Has bacteriolytic activity against Gram-positive bacteria (By similarity). May play a role in resistance to Gram-positive bacterium S.aureus infection (PubMed:24882217). 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. Expressed in pharyngeal muscle cell pm3, nerve ring and intestine. Induced by Gram-positive bacterium M.nematophilum CBX102 infection but not by Gram-negative bacterium P.aeruginosa PAO1 infection (PubMed:27525822). Induced by Gram-positive bacterium S.aureus infection (PubMed:24882217). Simultaneous RNAi-mediated knockdown of lys-5 results in a reduction in survival following S.aureus infection. Belongs to the glycosyl hydrolase 22 family. Type-I lysozyme subfamily.