Antimicrobial activities of microbially-synthesized silver nanoparticles against selected clinical pathogens in Akure, Nigeria

Silver nanoparticles (AgNPs) have stimulated interest of scientists due to their wide range of applications, including their potential antimicrobial activity. This study investigated the antimicrobial activities of AgNPs synthesized by rhizospheric soil and fish pond sediment microorganisms against selected clinical pathogens. The samples were cultured and organisms identified in accordance with standard procedures. The synthesis of AgNPs colloidal solution was monitored by UV-vis analysis. Presence of bands was determined by the Fourier Transform Infrared spectroscopy (FTIR). The antimicrobial activity of the synthesized AgNPs against selected clinical isolates was determined using agar well diffusion method. Ten species each of bacteria and fungi were isolated from the samples. Formation of AgNPs was indicated by colour transformation from yellow to brown. All synthesized AgNPs showed intense peak with wavelengths ranging of 410-440 nm in UV-vis. The FTIR revealed band at 3395 cm-1 and a strong peak at 3300-3500 cm-1. The AgNPs synthesized by some of the isolates exerted remarkable and varying degrees of antimicrobial activities against the susceptible test organisms. This study revealed that the microbially-synthesized AgNPs obtained from this study possess a high antimicrobial potency against most potential pathogens investigated, and, thus, can be exploited in the development of novel antimicrobial agents.   Key words: Antimicrobial agents, microbial resistance, microorganisms, pathogens, silver nanoparticles, zones of inhibition.