The λ phage endolysin is an 18-kDa soluble protein with murein transglycosylase activity[1]. In λ lysis system, enzymatically active endolysin accumulate in cytoplasm without harm to host bacteria before 'lysis time' because the holin accumulate in CM without disturbing its integrity during this time. However, at an allele-specific time, the holin oligomerizes to form a small number of large holes, allowing the endolysin to cross the CM and attack the PG [2][3] (Fig. 2).