Abstract
The present study described the extracellular synthesis of silver nanoparticles (AgNPs) using environmental bacterial isolate Citrobacter spp. MS5 culture supernatant. To our best knowledge, no previous study reported the biosynthesis of AgNPs using this bacterial isolate. The biosynthesized AgNPs were characterized using different techniques like UV-Vis spectroscopy, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX). The analysis of UV-Vis spectra revealed absorption maxima at 415 nm due to surface plasmon resonance (SPR) indicated the formation of AgNPs and FTIR spectrum confirmed the participation of proteins molecule in AgNPs synthesis. XRD and EDX spectrum confirmed the metallic and crystalline nature of AgNPs. TEM and SEM showed spherical nanoparticles with a size range of 5–15 nm. The biosynthesized AgNPs showed effective independent as well as enhanced combined antibacterial activity against extended spectrum β-lactamase (ESBL) producing multidrug resistant Gram-negative bacteria. Further, effective antifungal activity of AgNPs was observed towards pathogenic Candida spp. The present study provides evidence for eco-friendly biosynthesis of well-characterized AgNPs and their potential antibacterial as well as antifungal activity.
Highlights
Nanotechnology deals with design, fabrication, production, and application of 1–100 nm size of particles
To check their efficiency for extracellular synthesis of AgNPs, supernatant of each bacterial isolate was separately mixed with AgNO3 (1 mM) solution in a reaction tube and all tubes were incubated under the same experimental conditions
The present study describes an easy and eco-friendly extracellular synthesis approach of AgNPs using environmental bacterial isolate of Citrobacter spp
Summary
Nanotechnology deals with design, fabrication, production, and application of 1–100 nm size of particles. Silver nanoparticles (AgNPs) have been widely studied in biological fields for use as antibacterial, antifungal, anti-cancer, drug delivery, biomolecular detection, and catalysis [3,4]. AgNPs are well known for their antibacterial activity but very few studies reported its efficacy against extended spectrum β-lactamase (ESBL) producing bacteria [5,6]. The increasing prevalence of ESBLs producing bacteria creates great health care problems throughout the world, there is a current need to search alternative therapy to prevent them [10,11]. The increasing morbidity and mortality due to infection caused by pathogenic microbes oblige scientific community to develop novel compounds with new target sites to prevent them. In order to promote alternative strategies towards combating microorganisms, AgNPs could be a potent antimicrobial agent
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