Process optimization for green synthesis of silver nanoparticles by Sclerotinia sclerotiorum MTCC 8785 and evaluation of its antibacterial properties.

Juhi Saxena,Abhijeet Singh,Madan Mohan Sharma,Prashant Kumar Sharma

doi:10.1186/s40064-016-2558-x

Abstract

BackgroundEco-friendly synthesis of nanoparticles is viewed as an alternative to the chemical method and initiated the use of microorganisms for synthesis. The present study has been designed to utilize plant pathogenic fungi Sclerotinia sclerotiorum MTCC 8785 strain for synthesis and optimization of silver nanoparticles (AgNPs) production as well as evaluation of antibacterial properties. The AgNPs were synthesized by reduction of aqueous silver nitrate (AgNO3) solution after incubation of 3–5 days at room temperature. The AgNPs were further characterized using UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Reaction parameters including media, fungal biomass, AgNO3 concentration, pH and temperature were further optimized for rapid AgNPs production. The antibacterial efficacy of AgNPs was evaluated against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 by disc diffusion and growth kinetics assay at the concentration determined by the minimum inhibitory concentration (MIC).ResultsAgNPs synthesis was initially marked by the change in colour from pale white to brown and was confirmed by UV–Vis spectroscopy. Optimization studies showed that potato dextrose broth (PDB) media, 10 g of biomass, addition of 2 mM AgNO3, pH 11 and 80 °C temperature resulted in enhanced AgNPs synthesis through extracellular route. TEM data revealed spherical shape AgNPs with size in the range of 10 nm. Presence of proteins capped to AgNPs was confirmed by FTIR. AgNPs showed antibacterial activity against E. coli and S. aureus at 100 ppm concentration, corresponding MIC value.ConclusionS. sclerotiorum MTCC 8785 mediated AgNPs was synthesized rapidly under optimized conditions, which showed antibacterial activity.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2558-x) contains supplementary material, which is available to authorized users.

Highlights

Eco-friendly synthesis of nanoparticles is viewed as an alternative to the chemical method and initiated the use of microorganisms for synthesis
Extracellular synthesis of AgNPs Synthesis of AgNPs from AgNO3 solution using cell free filtrate (CFF) of S. sclerotiorum Microbial Type Culture Collection (MTCC) 8785 was observed by change in color of the solution (Fig. 1 inset)
The extracellular synthesis of AgNPs was confirmed in UV–visible spectroscopy

Summary

Introduction

Eco-friendly synthesis of nanoparticles is viewed as an alternative to the chemical method and initiated the use of microorganisms for synthesis. The present study has been designed to utilize plant pathogenic fungi Sclerotinia sclerotiorum MTCC 8785 strain for synthesis and optimization of silver nanoparticles (AgNPs) production as well as evaluation of antibacterial properties. The AgNPs were synthesized by reduction of aqueous silver nitrate (AgNO3) solution after incubation of 3–5 days at room temperature. Fungal biomass, AgNO3 concentration, pH and temperature were further optimized for rapid AgNPs production. In extracellular synthesis of silver nanoparticles from fungi, firstly biomass is allowed to grow in suitable medium. Enzymes or proteins and metabolites have been secreted by fungal biomass through reverse osmosis. Removal of biomass from deionized water (cell free filtrate) consists of specific enzymes which catalyze the reduction of aqueous silver ions for synthesis of AgNPs (Birla et al 2013)

Methods

Results

Conclusion