Antibacterial activity and hormetic response of silver nanoparticles synthesized using leaflet extract of wheat (Triticum aestivum) and rice (Oryza sativa) crop plants

Abstract

The application of silver nanoparticles (AgNPs)-based antibacterial therapeutics has emerged as a feasible alternative to traditional antibiotic therapy due to cost-effectiveness and lower possibility of non-evolution of resistant strains. In the present paper, the aqueous extract of wheat (Triticum aestivum) and rice (Oryza sativa) leaflets were used for the fabrication of well-dispersed AgNPs of average size 19.11 and 33.85 nm, respectively, under the controlled condition of pH 10.0 + 0.1 and temperature 80°C + 1°C. This bottom-up approach of AgNPs production was simple, eco-friendly, inexpensive, and highly reproducible. The synthesized AgNPs were characterized by UV-Visible spectroscopy, dynamic light scattering, fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray. Agarwell diffusion and (2, 3-bis [2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) (XTT) colorimetric methods revealed the bactericidal potential of synthesized AgNPs against Gram-positive and Gram-negative pathogenic bacteria with minimum inhibitory concentration (MIC) values ranges from 125 to 500 µg/ml. AgNPs presented better potency against Gram-negative bacteria compared to Gram-positive bacteria. Interestingly, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli demonstrated a hormetic response (positive stimulated growth) at a sub-lethal concentration (<7.81 µg/ml) of AgNPs, which were 0.39%-1.56% of MIC values of the respective bacterial strains.

Current Knowledge, Research Progress, and Future Prospects of Phyto-Synthesized Nanoparticles Interactions with Food Crops under Induced Drought Stress

“…Ag-NPs can be used as safe fertilizers in agricultural sectors instead of chemical fertilizers. These NPs can cause several potential impacts on the environment and regulatory issues, so it is necessary to understand their mode of action in promoting plant growth and disease control actions [85,[176][177][178].…”