الفهرس 
ContentsOnly 14 pages are availabe for public view
 |  | from | 197 |  |  |
| | | from | 197 | | |
Abstract
Fourty different actinomycetes isolates were obtained from different soil samples collected from different localities of Egypt. The actinomycetes species were screened for bio-production of silver nanoparticles (AgNPs). The formation of silver nanoparticles was preliminary confirmed by the color changes from pale yellow to dark brown after reduction for 24 hours in dark condition. A peak at 400nm indicated the surface Plasmon resonance of AgNPs based on the rapid reduction of AgNO3 into AgNPs, proficient actinomycetes strains were selected and used for further characterization. The most active isolates (SSHH-1 and SSHH-1E) were identified using morphological, Cultural, physiological properties and 16SrRNA sequence homology (90%) as: Streptomyces viridodiastaticusSSHH-1(GenBank accession no. KJ676475), and Streptomyces narbonensisSSHH-1E (GenBank accession no KT160248). Plackett-Burman design was used for optimization of AgNPs using 14 variables ( Temperature, pH, Incubation time, Inoculum size, Inoculum age, Agitation speed, Medium volume, Starch, NaNO3, K2HPO4, MgSO4 .7H2O, Yeast extract, Malt extract, and Peptone) through 20 trials. The properties of AgNPs were studied using: Electron microscope which indicates that silver nanoparticles which synthesized by Streptomyces viridodiastaticus SSHH-1 were spherical and with size range from 15-45 nm but those which produced by Streptomyces narbonensis SSHH-1E were also spherical but with size range from 20-40 nm. Energy-dispersive X-ray which indicate a strong peak for silver ions and other peaks for O’ N’ and C which indicate presence of silver nanoparticles coated with protein. FTIR analysis to detect the presence of some groups such as aromatic amines, OH and others. By using TEM for SAED analysis, SAED spots corresponding to the [111], [200], [311] planes of the face-centered cubic (fcc) structure of elemental silver are clearly seen. For Streptomyces viridodiastaticus SSHH-1the highest nitrate reductase activity (472.22 U/ml) was obtained at trial No. 9.The results of this study showed that AgNPs showed antimicrobial activity against S. aureus, E.coliand C.albicans. The highest antimicrobial activity was observed against C.albicans, where as a lower activity was found against E.coli. The biosynthesized AgNPs are found to be effective in cytotoxic activity against tumor cells and 15% inhibition of tumor growth was obtained compared with cisplatin the anticancer drug.