2.5. Antimicrobial activity of synthesized silver
nanoparticles
The antimicrobial activity of silver nanoparticles was investigated
utilizing agar well diffusion assay Nanda and
Saravanan (2009). The tested microorganisms were swabbed
uniformly on nutrient agar- or sabouraud dextrose agar plates
using sterile cotton swab, then, five wells of 6-mm diameter
were made using sterile well borer. Twenty microliter of silver
nanoparticles solutions with various concentrations (0.25,
0.50, 1.0, and 2.0 mM) was poured into the corresponding well.
Control sample (BPE) was used to assess the antimicrobial
activity of BPE. The plates were incubated at 37 C for 24 or 48 h
for the bacterial and yeast cultures, respectively. The diameter
of inhibition zone was measured. To determine the combined
effect of silver nanoparticles and the standard antibiotic
(levofloxacin), 15 ml of 0.5 mM antibiotic solution was mixed
with 15 ml of silver nanoparticles solution (0.5 mM), and placed
into the corresponding well of agar plate, inoculated with the
tested microorganisms. The plates were incubated at 37 C for
24 h. Zone of inhibition was measured and compared with
that of levofloxacin, AgNO3 solution and silver nanoparticles
individually.