Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrins. Usually lysozymes have a catalytic site with Asp and Glu, but B-enzyme has no Glu (two Asp for catalytic site).