The role of bacteriophage in biofilm development of pseudomonas aeruginosa

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen which can develop biofilms. Biofilm of P. aeruginosa has shown to give rise to phenotypic variants. The factors that contribute to the formation of variants in P. aeruginosa has not been extensively studied. It has been shown that emergence of variants corresponds with the detection of superinfective phage. Therefore, PAO1 (host) and superinfective-Pf4 (phage) were used as a model to study the effects of host-phage interaction on variant formations and virulence during biofilm development. In this study the transcriptome of PAO1 WT and PAO1ΔPf4 was monitored to test the effects of exposure to Pf4 in order to better understand the factors involved in variant formation. Upon infection of phage, genes involved in SOS response, were upregulated. As the polymerases involved in this response system tend to be error-prone, increase in mutation rates could result in formation of variants. Transcriptomic validation also showed that expression levels of pyoverdine genes in biofilms of PAO1 that harbours the Pf4 prophage. These findings indicate that activation of SOS response due to phage infection is a possible mechanism of variant formation in P. aeruginosa biofilm and pyoverdine might be one of the virulence factors regulated by the Pf4 phage.