| Abstract: |
The use of nanomaterials alone or in composites with proteins is a promising alternative
to inhibit pathogenic bacteria. In this regard, this study used seed proteins from both fenugreek
(Trigonella foenum-graecum L.) (FNP) and mung bean (Viga radiate) (MNP), with silver nanoparticles
(Ag-NPs) and nanocomposites of either Ag-NPs plus FNP (Ag-FNP) or Ag-NPs plus MNP (Ag-MNP)
as inhibitory agents against pathogenic bacteria. FNP and MNP were isolated from fenugreek seeds
and mung bean seeds, respectively, and fractionated using Sodium Dodecyl Sulfate–Polyacrylamide
Gel Electrophoresis (SDS–PAGE). Both FNP and MNP were immobilized with Ag-NPs to synthesize
the nanocomposites Ag-FNP and Ag-MNP, respectively. The physicochemical characteristics of
Ag-NPs and their composites with proteins were studied by X-ray Diffraction (XRD), dynamic light
scattering (DLS), the zeta potential, Scanning and Transmission Electron Microscopy (SEM and TEM,
respectively), Atomic Force Microscopy (AFM), and the Brunauer–Emmett–Teller isotherm (BET),
elucidating their structural parameters, size distribution, size charges, size surface morphology,
particle shape, dimensional forms of particles, and specific surface area, respectively. The sole
proteins, Ag-NPs, and their nanocomposites inhibited pathogenic Gram-positive and Gram-negative
bacteria. The inhibitory activities of both nanocomposites (Ag-FNP and Ag-MNP) were more than
those obtained by either Ag-NPs or proteins (FNP, MNP). Minimum inhibitory concentrations (MICs)
of Ag-FNP were very low (20 and 10 µg mL−1
) against Salmonella typhimurium and Pseudomonas
aerugenosa, respectively, but higher (162 µg mL−1
) against E. coli and Listeria monocytogenes. MICs of
Ag-MNP were also very low (20 µg mL−1
) against Staphylococcus aureus but higher (325 µg mL−1
)
against Listeria monocytogenes. TEM images of Staphylococcus aureus and Salmonella typhimurium,
treated with Ag-FNP and Ag-MNP, at their MIC values, showed asymmetric, wrinkled exterior
surfaces, cell deformations, cell depressions, and diminished cell number
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