Purification and properties of an extracellular inulinase‐like β‐fructosidase from Bacillus stearothermophilus

A novel extracellular β-fructosidase (EC 3.2.1.26) produced by Bacillus stearothermophilus has been identified and purified. The purified enzyme, obtained by using successive QEAE Sepharose fast flow and Sephacryl S300 HR columns, has a 600 kDa relative molecular weight (M r ) and is composed of 60 kDa subunits indicating a multimeric structure. The pH and temperature for optimal activity are 6-5 and 65°C respectively, the enzyme being thermostable at this temperature. The apparent K m values for sucrose and inulin are 3.56 mmol −1 and 1 mmol 1 −1 respectively, the total invertase (EC 3.2.1.26)/total inulinase (EC 3.2.1.7)ratio being 4