Effect of Biogenic Silver Nanoparticles on the Quorum-Sensing System of Pseudomonas aeruginosa PAO1 and PA14

Abstract

The increase in multidrug-resistant microorganisms represents a global threat requiring the development novel strategies to fight bacterial infection. This study aimed to assess the effect of silver nanoparticles (bio-AgNPs) on bacterial growth, biofilm formation, production of virulence factors, and expression of genes related to the quorum-sensing (QS) system of P. aeruginosa PAO1 and PA14. Biofilm formation and virulence assays were performed with bio-AgNPs. RT-qPCR was carried out to determine the effect of bio-AgNPs on the QS regulatory genes lasI, lasR, rhlI, rhlR, pqsA, and mvfR. Bio-AgNPs had an MIC value of 62.50 μM, for both strains. Phenotypic and genotypic assays were carried out using sub-MIC values. Experimental results showed that treatment with sub-MICs of bio-AgNPs reduced (p < 0.05) the motility and rhamnolipids and elastase production in P. aeruginosa PAO1. In PA14, bio-AgNPs stimulated swarming and twitching motilities as well as biofilm formation and elastase and pyocyanin production. Bio-AgNP treatment increased (p < 0.05) the expression of QS genes in PAO1 and PA14. Despite the different phenotypic behaviors in both strains, both showed an increase in the expression of QS genes. Demonstrating that the bio-AgNPs acted in the induction of regulation. The possible mechanism underlying the action of bio-AgNPs involves the induction of the rhl and/or pqs system of PAO1 and of the las and/or pqs system of PA14. These results suggest that exposure to low concentrations of bio-AgNPs may promote the expression of QS regulatory genes in P. aeruginosa, consequently inducing the production of virulence factors such as elastase, pyocyanin, and biofilms.

The two faces of pyocyanin - why and how to steer its production?

“…Among them are nanomaterials, including the ones that were proven to inhibit PYO production. Nevertheless, the stimulative effect of ZnO NPs, Ag NPs, CeO 2 NPs, and multi-walled carbon nanotubes was reported (García-Lara et al 2015;Xu et al 2018;Saeki et al 2022;Jabłońska et al 2022a). García-Lara et al (2015) showed that the effect of ZnO NPs may be strain-dependent, as four out of 18 tested strains expressed an increased pigment production, whereas for the rest the result was the opposite.…”

“…García-Lara et al (2015) showed that the effect of ZnO NPs may be strain-dependent, as four out of 18 tested strains expressed an increased pigment production, whereas for the rest the result was the opposite. Saeki et al (2022) reported that low concentrations of Ag NPs led to the upregulation of some QS regulatory genes. These findings were supported by Xu et al (2018).…”

Synergistic Antibacterial Proficiency of Green Bioformulated Zinc Oxide Nanoparticles with Potential Fosfomycin Synergism against Nosocomial Bacterial Pathogens

“…Recent nanotechnology advancements have resulted in the development of nano-scale particles with potent bioactivity against drug-resistant bacterial infections [ 10 , 11 ]. For the last decade, researchers have been interested in the biological generation of ZnO NPs [ 12 ].…”