Silver nanoparticles biosynthesis: Caracterization and antibacterial activity

AIASSA MARTINEZ I; PÁEZ PL; QUINTEROS MA; DALMASSO PR; PINO G; BERDAKIN M; ALBESA I

Rosario

Congreso; 2° Reunión Internacional de Ciencias Farmacéuticas; 2012

Introduction Nanoparticles show unique physical and chemical properties and have attracted much attention for their distinct characteristics. That’s why they represent an increasingly important material in the development of nanotechnology and nanoparticles which can be used in numerous applications. Microorganisms play an important role in the eco-friendly synthesis of metal nanoparticles [1,2]. Resistance of bacteria to antimicrobial agents has increased in recent years. Nanoparticles interaction with biomolecules and microorganisms is expanding the field of research. This study illustrates the synthesis of silver nanoparticles using the bacterium Pseudomonas aeruginosa and their antibacterial activity against Escherichia coli. Materials and methods The Ag-Nps were synthesized following the method described by Shahverdi et al. [3] being formed from the reduction of silver ions by the supernatant of bacterial cells of P. aeruginosa ATCC 27853. The size of silver nanoparticles in aqueous solution has been estimated using UV–Vis spectroscopy, and Dynamic Light Scattering technique (DLS). E. coli was grown aerobically in trypticase soy broth. The antimicrobial activity of the silver nanoparticles was evaluated by using the standard tube dilution method on Mueller Hinton Broth. Bacterial growth was observed at 18 h of incubation, following the indications of the Clinical and Laboratory Standards Institute. Results In the present study, extracellular biosynthesis of silver nanoparticles by the culture supernatant of P. aeruginosa was studied. Visual observation showed a change in colour of silver nitrate solution from yellow to brown whereas no colour change was observed in the culture supernatant without silver nitrate or in media with silver nitrate alone. The average size of the nanoparticles obtained was found to be in the order of 150 nm. The obtained nanoparticles were tested against reference and clinical strains of E. coli aislated from patients with Haemolytic Uremic Syndrome (HUS), a macrodilution method was used to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). This study shows that silver nanoparticles have antibacterial activity against E. coli. Conclusions Authors reported the extracellular biosynthesis Ag-Nps using the bacterium P. aeruginosa and their caracterization. The Ag-Nps were found bioactive showing inhibitory effect on important human pathogen, E. coli producing HUS. It is also clear that the bacterium P. aeruginosa can be used to synthesize bioactive nanoparticles efficiently and non-toxic manner.