Phage life cycles. After attachment, the phage injects all its genetic material through the cell wall into the cytoplasm. The phage might then enter the lytic cycle, where it replicates, produces new mature progeny, and eventually lyses the bacterial cell by the insertion of the pore forming holin in the inner membrane, thus allowing the endolysin to gain access to and degrade peptidoglycan. Certain phages, termed temperate phages, can under the right environmental circumstances instead enter the lysogenic life cycle and either integrate their genetic material into the host chromosome by the use of integrases or exist as stable extrachromosomal plasmids. These phages, so called prophages, are then replicated along with the bacterial chromosome. Once prophages are induced (activated), they will enter the lytic cycle, start to propagate, and eventually lyse their host. The figure is adapted from [32].
