Figure 1.

Illustration of the bacteriophage lifecycle and mechanism of bacterial lysis. (A) Lytic cycle, ①Recognition of host by phage; ②Absorption of bacteriophage to bacteria; ③Phage penetrates nucleic acid; ④Replication of phage nucleic acid; ⑤Synthesis of phage elements; ⑥Assembly of progeny phages; ⑦Bacterial lysis and release of progeny phages. (B) Role of phage endolysin in bacterial lysis: in the early stage of phage infection, the phage creates holes in the bacterial cell wall with the assistance of the VAPGH protein (which degrades a part of peptidoglycan) and injects nucleic acid into the host bacteria. Phage endolysins and holin are synthesized during the late stage of progeny phage reproduction. Holin forms pores in the bacterial inner membrane, allowing endolysins to reach the peptidoglycan.