Control of virulence factor expression in opportunistic pathogens using cyclodextrin immobilized gel

Cyclodextrins (CDs) could intercept a quorum sensing (QS) in Pseudomonas aeruginosa by trapping signal molecules for bacterial cell-to-cell communication systems. The QS in human pathogens is the cell density dependent system that regulates the expression of virulence determinants. The cellulose ether hydrogel immobilized with 2-hydroxypropyl-beta-CD (HP-beta-CD) was synthesized as an artificial QS signal receptor to develop a novel system for controlling the expression of virulence determinants in P. aeruginosa. Since the alpha- and beta-CD could form inclusion complex with N-acyl-L-homoserinelactone (AHL) as the gram-negative bacterial QS signal in the culture solution, both AHL-mediated rhl and las quorum-sensing systems could be intercepted by CD. Inhibitory control of the rhlA transcription could cause to produce less pyocyanin in the presence of 5 mM soluble alpha- or beta-CD in the liquid medium. Furthermore, production of the reporter enzyme beta-galactosidase was meaningfully decreased in P. aeruginosa PAO1 (pQF50-lasB) containing lasB-lacZ transcriptional fusion when HP-beta-CD immobilized gel was immersed in the culture solution to trap AHLs from the liquid medium. By adding the artificial AHL receptors to the culture medium, the expression of the QS-controlled genes could be remotely controlled from the outside of cells.