Development of ecofriendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology because of its tremendous impetus in modulating metals into nanosize to their potential use for human benefits. In this study an endophytic fungus, Penicillium sp., isolated from healthy leaves of Curcuma longa (turmeric) was subjected to extracellular biosynthesis of silver nanoparticles (AgNps) and their activity against MDR E. coli and S. aureus. The biosynthesized AgNps optimization was studied and characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Then produced AgNps were tested against MDR E. coli and S. aureus. The endophytic fungus Penicillium sp. from healthy leaves of C. longa (turmeric) was found to be a good producer of AgNps. Parametric optimization showed maximum absorbance of 420–425 nm at pH-7, 25°C with 1 mM AgNO3 concentration and 15–20 g of wet biomass. Further TEM revealed the formation of spherical, well-dispersed nanoparticles with size ranging between 25 and 30 nm and FTIR shows the bands at 1644 and 1538 cm−1 corresponding to the binding vibrations of amide I and II bands of proteins, respectively. Antibacterial activity against MDR E. coli and S. aureus showed good results showing maximum zone of inhibition of 17 mm and 16 mm, respectively, at 80 µL of AgNps.

Silver Nanoparticles (AgNPs), the real silver bullet, are known to have good antibacterial properties against pathogenic microorganisms. In the present study AgNPs were prepared from extracellular filtrate of Aspergillus niger. Characterization of AgNPs by UV-Vis spectrum reveals specific surface plasmon resonance at peak 416 nm; TEM photographs revealed the size of the AgNPs to be 20–55 nm. Average diameter of the produced AgNPs was found to be 73 nm with a zeta potential that was −24 mV using Malvern Zetasizer. SEM micrographs showed AgNPs to be spherical with smooth morphology. EDS revealed the presence of pure metallic AgNPs along with carbon and oxygen signatures. Of the different concentrations (0, 2.5, 5, 10, and 15 μg/mL) used 10 μg/mL were sufficient to inhibit 107 CFU/mL of E. coli. ROS production was measured using DCFH-DA method and the the free radical generation effect of AgNPs on bacterial growth inhibition was investigated by ESR spectroscopy. This paper not only deals with the damage inflicted on microorganisms by AgNPs but also induces cell death through the production of ROS released by AgNPs and also growth kinetics of E. coli supplemented with AgNPs produced by A. niger.

No abstract

An attractive possibility of green nanotechnology is to use microorganisms in the synthesis of silver nanoparticles. Recently, the biosynthesis especially from fungi has emerged as a novel method for the synthesis of silver nanoparticles. Nanoparticles are considered as building blocks of Nanotechnology. In the present work we have screened fungi for the extracellular production of silver nanoparticles. Aspergillus sps, Rhizopus sps, Fusarium sp. and Penicillium sp. were the isolates screened and subjected to silver nanoparticles production. Of the tested isolates, the fungus Aspergillus sp. showed maximum absorbance at 416 nm which is an indication of Silver nanoparticles production. Further characterization was made by TEM which revealed the shape to be spherical and size ranged between 20-55 nm, EDS showed the presence of elemental silver at 3kev, FTIR spectrum showed the different functional groups, XRD spectrum showed the crystalline nature of the particles and AFM revealed three dimensional structures of the nanoparticles. Of all kinds of nanoparticles silver nanoparticles show great promise in terms of biomedical applications as they exhibit different biomedical activities.

Abstract. Biological method is considered as eco-friendly and reliable process for the synthesis of silver nanoparticles (AgNps) in the field of nanotechnology due to its tremendous applications in various fields. In this study we have isolated a total of twelve endophytic fungi from leaves of Curcuma longa (turmeric) and Catharanthus roseus out of which six endophytic fungi showed their ability to synthesized AgNps from silver nitrate (AgNO 3) solution which splits into a positive silver ion (Ag + ) and a negative nitrate ion (NO 3 -) in order to turn the silver ions into solid silver (Agº). Of the six positive endophytic fungi VRD2 showed good and encouraging results and was identified as Penicillium spinulosum VRD2. UV-Visible Spectroscopy confirms the AgNps showing maximum peak at 425nm implying the bioreduction of AgNO 3 . Transmission Electron Microscopy (TEM) revealed the particle are spherical and well dispersed without agglomeration size ranging from 25-30nm.