Pseudomonas aeruginosa Quorum Signals; Associations with Virulence, and Impact of Therapeutic Gamma Radiation Doses.

Abstract

Quorum sensing (QS) signals are the fundamental regulators of P. aeruginosa cellular machinery. From this perspective, this study aimed to analyze a pathogenic Pseudomonas aeruginosa isolate quorum signals profile prior and following exposure to therapeutic gamma radiation doses, and associate them with their virulence. Analysis of quorum signals was conducted utilizing GC-Mass spectroscopy and CFM-ID 4.0 mass spectra prediction webserver. The correlation between these signals and P. aeruginosa virulence was investigated through in vitro and computational methods. The isolates pyocyanin, biosurfactant, and biofilm productions were quantified before and after gamma irradiation and the STRING-DB were used to scrutinize the QS synthesizing proteins interactions. Further, the Cytoscape software statistically analyzed the QS proteins-proteins interaction networks. The study reported the recovery of acyl-homoserine lactones (C2, C4, C6, and C12-HSLs) and fatty acid signals (DSFs) from the P. aeruginosa isolate ethyl acetate extract and proposed the potential isolation of longer-chain HSLs (> C12-HSLs). New functional associations were identified for QS synthesizing proteins, which involve spermidine, fatty acids, and siderophores biosynthesis. The irradiated P. aeruginosa extracts GC-MS chromatograms exhibited notable changes in the retention times of QS signals and their mass spectra with the retrieval of different forms of fatty acids esters. Additionally, irradiated P. aeruginosa demonstrated a modest increase in the production of both biofilms and biosurfactants. This finding indicated that changes in quorum signals profile post irradiation boosted P. aeruginosa virulence mechanisms, which may potentially lead to an exacerbation of infection pathogenesis following the application of therapeutic gamma radiation doses.