Antimicrobial and Biofilm-Inhibitory Potential of Green Synthesized Silver Nanoparticles from Lantana camara against Pseudomonas aeruginosa
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Background
Emerging antimicrobial resistance poses serious threat to human well-being. Current therapeutics often fail to treat bacterial infections as pathogenic bacteria often attach to various surfaces and form biofilm. One such pathogen, Pseudomonas aeruginosa , can form biofilm for its survival in the presence of antibacterial agents. This study aimed to evaluate the antibacterial, antibiofilm, and mechanistic activities of Lantana camara leaf extract mediated silver nanoparticles (LCLE-Ag NPs) against Pseudomonas aeruginosa , where the extract contributes for the reduction of Ag + to Ag 0 .
Methods
LCLE-Ag NPs were synthesized and characterized by using UV visible spectroscopy, dynamic light scattering, and electron microscopy. Antibacterial and antibiofilm activities of the synthesized NPs were assessed against P. aeruginosa isolates KPW.1-S1 and HRW.1-S3. Extracellular polysaccharides (EPS), and extracellular DNA (eDNA) and reactive oxygen species (ROS) generation were visualized using epifluorescence microscopy. The ability of the nanoparticles to eradicate preformed biofilm was also evaluated. The expressions of quorum-sensing genes were analyzed using semi quantitative polymerase chain reaction. Cytotoxicity was tested on human kidney epithelial-like cells.
Results
The synthesized LCLE-Ag NPs displayed an absorption peak at 416 nm and a size range of 30 to 35 nm. They exhibited significant antibacterial and antibiofilm activities correlating with decreased EPS and eDNA levels. LCLE-Ag NPs effectively disrupted both preformed and antibiotic-induced biofilms and such activities were found to be associated with increased ROS levels and decrease in lasI and pqsA expression. Cytotoxicity assays indicated no significant toxicity at effective concentrations.
Conclusions
LCLE- Ag NPs displayed promising antibacterial and antibiofilm activities against P. aeruginosa , acting through biofilm matrix disruption, ROS generation, and quorum-sensing inhibition.
