Antimicrobial Effectiveness of Bioactive Silver Nanoparticles Synthesized by Actinomycetes HGG16n Strain

Biologically synthetized silver nanoparticles are promising antimicrobial agent. Flow cytometry, well diffusion methods, colony-forming units (CFU) and spectroscopic approach are commonly used in antimicrobial study. The aim of this study was investigation of effectiveness of Bio- AgNPs synthesized by Actinomycetes HGG16n using fluorescence flow cytometry method as an alternative to the standard ones (well and disc diffusion method).

Flow cytometry technique was applied to monitor the antibacterial effect of biocolloidal silver and its combination with various commercial antibiotics against selected pathogens. The observed effectiveness was confirmed by fluorescence micrographs.

Silver nanoparticles synthesized by Actinomycetes HGG 16n strain were as effective antimicrobial agent as the tested commercial antibiotics. Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Salmonella infantis and Bacillus subtilis strains are not able to create the resistant mechanisms under treatment of biocolloidal silver. Furthermore, the flow cytometry technique was more sensitive than disc and well diffusion and confirmed the effectiveness of BioAgNPs against all tested bacterial cells. Precipitation and limited diffusion of biocolloidal silver was observed by using well diffusion method.

Specificity and selection of antimicrobial approach are related with different nature of lowmolecular compounds (e.g. antibiotic) compared with biocolloids. An alternative method, flow cytometry was designed for antimicrobial study of biocolloidal silver nanoparticles and compared to the classical microbial techniques. Moreover, this work highlights the development of novel and inexpensive antimicrobial agent for most oral and skin infections caused by Gram (+) and Gram (-) bacteria.