Inhibition of Biofilm Formation and Regulation of Virulence Properties by Iron Nanoparticles in Pseudomonas aeruginosa

Abstract

Biofilm formation is one of the resistance mechanisms of Pseudomonas aeruginosa against antimicrobial compounds. Biofilm formation also characterizes for the infection and pathogenesis of P. aeruginosa, along with production of various virulence factors. With recent development of nanotechnology, the present study evaluated the synthetic iron nanoparticle (FeOOH-NP) as an active agent to inhibit the formation of P. aeruginosa biofilm. The FeOOH-NP was synthesized and subjected to characterization using UV-visible spectroscopy, fourier transform infrared spectroscopy (FTIR), field emission transmission electron microscopy (FE-TEM), dynamic light scattering (DLS), and energy dispersive X-ray diffraction (EDX). The synthesized FeOOH-NP was characterized with rod shape and average size of 40 nm. Subsequently, the FeOOH-NP was evaluated for their inhibitory effects against P. aeruginosa bacterial growth, biofilm formation, virulence factor production, and motility. Results have shown that P. aeruginosa biofilm inhibited by FeOOH-NP was in a concentration-dependent manner, with inhibition of the bacterial biofilm formation increased as FeOOH-NP concentration increased. Microscopic observations as well as viable cell counts also confirmed the disruption in the biofilm structure in the presence of FeOOH-NP. In addition, the presence of FeOOH-NP was also found to modulate some important virulence factors produced simultaneously with biofilm formation such as pyocyanin, pyoverdine, rhamnolipid, proteolytic and hemolytic activities. Besides, the bacterial motility, including swimming and swarming, was affected by FeOOH-NP treatments. These findings provide insights to anti-biofilm effect of a new iron NP, contributing to the search for an effective anti-biofilm agent to combat P. aeruginosa infections associated with biofilm formation.