Rapid synthesis and characterization of Gold and Silver nanoparticles using exopolysaccharides and metabolites of Wesiella confusa as an antibacterial agent against Esherichia coli

Abstract

Characterization and the antibacterial potential of gold <strong>(</strong>AuNPs) and silver nanoparticle (SNPs) biosynthesized greenly using exopolysaccharides (EPS) and Culture Free Supernatant (CFS) of <em>Wesiella confusa </em>against some multidrug resistance (MDR) <em>E. coli </em>was investigated. The biosynthesized nanoparticles were characterized by UV-visible spectra, Fourier Transformed Infrared Spectroscopy and Scanning Electron Microscopy. The formation of AuNPs and SNPs were confirmed by changes in colour: Colour change from yellow to wine red and yellow to bluish purple, that indicate the formation of AuNPs from the EPS and CFS and colour change from colourless to brown that indicate the formation of SNPs from the EPS and CFS. Surface Plasmon Resonance (SRP) peaks were observed at 400nm. The particles were aggregate with size ranged from 0.5 – 2.6 µm and 0.08 - 1.00 µm for WCEPSAuNPs and WCCFSAuNPs and 0.2 -3.0 µm and 0.2 - 2.8 µm for WCEPSSNPs and WCCFSSNPs. The AuNPs and SNPs had antibacterial activity against the tested pathogens. The SNPs exhibited a broad spectrum of activity against the MDR <em>E. coli </em>strains tested pathogens. In conclusion EPS and CFS of <em>Wesiella confusa </em>were able to bio-reduced and bio-oxidized silver and gold for the biosynthesis of SNPs and AuNPs. The SNPs had broad spectra of activity against <em>E. coli</em> strains compared to the AuNPs.