**3.3 Bacteriophages**

Bacterial viruses that cause infections in bacterial cells are called as bacteriophages. it has an important role in the dissemination of virulence-associated and antibiotic resistance genes among foodborne pathogens, As we know viruses are found ubiquitously and are present in oceans, sewage, soils, and various microbial communities [60, 61]. Phages have an important role in protecting the bacterial colonization of mucosal surfaces [62]. In the case of lytic phages, there has an important role in bacterial DNA transfer, and the process is called transduction (generalized transduction), while temperate phages can transmit only some particular genes in the bacterial chromosome (specialized transduction)**.** During this some segments of bacterial DNA are co-edited with the prophage DNA for example tetracycline resistance gene from the *E. coli* O157:H7 to the K-12 AB-1157 strain of *E. coli* [60, 63]. Bacteriophages are actively in the acquisition of β-lactamase genes such as *blaCTX-M, blaSHV, blaTEM, qnr A, qnr B*, and *qnr S*. like P1 bacteriophage with *SHV-2* gene has been reported [64]. Additionally, phages are also involved in the dissemination and transformation of staphylo-kinase, superantigens, and phosphor-lipase or DNase virulence factors. Bacteriophage , transmit not only

adhesion genes of bacteria but also transfer the housekeeping genes of bacteria. Cytolethal distending toxins (Cdts) are inhibitory cyclomodulins, which prevent eukaryotic cell proliferation, *E. coli* strains are also associated with its production and it has been established that *Cdt-I* produced by EPEC strains the main source was lambdoid prophage [65]. Additionally, *E. coli* phage (lambdoid prophage) transfers the *Cdt* gene group encoding the *Cdt-A*, *Cdt-B*, and *Cdt-C* subunits of the *Cdt-I* holotoxin. One of the important toxins known as Shiga toxin 2, which is a virulence factor in *E. coli* O157:H7 strain being transferred by temperate phage. Furthermore, some other variants of Shiga toxin comprising of the infective *E. coli* O157 strain another variant Shiga toxin 2-c are also encoded by phages. For example, some phages such as phi-C119 can be used as biological control mediators, as they can lyse and infect their bacterial hosts [66].
