Isolation and properties of extracellular alkaline phosphatase from Bacillus intermedius

Alkaline phosphatase (APase) was isolated from the culture liquid of the st reptomycin-resistant strain of Bacillus intermedius S3-19 and purified as a homogeneous preparation by ion-exchange chromatography and FPLC. Electroph oresis and gel-filtration revealed that the active enzyme is a monomer with molecular weight of 46-47 kD. The enzyme possessed phosphomonoesterase and phosphodiesterase activities with maximal levels at pH 9.5 and 55 degrees C and was stable until 60 degrees C at pH 8.0-10.0. The isolated APase exhi bits a broad specificity towards a wide variety of substrates. The effect o f divalent metal ions and other reagents on its catalytic activities was st udied. It was concluded that alkaline phosphatase of B. intermedius is simi lar to the secreted alkaline phosphatases from other Bacillus species in it s physicochemical and catalytic properties.