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

Abstract

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°C and between pH 7.0 and pH 8.0. The enzyme exhibited thermostability with ∼80% activity at 70°C and pH 8.0 for up to 3 h in the presence/absence of 5 mM CaCl2. The phytase from B. laevolacticus showed high specificity for phytate salts of Ca+ > Na+. The enzyme showed an apparent Km 0.526 mM and Vmax 12.3 μmole/min/mg of activity against sodium phytate. © 2006 Society for Industrial Microbiology.