Negar Andisheh - student
Majid baseri salehi - Faculty member in microbiology branch

The particles with 10-9 meter in size described as nanoparticles. These particles show different physical, chemical and biological properties based on their bulk material. The present study was conducted to investigate on the production of silver nanoparticles by soil Actinomyces and their evaluation for antimicrobial effects against pathogenic microorganisms.A total two hundred soil samples were collected and subjected to isolation and phenotypic and molecular (16srRNA) identification of nanosilver producing Actinomyces. For detection and authentication of silver nanoparticles, the bacterial cultures were centrifuged and silver nitrate (1mM) were added to the supernatant. The change of the suspension color from yellow to brown considered as production of silver nanoparticles and finally it was confirmed by UV-visible spectral analysis, scanning electron microscope(SEM) and Inductively Coupled Plasma(ICP). In addition, antimicrobial property of the silver nanoparticles was assessed on the pathogenic microorganisms viz., Staphylococcus aureus (PTCC 1431), Acinetobacter baumanni(PTCC 19606), Bacillus cereus(PTCC 1816), Escherichia coli(PTCC 1397), Salmonella typhi(PTCC 1609), Pseudomonas aeruginosa (PTCC 1707) , Aspergillus niger(PTCC 5010) and candida albicans(PTCC 5072). The result obtained indicated that out of 48 Actinomyces, 26 strains could produce silver nano particles. Out of these strains , 3 isolates showed potent activity for production of silver nanoparticles. In addition, the silver nanoparticles produced by Actinomyces isolates exhibited antimicrobial effects against Salmonella typhi, Pseudomonas aeruginosa, Acinetobacter baumanni, Escherichia coli, Aspergillus niger. Phenotypic and molecular identification of these strains verified isolation Actinomyces Amycolicicoccus subflavus, Streptomyces flavoviridis and Streptomyces lateritius The present study showed the potent activity of some strain of Actinomyces for production of silver nanoparticles. Furthermore, these silver nano particles show antimicrobial effects against pathogenic microorganisms. Hence, silver nano particles produced by Actinomyces could be consider as a remedy in order to reduce frequency of occurrence antibiotic resistant microorganisms.

Silver nanoparticle , Actinomyces , antimicrobial activity