β-Glucosidase 1A, Bacillus halodurans (EC 3.2.1.21), is an enzyme that acts on β1→4 glycosidic bonds linking two glucose or glucose-substituted molecules, such as in the disaccharide cellobiose. As a member of the cellulase family, this enzyme is involved in the breakdown of cellulose and related polysaccharides. More specifically, it functions as an exocellulase, showing specificity toward various β-D-glucoside substrates by catalyzing the hydrolysis of the terminal non-reducing residues, thereby releasing glucose.