally active at 70 degrees C and between pH 7.0 and pH 8.0. The enzyme exhibited thermostability with approximately 80% activity at 70 degrees C and pH 8.0 for up to 3 h in the presence/absence of 5 mM CaCl(2). The phytase from B. laevolacticus showed high specificity for phytate salts of Ca(+) > Na(+). The enzyme showed an apparent K (m) 0.526 mM and V (max) 12.3 mumole/min/mg of activity against sodium phytate.