Green synthesis of sliver nanoparticles using different bacteria: Do the synthesized nanoparticles differ in their antimicrobial activity

Authors

  • M M K Peiris
  • T D C P Gunasekara
  • NDH Arachchi
  • P M Jayaweera
  • S S N Fernando

Abstract

Objectives: Biosynthesis and characterization of silver nanoparticles (AgNPs) from Escherichia coli,
Acinetobacter baumannii and Staphylococcus aureus and determination of antimicrobial activity
against selected pathogens.
Methods: E. coli (ATCC 25922), A. baumannii (clinical strain), S. aureus (ATCC 25923) were cultured
in nutrient broth medium and used for biosynthesis of AgNPs. AgNO3 concentration, pH, incubation
time and temperature were optimized for AgNP biosynthesis. Antimicrobial activity of the synthesized
AgNPs was studied using the well diffusion assay.
Results: All the selected bacteria produced silver nanoparticles at alkaline pH when the concentration
of AgNO3 was greater than 0.3 g/L. The optimum reaction temperature was 60oC. UV-Visible
spectroscopy with a maximum absorbance of approximately 420 - 430 nm confirmed the presence of
AgNPs. AgNPs produced by S. aureus resulted in larger zone of inhibition (ZOI) against the selected
pathogens where AgNPs produced by E. coli showed comparatively smaller ZOI. Gram negative
bacteria (E.coli, P. aeruginosa) were more sensitive to AgNPs compared to gram positive bacteria
(Methicillin Resistant S. aureus, S. aureus) and fungal species (Candida albicans).
Conclusion: AgNPs produced by S. aureus are the most effective among the tested AgNPs while E.
coli produced the least effective AgNPs.

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Published

2017-10-10