Digest Journal of Nanomaterials and Biostructures Vol. 10, No. 1, January - March 2015, p. 179 - 187 FACILE SYNTHESIS OF SILVER NANOPARTICLES USING STREPTOMYCES SP.VSMGT1014 AND THEIR ANTIMICROBIAL EFFICIENCY V. SHANMUGAIAH a* , H. HARIKRISHNAN a , N. S AL-HARBI b , K. SHINE b , J. M. KHALED b , N. BALASUBRAMANIAN c , R. SHYAM KUMAR d a Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, Madurai- 625 021, Tamil Nadu, India b Department of Botany & Microbiology, College of Science, King Saud University, Riyadh – 11451, Saudi Arabia c CREM & Department of Life Sciences, New University of Lisbon, Caparica, Portugal d Department of Biotechnology, Kamaraj College of Engineering and Technology, Virudhunagar, India – 626001 Microbial synthesis of nanoparticles has a prospective to develop simple, cost-effective and eco-friendly method for production of technologically important materials. The present investigation demonstrates the role of rice rhizosphere Streptomyces sp. mediated silver nanoparticles in bio control of various plant fungal pathogens and nosocomial infection causing bacteria by in vitro antagonistic activity and agar well diffusion method respectively. Isolated actinomycetes were screened for antagonism against plant fungal pathogens and the potent strain was further screened against human pathogenic bacteria. The potential strain, VSMGT1014 was identified by microscopic, physiological, biochemical characteristics and used for synthesis of silver nanoparticles. The nanoparticles were characterised by UV-Vis Absorption spectroscopy, AFM, FTIR and X- ray diffraction. The AgNPs were determined to be spherical through the observation under AFM. X-ray diffraction patterns displayed typical peaks from 24°-85° at position 2 Ɵ for crystalline silver. It was found that the synthesised nanoparticles showed MIC range of 10- 50µg/mL against selected plant fungal pathogens. Moreover these nanoparticles showed significant level of inhibition as MIC range from 10- 25 µg/mL against clinically important pathogenic bacteria. Through this investigation, we concluding with Streptomyces sp. VSMGT1014 mediated silver nanoparticles would be a potential nanomedicine against various pathogenic organisms. (Received December 3, 2014; Accepted February 23, 2015) Keywords: Streptomyces, silver nanoparticles, antimicrobial activity, Rhizoctonia solani, Nosocomial infection, atomic force microscope 1. Introduction Nanotechnology deals with the synthesis, characterization, exploration and application of nanosized (1-100 nm) materials for the development of science. The synthesis of silver nanoparticles extensively studied by using chemical and physical methods, but the development of reliable technology to produce them is an important aspect of nanotechnology. Biological synthesis provides a wide range of environmentally acceptable methodology, low cost production and minimum time. However for the past few years, various rapid chemical methods have been replaced by green synthesis because of avoiding toxicity of the process and high quality. The properties of many conventional materials change, when created into nanoparticles. Nanoparticles * Corresponding author: shanmugaiahv@gmail.com