Biogenic silver nanoparticles as antimicrobial agents: Plant-mediated bioactivity and metabolic disruption in E. coli

Bacterial infections due to Escherichia coli are still of serious clinical concern, and the quest for novel antimicrobial strategies is required. In this study, biogenic silver nanoparticles (bio-AgNPs) were prepared by Ayurvedic extracts of Emblica officinalis , Withania somnifera , and Terminalia chebula . The bio-AgNPs were spherical in shape with uniformly sized particles ranging from 38.36 ± 9.31 to 51.93 ± 14.77 nm, and were highly colloidal stable with zeta potentials of −41.55 mV ( E. officinalis ), −28.00 mV ( W. somnifera ), and −39.02 mV ( T. chebula ). Antimicrobial activity against E. coli K12 showed maximum inhibitory activity from the nanoparticles derived from E. officinalis , with minimum MIC values (9.7–4.8 ppm). One of the major features of the study was the concentration-dependent modulation of glycolytic enzymes. Hexokinase, phosphofructokinase, and pyruvate kinase were strongly inhibited by E. officinalis -derived bio-AgNPs at low concentrations (0.5–1 ppm, p < 0.001). On the other hand, W. somnifera - and T. chebula -derived nanoparticles initially raised the activity of glycolysis at 35 ppm and 14 ppm, respectively, but produced significant inhibition at higher doses, indicating a biphasic metabolic response. Whereas low levels favored glycolysis as an adaptive stress response, high levels of nanoparticles inhibited enzyme activity and thus disturbed energy metabolism and growth of bacteria. These results indicate the promise of bio-AgNPs as green antimicrobials that balance eco-friendly synthesis with selective metabolic inhibition. Through the elucidation of nanoparticle-induced metabolic reprogramming in E. coli , this work adds further evidence to the increasing proof that bio-AgNPs are potential next-generation antimicrobial compounds. • Biogenic silver nanoparticles were synthesized using Ayurvedic plant extracts. • Nanoparticles disrupted glycolysis in E. coli by inhibiting key enzymes. • Emblica officinalis -derived nanoparticles showed strongest antimicrobial activity. • Bio-AgNPs demonstrated environmentally friendly synthesis and reduced cytotoxicity. • Potential use of bio-AgNPs as sustainable alternatives to antibiotics.