N-acetylmuramyl-L-alanine amidase involved in innate immunity by degrading bacterial peptidoglycans (PGN) (PubMed:11106397, PubMed:12496260). Plays a scavenger role by digesting biologically active PGN into biologically inactive fragments (PubMed:12496260). Has no direct bacteriolytic activity (PubMed:12496260). Hydrolyzes the link between N-acetylmuramoyl residues and L-amino acid residues in certain cell-wall glycopeptides. Constitutively expressed at high level in gut, in addition to the induced expression in fat body. Up-regulated by PGN from B.subtilis. Belongs to the N-acetylmuramoyl-L-alanine amidase 2 family. Extended N-terminus.