N-acetylmuramyl-L-alanine amidase involved in innate immunity by degrading bacterial peptidoglycans (PGN), preferentially DAP-type PGNs. Probably plays a scavenger role by digesting biologically active PGN into biologically inactive fragments. Hydrolyzes the link between N-acetylmuramoyl residues and L-amino acid residues in certain cell-wall glycopeptides. In larvae, it is mainly expressed in fat body. Strongly up-regulated by PGN from B.subtilis. Weakly or not expressed in normal conditions. Regulated by the imd/Relish pathway. Belongs to the N-acetylmuramoyl-L-alanine amidase 2 family.