Extracellular mycosynthesis of silver nanoparticles and their microbicidal activity Faria Fatima a , Smita Rastogi Verma b , Neelam Pathak c , Preeti Bajpai c, * a Integral Institute of Agriculture, Science and Technology, Integral University, Lucknow 226026, India b Department of Biotechnology, Delhi Technological University, New Delhi 110042, India c Department of Biosciences, Integral University, Lucknow 226026, India A R T I C L E I N F O Article history: Received 25 September 2015 Received in revised form 5 July 2016 Accepted 20 July 2016 Available online 13 September 2016 Keywords: Aspergillus flavus Antibacterial Antifungal Silver myconanoparticles A B S T R A C T Myconanotechnology, a combination of mycology and nanotechnology that deals with the synthesis of nanoparticles using fungi or their metabolites, has great potential in the area of agriculture owing to the high surface-to-volume ratio and excellent biomedical, electronic, mechanical and physicochemical properties of these myconanoparticles. Extracellular mycosynthesis of Aspergillus flavus (KF934407) silver nanoparticles (AgNPs) was performed, which were produced by redox reaction. Furthermore, the extracellular synthesised AgNPs were characterised by ultraviolet/visible spectrophotometry, differential light scattering (DLS) and transmission electron microscopy. The bactericidal and fungicidal actions of synthesised silver myconanoparticles (myco-AgNPs) were studied against pathogenic bacteria and fungi. The formulated myco-AgNPs were spherical in shape, with a size in the range of 50 nm and DLS at an intensity of 107.8 nm. The myco-AgNPs showed effective antimicrobial properties against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Trichoderma spp. at high concentrations. In conclusion, AgNPs have a prolonged microbicidal effect as a result of continuous release of Ag + at sufficient concentrations. Thus, A. flavus-based myco-AgNPs have the potential to be used as a non-toxic and cheap antimicrobial agent against various pathogenic bacteria and fungi. ã 2016 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved. 1. Introduction The advancement of green processes for the production of different types of metal nanoparticles is evolving as an important branch of nanotechnology [1]. Since physical and chemical methods of metal synthesis are costly and involve assimilation of various toxic chemicals, biological synthesis using fungal, bacterial and plant extract sources has been found to be a preferred option [2,3] owing to their ease of availability, non-toxic nature and rapid synthesis. Myconanotechnology is an emerging field, where fungi can be harnessed for the production of nanostructures with desirable size and shape. Nowadays, silver nanoparticles (AgNPs) have drawn the attention of scientists because of their wide relevance in the development of novel technologies in the areas of material sciences, electronics, biomedicine, and in agriculture as antimicrobials at the nanoscale level [4]. Biosynthesised nano- particles are eco-friendly and are biocompatible for pharmaceuti- cal applications. Biosynthesis of nanoparticles using fungi as a source is a kind of approach where the main reaction is due to redox reaction, as fungal enzymes possessing high redox potential are usually capable of reducing metals into their respective nanoparticles. Thus, nanostructure synthesis mediated by biologi- cal sources has attracted scientific attention across the world. Currently, these AgNPs are being thoroughly surveyed and extensively investigated as potential antimicrobial agents. Their small size and high surface-to-volume ratio boost their interaction with micro-organisms to support a broad range of possible antimicrobial activities [5]. The inhibitory effects of AgNPs on bacteria and fungi has been proposed to be due to several mechanisms. It is assumed that AgNPs possess high affinity towards phosphorous and sulphur present within the cell. As silver ions (Ag + ) from AgNPs interact with DNA containing phosphorous moieties, this results in inactivation of DNA replication. Interaction of AgNPs with proteins containing sulphur present inside or outside the cell membrane leads to inhibition of enzyme functions [6]. AgNPs of * Corresponding author. Fax: +91 522 2890 809. E-mail address: preeti2874@gmail.com (P. Bajpai). http://dx.doi.org/10.1016/j.jgar.2016.07.013 2213-7165/ã 2016 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved. Journal of Global Antimicrobial Resistance 7 (2016) 88–92 Contents lists available at ScienceDirect Journal of Global Antimicrobial Resistance journal home page : www.e lsevier.com/loca te/jgar