Pseudomonas aeruginosa Cell Wall Polysaccharide-Iron Oxide Nanoparticle Augments the Formation of Biofilm by the Bacterium

Abstract

Pseudomonas aeruginosa is very ubiquitous microorganism which is a member of the normal microbial flora in human. The bacterium forms biofilm that is responsible for many persistent and chronic infections. P. aeruginosa biofilm formation is mediated by two soluble lectins, LecA (PA-IL) and LecB (PAIIL) that are essential extracellular virulence factor of P. aeruginosa. In this study bacteria isolated from direct biopsy samples of colorectal cancer (CRC) were used. Iron oxide nanoparticles (IONP) were prepared by coprecipitation method and subsequently coated with Pseudomonas aeruginosa polysaccharide using the principles of electrostatic interaction. The Fourier transform infrared spectroscopy (FTIR) and scanning probe microscope (SPM) analyses confirmed the successful coating of polysaccharide on the surface of iron oxide nanoparticles. The preparation appeared to have 1649 cm^-1 (CONH₂) and 1543 cm^-1 (N-H) band. Particle size for polysaccharide coated iron oxide increased from 85.09 nm for naked iron oxide nanoparticles to 107.20 nm. Bacterial polysaccharide coated iron oxide nanoparticles was used to inhibite Pseudomoas aeruginosa biofilm on saliva coated 96-well polystyrene.It was seen that exposure of cells to polysaccharide coated iron oxide showed increased biofilm formation on optimally coated saliva on polystyrene plates.The highest augmentation was recorded in a concentration of 100mg/ml and in saliva of Lewis group Lea⁺ and approaching (75%) p˃0.05 and the lowest augmentation was achieved in a concentration of 1mg/ml and approached (5%) p=1.4×10^-3, Lea-b- secretor gave (5%) augmentation p=2.6×10^-3 while Lea-b- secretor saliva coat showed (15%) augmentation p=0.05 compared with naked iron oxide nanoparticles.Percentage augmentation of polysaccharide coated iron oxide nanoparticles in concentration of 100mg/ml, 10mg/ml and 0.1mg/ml was non significant p˃0.05 except for Leb saliva used in concentration of 0.1mg/ml that was highly significant (44.5%) augmentation p=3.3×10^-3in compared with iron oxide nanoparticles. In 0.01 mg/ml polysaccharide-iron oxide nanoparticle concentration augmentation reached (5.9%) p=0.03 for Lea-b-non secretor while Leb saliva (46%) augmentation p=0.03 in addition Lea gave (15%) augmentation and Lea-b- secretor showed (26.7%) augmentation p˃0.05. This imply Lewis molecules determinants and bacterial lectin interaction in biofilm formation. Lectin are involved in biofilm formation.

Keywords: key words, polysaccharide-iron oxide, nanoparticles, Pseudomonas aeruginosa biofilm.