A Novel Screening System For Pseudomonas. Aeruginosa Quorum Sensing Inhibitors

Pseudomonas aeruginosa ( PA) is an important gram-negative opportunistic pathogen. Because it can give rise to various kinds of acute and chronic infections to people, especially ones who are immunocompromised or suffered seriously chronic disease at risk. It is regarded as the third most dangerous infectious agent in hospitals. PA is a multi-drug resistant organism which could attain effective antibiotic resistance via diverse ways. It is meaningful for human to study targeting and resistance mechanisms of PA.Quorum-sensing system ( QS ) is an important global regulatory system in PA which controls the expression of numerous genes related to pathogenicity according to the population density of bacteria. It uses small diffusible molecules as signals of cell-cell communication to coordinate behaviors of PA including production of cellular virulence factors and development of biofilms. It plays a critical role in infectious process.The purpose of this research is to design and construct a novel system to screen for Quorum-sensing inhibitors. We developed a screening system for quorum sensing inhibitors in P. aeruginosa with lasI' and rhlA' as promoter, promoterless sacB as reporter and pUCP26 as vector. Then a variety of extracts from Chinese herbs were identified. Three extracts which readily inhibit expression of QS-regulated gene were uncovered. These results suggest this screening system is effective, real-time and highly sensitive. It also serves as a useful tool to research pathogenesis and find some novel drugs to efficiently block infection of diseases as well as avoid antibiotics-resistance.