RESEARCH ARTICLE Green synthesis of silver nanoparticles by microorganism using organic pollutant: its antimicrobial and catalytic application S. V. Otari & R. M. Patil & N. H. Nadaf & S. J. Ghosh & S. H. Pawar Received: 23 March 2013 / Accepted: 22 April 2013 / Published online: 8 August 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of AgNO 3 using culture supernatant of phenol degraded broth is reported in this work. The synthesis was observed within 10 h, and AgNPs showed characteristic surface plasmon resonance around 410 nm. Spherical nanoparticles of size less than 30 nm were observed in transmission electron microscopy. X-ray diffraction pattern corresponding to 111, 200, 220, and 311 revealed the crystalline nature of the as-formed nanoparticles. It was found that the colloidal solution of AgNP suspensions exhibited excellent stability over a wide range of ionic strength, pH, and temperature. The effect of pH and ionic strength indicated that stabiliza- tion is due to electrostatic repulsion arising from the nega- tive charge of the conjugate proteins. The AgNPs showed highly potent antimicrobial activity against Gram-positive, Gram-negative, and fungal microorganisms. The as- prepared AgNPs showed excellent catalytic activity in re- duction of 4-nitrophenol to 4-aminophenol by NaBH 4 . By manufacturing magnetic alginate beads, the reusability of the AgNPs for the catalytic reaction has been demonstrated. Keywords Green synthesis . Phenol degradation . Silver nanoparticles . Antimicrobial . Catalytic activity . DLS Introduction Green nanoscience involves the application of green chem- istry principles which reduces or eliminates the use or gen- eration of hazardous substances to the design of nanoscale products, the development of nanomaterial production methods, and the application of nanomaterials (McKenzie and Hutchison 2004). Hazardous chemicals, low material conversions, high energy requirements, and difficult, wasteful purifications are involved in many preparations of building blocks of nanotechnology. So, there are many scopes to develop greener processes for the man- ufacture of nanomaterials. For a decade, investigators have used plants, fruit seeds, carbohydrates, bacteria, actinomycetes, fungi, yeasts, and viruses for the synthe- sis of gold, silver, gold–silver alloy, selenium, tellurium, platinum, palladium, silica, titania, zirconia, quantum dots, magnetite and uraninite nanoparticles (Narayanan and Sakthivel 2010). Microbial route for the synthesis of nanoparticles has one the most exciting process as several factors such as microbial cultivation methods and the extraction techniques can be optimized for the fast synthesis of monodisperse nanoparticles. Among the other nanoparticles, noble metals like Ag, Au, etc. have received much citation from researchers as noble metal nanostructures have contributed for the great enhancement of the nanobiology field, which have proven to be highly versatile and tunable materials for a range of bioapplications including biophysical studies, biological sensing, imaging, medical diagnostics, and cancer therapy. Among various metals, silver has been known since ancient times as an effective antimicrobial agent for the treatment of diseases, for food preserva- tion, and water purification (Jain et al. 2008). The Responsible editor: Philippe Garrigues S. V. Otari : R. M. Patil : S. J. Ghosh : S. H. Pawar (*) Center for Interdisciplinary Research, D. Y. Patil University, Kolhapur 416 006 Maharashtra State, India e-mail: pawar_s_h@yahoo.com N. H. Nadaf Department of Microbiology, Shivaji University, Kolhapur 416 004 Maharashtra State, India Environ Sci Pollut Res (2014) 21:1503–1513 DOI 10.1007/s11356-013-1764-0