Toxicity assessment of silver nanoparticles against Escherichia coli strains isolated from horse dung

On account of the spread of the phenomenon of microorganisms developing drug resistance, new and more effective methods for fighting pathogens are being sought. Therefore, silver nanoparticles (AgNPs) are increasingly used in various fields of industry and medicine due to their bactericidal properties. The aim of this work was to assess the toxicity of nanosilver prepared by chemical reduction process against Escherichia coli strains isolated from horse dung. AgNPs were prepared by chemical reduction involves the reduction of silver salt by a reducing agent in the presence of suitable stabiliser, which is necessary in protecting growth of AgNPs through aggregation. The environmental strains were isolated from horse dung, then identified and evaluated for their sensitivity to AgNPs using the disk diffusion method. Tested AgNPs suspensions exhibit strong antimicrobial activity. The minimum inhibitory concentration of bacterial isolates was found to be 15 g/mL, AgNPs resistance level for each tested strain were significantly diversified.