Biosynthesis of Antimicrobial Silver Nanoparticles by The Endophytic Fungus Aspergillus Clavatus

Abstract

Aim: To induce the biosynthesis of silver nanoparticles (AgNPs) using Aspergillus clavatus and evaluate their antimicrobial potential. Materials & methods:Aspergillus clavatus (AzS-275), an endophytic fungus isolated from sterilized stem tissues of Azadirachta indica A. Juss., was challenged with 1 mM AgNO₃ solution. The characterization of the AgNPs was carried out by x-ray diffraction spectrometry, transmission-electron microscopy and atomic force microscopy. Results & discussion: The synthesized AgNPs were found to be extracellular, polydispersed spherical or hexagonal particles ranging from 10 to 25 nm in size. Antimicrobial activity was performed using a disc-diffusion method against Candida albicans, Pseudomonas fluorescens and Escherichia coli. The results showed an average minimum inhibitory concentration of 5.83 µg ml^-1 and minimum fungicidal concentration of 9.7 µg ml^-1 against C. albicans. Conclusions: AgNPs can be mycosynthesized extracellularly using A. clavatus as the fungal system, which is highly advantageous over chemical synthesis not only because it can be synthesized on a large scale, but because of the ease of downstream processing and its biomedical application in antimicrobial activity.

Keywords::

• antimicrobial activity
• Azadirachta indica
• endophytic fungi
• mycosynthesis of nanoparticles
• silver nanoparticles

Authors’ contributions

VC Verma and RN Kharwar hypothesized and executed the experiments, collected and interpreted the data and wrote the manuscript. AC Gange was involved in statistics and editing of manuscript and interpretation of the results.

Financial & competing interests disclosure

This work is financially supported by the Council of Scientific and Industrial Research (CSIR), New Delhi, India (file No. 09/013(125)/2008/EMR-I, dt.24–09–2008). VC Verma greatly acknowledges the financial support obtained from CSIR (file No. 09/013(125)/2008/EMR-I, dt.24–09–2008) New Delhi, India. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Acknowledgements

The authors are thankful to the Head and Co-ordinator of Department of Botany for their support. We also extend our sincere thanks to D Pandey, School of Material Science and Technology, Institute of Technology, Banaras Hindu University, India, for assistance with the x-ray diffraction and atomic force microscopy studies and to G Singh and M Yashpal, Institute of Medical Sciences, Banaras Hindu University, for the transmission-electron microscopy analysis of the silver nanoparticles.

Additional information

Funding

This work is financially supported by the Council of Scientific and Industrial Research (CSIR), New Delhi, India (file No. 09/013(125)/2008/EMR-I, dt.24–09–2008). VC Verma greatly acknowledges the financial support obtained from CSIR (file No. 09/013(125)/2008/EMR-I, dt.24–09–2008) New Delhi, India. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.