Regulation of filamentous phage Pf4 activation by oxidative stress in .

The filamentous prophage Pf4 is activated to produce phage virions during biofilm formation, a process crucial for maintaining biofilm architecture and enhancing pathogenicity. However, the environmental cues triggering Pf4 activation have been inadequately explored. In this study, we discovered that oxidative stress, a significant stressor encountered by pathogens in biofilms or within eukaryotic hosts, triggers the production of the filamentous phage Pf4 in MPAO1 through OxyR. Under oxidative stress, the expression of is induced, leading to increased OxyR binding to the promoter region of the Pf4 excisionase gene , thereby facilitating Pf4 prophage excision and virion production. Thus, our study elucidates a mechanism by which bacteria exploit cytotoxic oxidative stress as a potent stimulant to activate the filamentous phage Pf4 within biofilms.