Purification and Characterization of a β-Glucosidase from Aspergillus niger and Its Application in the Hydrolysis of Geniposide to Genipin

An extracellular beta-glucosidase from Aspergillus niger Au0847 was purified to homogeneity by precipitation with ammonium sulfate, anion exchange, and gel filtration. The purified protein was composed of two subunits with molecular masses of 110 and 120 kDa. Au0847 beta-glucosidase exhibited relatively high thermostability and pH stability, and its highest activity was obtained at 65 degrees C and pH 4.6, respectively. As a potential metalloprotein, its enzymatic activity was potently stimulated by manganese ion and DTT. The beta-glucosidase displayed avid affinity and high catalytic efficiency for geniposide. Au0847 beta-glucosidase has potential value as an industrial enzyme for the hydrolysis of geniposide to genipin.