Pseudomonas aeruginosa is a versatile and ubiquitous bacterium that frequently infects humans as an opportunistic pathogen. P. aeruginosa competes with other strains within the species by producing killing complexes termed pyocins, which are only known to be induced by cells experiencing DNA damage and the subsequent SOS response. Here, we discovered that strains lacking a recombinase enzyme called XerC strongly produce pyocins independently of the SOS response.

The opportunistic pathogen Pseudomonas aeruginosa produces pyocins—intraspecific, interbacterial killing complexes. The canonical pathway for pyocin production involves DNA damage and RecA activation.