Pyoverdin mediated sunlight induced green synthesis of silver nanoparticles

Abstract

The objective of this work was to check the ability of a siderophore, pyoverdin, a natural iron chelating compound of bacterial origin to produce silver nanoparticles (AgNps) under sunlight. Among the 26 strains of siderophore producing fluorescent pseudomonads, a strain SBC-I was found to be latent applicant based on its percent decoloration of chrome azurol sulfonate reagent. The 16S rRNA gene sequence revealed the strain SBC-I to be Pseudomonas aeruginosa owing to 99% similarity with previously reported culture. The silver ions were examined for their coordination with the purified pyoverdin using UV-Vis spectrophotometric titrations. The AgNps were found crystallized in the face centered cubic with an average particle size of 6–12 nm. The predicted mechanism of AgNps synthesis involved photoreduction of metal ions by means of ligand-to-metal charge transfer. The synthesis of AgNps was confirmed by transmission electron microscopy, X-ray diffraction, attenuated total reflection-Fourier transform infrared spectroscopy and UV-Vis spectrophotometry. Synthesized AgNps showed antibacterial activity against Salmonella typhi, Escherichia coli, Bacillus spizizenii and Staphylococcus aureus.