Bacillus cereus inhibits quorum sensing in Pseudomonas aeruginosa

A quorum-sensing inhibitor blocks Pseudomonas aeruginosa virulence and biofilm formation.

The human pathogen Pseudomonas aeruginosa uses quorum sensing to control virulence and biofilm formation. Here, synthetic molecules were analyzed for inhibition of the two P. aeruginosa quorum-sensing receptors, LasR and RhlR. Meta-bromo-thiolactone (mBTL) was dhown to inhibit both the production of the virulence factor pyocyanin and biofilm formation. mBTL also protects Caenorhabditis elegans and human lung epithelial cells from killing by P. aeruginosa. Both LasR and RhlR are partially inhibited by mBTL in vivo and in vitro; however, RhlR, not LasR, is the relevant in vivo target. More potent antagonists do not exhibit superior function in impeding virulence. Because LasR and RhlR reciprocally control crucial virulence factors.