Plays a role in peptidoglycan recycling by cleaving the terminal beta-1,4-linked N-acetylglucosamine (GlcNAc) from peptide-linked peptidoglycan fragments, giving rise to free GlcNAc, anhydro-N-acetylmuramic acid and anhydro-N-acetylmuramic acid-linked peptides. Cleaves muropeptides, but not peptidoglycan. Hydrolysis of terminal non-reducing N-acetyl-D-hexosamine residues in N-acetyl-beta-D-hexosaminides. Optimum pH is 5.8-6.2. Cell wall biogenesis; peptidoglycan recycling. Detected in the culture supernatant, predominantly associated with cell wall-derived particulate material. A minor proportion is detected in the soluble fraction. Up-regulated during the late phase of exponential growth and during stationary phase. Belongs to the glycosyl hydrolase 3 family.