Biogenic production of silver nanoparticles by Enterobacter cloacae Ism26

Abstract

A bacterial isolate capable of tolerating 30 mM silver nitrate (AgNO3) was recovered from soil contaminated with industrialwaste. The isolate was identified by 16S rRNA as Enterobacter cloacae Ism26 (KP988024) and its capability to synthesize silvernanoparticles (AgNPs) was investigated. AgNPs were produced by mixing 1 mM AgNO3 solution with bacterial cell lysate under lightconditions. The UV-Vis spectrum of the aqueous medium containing AgNPs exhibited a peak at 440 nm corresponding to the surfaceplasmon resonance of the AgNPs. The crystalline nature of the particles was confirmed by X-ray diffractometer. High-resolutiontransmission electron microscopy revealed that the AgNPs were spherical and well dispersed and ranged in size from 7 to 25 nm. Theaverage size range of the produced AgNPs was confirmed by dynamic light scattering. Fourier transform infrared spectroscopy revealedpossible involvement of reductive groups on the surface of the nanoparticles. The biosynthesized AgNPs were stable for 6 months andinhibited both gram-positive and gram-negative bacteria. This work describes the exploitation of a low-cost biomaterial and an easymethod for the synthesis of AgNPs with desirable and advantageous characteristics.