Int.J.Curr.Microbiol.App.Sci (2016) 5(7): 785-793 785 Original Research Article http://dx.doi.org/10.20546/ijcmas.2016.507.090 Bactericidal Application of Biosynthesized Silver Nanoparticles Hala Ezzat Abou El-Hassayeb* Department of Marine Microbiology, National Institute of Oceanography and Fisheries, Alexandria, Egypt *Corresponding author ABSTRACT Introduction Nowadays, nanotechnology has been developing rapidly as an important field of modern research with potential effects in medicine, agriculture, textiles, electronics, and energy, etc. Nanotechnology involves the development of efficient systems at the molecular scale. Nanotechnology is responsible for the synthesis and design of structures ranging in size between 1 and 100 nm (Rai et al., 2014). The synthesis of silver nanoparticles is an important aspect of nanotechnology. Presently, different techniques are available for the synthesis of silver nanoparticles, such as: chemical, physical, and biological. In the past decade, a great attention has been paid to microbial production of nanoparticles. Biosynthesis of silver nanoparticles (AgNPs) is an eco- friendly approach by using different biological sources; for example, plants and microorganisms such as bacteria, fungi, and actinobacteria (Tsibakhashvili et al., 2011; v International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 5 Number 7 (2016) pp. 785-793 Journal homepage: http://www.ijcmas.com Silver bionanoparticles have been known to have inhibitory and bacterial effects. Apart from standardizing the best parameter for the synthesis of silver nanoparticles involved in reduction of silver ion to silver nanoparticles. The involvement of nitrate reductases as reducing agent was confirmed by biochemical assay. The nitrate reductase activity got reduced from 0.9876 mmole/min/ml to 0.3233 mmole/min/ml after biofabrication of silver nanoparticles. In the present study, Pseudomonas aeruginosa ATCC 9027 has been used for the biosynthesis of silver nanoparticles (SNPs). It was found that aqueous Ag 2 ions in solution when exposed to Pseudomonas aeruginosa ATCC 9027 get reduced, thereby leading to the formation of silver nanoparticles. The formation of silver nanoparticles was confirmed by the change in colour of the culture filtrate from yellow to brown after the addition of silver nitrate. The morphology and uniformity of silver nanoparticles were investigated by UV–Vis spectrum, X-ray diffraction and scanning electron microscope (TEM). These biosynthesized silver nanoparticles were also evaluated for their antimicrobial activity against Pseudomonas aeruginosa ATCC 9027, Staphylococcus aureus ATCC 2592 and Escherichia coli ATCC 8739. It was interesting to note that Pseudomonas aeruginosa ATCC 9027 that biosynthesized the silver nanoparticle was most affected by its antibacterial activity applications. Keywords Pseudomonas aeruginosa, Biosynthesis, Silver nanoparticles, Nitrate reductase, antimicrobial activity. Accepted: 25 June 2016 Available Online: 10 July 2016 Article Info