噬菌体的繁殖 Presence of infecting pha Bacterial growth produces progeny phages that results uniform coverage (a "lawn") in a clearing plaque) in where no phage is present. a small region Bacterial bactor Figure 8.16 Plaque formation. (A) In the absence of a phage, bacte rial cells grow and form a translucent Lawn Bacterial cells deposited in the vicinity of a phage are infected and lyse Progeny phages diffusing outward from the riginal site infect other cells and cause their lysis. Becaase of phage infection and lysis, no bactenia can grow in a small region atound the site et each phage particle originally present in the medium. The area devoid of bacteria remains transparent and is called a plaque. (B) Large plaques in a lawn of E, cl formed by infection with a mutant of bacteriophage A. Each plaque results from an inital iniection by a single bac-噬菌体的繁殖