N-acetylglucosaminidase involved in cortex peptidoglycan degradation during germination. Cleaves only partially degraded spore peptidoglycans. Recognizes muramic acid delta-lactam residues specific to spore peptidoglycans. Inhibited by diethylpyrocarbonate. Optimum pH is 6.0. Probably localizes to the exterior of the cortex layer. Belongs to the glycosyl hydrolase 18 family. Chitinase class II subfamily.