beta-Mannosidase (EC 3.2.1.25) is an exoglycosidase specific for the hydrolysis of terminal beta-linked mannoside in various sugar chains. cDNA corresponding to the beta-mannosidase gene was cloned from Aspergillus niger, sequenced, and expressed in the yeast Pichia pastoris. The beta-mannosidase gene contains an open reading frame which encodes the protein with 933 amino acid residues. The wild type and recombinant proteins were purified to apparent homogeneity and biochemically characterized (K-M 0.28 and 0.44 mmol/l for p-nitrophenyl beta-D-mannopyranoside, pI 4.2 and 4.0, and their pH optima were at pH 4.5 and 5.5 and 65 degrees C, respectively). (C) 2012 Elsevier Inc. All rights reserved.