Large preferential Site for packaging of bacterial DNA by phiC725A, a new Pseudomonas aeruginosa F116-like bacteriophage

Bacteriophage vB_PaeP_PAO1_phiC725A (short name phiC725A) was isolated following mitomycin C induction of C7-25, a clinical Pseudomonas aeruginosa strain carrying Pf725A as a prophage. The Pf725A genome sequence shows similarity to F116, a P. aeruginosa phage capable of generalized transduction. Similarly to F116, phiC725A is a podovirus with long tail fibers. phiC725A was able to lysogenize two additional P. aeruginosa strains in which it was maintained both as a prophage and in an episomal state. Investigation by deep sequencing showed that bacterial DNA carried inside phage particles originated predominantly from a 800kb region, immediately flanking the attL prophage insertion site, whether the phages were induced from a lysogen or recovered after infection. This indicates that during productive replication, occasional recombination of phage genomes with the bacterial chromosome at the att site occurs, allowing packaging of adjacent bacterial DNA.