Contribution of prophages to the physiology and the virulence of Pseudomonas aeruginosa 2192 strain

P. aeruginosa is one of the most common pathogens causing respiratory infections in hospitalized patients. P. aeruginosa 2192 is a clinical strain originally isolated from CF patient with chronic infection and it differs phenotypically from P. aeruginosa WT strain (PAO1). The accessory genome of 2192 is mainly composed of mobile genomic elements and six prophage regions. It is important to characterize the prophages in 2192 in an attempt to better understand their contribution to the strain lifestyle. Focus was given to the sixth prophage of 2192 (2192p6) and an adjacent bacterial gene #5958 that encodes for a bacterial regulatory protein with a DNA binding domain Cro/CI-type which might suggest a regulative role on this phage. The induction of the 2192 phages revealed that 2192p6 can be induced and its exact borders were determined by sequencing. The over-expression (OE) of 5958 did not alter the growth rate of neither 2192 nor PAO1 strains while deletion of the gene in 2192 resulted in a significant decrease in the growth rate and in the viability of this strain. The ∆5958 strain releases less phages compared to WT 2192 and the deletion of the gene resulted in reduced biofilm formation in comparison with WT 2192. The OE of 5958 in PAO1 provided this strain with partial defense against infection of phages from 2192. Taking together, 5958 shows more lysogenic stability properties rather than Cro-like properties.