Comparison of Antimicrobial Properties of Silver Nanoparticles Synthesized from Selected Bacteria.

Green silver nanoparticle (AgNP) biosynthesis is facilitated by the enzyme mediated reduction of Ag ions by plants, fungi and bacteria. The antimicrobial activity of green AgNPs is useful to overcome the challenge of antimicrobial resistance. Antimicrobial properties of biosynthesized AgNPs depend on multiple factors including culture conditions and the microbial source. The antimicrobial activity of AgNPs biosynthesized by ATCC 27853, ATCC 25922, ATCC 25923 and (confirmed clinical isolate) were investigated in this study. Biosynthesis conditions (AgNO concentration, pH, incubation temperature and incubation time) were optimized to obtain the maximum AgNP yield. Presence of AgNPs was confirmed by observing a characteristic UV-Visible absorbance peak in 420-435 nm range. AgNP biosynthesis was optimal at 0.4 g/L AgNO concentration under alkaline conditions at 60-70 °C. The biosynthesized AgNPs showed higher stability compared to chemogenized AgNPs in the presence of electrolytes. AgNPs synthesized by were the most stable while NPs of were the least stable. AgNPs synthesized by and showed good antimicrobial potential against MRSA and . AgNPs synthesized by had greater antimicrobial activity. The antimicrobial activity of NPs may vary depending on the size and the morphology of NPs.