Superior inhibition of virulence and biofilm formation of Pseudomonas aeruginosa PAO1 by phyto-synthesized silver nanoparticles through anti-quorum sensing activity

Abstract

Quorum sensing (QS)-regulated bacterial biofilm formation is a crucial issue in causing resistance against existing antibiotics. There is a considerable necessity to disrupt the interrelationship between bacterial QS, virulence, and biofilm formation. Disabling QS could be a novel tactic of great clinical importance. Here, we biosynthesized silver nanoparticles (Ka-AgNPs) using the aqueous leaf extract of Koelreuteria paniculata as a reducing and capping agents. The UV-Vis spectroscopy confirmed the synthesis of Ka-AgNPs as a characterization peak observed at 420 nm. TEM image revealed the spherical shape distribution of Ka-AgNPs with average particle size of 30.0 ± 5 nm. The anti-QS activity of Ka-AgNPs was tested against a bio-indicator bacterium Chromobacterium violaceum 12472 and a multi-drug resistant model strain of Pseudomonas aeruginosa (PAO1). The results demonstrated that the Ka-AgNPs superiorly inhibited QS-regulated virulence factors in PAO1 without affecting cell viability compared to chemically synthesized AgNPs (Cs-AgNPs). The Ka-AgNPs effectively suppressed the formation of biofilm of PAO1. RT-PCR results revealed that the Ka-AgNPs inhibited the expression of QS-regulated virulence genes of PAO1. These results suggest that the phyto-synthesized AgNPs could be used as promising anti-infective agents for treating drug-resistant P. aeruginosa.

Keywords: Biofilm formation; Biosynthesized nanoparticles; Pseudomonas aeruginosa; Quorum sensing; Virulence factors.