Signal molecule autoinducer 2 promotes biofilm formation and virulence production in Pseudomonas aeruginosa by quorum sensing system

Abstract

Objective To investigate the effects of signal molecule autoinducer 2 (AI-2) on the biofilm formation and virulence production in the wild type strain, PAO1 and the strain with deficient quorum sensing genes, lasR and rhlR (ΔlasRΔrhlR) of Pseudomonas aeruginosa (P.a). Methods The wild strain PAO1 and the P.a ΔLasRΔrhlR strain were used to establish biofilm model. The following experiments were performed on 4 groups, including PAO1 group, AI-2+PAO1 group, P.a ΔLasRΔrhlR group and AI-2+P.a ΔLasRΔrhlR group. The biofilm formation was measured by crystal violet assay and observed with confocal laser scanning microscopy (CLSM). Kirby-Bauer disk diffusion was used for drug sensitivity test. Virulence factor pyocyanin and elastase production were measured by chloroform extraction method and Congo red assay, respectively. Results Compared to the wild type PAO1, the biofilm formation and virulence production were significantly increased in AI-2+PAO1 group, as well as the diameter of inhibition zone was significantly decreased(P 0.05). Conclusion AI-2 enhances the biofilm formation and virulence production of P.a by the quorum sensing system.

Keywords

• pseudomonas aeruginosa
• biofilm
• quorum sensing
• system
• autoinducer 2