Biosynthesis, Characterization And Antibacterial Efficacy Of Silver Nanoparticles From The Soil Fungus Curvularia Tuberculata

Abstract

Abstract Nanobiotechnology has been recently widely applied in multidisciplinary fields including pharmaceutical applications. The last decade has witnessed an increase research interests focused on the biosynthesis of metal nanoparticles from fungi as a natural sources and as bionanofactories. However, silver nanoparticles (AgNPs) are of great importance particularly in medical therapy applications and can be used as antimicrobial agent. The objective of this study was to biosynthesize silver nanoparticles from the soil fungus Curvularia tuberculata and to examine their efficacy against five strains of pathogenic bacteria namely; Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi and Staphylococcus aureus using agar well diffusion technique. The synergistic efficacy of biosynthesized silver nanoparticles in a combination with commercially used antibiotic Gentamycin against the selected bacteria was also examined. The biosynthesized silver nanoparticles from fungal free-cell filtrate were characterized by using UV-Vis spectrophotometer analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). UV-Vis spectrophotometer analysis revealed a peak at 420 nm indicating the synthesis of silver nanoparticles. FTIR analysis verified the detection of protein capping of silver nanoparticles while SEM micrographs showed that the synthesized silver nanoparticles are dispersed and mostly having spherical shape within the size range between 10-50 nm. The biosynthesized silver nanoparticles possessed a varied growth inhibition activity ranged between 12- 28 mm diam inhibition zones at different concentrations against the tested pathogenic bacterial strains. A remarkable increase of bacterial growth inhibition (25.5-35.5 mm diam) was detected when a combination of silver nanoparticles and Gentamycin was used. A significant increase in fold area of antibacterial efficacy was observed when AgNPs in combination with Gentamycin was applied as compared with the efficacy of Gentamycin alone. The biosynthesized AgNPs did not show any toxicity against human blood. The synthesized silver nanoparticles by the fungus C.tuberculata is promising to be used as an antimicrobial agent in medical therapy due to their broad spectrum efficacy against pathogenic bacteria. Nevertheless, further studies are needed to investigate the activity of silver nanoparticles as antibacterial agent in vivo.