Fig. 3 . A model for the behavior of WT and mazEF cultures during phage P1 attack. (A) In WT cells, mazEF mediates the death of the infected cells. As a consequence, the development of the phage is restricted, the phage titer is low, and the culture survives. (B) In mazEF cultures, nothing interferes with the phage infections: the infected cells lyse and spread infecting particles to the rest of the cells in the culture. Thus, the WT culture can survive phage infections whereas the mazEF culture dies. PCD, programmed cell death.