Antimicrobial Effect of Silver Nanoparticles Biosynthesized using Cladosporium herbarum against Pathogenic Microorganisms

Abstract Background Green, eco-friendly, cost effective, safe, and reliable processes for the synthesis of nanoparticles using microorganisms as bio-nanofactories have attracted interest due to its ability in transforming metals into nanosize to their use in various fields. In this study silver nitrate and supernatants of Cladosporium herbarum isolated from water samples of Qarun Lake, Egypt was used for extracellular biosynthesis of silver nanoparticles (AgNPs) and their activity against different pathogenic microorganisms was tested. Methods Silver nanoparticles were biosynthesized using four isolated marine fungi, the reaction parameters were optimised and the biosynthesized nanoparticles were characterized by various analytical techniques such as Transmission Electron Microscopy (TEM), Fourier transform infrared (FT-IR) and X-Ray analysis. Antimicrobial activity and mode of action of the biosynthesized silver nanoparticles were tested against variety of pathogens (Gram-positive and Gram-negative bacteria, yeast, and fungi). Results The results revealed that biosynthesized silver nanoparticles mediated by marine fungus Cladosporium herbarum are proven to have potent antimicrobial effect against different pathogens with optimum substrate concentration of 5 Mm at 37 o C, 6 pH, and 24 h incubation time. TEM analysis revealed the formation of spherical, well-dispersed nanoparticles with size ranging between 4 and 23.1 nm and FTIR shows the bands at 556, 762, 1349, 1451, 1562, 1620, and 3352 cm − 1 corresponding to the binding vibrations of stretch of alkyl halides, C-H group, O-H group of phenol, C-N group of amides, NH 2 group, N-H group, and–OH group, respectively. Conclusions Biosynthesis of silver nanoparticles mediated by Cladosporium herbarum could be a promising product used as antimicrobial agents against various pathogenic microbes.