Hydrolyzes B-glucans containing mixed beta-1,3 and beta-1,4 linkages. Hydrolysis of (1->4)-beta-D-glucosidic linkages in beta-D-glucans containing (1->3)- and (1->4)-bonds. Optimum temperature is 65-70 degrees Celsius. Thermostable. Beta-glucanases of Bacillus have a substrate range similar to lichenase of germinating barley. Belongs to the glycosyl hydrolase 16 family.