Exoprotease exploitation and social cheating in a Pseudomonas aeruginosa environmental lysogenic strain with a non-canonical quorum sensing system.
Daniel Huelgas-MéndezDaniel CazaresLuis David AlcarazCorina Diana CeapãMiguel Cocotl-YañezToya ShotaroToshinari MaedaAna María Fernández-PresasOswaldo Tostado-IslasAna Lorena González-VadilloAldo Limones-MartínezCarlos Eduardo Hernandez-CuevasKaren González-GarcíaLuis Felipe Jiménez-GarcíaReyna-Lara MartínezCristian Sadalis Santos-LópezFohad Mabood HusainAltaf KhanMohammed ArshadKota KokilaThomas K WoodRodolfo Garcia-ContrerasPublished in: FEMS microbiology ecology (2023)
Social cheating is the exploitation of public goods that are costly metabolites, like exoproteases. Exoprotease exploitation in Pseudomonas aeruginosa has been studied in reference strains. Experimental evolution with reference strains during continuous growth in casein has demonstrated that non-exoprotease producers that are lasR mutants are selected while they behave as social cheaters. However, non-canonical quorum sensing systems exist in P. aeruginosa strains, which are diverse. In this work, the exploitation of exoproteases in the environmental strain ID4365 was evaluated; ID4365 has a nonsense mutation that precludes expression of LasR. ID4365 produces exoproteases under the control of RhlR, and harbors an inducible prophage. As expected, rhlR mutants of ID4365 behave as social cheaters, and exoprotease-deficient individuals accumulate upon continuous growth in casein. Moreover, in all continuous cultures, population collapses occur. However, this also sometimes happens before cheaters dominate. Interestingly, during growth in casein, ID4565's native prophage is induced, suggesting that the metabolic costs imposed by social cheating may increase its induction, promoting population collapses. Accordingly, lysogenization of the PAO1 lasR mutant with this prophage accelerated its collapse. These findings highlight the influence of temperate phages in social cheating.